Trans-Atlantic Study of Calanus: Large Scale Field Survey

The objective of this subtask of the Trans-Atlantic Study of Calanus programme was to describe the large scale distribution, abundance, and population structure of C. finmarchicus in the Nordic Seas for the summer and winter seasons, and assess the genetic cohesiveness of C. finmarchicus. Summer distributions of C. finmarchicus were determined by sampling with MOCNESS, BIONESS or MULTINET multiple sampling systems and WP-2 nets, and by acoustical mapping with shipborne echo sounders (38, 120, 200 kHz). Supporting information on hydrography (CTD), phytoplankton development (nutrients, chlorophyll, in situ fluoresence), zooplankton size-fractioned biomass, and distribution and abundance of fish (acoustics, pelagic trawl) were collected by continuous recording and vertical profiling. This study of genetics used the frequencies of different alleles of several genes to describe population structure. Allelic variation of the genes will be determined by variation in the DNA sequence of a portion of each gene for individual copepods. DNA was extracted from individual copepods. A region of mitochondrial DNA will be amplified using polymerase chain reaction (PCR) technology (Innis et al. 1990). Specific techniques are described in Bucklin and Kann (1991) and Stanton et al. (1992). Amplified DNA will be sequenced, and sequences will be alligned to those of other individuals of C. finmarchicus from the Norwegian Sea. The DNA sequencing will be carried out at University of Bergen where we have access to an Automated DNA Sequencer. The frequency of each sequence variant in each region will be determined. Standard population genetic analyses of population structure based on allele frequencies will be done to determine whether the species is significantly structured in the Norwegian Sea. Cruise: June 19 - July 16, 1997 RV Johan Hjort (Institute of Marine Research, Bergen)