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OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Universidad Autónoma de Sinaloa, Facultad de Ciencias del Mar (FACIMAR), Marine Biologist, PhD

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Articles

Discovery of protein-based natural hydrogel from the girdle of the 'sea cockroach' Chiton articulatus (Chitonida: Chitonidae)

by Emel Çakmak, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), and S. Williams

PeerJ, 2022

Hydrogels are widely used materials in biomedical, pharmaceutical, cosmetic, and agricultural fie... more Hydrogels are widely used materials in biomedical, pharmaceutical, cosmetic, and agricultural fields. However, these hydrogels are usually formed synthetically via a long and complicated process involving crosslinking natural polymers. Herein, we describe a natural hydrogel isolated using a 'gentle' acid treatment from the girdle of a chiton species (Chiton articulatus). This novel hydrogel is shown to have a proliferative effect on mouse fibroblast cells (cell line, L929). The swelling capacity of this natural hydrogel was recorded as approximately 1,200% in distilled water, which is within desired levels for hydrogels. Detailed characterizations reveal that the hydrogel consists predominantly (83.93%) of protein. Considering its non-toxicity, proliferative effect and swelling properties, this natural hydrogel is an important discovery for material sciences, with potential for further applications in industry. Whether the girdle has some hydrogel activity in the living animal is unknown, but we speculate that it may enable the animal to better survive extreme environmental conditions by preventing desiccation.

Maximum gonad investment of the sexes of the broadcast-spawning sea cucumber Holothuria (Halodeima) inornata (Echinodermata: Holothuroidea)

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Geoff Parker, heleni cancino, and Everardo Ramos Ramirez

Journal of the Marine Biological Association of the United Kingdom, 2022

An organism's maximum gonad investment (MGI) typically indicates its reproductive season and is... more An organism's maximum gonad investment (MGI) typically indicates its reproductive season and is often measured by the peak of the gonadosomatic index. Since external sexual dimorphism is often not evident, intrinsic sex differences remain unstudied. We analysed the reproductive seasonality of each sex of the broadcast-spawning sea cucumber Holothuria (Halodeima) inornata in two populations (Caleta de Campos, Michoacán ‘CC’ and Puerto Madero, Chiapas ‘PM’) in the southern coast of the Mexican Pacific by examining: intensity and duration of MGI, frequency of each gonadal developmental stage (GDS) through time, sexual asymmetry in GSI, sexual asymmetry in GDS, and adult sex ratio. We observed a trade-off between the intensity (%) and duration (months) of each sex's MGI: as intensity decreases, duration increases and conversely. The frequency of ripe and spawning stages was consistently higher in females than males. Sexual asymmetry in GSI was slightly female-biased in the PM population, but male-biased in the CC population. Sexual asymmetry in GDS showed a more recurrent sexual equality at PM than at CC. The adult sex ratio of each population did not differ significantly from unity, but showed a near-significant trend for male bias in the CC. Although H. inornata exhibited different MGI responses between males and females and more markedly in CC than in PM, it also showed a synchronized relation between its mass investment (GSI) and physiological investment (GDS), possibly reflecting an optimum reproductive strategy. Lastly, changes in GSI were not underpinned by changes in local temperature, but rather by regional temperature.

Oviducal gland transcriptomics of Octopus maya through physiological stages and the negative effects of temperature on fertilization

by Oscar E Juárez and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

PeerJ , 2022

Background: Elevated temperatures reduce fertilization and egg-laying rates in the octopus specie... more Background: Elevated temperatures reduce fertilization and egg-laying rates in the octopus species. However, the molecular mechanisms that control the onset of fertilization and egg-laying in the octopus' oviducal gland are still unclear; and the effect of temperature on the expression of key reproductive genes is unknown. This study aims to better understand the molecular bases of octopus fertilization and egg-laying, and how they are affected by elevated temperatures. Method: RNA-seq of oviducal glands was performed for samples before, during, and after fertilization and their transcriptomic profiles were compared. Also, at the fertilization stage, the optimal and thermal-stress conditions were contrasted. Expression levels of key reproductive genes were validated via RT-qPCR. Results: In mated females before egg-laying, genes required for the synthesis of spermine, spermidine, which may prevent premature fertilization, and the myomodulin neuropeptide were upregulated. Among the genes with higher expression at the fertilization stage, we found those encoding the receptors of serotonin, dopamine, and progesterone; genes involved in the assembly and motility of the sperm flagellum; genes that participate in the interaction between male and female gametes; and genes associated with the synthesis of eggshell mucoproteins. At temperatures above the optimal range for reproduction, mated females reduced the fertilization rate. This response coincided with the upregulation of myomodulin and APGW-amide neuropeptides. Also, genes associated with fertilization like LGALS3, VWC2, and Pcsk1 were downregulated at elevated temperatures. Similarly, in senescent females, genes involved in fertilization were downregulated but those involved in the metabolism of steroid hormones like SRD5A1 were highly expressed.

Biodiversity patterns of epibiotic invertebrates occupying an edible polyplacophoran across a latitudinal gradient of the Mexican Pacific

Journal of Experimental Marine Biology and Ecology, 2021

The broad perspective regarding marine-organisms biodiversity indicates a latitudinal gradient. U... more The broad perspective regarding marine-organisms biodiversity indicates a latitudinal gradient. Understanding gradients in diversity at large scales has important applications for understanding future impacts on local and regional communities. We use and propose the edible mollusk Chiton articulatus as the basibiont proxy to analyze the spatio-temporal changes in biodiversity patterns of the epibiotic community occupying its scleritome surface. The analyses covered approximately 1817 km of the Mexican Pacific, using seven sites that included samples from Sinaloa "SIN" (23 • 38 ′ N, 106 • 48 ′ W); Nayarit "NAY" (20 • 45 ′ N, 105 • 22 ′ W); Jalisco "JAL" (19 • 13 ′ N, 104 • 41 ′ W); Colima "COL" (19 • 06 ′ N, 104 • 20 ′ W); Michoacan "MIC" (17 • 54 ′ N, 102 • 11'"W); Guerrero "GRO" (16 • 48 ′ N, 99 • 52 ′ W) and Oaxaca "OAX" (15 • 39 ′ N, 96 • 30 ′ W). A temporal gradient (monthly sampling from October 2015 to October 2016) was also analyzed. Evaluation of the sampling effort demonstrated that 76-86% of the epibiotic fauna was recovered. The most representative epibionts were barnacles, a limpet and an acrothoracican. Abundances of the barnacles and the limpet tended to decrease southwards, while the acrothoracican tended to increase northwards. The epibiotic community did not exhibit the typical latitudinal gradient of diversity expected, but a fragmented pattern within three main areas, which coincide with three of the marine biogeographic ecoregions proposed for the shallow waters of the Warm Temperate Northern Pacific and Tropical Eastern Pacific provinces. These were a northern group within SIN, which belong to the southern border of the Magdalena Transition ecoregion (subtropical); a middle group within NAY, JAL, COL, MIC, and GRO, which belongs to the Mexican Tropical Pacific ecoregion (tropical); and a southern group within OAX exclusively, belonging to the northern border of the Chiapas-Nicaragua ecoregion (tropical). The southern localities showed larger dominances and the central localities exhibited more stable communities. Our evidence suggests that as we move across the different shore types of the Mexican Pacific, the coastline supports distinct biotic assemblages, and the community on the rocky shores is biologically heterogeneous and mainly influenced by conditions at the local level. In consequence, conservation and protection efforts should consider preserving the local heterogeneity of habitats in the study area. Furthermore, since C. articulatus is edible, its epibiota represents an incidental fishing bycatch, with the result that the extraction of the chiton and its epibiota can jeopardy the diversity in the intertidal rocky shore of the Mexican Pacific.

Plasticity in reproductive traits of an intertidal rocky shore chiton (Polyplacophora: Chitonida) under pre-ENSO and ENSO events

Journal of Molluscan Studies, 2021

Changes in growth and reproduction help to maximize fitness under given constraints. This might b... more Changes in growth and reproduction help to maximize fitness under given constraints. This might be interpreted as nonadaptive plasticity (morphological, physiological or behavioural) with the capacity to produce different phenotypes (i.e. the range of potential phenotypes that a single genotype could generate if exposed to a specified range of environmental conditions; see Stearns & Koella, 1986), so that local persistence is possible under different environmental conditions (e.g. thermal anomaly events). Since C. articulatus is commercially harvested in an emerging small-scale fishery (Garcia-Ibañez et al., 2013; Olea-de-la-Cruz et al., 2013), it would be useful to evaluate the potential plasticity of its reproductive traits in relation to annual thermal perturbation. A conceptual model of reproductive development in invertebrates with broadcast spawning was developed to improve the evaluation and understanding of the variability of three reproductive traits that are commonly used in fisheries biology (Fig. 1): Trait 1, the reproductive cycle, Trait 2, the reproductive or ‘breeding’ season, Trait 3, the size at sexual maturity.
SEE, SUPPLEMENTARY MATERIAL TABLE S1.

Large-scale project 'Chiton of the Mexican Tropical Pacific': Chiton articulatus (Mollusca: Polyplacophora

Research Ideas and Outcomes, 2020

The marine mollusc, commonly called sea cockroach or chiton Chiton articulatus, is a mollusc belo... more The marine mollusc, commonly called sea cockroach or chiton Chiton articulatus, is a mollusc belonging to the group known as Polyplacophora because its shell is composed of eight individual plates. This mollusc inhabits the rocky intertidal shore of the Mexican Tropical Pacific, where it is endemic. It has ecological, but also economic, importance. Ecologically, it is the preferred food of the snail Plicopurpura pansa, a protected species, in the cultural heritage of the country. Additionally, it is a basibiont (generates substrate for other individuals) that maintains the biodiversity of the Region. Economically, it has changed from artisanal consumption to become a culinary tourist attraction, offered at restaurants as an exotic and aphrodisiac dish, in tourist places like Huatulco or Acapulco. Despite being an exploited resource for decades, little is known about its life history. The Mexican Authorities have not yet recognised this mollusc as a fishing resource, so that it does not have any law that controls its extraction, sale and consumption, putting at risk the recruitment, survival and permanence of this species. The goal of this project is the preservation and support for the management of the species. The Project "Quiton del Pacifico Tropical Mexicano" seeks to provide the biological, ecological, reproductive, genetic, anatomical and morphometric bases of the populations of Chiton articulatus. The project was structured in four stages: 1) field sampling and obtaining samples, 2) disclosure and presentation of the project, 3) inclusion of students at the undergraduate and graduate level, 4) application of results. The inclusion and recognition of C. articulatus as a fishing resource will achieve impact at the national and regional level through the implementation of laws that regulate its fishing, as well as its inclusion in management and food security policies. Additionally, this Mexican Chiton Project is currently replicating with chiton species in Galapagos, Ecuador.

Plasticity in growth parameters of an intertidal rocky shore chiton (Polyplacophora: Chitonida) under pre-ENSO and ENSO events

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Guillermo Rodriguez Dominguez

Journal of Molluscan Studies, 2020

Chiton articulatus exhibited growth parameters (population size, number of size groups, number of... more Chiton articulatus exhibited growth parameters (population size, number of size groups, number of cohorts, growth rate and longevity) divergent between annual cold “La Niña” (ACE) and annual warm “El Niño” (AWE) events. We used a multi-model inference approach (Schnute models), considering the size-structure and individual growth in the absence of age data. The longevity of C. articulatus could reach until five years old. Our results suggest that Chiton articulatus could have the ability and/or plasticity to cope positively to adverse thermal situations or in global warming scenarios.

Complex abnormality combinations between the scleritome and the sclerites of Chiton articulatus (Mollusca: Polyplacophora): New findings for the teratological classification

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Brenda Paola Ramirez-Santana, and Carlos Melendez Galicia

Zoologischer Anzeiger, 2019

Teratological diagnosis in polyplacophorans has mostly been based on primary structure (Chiton sc... more Teratological diagnosis in polyplacophorans has mostly been based on primary structure (Chiton scleritome) with four types (hypermerism, hypomerism, coalescence and splitting), including some deformities in plates; however, diagnoses are hardly detailed for each sclerite. As part of a monthly research campaign conducted by a year investigating Chiton articulatus, we found several cases with a complex combination of abnormalities (chiton scleritome + sclerites) that complement the previous classification. Identification and diagnosis of abnormalities were assigned in terms of sclerite number, number of slits per side in the insertion area of intermediate sclerites and the merging grade between sclerites. Slit and slit-ray numbers were baseline to identify combination of abnormalities; the slit formula of Chiton articulatus is 13–18[I]/1[II-VII]/16–22[VIII]. We found four abnormality cases with combinations among them: a) perfect hypomerism, b) heterogeneous coalescence, c) homogeneous coalescence, d) imperfect hypermerism. Heterogeneous coalescence was most common abnormality, with a different merging degree between sclerites and with specimens showing combinations of abnormal states such as: normality/coalescence, coalescence/hypomerism, coalescence/hypermerism and normality/hypermerism; so these complex abnormalities can generates asymmetry between the right and left side of a chiton. We postulate that coalescence is an intermediate step toward perfect hypomerism or perfect hypermerism. The width/length ratio suggests that an abnormal chiton increases its width to compensate and retain a normal body appearance despite different degrees of abnormal development.

