Irigoien X, Obermuller B, Head RN, Harris RP, Rey C, Hansen BW, Hygum BH, Heath MR, Durb EG
Calanus, copepods, sex ratio, mesocosm, Espegrend, Bergen, Norway, 18.5 m3
The effect of food concentration on the sex ratio in Calanus spp. has been investigatedin laboratory and mesocosm experiments. The results of the experiments are comparedwith time series in the field and with physiological rates. The food concentration andquality had an effect on the sex ratio of adult Calanus, with higher percentages of malesobtained with increased food concentration. Laboratory experiments and field timeseries suggest that sex can still change at stage CIII–CIV, but is determined at stageCV. The energy budget of males was very unbalanced, suggesting that the shorterlifespan often reported could be due to exhaustion of lipid stores.