Attenuated Reproduction of Strombus gigas by an Apicomplexa Parasite

The queen conch is a marine resource of ecological and economical importance in the Caribbean region that suffers a reduction of its populations. An intense and generalized sporozoan infection was detected in populations from various Caribbean countries. The goal of this study was to establish a relationship between occurrence of an Apicomplexa parasite and reproduction. Conchs sampled were adults with a lip thickness 6 mm. A sample of 1 cm 3 , including digestive gland and gonad was processed through standard histological techniques. Sections were stained with a trichrome technique. A quantification of occurrence of the parasites was done counting the total of the different stages observed in three fields on five sections at 400x magnification. ANOVA and Tukey test were used to establish the significance of the differences in occurrence between months. Canonical variate analysis between stages of parasites and frequency of reproductive stages was made. Gametogenesis and spawn were always low, undifferentiated was the dominate stage. With the principal component analysis a positive correlation was established between parasite abundance and undifferentiated stage, and negative correlation was observed of parasite abundance with maturity and spawn stages. A General Liberalized Model analysis showed that undifferentiated organisms are the dominant stage the year through. This analysis shows how gametogenesis, maturity and spawn increase as the number of parasites decreases. These findings suggest that the occurrence of Apicomplexa could be a factor that affects the gonad development in S. gigas from San Andres Inland.