Fabiola Lango-Reynoso

Reproductive patterns of the Pacific oyster Crassostrea gigas in France

Summary In France, national management programs focus research on understanding reproductive factors in Crassostrea gigas to confront problems of the oyster industry. However, little information has been documented in which reproductive patterns include sexual changes. The reproductive cycle of oysters at three sites of the Atlantic coast of France was examined from 1996 to 1998, and the seasonal variations in oocyte size-frequencies, and sex ratio were described. The results showed a synchronism within the population concerning reproductive behavior. Young oocytes are generated after spawning and show no apparent changes during winter. Growth of oocytes begins in spring and cells reach maturity in April-May and are ready for a single spawning season in June-July. Oocytes that were not released during spawning are reabsorbed within the gonad. The significant difference between sites is that spawning occurred 1 month later in the southern area. A modal analysis showed that oocyte populations in the sample individuals are primordially bimodal, but with polymodal occurrences in June-July, in some cases. Irregular alternative sexuality was detected at all sites, and hermaphrodites appear to be a transition phase that allows changes from male to female during early spring. Previous observations, together with the study of the development of oocyte cohorts over time, permit a hypothetical model concerning the kinetics of gametogenesis in C. gigas. The model suggests that primary oocytes are generated from energy supplied from degenerating, as well as young oocytes that do not reach the mature stage within the gonad during autumn-winter. It seems that, during vitellogenesis, there is disintegration of smaller cells coupled with transfer of energy to the larger oocytes, which continue to grow and mature.

Elements of reproductive strategy in oysters, Crassostrea gigas, from the “Rade de Brest”, France

Summary In France oyster farming is very important from an economical point of view (150,000 t/y), but curiously, no data exist concerning the reproductive cycle of the cultivated species Crassostrea gigas. New selection programs in oyster hatcheries are based on the use of adults having proper characteristics (growth, resistance to diseases and known sexuality) for which we need to know how sex determination can be influenced by environmental factors. C. gigas individuals from a natural population of the “Rade de Brest”, Brittany, France, were examined every 2 weeks during a 2-year period from February 1996. Reproductive parameters including their condition index and their sex ratio were determined, and seasonal and annual differences assessed. Under microscopic examination the presence of sperm or oocytes or the absence of gametes allowed us to define individuals as male, female, hermaphrodite or sexually undetermined oysters. The maximum percentage of female oysters, 70%, was found in July, whereas mal...

Oocyte cohort analysis: reproductive patterns of Crassostrea virginica (Bivalvia) in tropical lagoons of the Gulf of Mexico

The Eastern oyster, Crassostrea virginica, was collected during 2004 from two tropical lagoons (1 – Laguna Tamiahua; Tantalamos, LT-1 and La Dalia, LT-2; and 2 – Laguna Grande; Vega de Alatorre, LG) in the Gulf of Mexico to document sexual and reproductive changes. Evolution of oocyte cohorts was described by analyzing frequency distributions of oocyte diameters and sex ratios. Each population (LT-1, LT-2, and LG) showed a distinct pattern in the number of cohorts, eight at LT-1 and LG, and five at LT-2. The main reproductive period was January through September with continuous spawning events and peaks in March and July. From modal analysis, oysters at LT-1 and LG, sites with a mean annual temperature >27°C, produced oocytes at a rate three times faster than oysters at LT-2, a site with a lower mean annual temperature. This suggests, apart from differences in spawning intensity among sites, a threshold temperature to attain maximum reproductive activity. Energy reserves were stored during lower temperatures, and it appears that the reserves are used later for gametogenesis. Higher frequency of hermaphrodites occurred throughout the reproduction cycle, suggesting continuous changes of sex from male to female, likely to be a reproductive strategy to maintain high rates of gametogenesis. These findings provide a better understanding of the reproductive biology of C. virginica in tropical areas.

Cultivo del coral cuerno de alce Acropora palmata en un sistema recirculado utilizando agua de mar sintética

This study assessed the survival of Acropora palmata fragments under controlled experimental conditions over a period of four months in a recirculating artificial seawater system. The coral fragments (5-9 cm long) were fixed in aragocrete and placed in an aquarium under a photoperiod of 12 h light: 12 h dark, using 150 W lamps (10000 K). The survival rate was 58%. Fragment mortality occurred mostly during the first month, which was associated to the process of bleaching stress as a result of fragmentation. These results showed that the conditioning in captivity of A. palmata using artificial seawater has potential as a viable tool to help the conservation of this species.

