Rearing cohorts of Calanus finmarchicus (Gunnerus) in mesocosms

Cohort development and nutritional conditions of Calanus finmarchicus were studied in experimental seawater mesocosms in a Norwegian fjord. Artificial ly added cohorts developed from early naupliar stages to copepodite stage I V in 41-43 days at ambient temperature increasing from 4.3 to 6.8 degreesC. A natural stock of C. finmarchicus, initially dominated by early copepodit e stages, developed to CV, males and females. Total storage lipid increased exponentially until CV. Individual body carbon weight increased sigmoidall y with age. Relationship of body carbon weight (W, mug) to prosome length ( L, mum) determined for copepodites and adults (W=2.6 x 10(.10) L-3.45, r(2) =0.92) showed a higher weight than from in situ studies. This investigation demonstrates (i) that cohorts of C. finmarchicus can be reared successfull y in mesocosms, (ii) a good nutritional state of copepods in terms of body carbon content and lipid reserves. and (iii) that part of the final CV moul ted to both males and females. (C) 2000 International Council for the Explo ration of the Sea.