Influence of environmental and anthropic factors in the oyster population of Crassostrea virginica (Bivalvia: Ostreidae), in Cauto River, Cuba

In Cuba, the "bottom oyster" (OF) Crassostrea virginica (Gmelin, 1791) contributed during 2008-2013 more than 30% to the national catch of oysters of the genus Crassostrea. From an initial non-exploited biomass (>= 1,500 t), the Cauto River population was reduced to 277 tin 2014. The objective of this study was to determine the main natural and anthropic factors that have affected the quality of the habitat and decreased the population of C. virginica in the Cauto River. Hydrological and biological-population data were obtained, before and after an accidental spill of residual waters from a sugar industry in the region, which together with abundant rainfall and terrigenous fluvial contributions drastically affected the quality of the water, registering values of turbidity (> 8 FTU), dissolved oxygen (< 3 mgO(2) L-1), chemical oxygen demand (COD, > 11 mgO(2) L-1) and salinity (< 10 UPS), which reduced survival (< 40%) and abundance of OF (< 30 oysters/m(2)). Natural and anthropic factors that affect the habitat and the oyster population were identified. Indicative reference values of good physicochemical quality of the water are proposed in sites where natural banks of C. virginica exist, or if their cultivation is intended.