Temporal Abundance of Naked Bacterivore Amoebae in Coastal East Antarctica

The densities of naked amoebae in the water column of two coastal sites off Eastern Antarctica were sampled throughout 1993. A few samples were also collected from nearby Ellis Fjord. This is the first study to detail abundances of bacterivore amoebae in Antarctic coastal waters. Overall numbers in the water column were highly variable (below detection to 2000 amoebae l−1) and showed no clear seasonal trends. The high scatter in the data is believed to reflect patchiness within the water column; amoebae are predominantly floc-associated. Highest abundances, up to 2626 amoebae l−1, were recorded at the ice – water interface. The majority of amoebae isolated throughout the year were flattened, fan-shaped vannellids and platyamoebae. Small morphotypes (less than 10 μm long) were occasionally abundant, comprising up to 45% of the total count. Despite the relatively constant population of amoebae in these coastal waters, their contribution to the total carbon pool of microbial plankton was less than 1%.