TEMPORAL AND SPATIAL ABUNDANCE OF NAKED AMEBAS (GYMNAMOEBAE) IN MARINE BENTHIC SEDIMENTS OF THE CLYDE-SEA AREA, SCOTLAND

The abundances of benthic naked amoebae in the sediments of the Clyde Sea Area, Scotland, were studied throughout 1991. Four sites differing in sediment grain size and organic carbon content were chosen for study. Amoebae were enumerated by enrichment cultivation methods and found to be numerically important, attaining densities of up to 14,883 amoebae/cm(3) on one occasion. They were most abundant, and temporally stable, in finer sediments where they averaged 2,224 cells/cm(3) and lower and more variable in the sandy sediments, averaging 874 cells/cm(3) throughout the year. In general, amoebae were most abundant in the surface sediment layers. Around 70 different morphotypes were recorded, and 61% of all amoebae counted were less than 10 mu m in length. This is the first detailed quantitative study of benthic marine gymanamoebae and shows that naked amoebae and flagellates are numerically the dominant interstitial fauna in sediments of this area. Moreover, the gymnamoebae comprised the largest proportion of total protozoan biomass (excluding foraminiferans) and clearly need to be considered in future models of benthic carbon flow.