The effect of environmental temperature on growth and muscle development in the European lobster Homarus gammarus
1. Although growth and moulting rates of larval and post-larval lobsters have often been monitored, very little is known about the effects of such regimes on the physiology of the animals, on their muscle properties, or on their performance and behaviour when released into the wild in re-stocking or ranching programmes. The extensive research on effects of environmental variables on fish development (Johnston and Temple, 2002), is unlikely to provide an accurate model for a crustacean such as the lobster, which have distinct larval and adult stages in different environments, and a development pattern with intermittent growth during the moult and metamorphosis. This project addresses these issues in the context of the practicalities of rearing the European lobster Homarus gammarus in a laboratory environment. It poses the question: do lobster rearing programmes produce animals that are suitably equipped to compete against their wild counterparts for food and space, once released? To address this question, groups of post-larval European lobsters, Homarus gammarus, were reared at 11°C, 15°C and 19°C from post-larval Stage 8 to 18 months old, and also from the egg through to 6 months of age at 15°C and 19°C at the larval rearing facilities of the Centre for Environmental, Fisheries and Aquaculture Science (CEFAS), Conwy, North Wales. 2. Rates of mortality were low at all rearing temperatures. Moulting frequencies were temperature-dependent, as shown by the complete moult records and also by the data based only on the median group. Long Inter-moult periods for the postlarval stages at 11°C indicate that this temperature was close to the null point for moulting. The standard measure of size, carapace length (CL) increased with age in a temperature-dependent manner from an initial value of 6 mm in the Stage 8 lobsters. Daily increases in CL were 18 mm, 28 mm for the 11°C, 15°C and 19°C groups respectively.