Ref ID : 3784
Gaytha A. Langlois; Effect of Algal Exudates on Substratum Selection by Motile Telotrochs of the Marine Peritrich Ciliate Vorticella marina. J.Protozool. 22(1):115-123, 1975
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Several species of marine peritrichs are found as epiphytes on small strands of filamentous green and red algae affixed to the substratum of marine intertidal rock pools. In pools located along the coast of Narragansett Bay, the motile vorticellid telotrochs appear to show a substratum selection of specific algae. Exudation products by marine algae have distinct differences; some Phaeophyta have particularly high values for dissolved organic matter (DOM), and for phenolic compounds. Algal exudates appear to influence population growth of vorticellids. The mean survival percentage of vorticellid populations increased with exposure to exudates from Cladophora gracilis, Polysiphonia harveyi and Polysiphonia lanosa; and decreased with exposure to those of Ascophyllum nodosum, Fucus spiralis and Scytosiphon lomentaria. Telotroch settlement of Vorticella marina was enhanced by exudates of Cladophora gracilis, Polysiphonia harveyi and Polysiphonia lanosa, but was reduced by exudates of Ascophyllum nodosum, and was prevented by exudates of Fucus spiralis and Scytosiphon lomentaria. Algal exudates were obtained by allowing photosynthetic activity of the experimental algae for 6 hr. The exudates were filtered and the concentration of DOM, total phenols and carbohydrates determined. The filtered seawater containing the exudate was placed in a box-type plastic dish on which the vorticellids had colonized. Survival percentages and the percentage of population dut to telotroch settlement were calculated. This investigation indicates that algal exudates may exert a significant influence on the selection of substrata by vorticellid telotrochs and suggests that the ecologic stability of a given rock pool may be considerably lessened by a high level of Phaeophtya and the consequent reduction of Aufwuchs species.