Natural variation in the concentrations of haemocyanin from three decapod crustaceans, Nephrops norvegicus, Liocarcinus depurator and Hyas aranaeus

Natural variation in the concentrations of haemocyanin (Hc]) is examined for three decapod species collected from two different locations (Gullmarsfjord and Kattegat) off the west coast of Sweden (August to September 1998). Only one of the frequency distributions for Hc] is normally distributed, and median values differ both between and within species. Differences in Hc] cannot be attributed to sex, reproductive condition or moulting condition (over the limited range of moult stages examined) for any of the species. While body size did not scale with Hc] for the Norway lobster Nephrops norvegicus or the swimming crab Liocarcinus depurator, it did for the spider crab Hyas araneus. To our knowledge this is the first time a negative relationship between body size and Hc] has been reported for any crustacean. Thus the right-skewed frequency distribution of spider crab Hc] could be accounted for by the right-skewed body size distribution recorded. The shape of the frequency distributions for Hc] from the other two species could not be accounted for through differences in the factors examined here, although it is suggested that the amount of food consumed (or not) may be important. Received: 19 July 1999 / Accepted: 4 October 1999