Omnivory by the coastal marine copepods Centropages hamatus and Labidocera aestiva

Abstract

Omnlvory by the 2 coastal marine copepods Centropages hamatus (Lilljeborg) and Labidocera aestiva Wheeler was examined in laboratory grazing and predation experiments. Co-occurring food items were utilized. C. hamatus ingested more carbon in the form of plant material (Z = 2.05 pgC copepod-' d-l) than did L. aestiva (2 = 0.66 pgC copepod-' d-l). Conversely, L. aestiva ingested more carbon in the form of animal food (F = 3.35 pgC copepod-' d-') than did C. hamatus (2 = 0.98 pgC copepod-' d-l). Rates of ingestion of copepod nauplii and phytoplankton by both C. hamatus and L. aestiva increased significantly with increasing food concentrations and temperatures. Average grazing and predation rates of C. hamatus and L. aestiva upon natural phytoplankton assemblages and nauplii appeared to follow biomass peaks. The maximum field concentration of C. hamatus (722 m-3) appeared capable of daily ingesting means of 0.85 % of phytoplankton carbon and 8.23 % of the copepod nauplli present. Maximum field concentration of adult L. aestiva (8 m-3) appeared capable of ingesting means of only 0.01 % of phytoplankton carbon and 0.29 % of the copepod nauplii present.