Density in sub-arctic zooplankton
Original version
This report is not to be quoted without prior consultation with the General Secretary.Abstract
Seasonal variations in specific density were measured for Thysanoessa inermis, Thysanoessa raschii, Meganyctiphanes norvegica, Calanus finmarchicus and Calanus hyperboreus. The density of a 20 mm T. inermis was lowest in December (1.052 g/cm³) and highest in Februar- March (1.065 g/cm³). Foe a 20 mm T. raschii the minimal density was determined in December (1.060 g/cm³), but reached their maximum density in July (1.074 g/cm³). M. norvegica individuals of 35 mm also had their lowest density in December (1.060 g/cm³), but reached their maximum density in July (1.076 g/cm³). The density of the euphausiids is found to be size dependent. The density increases as the size decreases.
C. finmarchicus and C. hyperboreus had densities less than seawater (1.026 g/cm³) during most of the year. Just before spawning the density increased to 1.036 g/cm³ and 1.028 g/cm³ for C. finmarchicus and C. hyperboreus respectively. The seasonal variations of the density were closely related to the lipid content of the animals.
Publisher
ICESSeries
ICES CM documents1985/L11