Pelagic Feeding Ecology of Dovekies, Alle alle, in Lancaster Sound and Western Baffin Bay

Adult (AD), Subadult (SA), and hatching year (HY) dovekies were collected at sea in 1976, 1978, and 1979 (n=410) for food habits studies. In May and June, AD and SA dovekies ate mostly copepods (99.8% of dry weight in AD, 100% in SA); in August, amphipods became more important (59% in AD, 90% in SA). Adult males accompanied chicks to sea where both groups fed largely on Parathemisto amphipods (99.7% in AD, 97% in chicks). Once abandoned by the adults, HY dovekies ate Parathemisto (59.8% of dry weight), Apherusa glacialis (13.6%), and Onisimus glacialis (5.6%) amphipods; arctic cod (Boreogadus saida) (14.5%); calenoid copepods (5.5%); and other items (1%). Seasonal changes in diet were, in part, related to a presumed seasonal increase of suitable amphipods in surface waters. HY dovekie diets varied geographically and with year. Some food taxa were larger in dovekies collected in waters associated with an intrusive current flowing into and out of the mouth of Lancaster Sound than in those collected in offshore Baffin Bay. In 1978, Parathemisto and Apherusa glacialis were smaller than in 1979 or 1976: HY dovekies apparently compensated by taking more copepods. HY dovekies were smaller on a given date in 1978 but ate similar total amounts of food and grew at similar rates in all three years. The small size of amphipods in 1978 was probably due to unusually late breakup of ice and its probable inhibitory effects on primary and secondary production. In 1978, many non-breeding (AD and SA) dovekies molted in pack ice that persisted until mid-August. In 1979, when pack ice dispersed early, no non-breeding dovekies were collected in August.Key words: dovekie, Alle alle, trophic relationships, pelagic seabird ecology, arctic marine systems, molt&nbsp

Occurrence, Habitat Use, and Behavior of Seabirds, Marine Mammals, and Arctic Cod at the Pond Inlet Ice Edge

In 1979, 17 species of birds were seen during studies near the Pond Inlet ice edge. Northern fulmars (Fulmarus glacialis) black-legged kittiwakes (Rissa tridactyla) thick billed murres (Uria lomvia) and black guillemots (Cepphus grylle) all avoided the ice edge when bordered with heavy pack ice and all but kittiwakes used the ice edge primarily for feeding. Guillemots and fulmars occurred in highest numbers in water along rough and moderately rough landfast ice: murres and kittiwakes showed no preference for such areas or for the other habitat surveyed (smooth landfast ice). Narwhals (Monodon monoceros) white whales (Delphinapterus leucas) and ringed seals (Phoca hispida) were the only marine mammals common at the ice edge. Whales repeatedly dived under the edge - probably feeding, searching for open water west of the ice edge, or both. Densities of seals near the ice edge were higher than elsewhere on landfast ice. Divers observed arctic cod (Boreogadus saida) close to the undersurface of landfast ice. Fish offshore were generally smaller, younger, and smaller-at-age than those inshore. Offshore, arctic cod were more numerous in areas with a rough under-ice surface than under smooth ice. Cod concentrated in crevices within rough under-ice surfaces. Inshore, cod were captured from ice cracks over shallow water. I conclude that vertebrates occur at ice edges for one or more of several reasons. Ringed seals and arctic cod live in close association with landfast ice: they probably occur near ice edges simply because landfast ice is present there. Ice edges seem to be primarily barriers against the further movements of whales toward summering locations. Finally, for murres and some other birds, ice edges seem to be favored feeding locations (relative to open sea conditions) due to greater access to preferred foods.Key words: arctic seabirds, ringed seal, narwhal, arctic cod, ice edges, Pond Inlet, habitat use, behavior, arctic waters, Lancaster Sound, Baffin Ba

Trophic Relationships at High Arctic Ice Edges

At ice edges in the Canadian High Arctic, seabirds and marine mammals eat arctic cod (Boreogadus saida) and to a lesser extent, zooplankton (calanoid copepods and Parathemisto) and ice-associated amphipods. Cod eat ice-associated amphipods, other ice-associated taxa (harpacticoid and cyclopoid copepods), and zooplankton. Calanoid copepods, Parathemisto, and the ice-associated amphipods studied (Onisimus glacialis, Apherusa glacialis, Gammarus wilkitzkü) all eat primarily diatom algae characteristic of the under-ice flora. From this information, a food web at the ice edge is constructed.Key words: trophic relationships, arctic, ice edges, seabirds, marine mammals, cod, epontic community, zooplankto

Stable isotope food-web analysis and mercury biomagnification in polar bears ( Ursus maritimus )

Mercury (Hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different food-web channels are not well known, particularly in high-latitude systems affected by the atmospheric Hg deposition associated with snow and ice. Here, we report on stable carbon and nitrogen isotope ratios, and Hg concentrations, determined for 26, late 19th and early 20th century, polar bear ( Ursus maritimus ) hair specimens, collected from catalogued museum collections. These data elucidate relationships between the high-latitude marine food-web structure and Hg concentrations in polar bears. The carbon isotope compositions of polar bear hairs suggest that polar bears derive nutrition from coupled food-web channels, based in pelagic and sympagic primary producers, whereas the nitrogen isotope compositions indicate that polar bears occupy > fourth-level trophic positions. Our results show a positive correlation between polar bear hair Hg concentrations and δ 15 N. Interpretation of the stable isotope data in combination with Hg concentrations tentatively suggests that polar bears participating in predominantly pelagic food webs exhibit higher mercury concentrations than polar bears participating in predominantly sympagic food webs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73930/1/j.1751-8369.2009.00114.x.pd

INVESTIGATION OF GRAPHITE BODIES. Progress Report No. 4 for period June 1, 1959 to August 31, 1959

Preliminary data are presented illustrating the properties of molded multicrystalline graphite made using calcined petroleum coke (in some instances mixed with a thermal carbon) bonded with coal tar pitch, furfuryl alcohol, or limited mixtures of the two. No conclusions have yet been drawn regarding the relation between these properties, since a large number of specimens remain to be measured. Most obvious is the difficulty of achieving a sound structure from bodies of maximum green density, particularly when the binder is not thermoplastic. Graphitized specimens made with furfuryl alcohol reflect the high density of the binder coke. Xray data show that this coke is poorly graphitizable as compared to pitch; modulus and electrical resistance data show it to be more dense. A full description of the use of differential thermal analysis and dilatometry in investigating the behavior of thermosetting resins is appended. For preceding period see ARF-6039-3. (auth

Using GPS technology to assess feeding areas of Atlantic puffins Fratercula arctica

Large areas of sea around Britain have been identified as potential sites for renewable energy development, heightening the need for information about important areas for seabirds. The Atlantic Puffin Fratercula arctica is one of the commonest seabirds in northeast Britain yet little is known about where individuals feed. We used back-mounted GPS loggers to track Atlantic Puffins breeding at a colony close to where wind farms are proposed. During chick rearing, birds made two types of feeding trip: long absences that included an overnight stay at distant (38–66 km) feeding areas and short daytime excursions to areas much nearer the colony (9–17 km). There was considerable overlap of the distant feeding area with the proposed wind farms. However, Atlantic Puffins are known to be sensitive to disturbance and comparison of individuals with and without loggers showed that the birds' behaviour had been disrupted by some aspect of the procedure. While the areas used by the birds carrying GPS loggers accorded with expectations based on other methods, it is possible that results from these birds represent a worst-case scenario and overestimate the degree of overlap with the proposed wind farms