An ovotestis event in the gonochoric sea urchin Loxechinus albus (Echinodermata: Echinoidea)

Brazilian Journal of Biology, 2019

Reproductive traits and relative gonad expenditure of the sexes of the free spawning Chiton articulatus (Mollusca: Polyplacophora)

by Q Yasu Abadia Chanona and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Invertebrate Reproduction and Development, 2018

Reproductive studies of an intertidal free-spawning population of Chiton articulatus (Mollusca: P... more Reproductive studies of an intertidal free-spawning population of Chiton articulatus (Mollusca: Polyplacophora) from Puerto Angel, Oaxaca, Mexico were undertaken during 2011. We used gonad histology and gonadal indices to assess the relative gonad expenditure of the sexes (RGES) and other reproductive traits, accounting for individual and seasonal variation within this population. At this location, C. articulatus is gonochoric, without sexual dimorphism, except internally by gonad colour (testis is 'salmon' coloured and ovary olive green). Annual and monthly sex ratios (m/f) do not differ significantly from 1:1. Highest population-level gonadosomatic index (GSI) corresponded to maximum (peak) ripe stage (i.e. maximum gonad investment), with a first peak in May with a high value (8.4 ± 0.5) and a second peak during August-September with a lower value (4.7 ± 0.3). GSI fluctuated throughout year implying that gonad expenditure may be seasonally constrained, but with overall synchrony between sexes of ripe and spawning stages. July to December was the main reproductive season with some facultative spawning occurring off-season. Ripe and spawning RGES did not differ between sexes, suggesting that either sperm competition is intense and/or that sperm limitation is high. Early spawning individuals may quickly replenish their gametes for a second phase of gamete release later.

Reproductive performance of Octopus maya males conditioned by thermal stress

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Laura Liliana Lopez Galindo, and Oscar Juárez

Ecological Indicators, 2019

Observations of wild male O. maya suggest that temperatures below 27 °C favour their reproductive... more Observations of wild male O. maya suggest that temperatures below 27 °C favour their reproductive performance. From these observations we hypothesize that, as in females, the temperature modulates the reproductive performance of adult O. maya males. The study aimed to evaluate the physiological condition, reproductive success, and histological damage in testis of male O. maya exposed to thermal stress, to determine the implications of ocean warming over their reproductive performance. High temperatures (28–30 °C) negatively affect the growth and health of male O. maya. In octopuses maintained at 30 °C, as a consequence of the thermal stress we observed an increment in the haemocytes number, a reduction in the oxygen consumption rate, and an inflammatory process in the testis. The number of spermatozoa per spermatophore was not affected by temperature , but higher spermatophores production was observed at 30 °C. The paternity analysis showed that the offspring had multiple paternity with an average of 10 males contributing in a single spawn. The paternal contribution was affected by temperature with high, medium, or no paternal contribution in animals maintained at 24 °C (control group), 28 °C and 30 °C, respectively. The temperatures from 28 °C to 30 °C deeply affected the reproductive performance of Octopus maya males, suggesting that, as embryos, reproductive performance of adult males of this octopus species can be used as a tool for monitoring thermal changes in Yucatán Peninsula, located at the entrance of Gulf of Mexico.

Variability in size at maturity and reproductive season of queen conch Lobatus gigas (Gastropoda: Strombidae) in the Wider Caribbean Region

by Erik Boman, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Erick R Baqueiro, and Caroline Bissada

Fisheries Research, 2018

Queen conch (Lobatus gigas), is an economically and culturally important marine gastropod. The sp... more Queen conch (Lobatus gigas), is an economically and culturally important marine gastropod. The species is subject to extensive exploitation throughout large parts of the Caribbean which has led to a decrease in population densities across much of the species' distribution range. Hence, there is a need for protective measures to safeguard the reproductive stock. This requires a better estimation of its size at maturity, which is best quantified as the thickness of the lip that the shell develops after reaching its maximum length. The lip thickness at 50% maturity (LT 50) was determined using a logistic and an accumulation model, from seven representative location of distribution of this species in the Wider Caribbean Region. LT 50 of both females (7–14 mm) and males (4–11.5 mm) varied between different locations in the Caribbean, although it did not correspond with variation in water temperature. In most cases females had a larger LT 50 than males indicating sexual dimorphism. LT 50 values estimated with the logistic model were smaller (7–14 mm for females, 4–11.5 mm for males) than values estimated with the accumulation model (13–26 mm for females, 16–24 mm for males), showing an over-estimation of LT 50 in queen conch in previous studies which used the accumulation model to estimate LT 50. Locations with a relatively high variation in water temperature had a significantly shorter reproductive season. The implementation of adequate minimum size regulation based on lip thickness (ca. 15 mm) and a Caribbean wide seasonal closure (May–September) using the most recent biological information from this study, taking into consideration the local differences in LT 50 and reproductive season, will assist in developing a long term sustainable queen conch fishery in the Caribbean.

Oviducal glands throughout the gonad development stages: a case study of Octopus mimus (Cephalopoda)

Molluscan Research, 2017

The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes... more The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes of each section of the ODG of Octopus mimus are described histologically throughout the gonad development stages (GDS). To do this, the epithelial height, stereociliated or non-stereociliated epithelium, nucleus type (pycnotic or non-pycnotic), epithelial secretions and the value range of the macroscopic maturity index (MaMI), which directly involves ODG status, were measured. The ODG are internally constituted of two glandular units (central and peripheral glands) and one set of receptacles (the spermathecae). High epithelia (40 to 80 μm) were observed in both gland units during periods with low MaMI values (< 0.1) corresponding to III-mature and IV-pre-spawning. The stereociliated epithelium was only apparent in II-maturing and III-mature in both gland units. The nuclei were noticeably pycnotic in the central gland during III-mature, IV-pre-spawning and V-spawning, but pycnotic in the peripheral gland only during VI-depletion. The epithelium was disorganised during VI-depletion, while sulphated acid mucin was only present during III-mature in the central gland. The epithelium transformations during the GDS are related to the functions of the gland units and to their multiple secretions. The ODG histology complements the GDS and provides better reproductive status assessment.

Temperature modulates spatio-temporal variability of the functional reproductive maturation of Octopus maya (Cephalopoda) on the shelf of the Yucatan Peninsula, Mexico

Journal of Molluscan Studies, 2017

Laboratory studies have demonstrated that high temperatures inhibit spawning of Octopus maya; the... more Laboratory studies have demonstrated that high temperatures inhibit spawning of Octopus maya; therefore, in oceanic warming scenarios the population dynamics may be affected. The aim of the present study was to go beyond laboratory studies under controlled temperatures to examine the possible relationship between large-scale thermal patterns and reproductive season (represented by functional maturation) of O. maya in the wild on the continental shelf of the Yucatan Peninsula, where it is endemic. The macroscopic maturity index (MaMI) was obtained in females, and reproductive complex index (RCI) and number of spermatophores in males. Associations between these indices and environmental temperature regime were inferred by sampling octopuses in an upwelling zone (Z-I), a transition zone (Z-II) and a nonupwelling zone (Z-III). The reproductive condition of O. maya differed between Z-I and Z-III. In all zones, the proportion of adults showing functional maturity was highest in both females (MaMI: 36–71% of values ≤0.2) and males (RCI: 12–40% of values ≥0.9; 41–49 spermatophores per octopus) during the season of winter storms ('nortes' season, November–February), when the sea-surface temperature oscillates around 25 °C. In Z-I, some individuals were functionally mature throughout the year, likely due to low temperatures maintained by summer upwelling. Zone-I had the greatest proportion of functionally mature males (up to 40% of adults in 'nortes' season) and the greatest number of spermatophores (mean 43–49 spermatophores per octopus in all seasons). Females in Z-III (without upwelling) were functionally mature mainly in the 'nortes' season when water temperature decreased, with only a small proportion mature in the rest of the year when water temperatures reached 31 °C. As predicted by laboratory studies, water temperature below 27 °C appears to be favourable for the functional reproductive maturation of wild O. maya.

Observation and establishment of gonad development stages in polyplacophorans (Mollusca): Chiton (Chiton) articulatus a case study

by Q Yasu Abadia Chanona and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Acta Zoologica, 2016

Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by perform... more Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by performing histology of some gonad portions. In polypla-cophorans, gametogenesis is not enough to define GDS; further anatomical gonad features are relevant. In most adult polyplacophorans, the gonad is a simple anatomical structure that resembles and operates as one single gonadal aci-nus without glandular structure. These features have gone unnoticed causing inaccurate GDS assignment and, consequently, imprecise reproductive season in polyplacophorans. Here, dissection protocols that allow extracting a compact gonad are established. Emphasizing the anatomical structure of the whole gonad and the displacement of gametes, five GDS were assigned to both sexes of Chi-ton (Chiton) articulatus: I-goniogenesis, II-development, III-ripe, IV-spawning, V-rest. Tissue platelets contribute importantly to GDS assignment and even help distinguishing between males and females. Neither a randomly selected portion of gonad nor a longitudinal section are recommended because it leads to misinterpretation higher than 50% in determining GDS and besides ignores displacement of gametes. A panoramic sweep across a complete transverse-section of each gonad was validated as the best option for establishing GDS. This new methodology was tested on several polyplacophorans species, and seems generally applicable for histological assessment of reproductive cycle and reproductive season in polyplacophorans.

Reproductive traits of Octopus maya (Cephalopoda: Octopoda) with implications for fisheries management

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Francisco Benítez-Villalobos, and Josefina Santos-Valencia

Molluscan Research, Apr 2016

Octopus maya is the main species caught in Mexico. From September 2007 to June 2008, its sex rati... more Octopus maya is the main species caught in Mexico. From September 2007 to June 2008, its sex ratio, reproductive season, frequency of non-vitellogenic and vitellogenic oocytes, reproductive indices, and size and weight at maturity, were evaluated. The monthly sex ratio was significantly different from 1:1. The major reproductive season occurs during February to June (dry season) in Yucatan. May−June is the common reproductive season to both Yucatán and Campeche populations. Higher frequencies of vitellogenic oocytes (> 50%) were found from January-March and in May. From five reproductive indices, only the macroscopic and microscopic maturity indices were the best descriptors of the reproductive season in females, whilst only the reproductive complex index was the best descriptor in males. The weight at sexual maturity (BW 50%) was 335 g for females and 242 g for males. The size at sexual maturity (DML 50%) was 12.58 cm for females and 7.42 cm for males. It is recommend revising the minimum catch size by following these results. The reproductive traits here evaluated could contribute to the recently created Plan for Management of Octopus Fisheries, in particular action line no. 1.4, which refers to protection of females during breeding, and to their protection throughout the entire reproductive season.

Gonad development stages and reproductive traits of Diadema mexicanum (Echinodermata: Echinoidea) from Oaxaca, Mexico

by Francisco Benítez-Villalobos and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Invertebrate Reproduction and Development , Dec 24, 2015

Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral... more Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral reefs dynamics. Several reproductive traits of D. mexicanum throughout one year at La Entrega Bay, Oaxaca (15°44′N), in the Mexican tropical Pacific, were analyzed. Maturity index or microscopic maturity index “MI” was calculated. Annual ratio of males to females (1:1) was not significantly different. Five gonad development stages “GDS” (i.e. development, mature, spawning, post-spawning, nutritive) were recognized. The nutritive stage was noticeably later to post-spawning. High values of gonadosomatic index “GSI” in December 2008 and February/March 2009 did not correspond to maturity but to the nutritive stage. MI values ratified the periodicity of each GDS and spawning preparedness. MI was a better descriptor than GSI for reproductive season of D. mexicanum, and probably for all sea urchins exhibiting the nutritive stage. D. mexicanum has a single annual reproductive season (maturity/spawning) from April to October, similar to the population of Panama (9°00′N), without a second season, as proposed previously for the population of Colima, Mexico (19°10′N). Previous disparities in its reproductive season reflect differences of the environments it inhabits, rather than an effect of the latitudinal gradient in the tropical region.

Seasonal changes of progesterone and testosterone concentrations throughout gonad maturation stages of the Mexican octopus, Octopus maya (Octopodidae: Octopus)

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Francisco Benítez-Villalobos

Molluscan Research, 2015

Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sis... more Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sisal in Yucatan State, Mexico, were investigated by radioimmunoassays and in relation to four gonad maturation stages (GMS) and to the reproductive cycle, as represented by two maturity indices (microscopic ‘MiMI’ and macroscopic ‘MaMI’). According to the GMS and the maturity indices, the reproductive season of O. maya from Yucatan occurred from February to June. In females, P4 and T displayed the same pattern, with a tendency to increase at the same time, although on average, P4 had seven-fold higher concentrations than T. In contrast, P4 and T in male gonads displayed a different pattern, where T concentrations were relatively stable throughout all of the study months. In the female gonad P4 was lowest (close to 0 pg g–1) during both developing (GMS-I) and maturing (GMS-II) stages, and increased (189 ± 53 pg g–1) approaching the mature stage (GMS-III) to a maximum value of 611 pg g–1. Concentrations of T in the male gonad were lowest (106 ± 9 pg g–1) during the maturing stage (GMS-II) and increased up to the mature stage (GMS-III), reaching a maximum of 440 pg g–1. Pearson's correlation (r) between hormones and maturity indices showed strong relationships for females (around 0.4 and −0.7; p < 0.05), but there were negligible or weak relationships for males (0.2 and −0.1; p > 0.05). Hormone correlations in females were inverse with MaMI and direct with MiMI. Our major findings showed that gonadal P4 levels were elevated during GMS-III and GMS-IV (i.e. periods of vitellogenic oocytes), where the characteristic aspect is an ovary with very high oocyte diameters, with the primary follicle cells deeply infolded in the ooplasm for yolk synthesis. These results suggested a synchrony between P4 and the process of folliculogenesis, and in turn, vitellogenesis.

