Length and weight relationships ofAcartia cluusi from Narragansett Bay, R.I?

Changes in the cephalothorax length and dry weight of Formalin-preserved copcpodite and adult Acartia clausi were followed from 12 March-l June 1976 and naupliar weights and lengths determined for one sample. Preservation in Formalin caused a significant loss of dry weight, carbon, and nitrogen in adult females, mostly during the first 24 h, but did not sig-nificantly affect the C:N ratio or the cephalothorax length of the animals. Length and weight were inversely related to seawater temperature at the time of sampling. As the animals became older this relationship was increasingly affected by their past tem-perature history. Separate linear relationships between log length and log weight were ob-served for the nauplii, the CIs, the CII-CVs, and the adults, making it possible to estimate the weight of individual stages from measurcmcnts of length. Animals collected on the same day frorn different stations sometimes showed significant differences in weight for a given length. Such differences could be more clearly expressed by calculation of a condition factor relating weight to the cube of cephalothorax length. The differences in the condition factor appeared to be related to food availability and such dif-ferences may be even more apparent when weights of live animals are examined. There are pronounced seasonal differ-ences in body size among marine cope-pods: length is inversely correlated with ambient temperature, while weight is positively related to food availability (e.g