Distribución y dinámica poblacional de la almeja asiática Corbicula fluminea (Bivalvia, Corbiculidae) en ríos de Uruguay

The Asian clam (Corbicula fluminea) is a bivalve native to southeast Asia, introduced into the River Plate Basin to the end of the sixties. Since then, it has invaded a large number of watercourses in Brazil and Argentina, until reaching Venezuela and Colombia; its current distribution in Uruguay is poorly known. In this paper, we analyze the spatial distribution and population characteristics of C. fluminea in the basins of the South-Central and Eastern regions of Uruguay, in relation to abiotic variables. Sampling was conducted during one year in a bimonthly basis, and abundance, growth and mortality were estimated in five sites in the Santa Lucia river basin. The incidence of the Asian clam in the region was 50%. The probability of occurrence and abundance increased with the percentage of sand in the sediment and decreased with that of gravel. Slow growth rates, high body sizes and low mortalities were observed in fine sediments (sands and silts), following opposite trends in coarse sediment (gravels). Growth and mortality parameters were not correlated with density, suggesting that this population would be primarily regulated by environmental factors. C. fluminea could continue its expansion in Uruguay, invading sandy sectors of watercourses with low percentages of gravel and silt.