Environmental factors affecting macroinvertebrate assemblages from Bañado Carilauquen.

SCHEIBLER, E.E.; CIOCCO, N.F.

La Punta, San Luis, Argentina

Congreso; XXVII Reunión Científica Anual de la Sociedad de Biología de Cuyo.; 2009

Sociedad Biológica de Cuyo

Bañado Carilauquen (BC) is part of the Laguna Llancanelo basin, area relevant to biodiversity conservation and oil production. Aims were to survey macroinvertebrate pleuston and benthic communi- ties and to examine how species richness and density respond to spatial changes and water characteristics. Biological samples and environmental parameters were taken seasonally during summer/2000-spring/2001 in 5 reaches of BC. In all, 47 taxa were identified, mainly insects. A growing gradient of conductivity and hardness was confirmed between headwaters (HD; relatively soft waters) and outlet (OL; very hard and saline waters). Highest taxonomic richness values were recorded at HD or nearby reaches, and lowest at OL. Benthos and pleuston were more similar to each other at HD and OL than in the middle reaches, probably in response to higher environmental stability at the gradient extremes (HD, OL). A decline in richness and density was observed from HD to OL. Berosus sp., Chironomus sp., Bembidiina, Dolichopodidae, Tabanidae, Nematoda and Heleobia parchappii showed affinity for hard waters such as those of OL, whereas Metrichia sp., Oxyethira sp., Cricotopus sp., Dicrotendipes sp., Polypedilum sp., Lancetes biremis, Hyalella curvispina, Heleobia hatcheri, Chilina mendozana and Dugesidae were present at HD, showing preference for soft, transparent and warmer waters. Excepting headwaters, very hard, eutrophic, polysaprobic and contaminated waters such as those of BC represent critical conditions for the development of macroinvertebrate assemblages.