Effect of different food types on the postembryonic developmental rates and demographic parameters of Phyllodiaptomus blanci (Copepoda: Calanoida)

Abstract

I studied the effects of different food types on the postembryonic (naupliar and copepodite) developmental rates and adult demographic parameters (longevity, egg-laying age and fecundity) of Phyllodiaptomus blanci, a common calanoid copepod in the lakes and ponds of India. The test diets, all cultured in the laboratory, included bacteria (Klebsiella aerogenes), cyanobacteria (Microcystis aeruginosa), green algae (Chlorella vulgaris, Scenedesmus acutus, Chlorococcum himocolo and Chlorogonium elongatum), a chrysophyte (Ophiocytium capitatum), a ciliate (Tetrahymena pyriformis) and a mixed diet of ciliates and Scenedesmus. All experiments were started with the N 1 naupliar stage of P blanci cultured in the laboratory. With the bacterial diet, postembryonic development was incomplete and adults failed to reproduce. With a diet of Microcystis aeruginosa, the development was complete but required longer time and the adults reproduced with a lower net reproductive rate than with algal diets. Among the algal diets, Chlorogonium and Chlorococcum contributed to the fastest postembryonic development and the highest reproductive rates. P. bland was able to complete its naupliar development and also to reproduce on a diet of the smaller algae Chlorella and Scenedesmus, but only when these diets were nutritionally enriched. Its performance on a diet of the chrysophyte Ophiocytium was marginally higher than with Microcystis aeruginosa but significantly lower than on a diet of the green algae. The calanoid was not only able to utilize the ciliate Tetrahymena as food but also achieved postembryonic developmental rates and reproductive output comparable to those achieved with green algal diets. The present study supports the possibility that in the natural environment P. blanci feeds regularly on the toxic strain of Microcystis aeruginosa and also on small ciliates, both common in its habitat.