Talla inicial de madurez sexual (Tim) y/o talla de madurez sexual (Tm50%) − medida de manejo pesquero para el poliplacóforo Chiton (Chiton) articulatus: caso de estudio

by Q Yasu Abadia Chanona, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), and Luis Miguel Flores Campaña

La edad/talla de madurez sexual (TM) es la base para establecer una talla mínima de captura (TMC)... more La edad/talla de madurez sexual (TM) es la base para establecer una talla mínima de captura (TMC) como medida de manejo pesquero de un recurso. El poliplacóforo Chiton (Chiton) articulatus, es un recurso altamente explotado que requiere de regulación pesquera a lo largo de la costa del Pacífico mexicano. El objetivo de este estudio es proporcionar la base biológico reproductiva de la talla de madurez sexual (Tm50%) y la implementación del término talla inicial de madurez sexual (Tim) de C. (C.) articulatus, tomando como base el análisis histológico de la gónada y varias variables biométricas. La estimación para la Tim fue de 17 mm de longitud total (LT, incluyendo el cinturón del manto) para machos y de 32 mm LT para hembras. Las Tm50% estimadas por variable biométrica para ambos sexos fueron de 55.72 mm LT, 51.39 mm de longitud de la concha (LC, sin el cinturón del manto), 33.43 mm de ancho total (AT, incluyendo el cinturón del manto), 26.91 mm de ancho de la concha (AC, sin el cinturón del manto) y 11.88 g de peso corporal total (PT). Con estos resultados se proporcionan los criterios para establecer una talla mínima de captura basada en diferentes variables biométricas y estadios de vida; contribuyendo de esta forma al desarrollo de la talla mínima de captura (TMC) como medida de manejo pesquero para el quitón C. (C.) articulatus.

Evidence for accumulation of Synechococcus elongatus (Cyanobacteria: Cyanophyceae) in the tissues of the oyster Crassostrea gigas (Mollusca: Bivalvia)

Tissue and Cell, Aug 2014

Cyanobacteria appear to have direct relations with mollusks in several aspects. This is the first... more Cyanobacteria appear to have direct relations with mollusks in several aspects. This is the first time, distinguishing gram-negative cyanoprokaryotic Synechococcus elongatus as bright yellow-gold autofluorescence by Lillie's and Hiss’ staining methods on paraffin-embedded tissues of Crassostrea gigas. Three diets: cyanoprokaryotes, cyanoprokaryotes with microalgae, and only microalgae were evaluated. Cyanoprokaryotes were intact, densely bundled, and immersed in the cytosol of the digestive gland, connective tissue, mantle, and gonad of C. gigas, revealing an accumulation systemic without tissue damage observed by histology. Unexpectedly, cyanoprokaryotes were slightly most accumulated with microalgae diet by each of the tissues of the C. gigas than with any other diets. Cyanoprokaryotes tend to be in mean slightly higher in the digestive gland than in any other tissues respectively for each diet, although these values are closely similar to connective tissue. A possible order of exposure of the oyster tissues to accumulation of cyanoprokaryotes was digestive gland, connective tissue, mantle, and gonad. Thereby, the digestive gland could be the major target tissue for the accumulation. Our observations provide a valuable insight regarding the ability of cyanoprokaryotes to penetrate, spread, and remain inside the oyster tissues, suggesting for S. elongatus: (1) a pre-accumulation in oyster tissues from the natural environment, (2) a phagocytosis and/or endocytosis process rather than ingestion and extracellular digestion, (3) an apparent cellular division in the cytosol of oyster tissues, (4) an apparent inter-tissue movement, and (5) a possible endosymbiosis between C. gigas and S. elongatus. Hereby, it is possible that S. elongatus have a well-developed host-endobiont relationship with oysters, and thereby support future work toward a description of the escape and spreading mechanisms of S. elongatus inside the tissues of mollusks, and put forward questions as why it is there?, and are the cells active or inactive?

Discovery of protein-based natural hydrogel from the girdle of the 'sea cockroach' Chiton articulatus (Chitonida: Chitonidae)

by Emel Çakmak, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), and S. Williams

PeerJ, 2022

Hydrogels are widely used materials in biomedical, pharmaceutical, cosmetic, and agricultural fie... more Hydrogels are widely used materials in biomedical, pharmaceutical, cosmetic, and agricultural fields. However, these hydrogels are usually formed synthetically via a long and complicated process involving crosslinking natural polymers. Herein, we describe a natural hydrogel isolated using a 'gentle' acid treatment from the girdle of a chiton species (Chiton articulatus). This novel hydrogel is shown to have a proliferative effect on mouse fibroblast cells (cell line, L929). The swelling capacity of this natural hydrogel was recorded as approximately 1,200% in distilled water, which is within desired levels for hydrogels. Detailed characterizations reveal that the hydrogel consists predominantly (83.93%) of protein. Considering its non-toxicity, proliferative effect and swelling properties, this natural hydrogel is an important discovery for material sciences, with potential for further applications in industry. Whether the girdle has some hydrogel activity in the living animal is unknown, but we speculate that it may enable the animal to better survive extreme environmental conditions by preventing desiccation.

Maximum gonad investment of the sexes of the broadcast-spawning sea cucumber Holothuria (Halodeima) inornata (Echinodermata: Holothuroidea)

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Geoff Parker, heleni cancino, and Everardo Ramos Ramirez

Journal of the Marine Biological Association of the United Kingdom, 2022

An organism's maximum gonad investment (MGI) typically indicates its reproductive season and is... more An organism's maximum gonad investment (MGI) typically indicates its reproductive season and is often measured by the peak of the gonadosomatic index. Since external sexual dimorphism is often not evident, intrinsic sex differences remain unstudied. We analysed the reproductive seasonality of each sex of the broadcast-spawning sea cucumber Holothuria (Halodeima) inornata in two populations (Caleta de Campos, Michoacán ‘CC’ and Puerto Madero, Chiapas ‘PM’) in the southern coast of the Mexican Pacific by examining: intensity and duration of MGI, frequency of each gonadal developmental stage (GDS) through time, sexual asymmetry in GSI, sexual asymmetry in GDS, and adult sex ratio. We observed a trade-off between the intensity (%) and duration (months) of each sex's MGI: as intensity decreases, duration increases and conversely. The frequency of ripe and spawning stages was consistently higher in females than males. Sexual asymmetry in GSI was slightly female-biased in the PM population, but male-biased in the CC population. Sexual asymmetry in GDS showed a more recurrent sexual equality at PM than at CC. The adult sex ratio of each population did not differ significantly from unity, but showed a near-significant trend for male bias in the CC. Although H. inornata exhibited different MGI responses between males and females and more markedly in CC than in PM, it also showed a synchronized relation between its mass investment (GSI) and physiological investment (GDS), possibly reflecting an optimum reproductive strategy. Lastly, changes in GSI were not underpinned by changes in local temperature, but rather by regional temperature.

Oviducal gland transcriptomics of Octopus maya through physiological stages and the negative effects of temperature on fertilization

by Oscar E Juárez and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

PeerJ , 2022

Background: Elevated temperatures reduce fertilization and egg-laying rates in the octopus specie... more Background: Elevated temperatures reduce fertilization and egg-laying rates in the octopus species. However, the molecular mechanisms that control the onset of fertilization and egg-laying in the octopus' oviducal gland are still unclear; and the effect of temperature on the expression of key reproductive genes is unknown. This study aims to better understand the molecular bases of octopus fertilization and egg-laying, and how they are affected by elevated temperatures. Method: RNA-seq of oviducal glands was performed for samples before, during, and after fertilization and their transcriptomic profiles were compared. Also, at the fertilization stage, the optimal and thermal-stress conditions were contrasted. Expression levels of key reproductive genes were validated via RT-qPCR. Results: In mated females before egg-laying, genes required for the synthesis of spermine, spermidine, which may prevent premature fertilization, and the myomodulin neuropeptide were upregulated. Among the genes with higher expression at the fertilization stage, we found those encoding the receptors of serotonin, dopamine, and progesterone; genes involved in the assembly and motility of the sperm flagellum; genes that participate in the interaction between male and female gametes; and genes associated with the synthesis of eggshell mucoproteins. At temperatures above the optimal range for reproduction, mated females reduced the fertilization rate. This response coincided with the upregulation of myomodulin and APGW-amide neuropeptides. Also, genes associated with fertilization like LGALS3, VWC2, and Pcsk1 were downregulated at elevated temperatures. Similarly, in senescent females, genes involved in fertilization were downregulated but those involved in the metabolism of steroid hormones like SRD5A1 were highly expressed.

Biodiversity patterns of epibiotic invertebrates occupying an edible polyplacophoran across a latitudinal gradient of the Mexican Pacific

Journal of Experimental Marine Biology and Ecology, 2021

The broad perspective regarding marine-organisms biodiversity indicates a latitudinal gradient. U... more The broad perspective regarding marine-organisms biodiversity indicates a latitudinal gradient. Understanding gradients in diversity at large scales has important applications for understanding future impacts on local and regional communities. We use and propose the edible mollusk Chiton articulatus as the basibiont proxy to analyze the spatio-temporal changes in biodiversity patterns of the epibiotic community occupying its scleritome surface. The analyses covered approximately 1817 km of the Mexican Pacific, using seven sites that included samples from Sinaloa "SIN" (23 • 38 ′ N, 106 • 48 ′ W); Nayarit "NAY" (20 • 45 ′ N, 105 • 22 ′ W); Jalisco "JAL" (19 • 13 ′ N, 104 • 41 ′ W); Colima "COL" (19 • 06 ′ N, 104 • 20 ′ W); Michoacan "MIC" (17 • 54 ′ N, 102 • 11'"W); Guerrero "GRO" (16 • 48 ′ N, 99 • 52 ′ W) and Oaxaca "OAX" (15 • 39 ′ N, 96 • 30 ′ W). A temporal gradient (monthly sampling from October 2015 to October 2016) was also analyzed. Evaluation of the sampling effort demonstrated that 76-86% of the epibiotic fauna was recovered. The most representative epibionts were barnacles, a limpet and an acrothoracican. Abundances of the barnacles and the limpet tended to decrease southwards, while the acrothoracican tended to increase northwards. The epibiotic community did not exhibit the typical latitudinal gradient of diversity expected, but a fragmented pattern within three main areas, which coincide with three of the marine biogeographic ecoregions proposed for the shallow waters of the Warm Temperate Northern Pacific and Tropical Eastern Pacific provinces. These were a northern group within SIN, which belong to the southern border of the Magdalena Transition ecoregion (subtropical); a middle group within NAY, JAL, COL, MIC, and GRO, which belongs to the Mexican Tropical Pacific ecoregion (tropical); and a southern group within OAX exclusively, belonging to the northern border of the Chiapas-Nicaragua ecoregion (tropical). The southern localities showed larger dominances and the central localities exhibited more stable communities. Our evidence suggests that as we move across the different shore types of the Mexican Pacific, the coastline supports distinct biotic assemblages, and the community on the rocky shores is biologically heterogeneous and mainly influenced by conditions at the local level. In consequence, conservation and protection efforts should consider preserving the local heterogeneity of habitats in the study area. Furthermore, since C. articulatus is edible, its epibiota represents an incidental fishing bycatch, with the result that the extraction of the chiton and its epibiota can jeopardy the diversity in the intertidal rocky shore of the Mexican Pacific.

Plasticity in reproductive traits of an intertidal rocky shore chiton (Polyplacophora: Chitonida) under pre-ENSO and ENSO events

Journal of Molluscan Studies, 2021

Changes in growth and reproduction help to maximize fitness under given constraints. This might b... more Changes in growth and reproduction help to maximize fitness under given constraints. This might be interpreted as nonadaptive plasticity (morphological, physiological or behavioural) with the capacity to produce different phenotypes (i.e. the range of potential phenotypes that a single genotype could generate if exposed to a specified range of environmental conditions; see Stearns & Koella, 1986), so that local persistence is possible under different environmental conditions (e.g. thermal anomaly events). Since C. articulatus is commercially harvested in an emerging small-scale fishery (Garcia-Ibañez et al., 2013; Olea-de-la-Cruz et al., 2013), it would be useful to evaluate the potential plasticity of its reproductive traits in relation to annual thermal perturbation. A conceptual model of reproductive development in invertebrates with broadcast spawning was developed to improve the evaluation and understanding of the variability of three reproductive traits that are commonly used in fisheries biology (Fig. 1): Trait 1, the reproductive cycle, Trait 2, the reproductive or ‘breeding’ season, Trait 3, the size at sexual maturity.
SEE, SUPPLEMENTARY MATERIAL TABLE S1.

