Spectral properties and photosynthetic action in red-tide populations of Prorocentrum micans and Gonyaulax polyedra

Three sets of experiments were carried out between April and September 1987 to assess reproductive energetics in a laboratory population of the capitellid polychaete Capitella capitata type I. In the first experiment, the population was sampled intensively over a short period of 3 wk. Weight-specific reproductive output did not differ significantly between females and hermaphrodites. However, because hermaphrodites were significantly bigger than females, their fecundity was significantly higher. In the second experiment, fecundity and weight-specific reproductive output were monitored weekly over the oscillation cycle of the population (30 wk). Both fecundity and weight-specific reproductive output varied drastically (40 to 80 eggs per female and 17 to 57%, respectively). In the third experiment, non-sexed juveniles were reared for 15 d on six ration levels (normalized on the basis of organic nitrogen) of four different food sources. The maximum weight-specific reproductive output was 70% (for females). Both fecundity and weight-specific reproductive output were positively correlated with food ration and varied with food type. The data on weight-specific reproductive output recorded in the present study have been compared with those of other iteroparous polychaetes in the literature. Reproductive output in C. Capitata type I varies more widely and is greater than in other iteroparous polychaetes. In this species, reproductive output and population dynamics vary concomitently with the level of organic matter in the habitat.