INFLUENCE OF TEMPERATURE AND FOOD ON LARVAL GROWTH IN THE NORWAY LOBSTER, Nephrops norvegicus

The aim of the present study was to analyse growth differences in Norway lobster larvae, Nephorps norvegicus. To date very few studies have used nucleic acids and protein contents to characterize larval stages in crustaceans. DNA, RNA and protein contents were quantified and used as potential indirect measures of growth. Fed and starved larvae were reared at different temperatures (6º, 12º, 18ºC) from hatching to the end of stage III (metamorphosis). During this time, larval growth was measured in samples taken every 1-4 days as a function of day-degrees. Growth was significantly higher in fed larvae compared to starved larvae at 12º and 18ºC, while no significant differences were observed at 6ºC. Starved individuals did not pass through the first moult. Duration of the larval moult-cycle varied with temperature. Stage III was reached during the third week at 18ºC, while it took five weeks at 12ºC. The RNA:DNA ratio and the protein:DNA ratio appeared to be viable indicators of growth in Norway lobster larvae.