The relationship between temperature, growth rate, and duration of planktonic life for larvae of the gastropod Crepidula fornicata (L.)

Abstract

To determine if a relationship exists between rate of development and ability to delay metamorphosis, larvae of the prosobranch gastropod Crepidula fornicata (L.) were reared at 18 and 24°C in the absence of metamorphosis-inducing cues. Average growth rates were determined directly by periodically subsampling and measuring larvae at both temperatures. Individual growth rates were estimated from size at, and date of, spontaneous metamorphosis. Larvae generally grew more quickly at the higher temperature, in terms of shell length, tissue dry weight, and protein content. Regardless of temperature, most (>95%) larvae eventually metamorphosed spontaneously in clean glass dishes. Rapid growth was associated with an apparently shorter pre-competent period and earlier spontaneous metamorphosis, reflecting increased rates of differentiation. These results suggest a developmental mechanism through which selective pressures may operate to determine dispersal potential in this, and perhaps other species. Specifically, pre-competent and delay periods may be altered through selection for different rates of development. Demonstration of such a mechanism may ultimately increase our ability to predict the potential duration of planktonic existence of planktotrophic marine invertebrate larvae under a variety of environmental circumstances.