Effects of Food Concentration on Larval Growth and Development of Two Polychaete Worms, Capitella Capitata (Fabricius) and Polydora Ligni Webster

We examined the effects of phytoplankton concentration on larval growth and development of Capitella capitata (Fabricius) and Polydora ligni Webster. Larvae of both species were provided with freshly collected phytoplankton at the following concentrations: 50×, 25×, 10×, 5×, 1.0× (as control) and 0.5×. Results indicated that larvae of C. capitata and P. ligni grew faster and had shorter pelagic periods when fed with phytoplankton at concentrations of 10× and 25× ambient concentration. Larvae of both species had higher energy content than the control when fed with 10× concentration. Survival rate of C. capitata did not differ significantly at different food concentrations except at 50×, where larval mortality was higher than that of the control. Survival rate of P. ligni decreased with an increase in food concentrations of 10–50×.