Large-scale project 'Chiton of the Mexican Tropical Pacific': Chiton articulatus (Mollusca: Polyplacophora

Research Ideas and Outcomes, 2020

The marine mollusc, commonly called sea cockroach or chiton Chiton articulatus, is a mollusc belo... more The marine mollusc, commonly called sea cockroach or chiton Chiton articulatus, is a mollusc belonging to the group known as Polyplacophora because its shell is composed of eight individual plates. This mollusc inhabits the rocky intertidal shore of the Mexican Tropical Pacific, where it is endemic. It has ecological, but also economic, importance. Ecologically, it is the preferred food of the snail Plicopurpura pansa, a protected species, in the cultural heritage of the country. Additionally, it is a basibiont (generates substrate for other individuals) that maintains the biodiversity of the Region. Economically, it has changed from artisanal consumption to become a culinary tourist attraction, offered at restaurants as an exotic and aphrodisiac dish, in tourist places like Huatulco or Acapulco. Despite being an exploited resource for decades, little is known about its life history. The Mexican Authorities have not yet recognised this mollusc as a fishing resource, so that it does not have any law that controls its extraction, sale and consumption, putting at risk the recruitment, survival and permanence of this species. The goal of this project is the preservation and support for the management of the species. The Project "Quiton del Pacifico Tropical Mexicano" seeks to provide the biological, ecological, reproductive, genetic, anatomical and morphometric bases of the populations of Chiton articulatus. The project was structured in four stages: 1) field sampling and obtaining samples, 2) disclosure and presentation of the project, 3) inclusion of students at the undergraduate and graduate level, 4) application of results. The inclusion and recognition of C. articulatus as a fishing resource will achieve impact at the national and regional level through the implementation of laws that regulate its fishing, as well as its inclusion in management and food security policies. Additionally, this Mexican Chiton Project is currently replicating with chiton species in Galapagos, Ecuador.

Plasticity in growth parameters of an intertidal rocky shore chiton (Polyplacophora: Chitonida) under pre-ENSO and ENSO events

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Guillermo Rodriguez Dominguez

Journal of Molluscan Studies, 2020

Chiton articulatus exhibited growth parameters (population size, number of size groups, number of... more Chiton articulatus exhibited growth parameters (population size, number of size groups, number of cohorts, growth rate and longevity) divergent between annual cold “La Niña” (ACE) and annual warm “El Niño” (AWE) events. We used a multi-model inference approach (Schnute models), considering the size-structure and individual growth in the absence of age data. The longevity of C. articulatus could reach until five years old. Our results suggest that Chiton articulatus could have the ability and/or plasticity to cope positively to adverse thermal situations or in global warming scenarios.

Complex abnormality combinations between the scleritome and the sclerites of Chiton articulatus (Mollusca: Polyplacophora): New findings for the teratological classification

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Brenda Paola Ramirez-Santana, and Carlos Melendez Galicia

Zoologischer Anzeiger, 2019

Teratological diagnosis in polyplacophorans has mostly been based on primary structure (Chiton sc... more Teratological diagnosis in polyplacophorans has mostly been based on primary structure (Chiton scleritome) with four types (hypermerism, hypomerism, coalescence and splitting), including some deformities in plates; however, diagnoses are hardly detailed for each sclerite. As part of a monthly research campaign conducted by a year investigating Chiton articulatus, we found several cases with a complex combination of abnormalities (chiton scleritome + sclerites) that complement the previous classification. Identification and diagnosis of abnormalities were assigned in terms of sclerite number, number of slits per side in the insertion area of intermediate sclerites and the merging grade between sclerites. Slit and slit-ray numbers were baseline to identify combination of abnormalities; the slit formula of Chiton articulatus is 13–18[I]/1[II-VII]/16–22[VIII]. We found four abnormality cases with combinations among them: a) perfect hypomerism, b) heterogeneous coalescence, c) homogeneous coalescence, d) imperfect hypermerism. Heterogeneous coalescence was most common abnormality, with a different merging degree between sclerites and with specimens showing combinations of abnormal states such as: normality/coalescence, coalescence/hypomerism, coalescence/hypermerism and normality/hypermerism; so these complex abnormalities can generates asymmetry between the right and left side of a chiton. We postulate that coalescence is an intermediate step toward perfect hypomerism or perfect hypermerism. The width/length ratio suggests that an abnormal chiton increases its width to compensate and retain a normal body appearance despite different degrees of abnormal development.

An ovotestis event in the gonochoric sea urchin Loxechinus albus (Echinodermata: Echinoidea)

Brazilian Journal of Biology, 2019

Reproductive traits and relative gonad expenditure of the sexes of the free spawning Chiton articulatus (Mollusca: Polyplacophora)

by Q Yasu Abadia Chanona and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Invertebrate Reproduction and Development, 2018

Reproductive studies of an intertidal free-spawning population of Chiton articulatus (Mollusca: P... more Reproductive studies of an intertidal free-spawning population of Chiton articulatus (Mollusca: Polyplacophora) from Puerto Angel, Oaxaca, Mexico were undertaken during 2011. We used gonad histology and gonadal indices to assess the relative gonad expenditure of the sexes (RGES) and other reproductive traits, accounting for individual and seasonal variation within this population. At this location, C. articulatus is gonochoric, without sexual dimorphism, except internally by gonad colour (testis is 'salmon' coloured and ovary olive green). Annual and monthly sex ratios (m/f) do not differ significantly from 1:1. Highest population-level gonadosomatic index (GSI) corresponded to maximum (peak) ripe stage (i.e. maximum gonad investment), with a first peak in May with a high value (8.4 ± 0.5) and a second peak during August-September with a lower value (4.7 ± 0.3). GSI fluctuated throughout year implying that gonad expenditure may be seasonally constrained, but with overall synchrony between sexes of ripe and spawning stages. July to December was the main reproductive season with some facultative spawning occurring off-season. Ripe and spawning RGES did not differ between sexes, suggesting that either sperm competition is intense and/or that sperm limitation is high. Early spawning individuals may quickly replenish their gametes for a second phase of gamete release later.

Reproductive performance of Octopus maya males conditioned by thermal stress

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Laura Liliana Lopez Galindo, and Oscar Juárez

Ecological Indicators, 2019

Observations of wild male O. maya suggest that temperatures below 27 °C favour their reproductive... more Observations of wild male O. maya suggest that temperatures below 27 °C favour their reproductive performance. From these observations we hypothesize that, as in females, the temperature modulates the reproductive performance of adult O. maya males. The study aimed to evaluate the physiological condition, reproductive success, and histological damage in testis of male O. maya exposed to thermal stress, to determine the implications of ocean warming over their reproductive performance. High temperatures (28–30 °C) negatively affect the growth and health of male O. maya. In octopuses maintained at 30 °C, as a consequence of the thermal stress we observed an increment in the haemocytes number, a reduction in the oxygen consumption rate, and an inflammatory process in the testis. The number of spermatozoa per spermatophore was not affected by temperature , but higher spermatophores production was observed at 30 °C. The paternity analysis showed that the offspring had multiple paternity with an average of 10 males contributing in a single spawn. The paternal contribution was affected by temperature with high, medium, or no paternal contribution in animals maintained at 24 °C (control group), 28 °C and 30 °C, respectively. The temperatures from 28 °C to 30 °C deeply affected the reproductive performance of Octopus maya males, suggesting that, as embryos, reproductive performance of adult males of this octopus species can be used as a tool for monitoring thermal changes in Yucatán Peninsula, located at the entrance of Gulf of Mexico.

Variability in size at maturity and reproductive season of queen conch Lobatus gigas (Gastropoda: Strombidae) in the Wider Caribbean Region

by Erik Boman, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Erick R Baqueiro, and Caroline Bissada

Fisheries Research, 2018

Queen conch (Lobatus gigas), is an economically and culturally important marine gastropod. The sp... more Queen conch (Lobatus gigas), is an economically and culturally important marine gastropod. The species is subject to extensive exploitation throughout large parts of the Caribbean which has led to a decrease in population densities across much of the species' distribution range. Hence, there is a need for protective measures to safeguard the reproductive stock. This requires a better estimation of its size at maturity, which is best quantified as the thickness of the lip that the shell develops after reaching its maximum length. The lip thickness at 50% maturity (LT 50) was determined using a logistic and an accumulation model, from seven representative location of distribution of this species in the Wider Caribbean Region. LT 50 of both females (7–14 mm) and males (4–11.5 mm) varied between different locations in the Caribbean, although it did not correspond with variation in water temperature. In most cases females had a larger LT 50 than males indicating sexual dimorphism. LT 50 values estimated with the logistic model were smaller (7–14 mm for females, 4–11.5 mm for males) than values estimated with the accumulation model (13–26 mm for females, 16–24 mm for males), showing an over-estimation of LT 50 in queen conch in previous studies which used the accumulation model to estimate LT 50. Locations with a relatively high variation in water temperature had a significantly shorter reproductive season. The implementation of adequate minimum size regulation based on lip thickness (ca. 15 mm) and a Caribbean wide seasonal closure (May–September) using the most recent biological information from this study, taking into consideration the local differences in LT 50 and reproductive season, will assist in developing a long term sustainable queen conch fishery in the Caribbean.

Oviducal glands throughout the gonad development stages: a case study of Octopus mimus (Cephalopoda)

Molluscan Research, 2017

The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes... more The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes of each section of the ODG of Octopus mimus are described histologically throughout the gonad development stages (GDS). To do this, the epithelial height, stereociliated or non-stereociliated epithelium, nucleus type (pycnotic or non-pycnotic), epithelial secretions and the value range of the macroscopic maturity index (MaMI), which directly involves ODG status, were measured. The ODG are internally constituted of two glandular units (central and peripheral glands) and one set of receptacles (the spermathecae). High epithelia (40 to 80 μm) were observed in both gland units during periods with low MaMI values (< 0.1) corresponding to III-mature and IV-pre-spawning. The stereociliated epithelium was only apparent in II-maturing and III-mature in both gland units. The nuclei were noticeably pycnotic in the central gland during III-mature, IV-pre-spawning and V-spawning, but pycnotic in the peripheral gland only during VI-depletion. The epithelium was disorganised during VI-depletion, while sulphated acid mucin was only present during III-mature in the central gland. The epithelium transformations during the GDS are related to the functions of the gland units and to their multiple secretions. The ODG histology complements the GDS and provides better reproductive status assessment.

Temperature modulates spatio-temporal variability of the functional reproductive maturation of Octopus maya (Cephalopoda) on the shelf of the Yucatan Peninsula, Mexico

Journal of Molluscan Studies, 2017

Laboratory studies have demonstrated that high temperatures inhibit spawning of Octopus maya; the... more Laboratory studies have demonstrated that high temperatures inhibit spawning of Octopus maya; therefore, in oceanic warming scenarios the population dynamics may be affected. The aim of the present study was to go beyond laboratory studies under controlled temperatures to examine the possible relationship between large-scale thermal patterns and reproductive season (represented by functional maturation) of O. maya in the wild on the continental shelf of the Yucatan Peninsula, where it is endemic. The macroscopic maturity index (MaMI) was obtained in females, and reproductive complex index (RCI) and number of spermatophores in males. Associations between these indices and environmental temperature regime were inferred by sampling octopuses in an upwelling zone (Z-I), a transition zone (Z-II) and a nonupwelling zone (Z-III). The reproductive condition of O. maya differed between Z-I and Z-III. In all zones, the proportion of adults showing functional maturity was highest in both females (MaMI: 36–71% of values ≤0.2) and males (RCI: 12–40% of values ≥0.9; 41–49 spermatophores per octopus) during the season of winter storms ('nortes' season, November–February), when the sea-surface temperature oscillates around 25 °C. In Z-I, some individuals were functionally mature throughout the year, likely due to low temperatures maintained by summer upwelling. Zone-I had the greatest proportion of functionally mature males (up to 40% of adults in 'nortes' season) and the greatest number of spermatophores (mean 43–49 spermatophores per octopus in all seasons). Females in Z-III (without upwelling) were functionally mature mainly in the 'nortes' season when water temperature decreased, with only a small proportion mature in the rest of the year when water temperatures reached 31 °C. As predicted by laboratory studies, water temperature below 27 °C appears to be favourable for the functional reproductive maturation of wild O. maya.

Observation and establishment of gonad development stages in polyplacophorans (Mollusca): Chiton (Chiton) articulatus a case study

by Q Yasu Abadia Chanona and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Acta Zoologica, 2016

Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by perform... more Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by performing histology of some gonad portions. In polypla-cophorans, gametogenesis is not enough to define GDS; further anatomical gonad features are relevant. In most adult polyplacophorans, the gonad is a simple anatomical structure that resembles and operates as one single gonadal aci-nus without glandular structure. These features have gone unnoticed causing inaccurate GDS assignment and, consequently, imprecise reproductive season in polyplacophorans. Here, dissection protocols that allow extracting a compact gonad are established. Emphasizing the anatomical structure of the whole gonad and the displacement of gametes, five GDS were assigned to both sexes of Chi-ton (Chiton) articulatus: I-goniogenesis, II-development, III-ripe, IV-spawning, V-rest. Tissue platelets contribute importantly to GDS assignment and even help distinguishing between males and females. Neither a randomly selected portion of gonad nor a longitudinal section are recommended because it leads to misinterpretation higher than 50% in determining GDS and besides ignores displacement of gametes. A panoramic sweep across a complete transverse-section of each gonad was validated as the best option for establishing GDS. This new methodology was tested on several polyplacophorans species, and seems generally applicable for histological assessment of reproductive cycle and reproductive season in polyplacophorans.

