Nucleic acids as indicators of nutritional condition in the Norway lobster Nephrops norvegicus

Changes in nucleic acid concentration of the gill, hepatopancreas and abdominal muscle tissue of the Norway lobster Nephrops norvegicus (L.) were examined after 6 and 12 wk of,starvation. Significant decreases in RNA concentration, RNA:protein ratio and RNA:DNA ratio were recorded in abdominal muscle tissue following starvation, but not in gill or hepatopancreas tissue. Samples of abdominal muscle tissue were taken from lobsters from 2 sites in the Clyde Sea area, Scotland. These were south of Ailsa Craig, where N, norvegicus are thought to be nutritionally limited as a result of the high population densities that occur in this area, and south of Little Cumbrae island, where population density is lower. Evidence of nutritional limitation was provided by nucleic acid analysis which showed that the RNA concentration, RNA:protein ratio and RNA:DNA ratio of lobsters from south of Ailsa Craig were significantly lower than in lobsters of equivalent size from south of Little Cumbrae. Further studies demonstrated that animals from each site were capable of obtaining nucleic acid levels similar to those at the other site after a few weeks when exposed to different feeding regimes.