The Biology of The Small Planktonic Copepods of Plymouth

The life histories of the small planktonic copepods of Plymouth were studied during 1947. The samples were taken at Station L4 with Harvey measuring nets, and are thus truly quantitative. The main species concerned were Pseudocalanus elongatus, Paracalanus parvus, Centropages typtcus, Temora longicornis, Acartia clausi, Oithona similis, O. nana, Oncaea venusta and Corycaeus anglicus . The species common in summer—all but the last three of the above—behaved in a very similar way, producing probably five generations in the course of the year, but differing from each other in the relative and absolute abundance of the different stages at different times of the year.