CONICET | Buscador de Institutos y Recursos Humanos

Shallow coastal environments of Antarctica are strongly influenced by glacial melting, which brings significant amounts of fresh water and particles into the water column during summer, affecting microalgae growth. In the frame of the cooperation between the Alfred Wegener Institut f¨¹r Polar und Meeresforschung in Germany and the Instituto Ant¨¢rtico Argentino in Argentina, we have studied the diatom species richness and temporal distribution in waters of Potter Cove, in relation with some environmental variables like winds and seasonal ice cover. Qualitative samples of phytoplankton within the microplankton fraction size range, collected between February 2002 and February 2003 with a 20 ¦Ìm mesh net, were analyzed using light and electron microscopy. At least 67 species of diatoms were identified, the majority of which have acosmopolitan distribution. The exception were Trichotoxon reinboldii, Actinocyclus actinochilus, Chaetoceros criophilus, Coscinodiscus bouvet and Rhizosolenia antennata f. antennata, which were described as restricted to Antarctic waters. Moreover, recent reports confirm that other observed species like Cocconeis californica, C. gauthieri and Licmophora antarctica, could also be considered endemic to the Southern Ocean. Rich diatom assemblages dominated by some benthicepiphytic organisms of the genera Achnantes, Cocconeis, Gyrosigma, Pleurosigma and Licmophora were mainly associated to strong wind periods observed during spring and summer, suggesting the importance of resuspension events in this area. By contrast, a poor assemblage generally dominated by planktonic Fragilariopsis spp. and Eucampia antarctica (usually observed in resting stage) was observed during winter, when Potter Cove was completely covered by sea-ice.

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