Abstract

BONICELLI P., Jessica; LOPEZ P., Diana; OCHOA L., Noemí  and  SHREEVE, Rachael S.. Zooplankton community structure and its association with the phytoplankton and water masses from the Bransfield strait and elephant island during 2006 austral summer. Ecol. apl. [online]. 2008, vol.7, n.1-2, pp.159-164. ISSN 1726-2216.

During the austral summer of 2006 the spatial distribution of zooplankton and its association with some abiotic (water masses) and biotic variables (phytoplankton) were investigated in the Bransfield Strait and to the southeast of Elephant Island, Southern Ocean. The zooplankton community was mainly composed of copepods; the main species present were Metridia gerlachei and Ctenocalanus sp. Nearest neighbor cluster analysis of zooplankton indicated the presence of three major station groupings which were influenced by water masses. One group was found in the southeast of the Bransfield Strait and Elephant Island, where the Weddell water masses predominated. This showed low phytoplankton abundance, whilst zooplankton abundance was high. This may be an example of top down grazing control. A second group was found in the northwest of the Strait, where the Bellingshausen water masses predominated. Here the zooplankton abundance was low, whilst the phytoplankton was found in high concentrations. A third group was found in the Bransfield front. Despite the high abundances of phytoplankton located here, zooplankton abundance was low. This could be due to the strong turbulence at the front. However, Metridia gerlachei was found in much higher concentrations here than other copepods. This species may be able to cope with such conditions due to its extensive diurnal vertical migrations.

Keywords : Community structure; zooplankton; phytoplankton; Antarctic; Bransfield Strait; Elephant Island; Bransfield Front.

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