Physiological Responses of the Copepods Acartia tonsa and Eurytemora carolleeae to Changes in the Nitrogen:Phosphorus Quality of Their Food

Two contrasting estuarine copepods, Acartia tonsa and Eurytemora carolleeae, the former a broadcast spawner latter brood spawner, were fed constant carbon-based diatom diet, but which had variable N:P content, elemental composition (C, N, P) of tissue eggs, as well changes in rates grazing, excretion, egg production viability measured. To achieve varied Thalassiosira pseudonana was grown continuous culture at growth rate with varying P supply. Both copepods altered their chemical response to prey, different degrees. Grazing (clearance) increased for A. not E. carolleeae prey increased. Variable NH4+ excretion observed between copepod species, while PO43? declined Egg by highest when eating high that showed opposite pattern. always greater than carolleeae. These results suggest anthropogenically changing nutrient loads may affect nutritional quality food turn affecting stoichiometry reproductive success, having implications webs.