Regional and interannual variations in biomass and productivity of the marine copepod, calanus-finmarchicus, in sub-arctic environments

A model for estimating the productivity of Calanus finmarchicus in subarctic waters is developed based on data on individual growth, developmental rates, feeding, vertical behaviour and population parameters obtained from the same region. In fjords and coastal waters of Northem Norway and in the Barents Sea C. finmarchicus is considered to produce one generation every year. Population data obtained monthly from November 1976 to December 1977 in Balsfjorden, Northem Norway, show that C. finmarchicus reproduces during March and April, and has a quantitatively important growth and production period in May and June. A physiological model is developed to simulate the dynamics of population development and productivity from March to July, and details on individual production, energy expenditure and assimilation rates are compared with data from C. pacificus. Based on the abundance of the obtained populations, production is scaled for the following regions and time periods: 15 gC m-2 in Atlantic waters in the Barents Sea in 1982 (scenario 1), 3.1 gC m-2 in Balsfjorden in 1977 (scenario II), and 0.1, 5.4 and 20.2 gC m-2 in 1986 in Balsfjorden, Malangen and Grotsund, respectively (scenario III). The results are discussed in relation to latitudinal and regional differences in productivity.