On the biology of the prosobranch Lacuna Parva in the Øresund

Abstract

The habitats of 2 sparse populations of Lacuna parva in the northern Øresund are described. The species was cultured throughout its life cycle. It feeds on the red algae Phyllophora, Delesseria and Phycodrys. Phyllophora is the main substratum for spawn deposition. Egg masses contain up to 16 eggs, most often 6–10 eggs. Development is direct and takes ca. 2 months at 10–11 °C. Potential reproductive effort resembles that of L. pallidula and parity between spawn production and body size (measured in terms of dry organic matter) is reached after 24–39 days. After copulation females may produce fertilized eggs for 2–3 months. The species has an annual life cycle with copulation prior to the production of spawn in March–June, death of adults in May–June and main hatching of young in June–July. Differences in morphology, food plants and life cycle between populations from the Øresund and Roscoff are pointed out.