Effect of detrital nutritional quality on population dynamics of a marine nematode (Diplolaimella chitwoodi)

The quantity and nutritional quality of detritus significantly affected the population growth rate (r) and carrying capacity (K) of Diplolaimella chitwoodi (Nematoda) in laboratory cultures. The rate of increase (r) was roughly constant for cultures fed Ulva fasciata, Pablum, Gracilaria foliifera and one Spartina alterniflora detritus, but was lower for Thalassia testudinum detritus and another S. alterniflora detritus. Rate of increase was unaffected by amount of food supplied except for seaweed detritus where r was lower for lower ratios. Carrying capacity (K) was strongly affected by both detrital type and rate of food supply. The best predictor of K was the rate of nitrogen supply to these cultures implying that natural populations may be N-limited. The nitrogen content of detritus appears to be the best measure of its nutritional quality.