whales (Balaena mysticetus), and Arctic Cod (Boreogadus saida) (Plate 11.3), all
mostly feeding on copepods. The cod serves as the main food for the ringed seals
(Pusa hispida), glaucous gulls (Larus hyperboreus), beluga whales (Delphinapterus
leucas), and narwhals (Monodon monoceros), that comprise the next trophic level.
Arctic cod form dense schools in the Canadian Arctic and attract large numbers of
seabirds and beluga whales (Plate 11.3).The apex predators are the polar bears (Ursus
maritimus) that consume ringed seals, and the indigenous people who consume seals
and whales.
Fig. 11.21 Structure proposed by Tremblay et al. (2006) for the pelagic food-web in
the North Water Polynya in northern Baffin Bay, based on carbon budgets, stable
isotopes, analyses of gut contents, and the literature. Numbers in the margin indicate
the trophic level inferred from stable isotopes. The size of the arrows reflects the
relative importance of a food item for a given consumer, not the magnitude of the
carbon flux. Themisto is a planktonic amphipod. Alle is a planktivorous bird.
Bowhead whales are a threatened species found in shelf areas. Eubalaena glacialis is
the northern right whale, also a threatened species.
(^) (After Tremblay et al. 2006.)