Reproductive traits of Octopus maya (Cephalopoda: Octopoda) with implications for fisheries management

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Francisco Benítez-Villalobos, and Josefina Santos-Valencia

Molluscan Research, Apr 2016

Octopus maya is the main species caught in Mexico. From September 2007 to June 2008, its sex rati... more Octopus maya is the main species caught in Mexico. From September 2007 to June 2008, its sex ratio, reproductive season, frequency of non-vitellogenic and vitellogenic oocytes, reproductive indices, and size and weight at maturity, were evaluated. The monthly sex ratio was significantly different from 1:1. The major reproductive season occurs during February to June (dry season) in Yucatan. May−June is the common reproductive season to both Yucatán and Campeche populations. Higher frequencies of vitellogenic oocytes (> 50%) were found from January-March and in May. From five reproductive indices, only the macroscopic and microscopic maturity indices were the best descriptors of the reproductive season in females, whilst only the reproductive complex index was the best descriptor in males. The weight at sexual maturity (BW 50%) was 335 g for females and 242 g for males. The size at sexual maturity (DML 50%) was 12.58 cm for females and 7.42 cm for males. It is recommend revising the minimum catch size by following these results. The reproductive traits here evaluated could contribute to the recently created Plan for Management of Octopus Fisheries, in particular action line no. 1.4, which refers to protection of females during breeding, and to their protection throughout the entire reproductive season.

Gonad development stages and reproductive traits of Diadema mexicanum (Echinodermata: Echinoidea) from Oaxaca, Mexico

by Francisco Benítez-Villalobos and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Invertebrate Reproduction and Development , Dec 24, 2015

Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral... more Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral reefs dynamics. Several reproductive traits of D. mexicanum throughout one year at La Entrega Bay, Oaxaca (15°44′N), in the Mexican tropical Pacific, were analyzed. Maturity index or microscopic maturity index “MI” was calculated. Annual ratio of males to females (1:1) was not significantly different. Five gonad development stages “GDS” (i.e. development, mature, spawning, post-spawning, nutritive) were recognized. The nutritive stage was noticeably later to post-spawning. High values of gonadosomatic index “GSI” in December 2008 and February/March 2009 did not correspond to maturity but to the nutritive stage. MI values ratified the periodicity of each GDS and spawning preparedness. MI was a better descriptor than GSI for reproductive season of D. mexicanum, and probably for all sea urchins exhibiting the nutritive stage. D. mexicanum has a single annual reproductive season (maturity/spawning) from April to October, similar to the population of Panama (9°00′N), without a second season, as proposed previously for the population of Colima, Mexico (19°10′N). Previous disparities in its reproductive season reflect differences of the environments it inhabits, rather than an effect of the latitudinal gradient in the tropical region.

Seasonal changes of progesterone and testosterone concentrations throughout gonad maturation stages of the Mexican octopus, Octopus maya (Octopodidae: Octopus)

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Francisco Benítez-Villalobos

Molluscan Research, 2015

Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sis... more Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sisal in Yucatan State, Mexico, were investigated by radioimmunoassays and in relation to four gonad maturation stages (GMS) and to the reproductive cycle, as represented by two maturity indices (microscopic ‘MiMI’ and macroscopic ‘MaMI’). According to the GMS and the maturity indices, the reproductive season of O. maya from Yucatan occurred from February to June. In females, P4 and T displayed the same pattern, with a tendency to increase at the same time, although on average, P4 had seven-fold higher concentrations than T. In contrast, P4 and T in male gonads displayed a different pattern, where T concentrations were relatively stable throughout all of the study months. In the female gonad P4 was lowest (close to 0 pg g–1) during both developing (GMS-I) and maturing (GMS-II) stages, and increased (189 ± 53 pg g–1) approaching the mature stage (GMS-III) to a maximum value of 611 pg g–1. Concentrations of T in the male gonad were lowest (106 ± 9 pg g–1) during the maturing stage (GMS-II) and increased up to the mature stage (GMS-III), reaching a maximum of 440 pg g–1. Pearson's correlation (r) between hormones and maturity indices showed strong relationships for females (around 0.4 and −0.7; p < 0.05), but there were negligible or weak relationships for males (0.2 and −0.1; p > 0.05). Hormone correlations in females were inverse with MaMI and direct with MiMI. Our major findings showed that gonadal P4 levels were elevated during GMS-III and GMS-IV (i.e. periods of vitellogenic oocytes), where the characteristic aspect is an ovary with very high oocyte diameters, with the primary follicle cells deeply infolded in the ooplasm for yolk synthesis. These results suggested a synchrony between P4 and the process of folliculogenesis, and in turn, vitellogenesis.

Talla inicial de madurez sexual (Tim) y/o talla de madurez sexual (Tm50%) − medida de manejo pesquero para el poliplacóforo Chiton (Chiton) articulatus: caso de estudio

by Q Yasu Abadia Chanona, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), and Luis Miguel Flores Campaña

La edad/talla de madurez sexual (TM) es la base para establecer una talla mínima de captura (TMC)... more La edad/talla de madurez sexual (TM) es la base para establecer una talla mínima de captura (TMC) como medida de manejo pesquero de un recurso. El poliplacóforo Chiton (Chiton) articulatus, es un recurso altamente explotado que requiere de regulación pesquera a lo largo de la costa del Pacífico mexicano. El objetivo de este estudio es proporcionar la base biológico reproductiva de la talla de madurez sexual (Tm50%) y la implementación del término talla inicial de madurez sexual (Tim) de C. (C.) articulatus, tomando como base el análisis histológico de la gónada y varias variables biométricas. La estimación para la Tim fue de 17 mm de longitud total (LT, incluyendo el cinturón del manto) para machos y de 32 mm LT para hembras. Las Tm50% estimadas por variable biométrica para ambos sexos fueron de 55.72 mm LT, 51.39 mm de longitud de la concha (LC, sin el cinturón del manto), 33.43 mm de ancho total (AT, incluyendo el cinturón del manto), 26.91 mm de ancho de la concha (AC, sin el cinturón del manto) y 11.88 g de peso corporal total (PT). Con estos resultados se proporcionan los criterios para establecer una talla mínima de captura basada en diferentes variables biométricas y estadios de vida; contribuyendo de esta forma al desarrollo de la talla mínima de captura (TMC) como medida de manejo pesquero para el quitón C. (C.) articulatus.

Evidence for accumulation of Synechococcus elongatus (Cyanobacteria: Cyanophyceae) in the tissues of the oyster Crassostrea gigas (Mollusca: Bivalvia)

Tissue and Cell, Aug 2014

Cyanobacteria appear to have direct relations with mollusks in several aspects. This is the first... more Cyanobacteria appear to have direct relations with mollusks in several aspects. This is the first time, distinguishing gram-negative cyanoprokaryotic Synechococcus elongatus as bright yellow-gold autofluorescence by Lillie's and Hiss’ staining methods on paraffin-embedded tissues of Crassostrea gigas. Three diets: cyanoprokaryotes, cyanoprokaryotes with microalgae, and only microalgae were evaluated. Cyanoprokaryotes were intact, densely bundled, and immersed in the cytosol of the digestive gland, connective tissue, mantle, and gonad of C. gigas, revealing an accumulation systemic without tissue damage observed by histology. Unexpectedly, cyanoprokaryotes were slightly most accumulated with microalgae diet by each of the tissues of the C. gigas than with any other diets. Cyanoprokaryotes tend to be in mean slightly higher in the digestive gland than in any other tissues respectively for each diet, although these values are closely similar to connective tissue. A possible order of exposure of the oyster tissues to accumulation of cyanoprokaryotes was digestive gland, connective tissue, mantle, and gonad. Thereby, the digestive gland could be the major target tissue for the accumulation. Our observations provide a valuable insight regarding the ability of cyanoprokaryotes to penetrate, spread, and remain inside the oyster tissues, suggesting for S. elongatus: (1) a pre-accumulation in oyster tissues from the natural environment, (2) a phagocytosis and/or endocytosis process rather than ingestion and extracellular digestion, (3) an apparent cellular division in the cytosol of oyster tissues, (4) an apparent inter-tissue movement, and (5) a possible endosymbiosis between C. gigas and S. elongatus. Hereby, it is possible that S. elongatus have a well-developed host-endobiont relationship with oysters, and thereby support future work toward a description of the escape and spreading mechanisms of S. elongatus inside the tissues of mollusks, and put forward questions as why it is there?, and are the cells active or inactive?

ESTRUCTURA POBLACIONAL Y CAPTURA POR UNIDAD DE ESFUERZO A PARTIR DE LA PESCA ARTESANAL DE LA CUCARACHA DE MAR Chiton articulatus (MOLLUSCA: POLYPLACOPHORA) EN ACAPULCO, MÉXICO: UN ESTUDIO DE CASO

MSc. THESIS -- CARLOS VALENCIA-CAYETANO, 2020

El molusco poliplacóforo Chiton articulatus comúnmente conocido como “cucaracha de mar” o “lengua... more El molusco poliplacóforo Chiton articulatus comúnmente conocido como “cucaracha de mar” o “lengua de perro” es una especie endémica del Pacífico Tropical Mexicano con potencial económico. En Acapulco, Guerrero, esta especie presenta la mayor oferta y demanda, por lo cual es objeto de la pesca artesanal. Con el pie musculoso de la cucaracha de mar se elaboran platillos para consumo de lugareños y turistas. Este estudio analizó la estructura de tallas de la cucaracha de mar C. articulatus de Acapulco, México, capturados por un “cucarachero” (pescador exclusivo de quitones). Entre mayo 2018 y mayo 2019 se acompañó (2 días/mes) al cucarachero a las faenas de pesca y se cuantifico la cantidad de organismos por hora. Se describió la estructura de tallas; se estimó la longitud de captura (Lc50 %) y se contrastó con la longitud de madurez sexual (Lm50 %) de la literatura y por estadio de vida (subjuvenil, juvenil, subadulto, adulto) de la especie. Así mismo se extrapoló a captura total mes (org/mes/pescador y kg/mes/pescador) y se calculó la captura por unidad de esfuerzo “CPUE” (org/h/día y kg/h/pescador). Se registró la captura de 16,211 organismos, representados principalmente por organismos en estadio de vida subadulto y adulto. La Lc50 % durante el periodo de estudio fue inferior a Lm50 %. Se estimó una captura anual de 233,844 quitones con un peso aproximado a 1.5 toneladas. La CPUE promedio en número de organismos fue de 515.4 (182.3) org/h/pescador, mientras que CPUE promedio en kilogramos fue de 4.42 (1.19) kg/h/pescador. La pesca de la cucaracha de mar estuvó concentrada sobre organismos de mayor tamaño que ofrecieron mejores rendimientos de carne para el pescador, sin embargo, un porcentaje importante (45 %) de organismos fueron capturados antes de reproducirce al menos una vez. Las tendencias de CPUE observadas reflejan la disponibilidad de organismos vulnerables a la pesca, así como la oferta y la demanda del recurso, en un puerto turístico como Acapulco. Finalmente, para implementar gestiones de pesca que brinden mejores resultados y evitar un consecuente colapso de la pesquería, se recomienda considerar el comportamiento y expectativas de los pescadores tales como la rotación de las zonas de pesca de acuerdo a las fracciones retenidas de quitones.

Filogeografía y estructura genética de Chiton articulatus (Mollusca: Polyplacophora) endémico del Pacífico tropical mexicano

B.Sc. Thesis UAS-FACIMAR -- THELMA ABRIL AGUILAR-RENDÓN, 2018

Chiton articulatus is a polyplacophore that lives on the intertidal rocky and is distributed alon... more Chiton articulatus is a polyplacophore that lives on the intertidal rocky and is distributed along the Mexican Tropical Pacific (MTP), from southern Sinaloa to Oaxaca, where is an endemic species. Ecologically, it is a key species of rocky coastal ecosystems, due its herbivory that controls the algae growth, and because it is a basibionte for other organisms. It is a gonochoric species and a free spawner with a short time trochophore larvae of (~ six days), before it metamorphoses to settles in rocky substrate; so its dispersal potential is low. These biological and ecological characteristics influence the genetic architecture of populations, promoting a genetic differentiation along its geographical distribution. The objective was to evaluate phylogeographic patterns of C. articulatus along its geographical distribution, for which chiton tissues were collected in seven localities: Mazatlán (Sinaloa), La Cruz de Huanacaxtle (Nayarit), Melaque (Jalisco), Manzanillo (Colima), Lázaro Cárdenas (Michoacán), Acapulco (Guerrero), and Puerto Ángel (Oaxaca). A total of 84 haplotypes were identified of Cytochrome c oxidase subunit I (coI) gene of mitochondrial DNA with 609 bp. The genetic diversity was high for all sampling locations with an average of h = 0.914. The analysis of molecular variance showed a significant genetic differentiation among all sampling locations (ΦST = 0.58, p <0.001), therefore there are 4 subpopulations along the MTP: 1) Mazatlán, 2) La Cruz de Huanacaxtle-Melaque-Manzanillo, 3) Lázaro Cárdenas-Acapulco, and 4) Puerto Ángel. The phylogeographic pattern indicated a divergence between northern and southern localities forming two clusters; also, ancestral haplotypes were located in central localities in both clusters. Due to this, it is possible that migration has occurred from center (Melaque and Manzanillo) towards peripheral (Mazatlán and Puerto Ángel) localities. In addition, the genetic connectivity was mediated by geographical distance between localities (r2 = 0.48, p = 0.011). The historical demography results indicate that almost all localities have suffered sudden population expansions due to bottlenecks and/or a founder effect; the population reductions could be due to geological events such as the closure of the Isthmus of Panama between ~1-3 million years ago in the late Pliocene, and to glaciation events between ~4,000-372,000 years ago between the late Pleistocene and the early Holocene.

