A short note on the biogeographic patterns of the Chaetognatha fauna in the North Atlantic

Three different hydrographic regimes were identified during the MAR-ECO cruise in the North Atlantic in June 2004 between 59°N and 42°N. Chaetognaths were sampled with a non-quantitative open plankton net through the entire water column. The species composition of the chaetognaths differed between the Sub-Arctic Province (SAP) and the Cold Temperate Province (CTP), and a frontal region. In the SAP with Sub-Arctic Intermediate Water six species were found, and the species composition was dominated by three species: two of the genus Eukrohnia and one of the genus Sagitta making up 83% of the total number of specimens. In the samples from the CTP with North Atlantic Central Water 16 species were present and here five to six species made up 83% of the total number of specimens. There were no differences between the chaetognath assemblages on either side of the Mid-Atlantic Ridge. Greatest abundances were found at station 18 just northwest of the Charlie-Gibbs Fracture Zone.