Abstract

The queen conch Strombus gigas is a marine resource of ecological and economical importance in the Caribbean region that suffers a reduction of its populations in most Caribbean countries. An intense and generalized sporozoan infection was detected in Strombus gigas populations from various Caribbean countries. The parasite, apparently a Coccidian, Apicomplexa was observed on histological sections of the digestive gland of every sampled organism throughout the various sites: in the samples from San Andres, Colombia; Guadeloupe and St. Barthelemy, French West Indies; Alacranes reef and Chinchorro bank, Mexico; Parguera, Puerto Rico; Margarita Island, Venezuela. To the present light-microscopy analysis, the parasites from all localities could be the same and apparently, they complete their cycle in the digestive gland tissue. The parasite was abundant in Puerto Rico, Colombia and Mexico samples, coinciding with observed anomalies in reproductive cycle, reduced gametogenesis and maturity in Alacranes, Mexico (20-40%) and no gonad activity was observed in conchs from San Andrés. The damage to the digestive diverticula begins in the cryptic cells and attains secretory cells later, giving way to discharge of cysts to the stomach through the digestive gland ducts. Various stages are identified. Five different stages were identified: Apicomplexa-like trophozoites, gametocysts, gamonts, gamets and oocysts. Given the presence of multiple stages at any time a re-infection and the life cycle is asumed to occurred within the same host. These results raise several questions: Given the generalized infection at so distant sites, if the parasite is the same, are S. gigas populations more connected than it has been supposed? What are the environmental factors inducing such an intense and generalized infection? What is the impact on recruitment and therefore on the fishery? It is necessary to identify the geographic distribution of this parasite, to discriminate damages to the digestive gland from the physiological cycle destruction of digestive gland cells; to evaluate its impact on the reproductive activity

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