Biodiversidad de invertebrados epibióticos de las poblaciones adultas de Chiton articulatus (Mollusca: Polyplacophora) en el Pacífico tropical Mexicano

MSc. THESIS -- LAURA REGINA ALVAREZ-CERRILLO, 2017

Este estudio utiliza como modelo ecológico al quitón Chiton articulatus, una especie endémica de ... more Este estudio utiliza como modelo ecológico al quitón Chiton articulatus, una especie endémica de la zona intermareal rocosa, entre los 23-15°N en el Pacífico tropical Mexicano (PTM). Los quitones se han estudiado brevemente con enfoque epibiótico, donde el quitón es el basibionte u organismo sustrato que representa microhábitats disponibles para organismos que viven sobre él (epibiontes). Los estudios epibióticos reflejan microhábitats para comunidades que potencialmente representan la biota de zonas adyacentes, en este caso del intermareal rocoso del PTM. Chiton articulatus como basibionte representa un sustrato importante para la diversidad del intermareal rocoso. La recolección de C. articulatus se está convirtiendo en una pesquería emergente, con lo cual la pesca incidental de la fauna de acompañamiento (epibiontes) podría afectar la estructura de la comunidad intermareal. Aquí se analiza la comunidad epibiótica sobre las placas del quitón, a escala local, regional y temporal en el PTM, bajo el supuesto de que la estructura de la comunidad de epibiontes y endobiontes de C. articulatus no difiere de aquella presente en el ambiente. Siete localidades fueron muestreadas: Mazatlán (23°N), Cruz de Huanacaxtle (20°N), Melaque (19°N), Manzanillo (18°N), Lázaro Cárdenas (17°N), Acapulco (16°N) y Puerto Ángel (15°N). Los muestreos fueron mensuales y simultáneos, 13 por localidad en total, de octubre de 2015 a octubre de 2016 (91 muestras con un promedio de 36±7 quitones cada una). Se analizó la riqueza (S), diversidad (Shannon, H’), uniformidad (Pielou, J’) y dominancia (Simpson, λ’); así como la similitud mediante análisis CLUSTER, MDS y ANOSIM. El registro comprende la densidad de la comunidad epibiótica (organismos/cm2) sobre las placas de 3,313 quitones en total. Para toda la región se observaron 19 morfotipos de invertebrados (18 epibiontes y 1 endobionte). Regionalmente se estimaron alrededor de 21 morfotipos: Chao2=21.50±2.96, Jacknife1=23.95, Jacknife2=24 y Bootstrap=21.59. El modelo de Bootstrap denotó un muestreo suficiente. Regionalmente los morfotipos con alta dominancia fueron tres: balanos Chthamalus spp., lapas Lottia mitella y acrotorácicos Cryptophialus wainwrighti. La densidad de los balanos careció de relación con la latitud, la de lapas disminuyó hacia latitudes menores, mientras que la de acrotorácicos incrementó. A escala local y regional la mayor riqueza (S) y diversidad correspondieron a Mazatlán (23°N) y Manzanillo (19°N). La mayor uniformidad (J’) se presentó en Manzanillo y la mayor dominancia (λ’) en las tres localidades de menor latitud: Lázaro Cárdenas, Acapulco y Puerto Ángel. Localmente, el análisis CLUSTER originó agrupaciones que con el MDS fueron subjetivas, a excepción de Puerto Ángel, que presentó mayor homogeneidad en la estructura de la comunidad epibiótica. A escala regional el CLUSTER, MDS y ANOSIM reflejaron que la comunidad epibiótica forma cinco agrupaciones diferentes (R global=0.559, p=0.001). La comunidad de invertebrados epibióticos de Chiton articulatus coincide con patrones promedio anuales de variables reportadas en la literatura como las mareas, salinidad y temperatura que influyen en la zona costera. Inesperadamente, no se observó un gradiente latitudinal de la biodiversidad (menor diversidad a mayor latitud), pero si se observó que la biodiversidad de invertebrados epibióticos varía a escala local.

Estructura de las capturas y longitud de madurez del huachinango Lutjanus peru (Perciformes: Lutjanidae), en la Bahía de la Ventana, B.C.S., México

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Walter Antonio Barbosa-Ortega

MSc. THESIS -- WALTER ANTONIO BARBOSA-ORTEGA, 2016

Lutjanus peru o huachinango del Pacífico, es considerada una de las especies de escama más import... more Lutjanus peru o huachinango del Pacífico, es considerada una de las especies de escama más importante en el Pacífico mexicano. Los altos precios que alcanza en el mercado han estimulado su capturada durante todo el año, inclusive durante su época reproductiva cuando es más abundante. Se reporta que entre un 45% y 65% de las capturas están conformadas por juveniles y subadultos. Por lo anterior, actualmente la Carta Nacional Pesquera, cataloga al huachinango con estatus de sobreexplotado y ha recomendado el monitoreo constante del recurso. El objetivo del presente trabajo fue caracterizar las capturas de L. peru, a través de sus estructuras de tallas, sexo, tipo de crecimiento, condición y con base a evidencias histológicas y variables morfofisiológicas estimar la longitud de madurez (Lm), así como determinar las características de los estadios de vida adultos, subadultos y juveniles. Durante el año 2012 mensualmente fueron muestreados un promedio 30 individuos, producto de la pesca artesanal, en la Bahía de La Ventana, B.C.S. De cada individuo se registró la longitud total, el peso total corporal y el de sus gónadas, y se recolectó una porción transversal de la gónada (1 cm3) para realizar análisis histológicos que permitieran determinar el sexo de cada individuo, así como su ubicación en alguno de los estadios de vida: juvenil, subadulto y adulto. La Lm de L. peru fue estimada por tres métodos diferentes, y se seleccionó de entre las Lm estimadas, la que más se ajustó a las evidencias histológicas y morfofisiológicas de organismos adultos. Los resultados reflejaron que la pesquería del huachinango se sustentó en un 86% de organismos juveniles y subadultos. Las hembras, machos, adultos, subadultos y juveniles presentaron un tipo de crecimiento isométrico. Los intervalos de tallas para los organismos juveniles y subadultos fueron de 25.9 ± 2.9 y 29.3 ± 3.8 cm, respectivamente, mientras que los adultos se presentaron de 40 cm de LT en adelante. Se encontró que los adultos presentan una mayor tasa de incremento en peso que los juveniles y subadultos. El factor de condición presentó una relación directa con la época reproductiva (junio y julio) y además, evidenció que los juveniles y subadultos presentaron su mejor condición justo en esta misma época. La longitud de madurez que más se ajustó a las características de los organismos adultos fue de 40 cm LT.

MADURACIÓN GONÁDICA, CICLO REPRODUCTIVO Y TALLA DE MADUREZ SEXUAL DEL QUITÓN Chiton (Chiton) articulatus (MOLLUSCA: POLYPLACOPHORA) DE LA COSTA ROCOSA DE PUERTO ÁNGEL, OAXACA, MÉXICO

MSc. Thesis -- QUETZALLI YASU ABADIA-CHANONA, Jul 2015

The chiton, Chiton (Chiton) articulatus commonly known as "dog tongue" or "sea cockroach" is coll... more The chiton, Chiton (Chiton) articulatus commonly known as "dog tongue" or "sea cockroach" is collected as bait for artisanal fisheries and offered in restaurants like gourmet dish, along the Pacific coast of Mexico, so their consumption is generating a potentially exploitable fisheries and economic interest. Considering reproduction as fundamental in the life history, the economic importance of the resource and that does not have control in their consumption and marketing; studies on aspects of reproductive biology of this species are needed. The aim of this study is to contribute to the basic knowledge of C. (C) articulatus in aspects such as gonadal maturation, reproductive cycle, reproductive season and its relationship with environmental variables, sex ratio and size at maturity (Tm50%). During 2011, 32 adult chitons were monthly collected in Puerto Angel, Oaxaca. A technique for relaxation, fixation and dissection of animals was established. Were taken body measurements (total length: LT, Shell length: LC, total width: AT, Shell width: AC) and total weight (PT). By histological analysis of the gonad the maturation sequence of the female gamete was described, a method for viewing and setting of the gonad maturation stages (GMS) is proposed, and the reproductive cycle was obtained. The reproductive season was characterized with the gonadosomatic index (GSI) and the index of microscopic maturity (IMMi). The sex ratio was calculated. The TM50% were estimated considering the four measurements morphological and the body weight. The gonad of C. (C.) articulatus produces synchronously gametes and the mature oocytes have the "hull egg" characteristic of polyplacophorans. Five gonad maturation stages (GMS) were established and described: I-goniogenesis, II-development, III-mature, IV-spawning, V-rest or recovery. Although C. (C) articulatus is a total spawner and it reproduce throughout all year, the main reproductive season (maturity and spawning) occurs in the second half of the year (July to December), and coincides with the rainy season. The sex ratio during the entire sampling period was 1:1. The TM50% for both sexes was: LT 55.43 mm, LC 50.70 mm, AT 33.27 mm, AC 28.06 mm and PT 11.86 g. It is suggested that a panoramic observation of the gonad for the establishment of GMS. By using different morphometrics for estimating the Tm50% are given more options to establish minimum catch sizes, besides to facilitate data collection in the field. With these results we contribute to the basic knowledge of reproductive biology of Chiton (Chiton) articulatus, which allow proposing future regulatory measures (i.e., closed season and minimum catch size).

Descripción del desarrollo y el efecto de la alimentación en la estructura de la glándula digestiva de juveniles tempranos de Octopus maya (Mollusca: Cephalopoda) Voss y Solís-Ramírez, 1966

B.Sc. THESIS -- ESTEFANY DEL ROSARIO LOPEZ-RIPOLL, 2010

Histología del manto de Strombus gigas Linnaeus, 1758 (Gastropoda: Caenogastropoda: Strombidae)

El Caracol Strombus gigas: Conocimiento Integral para su manejo sustentable en el Caribe

The populations of Queen conch are overfishing, requiring the histological studies of its tissue,... more The populations of Queen conch are overfishing, requiring the histological studies of its tissue, as the mprphological base to understand the functioning of this organism. The mantle is the responsible tissue to formation of the shell, to chemically and physically interacts with the environment, and it secretes mucus. This work describes the histology of the mantle tissue. The mantle iscomposed by five layer, from the outside (adjacent to the shell) until inside (adjacent to the mantle cavity) are: 1) a squamous epithelium layer, 2) a collagen fiber layer, 3) a connective tisue layer, 4) a layer of muscular tissue, 5) a transitional epithelium. Cytoplasm of the cells of five layer contains collagen.

Histology of foot epithelium of Strombus gigas Linnaeus, 1758 (Gastropoda: Caenogastropoda: Strombidae)

El Caracol Strombus gigas: Conocimiento Integral para su manejo sustentable en el Caribe

El tegumento, compuesto por piel y sus apéndices, forma en conjunto un órgano que recubre el cuer... more El tegumento, compuesto por piel y sus apéndices, forma en conjunto un órgano que recubre el cuerpo, ofreciendo a los tejidos blandos subyacentes (dermis, hipodermis) una cubierta de protección contra lesiones. Además, participa en procesos de locomoción, de interacción física y química con el ambiente y de respiración. A fin de conocer la estructura del pie de Strombus gigas, se realizó éste estudio histológico. Esta investigación ilustra la diferencia epitelial encontrada en la suela del pie y en el lado del pie. El epitelio tegumentario del pie presenta: (1) células columnares con disposición lineal, y (2) un epitelio columnar ciliado seudo-estratificado con disposición lobulada y pareada. El epitelio del lado del pie presenta: (1) Epitelio columnar glandular ciliado (glándula pedal) formando pliegues tubulares, y (2) epitelio columnar seudo-estratificado ciliado, formando sinuosidades pareadas con aristas angulares. La glándula pedal presenta una función lubricante, manifestada por la secreción de mucosa y gránulos; en tanto que los lóbulos en la suela del pie actúan como tractor para la locomoción, característica presente en la clase gasterópoda. :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: Tegument, made up of skin and its appendices, altogether forms an organ that cover the body, offering to underlying soft tissues (dermis, hypodermis) a protection against injuries. In addition, it contributes in processes of locomotion, physical and chemical interaction with the environment and of breathing. In order to know and to understand the structure of foot of Strombus gigas, the histological study of foot was realized. Different epithelia were observed on the foot sole and the foot side. The epithelia of the sole present: 1) In the dorsal surface is formed by columnar cells with lineal disposition, and 2) in the ventral surface presents pseudostratified columnar ciliated epithelia, forming twinned lobule. Side epithelia present: 1) Glandular columnar ciliated epithelia forming tubular folds and 2) columnar pseudostratified ciliated epithelia forming sinuosities with angular borders. The pedal gland at the side of the foot present a lubricant function, showed by the secretion mucus and grains; whereas the lobules in the sole of the foot, operate as tractor for the locomotion; characteristics that are present in the class gasterópoda.

Desarrollo gonádico, ciclo reproductivo y perfiles de progesterona y testosterona gonadal de Octopus maya Voss y Solís-Ramírez, 1966, a lo largo de su historia de vida: neonato, juvenil, subadulto y adulto

PhD. Thesis, 2014

The main objective of this research was to provide reproductive knowledge of Octopus maya Voss y ... more The main objective of this research was to provide reproductive knowledge of Octopus maya Voss y Solís-Ramírez, 1966, through its life history, as support for the recent Octopus Fisheries Management Plan and its respective action line No. 1.4. (DOF, 28 March 2014), which refers to protect the females in reproduction and its reproductive season.

