Experimental studies of a benthic predator-prey relationship. I. Feeding, growth, and egg-collar production in long-term cultures of the gastropod drill Polinices alderi (Forbes) feeding on the bivalve Tellina tenuis (da Costa)

Abstract

Groups of naticid gastropod drills, Polinices alderi (Forbes) were kept in constant temperature laboratory culture, using the bivalve Tellina tenuis (da Costa) as prey, for periods in excess of 2 yr, to study rates of feeding, growth, and egg collar production. Following an initial growth phase, further growth, egg production, and food consumption all showed a clear annual cycle of variation in those cultures which contained both sexes. During the growth phase, growth rates varied with temperature with the highest rates at 20°C; in this phase, temperature and predator size accounted for most of the variation found in rates of predation and food consumption. During the reproductive phase, somatic growth was small and showed no temperature dependence; in this phase, temperature and rate of egg collar production accounted for most of the variation found in rates of predation and food consumption. In single sex cultures there was no egg production but, in separate experiments, isolated mated females continued to produce eggs >1 yr after isolation. Maximum rates of egg production were found at 15–20°C. The maximum reproductive potential, at 15°C, was equivalent to 10 times the mean tissue mass during a single annual reproductive period. Neither the timing nor duration of the reproductive period was significantly different at 10, 15 or 20°C, but there was no egg production at 25°C.