Influence of temperature and food supply on development of Eupolymnia nebulosa (Montagu, 1818) (Polychaeta: Terebellidae)

Abstract

The influence of temperature and food supply on the growth rate of juvenile Eupolymnia nebulosa (Montagu, 1818) was tested in laboratory. The growth rate was positively correlated with temperature: between 10 and 20 °C, in an experiment lasting 38 days, the length of the worms doubled at 20 °C as compared with 10 °C and the number of segments increased from 17 to 25. The growth rate is also sensitive to the amount of the food supply; in the field food is not always available in optimal quantities. As the seawater warms up during the spawning period, which extends from early March to the end of May, and as there is a positive correlation between growth rate and temperature, the range of size variation in the juvenile population becomes narrower in spite of the long spawning period. It is suggested that a narrow range of juvenile sizes may enhance adaptation to spatial spreading and to the competition for food between individuals. It appears that reproductive events are so regulated as to reduce the range of sizes of juveniles emerging from the 3-month spawning period. This adaptation greatly enhances the individual's competitive efficiency and lessens waste in the recruitment period.