On the abundance of marine naked amoebae on the surface of five 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 × 10 6 amoebae m −2 . A total of 27 different species were recognized and, of these, six species were less than 10 μm 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.