Erick Baqueiro Cárdenas

COCCIDIAN (APICOMPLEXA) PARASITE INFECTING STROMBUS GIGAS LINNÉ, 1758 DIGESTIVE GLAND

Abstract This study reports on a new parasite of the digestive gland of the queen conch, Strombus gigas. An intense and generalized sporozoan infection was detected during a reproductive study of S. gigas in San Andres island (Colombia). The parasite was found in the digestive gland of every sampled S. gigas, with a heavy intensity of infection (invasion of every cell) in many animals. The infection of the digestive gland began in the cryptic cells and later secretory cells were also infected, giving way to discharge of sporocysts to the stomach through the digestive gland ducts. Apicomplexa-like trophozoites were embedded in the digestive gland epithelial cells and attached to host cell wall by their conoid end. Several stages were detected: trophozoites, sporocysts, and gamonts containing macrogametes or microgametes. Given the presence of multiple stages at the same time, the entire life cycle of the parasite is assumed to occur within the same host and tissue. The taxonomic position of the parasite should be ascertained by DNA analysis.

Eye Lens Structure of the Octopus Enteroctopus megalocyathus: Evidence of Growth

ABSTRACT The need for age determination for the proper management of octopus fisheries has directed research attention to the few hard structures in the octopods soft body, beak, statoliths, and the vestigial shell. So far, none of these structures have proved reliable or practical for the purpose. Eye weight, pigment, and nitrogen content have been used successfully in age determination of vertebrates. Given the structural similarity of lenses between octopus and vertebrate, we explore the possibility of using octopus eye lens weight, diameter, and structural marks as age indicators. The lenses of 228 octopi were obtained from the commercial catch from Ancud and Quellén, in Chiloe, Chile. They were measured, weighed, and prepared for histological analysis of the concentric lines structure. The prehatching nucleus was identified, and the total number of lines counted. The lines start to form in the prehatching larvae. Lens diameter and weight showed a much smaller variation than body length or weight, with an apparent correspondence of size or weight classes of body measurements to a lens diameter or weight.

REPRODUCTIVE STRATEGIES OF THE EASTERN OYSTER CRASSOSTREA VIRGINICA (GMELIN 1791) IN TROPICAL LAGOONS OF THE MEXICAN GULF OF MEXICO

ABSTRACT The oyster fishery is 1 of the most important coastal fisheries in Mexico. Management is based on a minimum legal size of 80 mm and several seasonal bans that vary along the coast of the Gulf of Mexico. We describe the gonad development cycle of Crassostrea virginica (Gmelin 1791) along the Mexican coast of the Gulf of Mexico for 5 lagoons for the years 2000 and 2004, between latitudes 21°41′16.75″ N and 18°23′51.08″ N. Significant differences in duration and intensity were observed among reproductive stages associated with different environmental conditions. Gametogenesis and mature stages correlated positively with temperature and total chlorophyll, respectively. Spawning correlated negatively with salinity in both years. Maturity correlated positively with total chlorophyll levels. The reproductive stages varied from seasonal, a few months, to continuous throughout the year. Recovery, expressed as the number of organisms in postspawning and resting stages, was fast for populations that presented constant gametogenesis and spawning, with less than 50% of the population in postspawning and resting stages. Environmental fluctuations in total chlorophyll are the regulating factors for gametogenic activity, rather than latitudinal temperature variations. This makes monitoring environmental conditions in the lagoons or gonad development a necessity to predict reproduction and recruitment for proper management of the oyster resource.

GONAD DEVELOPMENT AND REPRODUCTIVE PATTERN OF THE FIGHTING CONCH STROMBUS PUGILIS (LINEÉ, 1758) (GASTROPODA, PROSOBRANCHIA) FROM CAMPECHE, MEXICO

Abstract The processes of gonad development through a year are analyzed for Strombus pugilis from Seybaplaya, Campeche. During gametogenesis second order oocytes appear close to the wall of the follicles, with a diameter 90–250 μm. The cytoplasm is granular, the nucleus is located on the periphery, with a diameter of 15–35 μm, a nucleolus 7–8 μm. Spermatozoids have an acrosome of 5–7 μm, shaped like a coma. In females gametogenesis was registered in two pulses, with 2 peaks of 60%, February to June and September to October. Mature females were found during the 8 months of sampling with peaks during May and August (80%). Spawning was discontinuous, suggesting storage of mature gametes for the right time to spawn. In males gametogenesis was present in a low percentage from March to October, with a maximum of 20%. Maturity was present on just a 10% during July, with constant spawn through the year. Copula has been observed only during egg laying seasons; males seem to keep mature sperms in the prostate gland. Strombus pugilis from the coasts of Campeche presented a fast gonad recovery for males, requiring longer for females. Having missed most of the autumn and early winter months leaves a big gap on the processes of gonad recovery and early gametogenesis. Apparently there is no correlation between salinity, temperature and the reproductive cycle, but this population has the potential for reproducing through the year.

Attenuated reproduction of Strombus gigas by an Apicomplexa: Emeriidae-like parasite in the digestive gland

An intense and generalized sporozoan infection was detected in every population of the queen conch, Strombus gigas through the Caribbean. In this contribution we establish the relationship between occurrences of an Apicomplexa: Emeriidae-like organism and reproductive activity at San Andres archipelago, Colombia. Occurrence of the parasites was estimated counting the feeding stage Merozoites and cysts Sporozoites at 40× magnification. Nonmetric multidimensional scaling analysis (NMDS) was made to correlate the parasites stages abundance with frequency of the reproductive stages. Gametogenesis and spawning were always low coinciding with high numbers of Merozoites, a positive correlation was established between parasite abundance with reabsorption and undifferentiated stages, and negative correlation was observed between parasite abundance with maturity and spawning stages. The nonmetric multidimensional scaling (NMDS) shows that gametogenesis, maturity and spawning increase as the number of parasites decrease, factor that could be threatening reproduction of S. gigas through the Caribbean.