ON THE ABUNDANCE OF MARINE NAKED AMEBAS ON THE SURFACES OF 5 SPECIES OF MACROALGAE

Naked amoebae constituted a numerically significant component of the surface microbial community of five species of seaweeds. They were most abundant in the summer months on the brown macrophytes, Fucus and Laminaria, where numbers up to 23 cells cm-2 of algal surface were recorded. This implies that littoral algal stands can support populations of up to 3.2 x 10(6) amoebae m-2. A total of 27 different species were recognized and, of these, six species were less than 10-mu-m in length, a size class overlooked in previous studies. Damaged tissue contained higher numbers of amoebae, up to 43 cells cm-2, presumably due to higher bacterial densities and increased shelter at these sites. Some amoebae may have been utilizing algal carbon exudates directly, especially isolates of Trichosphaerium, which showed evidence of algal digestion. The numbers of amoebae found in this study suggest that these protozoa may play a significant, and previously overlooked, role in the cycling of estuarine carbon.