BENTHIC MACROINVERTEBRATES COMMUNITY STRUCTURE IN PATAGONIAN LAKES

D.A. AÑÓN SUÁREZ, M.C. DIÉGUEZ AND N. BACCALÁ.

Santa Fe, Nuevo Mexico, USA.

Simposio; ASLO/NABS Summer Meeting 2010; 2010

ASLO/NABS

BENTHIC MACROINVERTEBRATES COMMUNITY STRUCTURE IN PATAGONIAN LAKES Benthic organisms are important components of lakes’ communities and represent important links in freshwater food webs. They are often the most important food source for game and commercial fisheries. We searched for patterns in the composition, distribution and abundance of the benthic invertebrates in Patagonian lakes and assessed their relationships with physical-chemical variables and trophic status. Samples were collected from thirty tree lakes belonging to the Río Negro and Chubut provinces of Argentina. The study lakes are spread along a strong environmental gradient of rainfall. The recorded taxa were mainly chironomids, annelids, amphipods, nematods, gastropods, bivalves, trichopterans and odonates. Characteristically, chironomids and oligochaetes showed high population densities. Redundancy analysis identified two major groups within the studied lakes: “steppe” lakes (n=8) and "mountain" lakes (n=25). Steppe lakes are relatively shallow, have higher Chl a, DOC and pH values and tend to exhibit higher individual densities while, mountain lakes have a richer community composition (i.e., higher number of taxa). The abundance of the most frequent taxa (chironomids, oligochaets and leeches) increased with Chl a, pH and DOC.