Travel time and speed of gray whales and amphipod abundance along Chukotka Peninsula in 2006

The purpose of this study was to evaluate summer and fall residency and habitat selection by gray whales, Eschrichtius robustus, together with the biomass of benthic amphipod prey on the coastal feeding grounds along the Chukotka Peninsula. Thirteen gray whales were instrumented with satellite transmitters in September 2006 near the Chukotka Peninsula, Russia. Nine transmitters provided positions from whales for up to 81 days. The whales travelled within 5 km of the Chukotka coast for most of the period they were tracked with only occasional movements offshore. The average daily travel speeds were 23 km/day (range 9-53 km/day). Four of the whales had daily average travel speeds <1 km/day suggesting strong fidelity to the study area. The area containing 95% of the locations for individual whales during biweekly periods was on average 13,027 km**2 (range 7,097-15,896 km**2). More than 65% of all locations were in water <30 m, and between 45 and 70% of biweekly kernel home ranges were located in depths between 31 and 50 m. Benthic density of amphipods within the Bering Strait at depths <50 m was on average ~54 g wet wt/m**2 in 2006. It is likely that the abundant benthic biomass is more than sufficient forage to support the current gray whale population. The use of satellite telemetry in this study quantifies space use and movement patterns of gray whales along the Chukotka coast and identifies key feeding areas.

Spider crab Hyas araneus larval dry weight, C/N ratio and developmental time during experiments from different latitudes (54° vs 79°N), 2010

The combined impacts of future scenarios of ocean acidification and global warming on the larvae of a cold-eurythermal spider crab, Hyas araneus L., were investigated in one of its southernmost populations (living around Helgoland, southern North Sea, 54°N) and one of the northernmost populations (Svalbard, North Atlantic, 79°N). Larvae were exposed at temperatures of 3, 9 and 15°C to present day normocapnia (380 ppm CO2) and to CO2 conditions expected for the near or medium-term future (710 ppm by 2100 and 3000 ppm CO2 by 2300 and beyond). Larval development time and biochemical composition were studied in the larval stages Zoea I, II, and Megalopa. Permanent differences in instar duration between both populations were detected in all stages, likely as a result of evolutionary temperature adaptation. With the exception of Zoea II at 3°C and under all CO2 conditions, development in all instars from Svalbard was delayed compared to those from Helgoland, under all conditions. Most prominently, development was much longer and fewer specimens morphosed to the first crab instar in the Megalopa from Svalbard than from Helgoland. Enhanced CO2 levels (710 and particularly 3000 ppm), caused extended duration of larval development and reduced larval growth (measured as dry mass) and fitness (decreasing C/N ratio, a proxy of the lipid content). Such effects were strongest in the zoeal stages in Svalbard larvae, and during the Megalopa instar in Helgoland larvae.