The chapters of this dissertation consist of individual manuscripts, prepared to submit/send to journals in areas like malacology and/or marine science and/or biology of reproduction, except Chapter 1 (general introduction) and Chapter 6 (general conclusion). Although each chapter is intended to be independent and can be understood without reference to the other, there is an overlap of the subject and all chapters are devoted to reproductive and biological aspects consecutive along the life history of O. maya.

Chapter 1 presents a general introduction on reproductive aspects of octopuses (e.g., structures, maturity, hormonal control), the antecedents about reproductive biology to O. maya, the measurements of fisheries management, and the recently created Plan for Management of Octopus Fisheries with its components and action lines. The objectives of this doctoral research are also reflected.

Chapter 2 describes the development of the gonad during early life of O. maya in terms of histology and morphology, using maintenance octopus (culture), since hatching and through the juvenile stage. In this chapter sets the stage for (a) understand the stages from early life history of O. maya, (b) to recognize the length-weight relationship in an attempt to separate the sexes at the beginning of the life history (for maintenance of culture), (c) to determine whether sexual maturation is a process that starts early in this, and (d) to distinguish sequences of growth or "life history stages", based on consistent terminology: juvenile, sub-adult, and adult.

In the Chapter 3 adapts, develops and validates a solid phase radioimmunoassay, using two components commercially available: 125I-labeled hormones and specific antibody. Also, a hormone extraction protocol was described in order to measure the concentrations of progesterone and testosterone in extracts of gonads octopus O. maya. The third chapter provides the tools and methodology for assessing the reproductive endocrine context of organisms moving a stock (recruitment) reproductive (i.e., adults).

Chapter 4 describes some reproductive aspects of O. maya from Sisal, Yucatan, Mexico, such as: (1) sex ratio, (2) the reproductive cycle based on histology and through five reproductive indices and by frequency of gonad developmental stages, (3) the frequency of non- vitellogenic and vitellogenic oocytes, (4) and the mean size of sexual maturity. The possible effect of weather (seasons) on the reproductive aspects of this species in the study area is also analyzed. This chapter provides the basic knowledge of reproductive biology that can help improve the current fishing regulation measures such as closures season (with the reproductive cycle) and minimum landing sizes (the mean size of sexual maturity).

In Chapter 5, the seasonal changes of progesterone and testosterone in the gonads of females and males through annual period are quantified. The relationship between the concentrations of steroid hormones (progesterone and testosterone) to events of the reproductive cycle represented by maturity indices (macroscopic and microscopic) in the octopus O. maya also examined. Since the process of sexual maturation and gonad development in octopus has a hormonal control, finally this chapter shows the relationship between hormones (progesterone and testosterone) with the reproductive cycle of O. maya.

Cite as: Avila-Poveda OH (2014) Desarrollo gonádico, ciclo reproductivo y perfiles de progesterona y testosterona gonadal de Octopus maya Voss y Solís-Ramírez, 1966, a lo largo de su historia de vida: neonato, juvenil, subadulto y adulto. Ph.D. thesis. División de estudios de postgrado, Universidad del Mar, Puerto Ángel.

Ciclo reproductivo del Caracol Pala Strombus gigas Linnaeus 1758 (Gastropoda: Caenogastropoda: Strombidae) del Archipiélago de San Andrés, …

Master of Science, 2004

The lack of direct studies on the reproductive cycle of Queen conch Strombus gigas, has made diff... more The lack of direct studies on the reproductive cycle of Queen conch Strombus gigas, has made difficult to raise agreed measures of regulation to their cycle; that they allow the rational and sustainable use of this communitarian resource for all Caribbean. This thesis investigates by means of the histological analysis of gonad the reproductive cycle and the spawn season of Strombus gigas at south keys of the Archipelago of San Andres, Providence and Santa Catalina, Colombian insular Caribbean. In addition, appear no more than with major organisms to 20 cm of shell total length, the sexes proportion, the mean length of sexual maturity, and the relation shell total length-lip thickness by a linear model. 346 organisms collected from February of 2003 to January of 2004, were analysed. Biometrics data (Shell total length and lip thickness) and samples from visceral mass (gonad and digestive gland) were taken. The sample were postfixed in Bouin’s fixative, processed with standardized histological methods and stained with Harris’s Haematoxylin and Eosin, regressive stain method. Organisms collected are in a range between 200 and 302 mm shell total length, and 1 to 31 mm lip thickness. The linear model for all the year explained a 22% the data variability (Ln[Gc] = -27,750 + 5.308Ln[Lc]). Females and males proportions do not differ from 1:1. The mean length of sexual maturity in shell total length (L50) was 249 mm to females, 234 mm to males and 241 mm to both sexes. In lip thickness (G50) was 17.5 mm to females, 13 mm to males and 13.5 mm to both sexes. Two qualitative graphical schemes of the gonad cycle were designed, by means of which each gonad development stage was identified and described. The reproductive cycle was defined in 5 gonad development stages: Resting, gametogénesis, mature, emission (spawning and ejaculation) and post-emission. Queen conch is a species with gametogenesis, post-spawn and post-ejaculation all the year. Spawn and ejaculation stages appears synchronous to each other, with a gametogenic strategy of intensity low and duration low, indicating a capacity of slow regeneration. The spawn season it happens in two seasons: (1) March-April and (2) September. The actual prohibition of fishing for the Queen conch Strombus gigas at all Colombian Caribbean, allows to capture organisms at the time of spawn of March to April, observed in this study. it is proposed two situations to temporary fishing ban, derivates from results obtained in this study.

Estudio histológico del caracol pala Strombus gigas Linnaeus, 1758

Thesis for: Bachelor of Science, 2001

Six organisms of Strombus gigas were collected at 22°22” North and 89°41” West in Alacranes reef,... more Six organisms of Strombus gigas were collected at 22°22” North and 89°41” West in Alacranes reef, located 135 Kilometers in front to the coasts of the municipality of Progress, in the State of Yucatan, of the Mexican United States, in June of 2001. To know and identify the structural characteristics at cellular and tissue scale to develop a histological atlas of Strombus gigas Linnaeus, 1758. The three males and three females collected presented a length of the shell (of the end of the turn at the end of the sifonal channel) with an average of 228 mm (Standard desviation D.E.=20.4, n=6) and thickness of the lip (in the central part of the lip to 40 mm of the edge of the shell) with an approximated average of 16 mm (D.E.=1.8, n=6). The selected anatomical parts for this study were: Probosis, eye, antenna of the eye, foot, body muscle (females), penis (male), mantle, male gonad, female gonad, digestive gland, style sac, ctenidium, kidney and anal pore. Each animal was removed from its shell and samples were taken of 1 cm3. The samples were fixed for 4 days in Davidson A.F.A. solution, previous to the histological processes. The tissues were washed in 70% ethanol, dehydrated through a graded series ethanols of 70%, 96% and 100%, and embedded in Paraplast paraffin. Sections were cut at six microns of thickness and mounted on albuminized slides. The staining was made with Harris Hematoxylin - yellowish Eosin (HHE2), regressive stain method (modified of Howard y Smith, 1983). All material analized was photographed using a Sony video camera colour of hight resolution join light microscope Carl Zeiss MC-63A.

Reproductive performance in Octopus maya males is affected by thermal stress: A physiological and transcriptomic approach

by Oscar E Juárez and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Cephalopod International Advisory Council "CIAC", Conference 2018At: St Petersburg, FL 12-16 nov, 2018, 2018

Octopus maya endemic to the Yucatan peninsula, Mexico, is an ectotherm organism particularly temp... more Octopus maya endemic to the Yucatan peninsula, Mexico, is an ectotherm organism particularly temperature-sensitive. In females O. maya studies reveal that temperature affects the spawning, number of eggs, fecundity and the viability of embryos. The aim of this work was directed to evaluate the physiological condition, the reproductive success, and transcriptomics of the testis of males O. maya exposed to chronic thermal stress. O. maya males were exposed to different temperatures (24°C and 30°C) for 30 d (PRE-before mating). After thermal exposure, six males of each experimental temperature were mated with females acclimated at 24°C (POST-after mating). In octopuses maintained at 30°C the growth rate and health was negatively affected. An increment in the haemocytes count and a reduction in the oxygen consumption were registered. In octopuses exposed to 30°C, the testis histology showed dilation of the seminiferous tubules, shrinkage of the proliferative stratum and high quantities of acidophilic bodies. The sperm quality showed that high temperatures increments the spermatophores production. The reproductive success assessed through paternity analysis confirmed multiple paternity in this species. In temperatures from 24°C -28°C, paternal contributions were assigned to experimental sires. Meanwhile at 30°C there was no parental contribution of the experimental sires. At transcriptomic level, we identified a total of 85,249 contigs in the testis, where 1,370 contigs were differentially expressed (>= 2-fold) at 30°C. We identified putative proteins that regulates processes as spermatogenesis, gamete generation, response to stress, inflammatory response and apoptosis among others, where, in some cases, the up-regulation and down-regulation of these genes can be linked to sterility in males, and could explain the lack of parental contribution. These results indicate that high temperatures directly affect reproductive performance and success of Octopus maya males.

Comunidad de macroalgas epibiontes del quitón comestible Chiton articulatus (Mollusca, Polyplacophora) del intermareal rocoso del Pacífico Tropical Mexicano

by Laura Regina Alvarez-Cerrillo, OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), and Juliana Gimenez

Conference Paper: X CLAMA (10° Congreso Latinoamericano de Malacología), 1-6 octubre de 2017, Piriápolis, Uruguay, 2017

Las algas constituyen un componente fundamental del ecosistema intermareal rocoso debido a su pap... more Las algas constituyen un componente fundamental del ecosistema intermareal rocoso debido a su papel como productores primarios y fuente de alimento para invertebrados herbívoros. La recolecta incidental de macroalgas epibiontes puede vulnerar la biodiversidad y el ecosistema. Bajo el supuesto que la estructura de la comunidad de macroalgas epibiontes de C. articulatus no difiere de aquella presente en el ambiente, este estudio describe la comunidad de macroalgas epibiontes (riqueza S, diversidad Shannon H’, uniformidad Pielou J’ y dominancia Simpson λ’) extraídas incidentalmente (by-catch) con la pesca de Chiton articulatus. Este molusco poliplacóforo es un herbívoro dominante y endémico del intermareal rocoso del Pacífico Tropical Mexicano (23-15°N), y un recurso con potencial pesquero capturado artesanalmente para consumo humano. Mensualmente, de octubre 2015 a octubre 2016, se recolectaron en total 3313 quitones adultos de siete localidades a lo largo del Pacífico Mexicano en las latitudes: 23°N, 20°N, 19°N, 18°N, 17°N, 16°N y 15°N. El muestreo fue suficiente según estimadores de riqueza específica (Chao2, Jacknife 1 y 2, Bootstrap). En la región se observaron 21 morfotipos (5 costrosos y 16 filamentosos), S=5±1.30, H’=0.42±0.11, J’ =0.61±0.14 y λ’=0.46±0.14. La especie dominante fue Porolithon sp. Los descriptores permitieron agrupar las localidades en dos regiones: Región-1 (23°N, 20°N, 19°N y 18°N) y Región-2 (17°N, 16°N y 15°N). Exceptuando las localidades del margen (23°N:S=6±1.75 y 15°N: S=5±1.38), cada región presentó un valor de riqueza, diversidad y uniformidad negativamente relacionados con la latitud: 20° (S=4±0.69, H’=0.41±0.10, J’=0.67±0.14), 19° (S=5±1.11, H’=0.48±0.09, J’=0.67±0.15), 18°(S=6±1.28, H’=0.51±0.08, J’=0.67±0.07); 17°(S=4±1.48, H’=0.33±0.13, J’=0.56±0.17), 16° (S=5±1.44, H’=0.41±0.09, J’=0.60±0.09) y 15°(S=5±1.38, H’=0.35±0.11, J’=0.52±0.18). El equilibrio encontrado en la comunidad de macroalgas (J’y λ’) brinda un panorama de especies que ocurren en el intermareal rocoso del Pacífico Tropical Mexicano y garantiza la disponibilidad de alimento para herbívoros de esa zona, como Chiton articulatus.

Erosion facing size and latitude in a dominant herbivore polyplacophoran widely distributed in the intertidal rocky shore of the Mexican tropical Pacific

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Laura Regina Alvarez-Cerrillo, and Guillermo Rodriguez Dominguez

The rocky intertidal communities are subjected to physical and biological processes that erode th... more The rocky intertidal communities are subjected to physical and biological processes that erode them, so species require robust armor for their protection. The chitons have an articulated natural armor that provides them protection and robustness; however erosion on its plates has been observed, which can affect their fitness condition and mobility. In order to test the hypothesis that the erosion in chiton plates is directly correlated with the increases in size of the adult population, since the biggest chitons (oldest) have been exposed for more time to environmental factors, herein is used Chiton articulatus (Mollusca: Polyplacophora), the largest dominant herbivorous (reaching 90 mm in length) in the rocky intertidal shore from the Mexican tropical Pacific (23°N to 15°N), where it is endemic. It is investigated whether for adult populations; the old adult chitons have greater coverage and degree of erosion than young adult chitons. Herein were analyzed 1357 adult specimens (<40 mm in length, max=86, min=43) collected haphazardly monthly, from October 2015 to October 2016, in three sites: north (Sinaloa, 23°N), middle (Colima, 19°N) and south (Oaxaca, 15°N). Total length was measured with a vernier caliper (± 0.1 mm) on relaxed and fixed specimens. Area eroded was assigned according to coverage percentage of the worn plates; and erosion degrees by depth (none, moderate and deep). Erosion was presented in the 98% of the sampled chitons. Eroded area was highly erratic, with fluctuations between 0-74%. The major coverage of erosion (45%±29) was presented in the chitons from the north site, compared to the middle and south sites (23%±19 and 25%±20, respectively). The spearman correlation coefficient between size and erosion coverage were weak (r<0.2) at the three localities. Erosion degree was deep (61%) at 23°N, moderate (53%) at 19°N and deep (57%) at 15°N. Contrary to expectations, erosion coverage and degree are independent from the adult length of the chiton. The erosion degrees, moderate and deep, show that the chitons are exposed to different factors that affect their plates, and in turn, can affect their fitness and other physiological processes, a hypothesis subject to additional testing.

