TABLE CONTENTS

Free-living Marine Nematode Communities from Patagonian Littoral
Coasts
Pastor, C.T. (1), V. Lo Russo (1), C. Harguinteguy (1), H. Zaixso (2) & E. Gómes Simes (2)
(1) Centro Nacional Patagónico (CONICET). Boulevard Brown 2825 U 9120 Puerto Madryn, Chubut,
Argentina; (2) UNPSJB Ciudad Universitaria Km. 4 CP 9000 C. Rivadavia, Chubut, Argentina.
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) to 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 supported by PNUD-GEF- Secretaría de Medio Ambiente de Nación-
CONICET, Argentina.
5 th International Congress of Nematology, 2008 116