Free-living Marine Nematode Communities from Patagonian Littoral Coasts

C.T. PASTOR; V. LO RUSSO; C. HARGUINTEGUY; H. ZAIXSO; E. GÓMES SIMES

Brisbane, Australia.

Congreso; 5th International Congress of Nematology; 2008

Asociación Internacional de Nematólogos

This talk will describe a baseline study on nematode biodiversity from three different latitudes: San Antonio Oeste, 40ºS (Rio Negro); Puerto Madryn 43ºS (Chubut) and Comodoro Rivadavia (Chubut) 45ºS, in four urban coastal cities, in contrast with pristine areas.This project titled: "Biodiversity of meiofauna communities in sand beaches of Río Negro and Chubut" had three main objectives: a) To contribute to the biodiversity knowledge of meiofauna and nematodes on Rio Negro and Chubut province coasts. b) Characterize, using communitarian structures the degree of disturbance in four urban coastal cities. c) To form doctorate students.Seven littoral areas have been sampled at the three latitudes. The samples have been fixed in 5% formalin with rose Bengal in the field. The geographical position (GPS), salinity, temperature, granulometry, organic matter, DPR layer and dissolved Oxygen have been taken. Nematodes were extracted using the elutriation/decantation/LUDOX TM method and specimens mounted on slides. The Nematodes found were identified up to the lowest taxonomy level possible, and photographs were taken using a Photomicroscope. For nematode identifications the keys of Platt & Warwick and Warwick et al. were used.The differences in meiofauna and nematode species composition between latitudes and environments were analyzed by multivariate methods. As main results we found that Nematodes were the most abundant taxa at the three latitudes. The environmental parameter showed in urban areas, a decrease in salinity at high littoral levels and a DPR layer near to the sediment surface, contrary to the expected for Patagonia coasts. Detailed information about species found plus dominant genera/species at each latitude will be presented as well. The paradigm of two different biogeography units for Patagonia coasts is confirmed for meiofauna and in particular for free-living marine nematodes.This project was support by PNUD-GEF- Secretaría de Medio Ambiente de Nación- CONICET, Argentina.