Carlos Alejandro Echeverría

Factors influencing spatial patterns of molluscs in a eutrophic tropical bay

r.a.f. neves, c.a. echeverria, l.a. pessoa, p.c. paiva, r. paranhos and j.l. valentin Programa de Pós-Graduação em Ecologia, Departamento de Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, CEP 21941-902, Brazil, Laboratório de Pesquisas Costeiras e Estuarinas, Núcleo Interdisciplinar UFRJ-Mar, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, Instituto Virtual Internacional de Mudanças Globais (IVIG–COPPE, UFRJ), Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia, Universidade Federal do Rio de Janeiro, Brazil, Programa de Pós-Graduação em Biologia Marinha, Departamento de Biologia Marinha, Instituto de Zoologia, Universidade Federal Fluminense, Laboratório de Polychaeta, Departamento de Zoologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Laboratório de Hidrobiologia, Departamento de Biologia Marinha, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Laboratório de Zooplâncton Marinho, Departamento de Biologia Marinha, Instituto de Biologia, Universidade Federal do Rio de Janeiro

Composition and biomass of shallow benthic megafauna during an annual cycle in Admiralty Bay, King George Island, Antarctica

Composition and biomass of an Antarctic megafauna community were studied during a discontinuous 12 months cycle (March–December 1999 and December 2000–March 2001) at two stations (12 and 25 m depth) in Admiralty Bay, King George Island, Antarctica. During this period iceberg impacts were monitored in order to analyse their role in structuring the community. Organic matter content of the sediment showed a seasonal cycle for both depths, with lower values during winter and higher in summer. Composition and biomass of the megafauna were comparable to those described in previous surveys for the maritime Antarctica. Interannual or summer/winter changes in the density or biomass of the megafauna community were not significant, although significant differences between depths occurred during the whole survey. The observed community composition can be the considered result of a continuous invasion from a deeper fauna, constrained at shallower waters by the effects of ice and storms.

A new mini box corer for sampling muddy bottoms in antarctic shallow waters

A new Mini Box Corer (MBC-GEAMB) was developed for bottom sampling in Antarctic shallow waters down to 100 m depth from a small vessel. It consists of a detac hable stainless steel box with a total sampling are a of 0.0625 m 2 , and a closing arm with a detachable blade without a n external frame. MBC allowed stratified bottom sam pling and good quality samples comparable to those obtained t hrough diving. A comparison between the MBC-GEAMB a nd a 0.056 m 2 van Veen grab (VV) was undertaken for the benthic macrofaunal composition in Admiralty Bay, King George Island (Antarctica). MBC and VV samples were taken from three depths (20, 30 and 60m) in two si tes. Total densities sampled with the MBC were up to 10 times higher than those obtained with van Veen grab. VV s amples might lead to faunistic abundance underestimation c ompared to the MBC samples. Besides, MBC showed a h igher performance on discriminating different sites as re gards total macrofaunal density. It is suggested th at MBC could be employed as an efficient remote sampling device for shallow-waters where direct sampling by SCUBA w as not advisable.