Phytoplankton of Bransfield Strait and Elephant Island during austral summer of 2006

Abstract

The distribution and structure of the phytoplankton community in Bransfield Strait and Elephant Island were studied during Austral Summer of 2006. The seawater samples were collected using a Niskin bottle at different depths. The quantitative analysis was performed by the Utermöhl sedimentation method. The integrated values of density in the water column, from the surface to a depth of 100 m, were higher than 300,000 celx103.m-2. The dominant species were Fragilariopsis sp., Thalassiosira antarctica, Pseudonitzschia prolongatoides, P. delicatissima and Porosira glacialis. Vertically, the higher densities were recorded from surface to a depth of 30 m. With a few exceptions the phytoplankton was dominated by microflagellates (78%) while the diatoms were the second group in importance (18%). The diversity index values were lower than 1.6 bits/cel. In the evaluated area the phytoplankton showed a high homogeneity denoted by the high similarity among samples (90%).