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In the North Atlantic, the waters surrounding the Cape Verde Islands are a "potential hot spot" for cookiecutter shark Isistius spp. interactions with cetaceans. These occurrences were recently identified by the improved efforts of researchers to document cetacean strandings in the Cape Verde archipelago, as well as by the photo identification efforts of live whales and dolphins. The documentation of individual and mass stranding events confirmed that cookiecutter shark interactions with cetaceans in Cape Verde seas are remarkably common.
Understanding how temperature affects cod (Gadus morhua) ecology is important for forecasting how populations will develop as climate changes in future. The effects of spawning-season temperature and habitat size on cod recruitment dynamics have been investigated across the North Atlantic. Ricker and Beverton and Holt stock–recruitment (SR) models were extended by applying hierarchical methods, mixed-effects models, and Bayesian inference to incorporate the influence of these ecosystem factors on model parameters representing cod maximum reproductive rate and carrying capacity. We identified the pattern of temperature effects on cod productivity at the species level and estimated SR model parameters with increased precision. Temperature impacts vary geographically, being positive in areas where temperatures are <5°C, and negative for higher temperatures. Using the relationship derived, it is possible to predict expected changes in population-specific reproductive rates and carrying capacities resulting from temperature increases. Further, carrying capacity covaries with available habitat size, explaining at least half its variability across stocks. These patterns improve our understanding of environmental impacts on key population parameters, which is required for an ecosystem approach to cod management, particularly under ocean-warming scenarios. Key words: carrying capacity , cod , hierarchical models , North Atlantic , temperature , uncertainty
Taxonomy of fourteen very little known species of Nodosariinae Ehrenberg, 1838 in Icelandic waters is revised. Knowledge of these species in the North Atlantic relies mainly on studies in the late 19th and early 20th centuries, using large volume samplers. Later studies have emphasized quantitative samples of a few cm3 where the Nodosariinae are very rare. This study analysed 879 dredging samples where Nodosariinae occurred in 492 samples, comprising 7598 specimens of about 415 000 of all picked foraminifera. Ordination analysis of species distributions reflects prominent temperature and salinity differences that exist in the sampling area (753 000 km2) north and south of the Greenland-Scotland Ridge (GSR). Eight species are restricted to southern temperate waters (> 2°C): Dentalina mutabilis (Costa, 1855), Dentalina antarctica Parr, 1950, Dentalina antennula d’Orbigny, 1846, Dentalina filiformis (d’Orbigny, 1826), Grigelis pyrula (d’Orbigny, 1826), Grigelis guttifera (d’Orbigny, 1846) comb. nov., Grigelis semirugosus ? (d’Orbigny, 1846) and Nodosaria subsoluta Cushman, 1923. Four species (Nodosaria haliensis Eiland & Guðmundsson, 2004, Nodosaria incerta Neugeboren, 1856, Dentalina elegans d’Orbigny, 1846 and Dentalina frobisherensis Loeblich & Tappan, 1953) occur mainly north of Iceland. Two species, Dentalina obliqua (Linnaeus, 1758) and Pseudonodosaria subannulata (Cushman, 1923), have wide tolerance ranges for physical variables.