Vertical redistribution of principle water masses on the Northeast Greenland Shelf.

The Northeast Greenland shelf (NEGS) is a recipient of Polar Water (PW) from the Arctic Ocean, Greenland Ice Sheet melt, and Atlantic Water (AW). Here, we compile hydrographical measurements to quantify long-term changes in fjords and coastal waters. We find a profound change in the vertical distribution of water masses, with AW shoaling >60 m and PW thinning >50 m since early 2000's. The properties of these waters have also changed. AW is now 1 °C warmer and the salinity of surface waters and PW are 1.8 and 0.68 lower, respectively. The AW changes have substantially weakened stratification south of ~74°N, indicating increased accessibility of heat and potentially nutrients associated with AW. The Atlantification earlier reported for the eastern Fram Strait and Barents Sea region has also propagated to the NEGS. The increased presence of AW, is an important driver for regional change leading to a likely shift in ecosystem structure and function.

A mitogenomic approach to the taxonomy of pollocks: Theragra chalcogramma and T. finnmarchica represent one single species.

BACKGROUND: The walleye pollock (Theragra chalcogramma) and Norwegian pollock (T. finnmarchica) are confined to the North Pacific and North Atlantic Oceans, respectively, and considered as distinct species within the family Gadidae. We have determined the complete mtDNA nucleotide sequence of two specimens of Norwegian pollock and compared the sequences to that of 10 specimens of walleye pollock representing stocks from the Sea of Japan and the Bering Sea, 2 specimens of Atlantic cod (Gadus morhua), and 2 specimens of haddock (Melanogrammus aeglefinus). RESULTS: A total number of 204 variable positions were identified among the 12 pollock specimens, but no specific substitution pattern could be identified between the walleye and Norwegian pollocks. Phylogenetic analysis using 16,500 homologous mtDNA nucleotide positions clearly identify the Norwegian pollock within the walleye pollock species cluster. Furthermore, the Norwegian pollock sequences were most similar to mitochondrial genotypes present in walleye pollock specimens from the Sea of Japan, an observation supported both by neighbor-joining, maximum parsimony, and maximum likelihood analyses. CONCLUSION: We infer that walleye pollock and Norwegian pollock represent one single species and that Norwegian pollock has been recently introduced from the Pacific to the Atlantic Oceans.

Irreversible binding of o,p'-DDD in interrenal cells of Atlantic cod (Gadus morhua).

Precision-cut tissue slices of the anterior kidney from Atlantic cod (Gadus morhua) were prepared with a Krumdieck tissue slicer and exposed to 2-(2-chlorophenyl)-2-(4-chloro-(14C)phenyl)-1,1-dichlorethane (o,p(')-[14C]DDD) in vitro. Microautoradiography revealed irreversible o,p(')-DDD-derived binding confined to the glucocorticoid producing interrenal cells (adrenocortical analogues). This cell-selective binding was confirmed by means of autoradiography at different levels of resolution on Atlantic cod administered o,p(')-[14C]DDD intragastrically. The results provide evidence for a site-specific metabolic activation and irreversible binding of o,p(')-DDD in the interrenal cells, which, in turn, may modify glucocorticoid homeostasis.