Helminth Parasite Communities of Two Scorpaena spp. (Scorpaenidae) From Reefs of Veracruz, Mexico

Scorpaena brasiliensis and S. plumieri are relevant fish species in reef systems, but little is known about their parasitic helminth communities and their structure. This paper describes such community in terms of species richness and diversity. A helminthological study was conducted on 33 specimens of S. brasiliensis and 36 S. plumieri, captured in the Pajaros and Cabezo Reefs, in the Veracruz Reef System National Park (VRSNP), Veracruz, Mexico. The helminth community structure was analyzed in both host species. A total of 10 parasitic species was registered in S. brasiliensis (5 digeneans, 1 cestode, 3 nematodes, 1 acanthocephalan), while S. plumieri hosted 11 species (4 digeneans, 1 monogenean, 1 cestode, 4 nematodes, 1 acanthocephalan), with 8 common species. The species with the highest prevalence were Pseudocapillaria (Icthyocapillaria) sp., with 18.2% and 19.4% in S. brasiliensis and S. plumieri, respectively. Component community richness for S. brasiliensis was S = 10, with Shannon index diversity value of H’ = 2.08. For S. plumieri, such values were of S = 11 and H’ = 1.91. Richness and diversity in the component and infracommunity levels for both hosts are lower than in other parasite communities of marine fishes in the southern Gulf of Mexico.

Helminth Parasites of Scorpaena brasiliensis and S. plumieri (Perciformes: Scorpaenidae) from reefs of Veracruz, Mexico, Southern Gulf of Mexico

6 7 1Laboratorio de Investigación Acuícola Aplicada, Tecnológico Nacional de México, Instituto 8 Tecnológico de Boca del Río. E-mail: jesusmontoya@itboca.edu.mx 9 10 ABSTRACT 11 Both S. brasiliensis and S. plumieri are relevant species in reef systems, but little is known about 12 their parasitic helminths and community structure. This work describes such community in terms 13 of species richness and diversity. A helminthological study was conducted on 33 specimens of S. 14 brasiliensis and 36 of S. plumieri, captured in the Pájaros and Cabezo Reefs, in the Veracruz Reef 15 System National Park (VRSNP), Ver., Mexico. The helminth community structure was analyzed 16 in both hosts. A total of 10 parasitic species was registered for S. brasiliensis (trematodes, 5; 17 nematodes, 3; cestodes, 1; acanthocephals, 1). S. plumieri hosted 11 species (trematodes, 4; 18 nematodes, 4; monogeneans, 1; cestodes, 1; acanthocephals, 1), with 8 common species. Overall, 19 parasites had prevalences < 20%, as Pseudocapillaria (Icthyocapillaria) sp., with 18.2% and 20 19.4% in S. brasiliensis and S. plumieri, respectively. Community component richness for S. 21 brasiliensis was S=10, with Shannon index diversity value of H’=2.08. For S. plumieri, such values 22 were of S=11 and H’=1.91. The richness and diversity in the components community and 23 infracommunity of parasitic helminths for both hosts are lower than in other parasite community 24 of marine fish Southern Gulf of Mexico. 25

Biosorption of Cadmium by Non-Toxic Extracellular Polymeric Substances (EPS) Synthesized by Bacteria from Marine Intertidal Biofilms

Cadmium is a major heavy metal found in polluted aquatic environments, mainly derived from industrial production processes. We evaluated the biosorption of solubilized Cd2+ using the extracellular polymeric substances (EPS) produced by Bacillus sp. MC3B-22 and Microbacterium sp. MC3B-10 (Microbactan); these bacteria were originally isolated from intertidal biofilms off the coast of Campeche, Mexico. EPS were incubated with different concentrations of cadmium in ultrapure water. Residual Cd2+ concentrations were determined by Inductive Coupled Plasma-Optic Emission Spectrometry and the maximum sorption capacity (Qmax) was calculated according to the Langmuir model. EPS were characterized by X-ray photoelectron spectroscopy (XPS) before and after sorption. The Qmax of Cd2+ was 97 mg g−1 for Microbactan and 141 mg g−1 for MC3B-22 EPS, these adsorption levels being significantly higher than previously reported for other microbial EPS. In addition, XPS analysis revealed changes in structure of EPS after biosorption and showed that amino functional groups contributed to the binding of Cd2+, unlike other studies that show the carbohydrate fraction is responsible for this activity. This work expands the current view of bacterial species capable of synthesizing EPS with biosorbent potential for cadmium and provides evidence that different chemical moieties, other than carbohydrates, participate in this process.

Helminth Parasites of Red Lionfish, Pterois volitans from the Veracruz Coral Reef System, Mexico, Southern Gulf of Mexico

A helminthological survey was conducted on 78 red lionfish, Pterois volitans, collected in the Veracruz Reef System National Park (VRSNP). Register: trematodes (5 spp.), cestodes (1), and nematodes (2). Prevalence per species < 30% and mean intensity < 6.0. Three new host records are reported herein. The red lionfish is infected by species of endoparasites generalist and played a role as accidental host.