Epibionts biodiversity from the basibiont Chiton articulatus (Mollusca: Polyplacophora) through the Mexican Tropical Pacific

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Laura Regina Alvarez-Cerrillo

Ciclo reproductivo de Octopus maya (Cephalopoda: Octopoda) de Yucatán y su utilidad en la implementación de una veda

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Francisco Benítez-Villalobos

Periodo reproductivo de Chiton (Chiton) articulatus (Mollusca: Polyplacophora) de Oaxaca, México

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Q Yasu Abadia Chanona

Adaptaciones morfológicas y digestivas durante los primeros días de vida de los juveniles del pulpo de costa Octopus maya (Voss y Solís-Ramírez)

Gonad development of females Octopus maya and its relationship to sex steroids

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Ruben Montes

Gonad development of female Octopus maya from Sisal, Yucatan, Mexico (Mollusca: Cephalopoda).

Descripción histológica del desarrollo de la glándula digestiva de juveniles tempranos (0 a 30 días) de Octopus maya.

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Rosario Martínez-Yáñez, and Carlos Rosas

Reproductive biology of Octopus maya: Rescuing Arkhipkin´s (1992) maturity scales

by Josefina Santos-Valencia, Reyna Calva Fierro, Maite Mascaró, and OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH)

Cytology of the digestion of Octopus maya early juveniles

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Reyna Calva Fierro

OBSERVATION AND ESTABLISHMENT OF THE GONAD DEVELOPMENT STAGES IN POLYPLACOPHORA: Chiton (Chiton) articulatus, A CASE STUDY

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Q Yasu Abadia Chanona

PROTOCOL FOR RELAXATION, FIXATION AND DISSECTION OF POLYPLACOPHORA GONAD FOR HISTOLOGICAL AND MORPHOLOGICAL STUDIES

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH) and Q Yasu Abadia Chanona

ASPECTOS REPRODUCTIVOS DE UNA POBLACION DE Chiton (Chiton) articulatus (MOLLUSCA: POLYPLACOPHORA) DE OAXACA, MEXICO

PRELIMINARY DATA OF THE GAMETOGENIC CYCLE OF Strombus gigas FROM ARCHIPELAGO OF SAN ANDRES, PROVIDENCIA AND SANTA CATALINA, COLOMBIA (SEAFLOWER BIOSPHERE …

by OMAR HERNANDO AVILA-POVEDA: (AVILA-POVEDA OH), Erick R Baqueiro, and Erick Baqueiro

Proceedings of the Gulf and Caribbean Fisheries Institute, Jan 1, 2005

HISTOLOGICAL STRUCTURE OF Strombus gigas (GASTROPODA: CAENOGASTROPODA: STROMBIDAE)

Proceedings of the Gulf and Caribbean Fisheries Institute, 2005

Effects of chronic thermal stress on the reproductive performance of male Octopus maya

In female Octopus maya the reproductive success has well-defined thermal limits; beyond which, sp... more In female Octopus maya the reproductive success has well-defined thermal limits; beyond which, spawning, number of eggs, fecundity, and the viability of the embryos are reduced. Observations of wild male O. maya suggest that temperatures below 27°C favour their reproductive performance. From these observations we hypothesize that, as in females, the temperature modulates the reproductive performance of adult O. maya males. The study was directed to evaluate the physiological condition, reproductive success, and histological damage in testis of male O. maya exposed to thermal stress, to determine the implications of ocean warming over their reproductive performance. High temperatures (28-30°C) negatively affect the growth and health of male O. maya. In octopuses maintained at 30°C, as a consequence of the thermal stress we observed an increment in the haemocytes number, a reduction in the oxygen consumption rate, and an inflammatory process in the testis. The number of spermatozoa pe...

Complex abnormality combinations between the scleritome and the sclerites of Chiton articulatus (Mollusca: Polyplacophora): new findings to the teratological classification

Zoologischer Anzeiger

Oviducal glands throughout the gonad development stages: a case study of Octopus mimus (Cephalopoda)

Molluscan Research

The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes... more The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes of each section of the ODG of Octopus mimus are described histologically throughout the gonad development stages (GDS). To do this, the epithelial height, stereociliated or non-stereociliated epithelium, nucleus type (pycnotic or non-pycnotic), epithelial secretions and the value range of the macroscopic maturity index (MaMI), which directly involves ODG status, were measured. The ODG are internally constituted of two glandular units (central and peripheral glands) and one set of receptacles (the spermathecae). High epithelia (40 to 80 μm) were observed in both gland units during periods with low MaMI values (&lt; 0.1) corresponding to III-mature and IV-pre-spawning. The stereociliated epithelium was only apparent in II-maturing and III-mature in both gland units. The nuclei were noticeably pycnotic in the central gland during III-mature, IV-pre-spawning and V-spawning, but pycnotic in the peripheral gland only during VI-depletion. The epithelium was disorganised during VI-depletion, while sulphated acid mucin was only present during III-mature in the central gland. The epithelium transformations during the GDS are related to the functions of the gland units and to their multiple secretions. The ODG histology complements the GDS and provides better reproductive status assessment.

Observation and establishment of gonad development stages in polyplacophorans (Mollusca):Chiton (Chiton) articulatusa case study

Acta Zoologica, 2016

Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by perform... more Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by performing histology of some gonad portions. In polypla-cophorans, gametogenesis is not enough to define GDS; further anatomical gonad features are relevant. In most adult polyplacophorans, the gonad is a simple anatomical structure that resembles and operates as one single gonadal aci-nus without glandular structure. These features have gone unnoticed causing inaccurate GDS assignment and, consequently, imprecise reproductive season in polyplacophorans. Here, dissection protocols that allow extracting a compact gonad are established. Emphasizing the anatomical structure of the whole gonad and the displacement of gametes, five GDS were assigned to both sexes of Chi-ton (Chiton) articulatus: I-goniogenesis, II-development, III-ripe, IV-spawning, V-rest. Tissue platelets contribute importantly to GDS assignment and even help distinguishing between males and females. Neither a randomly selected portion of gonad nor a longitudinal section are recommended because it leads to misinterpretation higher than 50% in determining GDS and besides ignores displacement of gametes. A panoramic sweep across a complete transverse-section of each gonad was validated as the best option for establishing GDS. This new methodology was tested on several polyplacophorans species, and seems generally applicable for histological assessment of reproductive cycle and reproductive season in polyplacophorans.

Reproductive traits ofOctopus maya(Cephalopoda: Octopoda) with implications for fisheries management

Molluscan Research, 2016

Octopus maya is the main species caught in Mexico. From September 2007 to June 2008, its sex rati... more Octopus maya is the main species caught in Mexico. From September 2007 to June 2008, its sex ratio, reproductive season, frequency of non-vitellogenic and vitellogenic oocytes, reproductive indices, and size and weight at maturity, were evaluated. The monthly sex ratio was significantly different from 1:1. The major reproductive season occurs during February to June (dry season) in Yucatan. May−June is the common reproductive season to both Yucatán and Campeche populations. Higher frequencies of vitellogenic oocytes (&gt; 50%) were found from January-March and in May. From five reproductive indices, only the macroscopic and microscopic maturity indices were the best descriptors of the reproductive season in females, whilst only the reproductive complex index was the best descriptor in males. The weight at sexual maturity (BW 50%) was 335 g for females and 242 g for males. The size at sexual maturity (DML 50%) was 12.58 cm for females and 7.42 cm for males. It is recommend revising the minimum catch size by following these results. The reproductive traits here evaluated could contribute to the recently created Plan for Management of Octopus Fisheries, in particular action line no. 1.4, which refers to protection of females during breeding, and to their protection throughout the entire reproductive season.

Gonad development stages and reproductive traits of Diadema mexicanum (Echinodermata: Echinoidea) from Oaxaca, Mexico

Invertebrate Reproduction & Development, 2015

Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral... more Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral reefs dynamics. Several reproductive traits of D. mexicanum throughout one year at La Entrega Bay, Oaxaca (15°44′N), in the Mexican tropical Pacific, were analyzed. Maturity index or microscopic maturity index “MI” was calculated. Annual ratio of males to females (1:1) was not significantly different. Five gonad development stages “GDS” (i.e. development, mature, spawning, post-spawning, nutritive) were recognized. The nutritive stage was noticeably later to post-spawning. High values of gonadosomatic index “GSI” in December 2008 and February/March 2009 did not correspond to maturity but to the nutritive stage. MI values ratified the periodicity of each GDS and spawning preparedness. MI was a better descriptor than GSI for reproductive season of D. mexicanum, and probably for all sea urchins exhibiting the nutritive stage. D. mexicanum has a single annual reproductive season (maturity/spawning) from April to October, similar to the population of Panama (9°00′N), without a second season, as proposed previously for the population of Colima, Mexico (19°10′N). Previous disparities in its reproductive season reflect differences of the environments it inhabits, rather than an effect of the latitudinal gradient in the tropical region.

Talla inicial de madurez sexual (Tim) y/o talla de madurez sexual (Tm50%) − medida de manejo pesquero para el poliplacóforo Chiton (Chiton) articulatus: caso de estudio

ABSTRACT

Histology of the select regions of the alimentary system of Strombus gigas (Caenogastropoda: Strombidae) Linnaeus, 1758

American Malacological Bulletin

The histology of the alimentary system of Strombus gigas was examined, focusing on the epithelial... more The histology of the alimentary system of Strombus gigas was examined, focusing on the epithelial and subepithelial connective tissue of the mouth, style sac, digestive gland, and anus. Four structures were chosen because of their functions: (1) ingestion of food (mouth); (2) digestion, absorption, and storage of nutrients (style sac and digestive gland); and (3) elimination of feces (anus). The cilia on the columnar epithelium were dispersed; the cilia on the cuboidal epithelium formed tufts. The glandular epithelium was arranged in acini. The mouth had a pseudostratified epithelium; the style sac had simple cuboidal and stratified epithelia. The digestive gland was glandular and the anus had columnar and pseudostratified epithelia. Fibrous connective tissue was found in the mouth and in the anus. The loose connective tissue occurred in the style sac, digestive gland, and in the anus. Interwoven in the fibrous connective tissue of the mouth and anus were muscle fibers, connective t...

Cytology of the digestion of Octopus maya early juveniles

Seasonal changes of progesterone and testosterone concentrations throughout gonad maturation stages of the Mexican octopus, Octopus maya (Octopodidae: Octopus)

Molluscan Research, 2015

ABSTRACT Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya... more ABSTRACT Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sisal in Yucatan State, Mexico, were investigated by radioimmunoassays and in relation to four gonad maturation stages (GMS) and to the reproductive cycle, as represented by two maturity indices (microscopic ‘MiMI’ and macroscopic ‘MaMI’). According to the GMS and the maturity indices, the reproductive season of O. maya from Yucatan occurred from February to June. In females, P4 and T displayed the same pattern, with a tendency to increase at the same time, although on average, P4 had seven-fold higher concentrations than T. In contrast, P4 and T in male gonads displayed a different pattern, where T concentrations were relatively stable throughout all of the study months. In the female gonad P4 was lowest (close to 0 pg g–1) during both developing (GMS-I) and maturing (GMS-II) stages, and increased (189 ± 53 pg g–1) approaching the mature stage (GMS-III) to a maximum value of 611 pg g–1. Concentrations of T in the male gonad were lowest (106 ± 9 pg g–1) during the maturing stage (GMS-II) and increased up to the mature stage (GMS-III), reaching a maximum of 440 pg g–1. Pearson&#39;s correlation (r) between hormones and maturity indices showed strong relationships for females (around 0.4 and −0.7; p &lt; 0.05), but there were negligible or weak relationships for males (0.2 and −0.1; p &gt; 0.05). Hormone correlations in females were inverse with MaMI and direct with MiMI. Our major findings showed that gonadal P4 levels were elevated during GMS-III and GMS-IV (i.e. periods of vitellogenic oocytes), where the characteristic aspect is an ovary with very high oocyte diameters, with the primary follicle cells deeply infolded in the ooplasm for yolk synthesis. These results suggested a synchrony between P4 and the process of folliculogenesis, and in turn, vitellogenesis.

Morphological, physiological and behavioral changes during post-hatching development of Octopus maya (Mollusca: Cephalopoda) with special focus on the digestive system

Aquatic Biology, 2010

Histological structure of Strombus gigas (Gastropoda: Caenogastropoda: Strombidae)