Abstract

The queen conch, Strombus gigas distribute itself on seagrass beds, especially during the juvenile stage. Because conch feeds on epiphytes attached to the Thalassia and other microalgae it is important to determine quantity of food available on different environments. At Punta Gavilan (PG) and Banco Chinchorro (BCH) corrals to culture conch were installed in areas of "thalassia" (T) and "thalassia+sand" (T+A). To evaluate vegetative biomass of each site, monthly collections of vegetative coverage were carried out using a 0.01 m2 cuadrant during the period October 1993 and March 1994. At each site one sample and three replicas were obtained. Biomass of seagrass and epiphytes were determined using the method of Nugent (1978). In PG, biomass of Thalassia and its epiphytes obtained an average of 40.5 g.dw.m2 and 29.4 g.dw.m2 in T as well as T+A sites respectively, and in BCH biomass obtained were 23.4 g.dw.m2 for T and 16.2 g.dw.m2 for T+A. Comparison of total biomass of collection sites showed that in BCH vegetative biomass is grater than in PG. In PG food (epiphytic algae) availability for juvenile conch is significantly higher, showing that marginal growth of conch is grather at T+A, with an averege of 2.150 mm monthly, for BCH there was no significant difference among sites and average growth was 1.582 mm monthly.

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