Sporadic high abundances of naked amoebae in Black Sea plankton

The abundance of non-testate ('naked'), free-living amoebae was examined in surface waters of the Black Sea during 5 cruises in 1992 and 1993. Amoebae (less than or equal to 20 mu m in size) were observed in samples collected during 2 of the 5 cruises at abundances up to approximately 380 ml(-1). The abundance dance and biomass of amoebae were low relative to other nanoplanktonic protozoa when averaged over ail stations, but amoebae occasionally constituted a major component of the heterotrophic nanoplanktonic assemblage (up to 16% of abundance and 93% of biomass of the protozoa 2 to 20 mu m in size). Abundances of amoebae correlated weakly with the total number of heterotrophic nanoplankton, and with ash free dry weight, but not with several other physical, chemical and biological parameters. Based on the highest abundances of naked amoebae observed in this study we suggest that these protozoa can occasionally be important in energy and elemental cycling in Black Sea plankton.