Ecology of the Asian clam, Corbicula fluminea (Muller), and its impact on the benthic invertebrates in Guajataca and La Plata reservoirs, Puerto Rico

Corbicula fluminea (Müller, 1774) is one of the most invasive freshwater bivalves. It is non-native to America, where it has impacted the benthic macroinvertebrates and phytoplankton communities of many lakes. The first report of this species in Puerto Rico was from Cayey River in 1998. By 2000, populations estimated at 10 individuals/m2 were reported at La Plata and Cidra reservoirs. Since 2001, this species and its effect on the benthic macroinvertebrates have not been monitored. The C. fluminea populations in Guajataca and La Plata reservoirs were sampled three times during early Spring of 2011. Samples were taken with an Ekman dredge at Lacustrine, Transitional, and Riverine stations, at depth ranging 0-6 meters. Samples were sieved through 0.5 mm, preserved and transported to the laboratory for analysis. Benthic invertebrates were counted and identified to the lowest possible taxonomic level. The relative abundance of C. fluminea in both reservoirs was <5% of the total benthic macroinvertebrates. The estimated mean density of C. fluminea was 1,754/m 2 in Guajataca Reservoir and 204/m2 in La Plata Reservoir. Most of the individuals were small and juveniles (less than 13 mm). The benthic macroinvertebrate communities in both reservoirs were dominated by the gastropod Tarebia granifera and the entoproct Urnatella gracilis. This is the first systematic and ecological study on the zoobenthic community of reservoirs conducted in Puerto Rico and sets a baseline for future studies in reservoirs of the Island.