Grazing by Mayorella sp (Protozoa: Sarcodina) on Cyanobacteria

The feeding selectivity and reproductive rates of a Mayorella sp., an amoeba isolated from a salt marsh in Morecambe Bay, Lancashire, and fed on the cyanobacteria Anabaena cylindrica, Anabaena sp., Nostoc sp. and Calothrix sp. and the green alga Chlorella, were investigated at 26oC. Different rates of plaque extension and, in the case of cyanobacteria, reduced N-fixation (acetylene reduction), occurred with different food species. Calothrix was not observed inside food vacuoles; its morphology prevented it from being ingested. Amoeba reproductive rates varied in relation to diet, with generation times ranging between 41.6 h and 100 h, but rates of reproduction did not relate to the rates of plaque extension or acetylene reduction on any given diet, suggesting varying degrees of digestive efficiency on different algal and blue-green diets.-from Authors