varying seasons, then redistribute seaward, and capelin (Mallotus villosus) in northern
reaches around Iceland and Norway. Both of those stocks support significant fisheries,
while most of the larger fish of commercial importance (cod, hake, haddock, and
several flatfish) are demersal and are fished primarily over shelves and banks. The
North Atlantic supported very great stocks of the Calanus-eating northern right whale
(Eubalaena glacialis) centuries ago. These whales were hunted to commercial
extinction before whalers had motorized ships; stocks currently number a few
hundred. Fin whales and killer whales remain moderately numerous, as do several
species of porpoise, dolphin, and seals.
(^) The circumglobal subantarctic band is certainly a “westerlies biome”, but it is
convenient to consider it with the rest of the Southern Ocean.
Polar Biomes
(^) By polar ocean biomes, Longhurst meant the areas covered permanently or seasonally
by sea ice and consistently cold, with surface temperatures remaining below about
5°C. Included are the Arctic Ocean, part of the Bering Sea, and the Antarctic out to
nearly the antarctic circumpolar convergence (below called the subantarctic front). Ice
has a high albedo and shades the water column below. Of course, where the sea is
frozen in winter the sun is low or below the horizon, so photosynthetic production is
slight. When the sun does not rise significantly above the horizon, the satellite sensors
do not see ocean color for estimation of pigments, so they provide no data. There are
substantial variations in seasonal cycles, on a regional and subregional basis. The
Arctic Ocean actually is a medium-sized marginal sea, but an extremely important one
with distinctive ecology, which we will treat separately.
Southern Ocean Provinces
(^) Most of the Southern Ocean from the antarctic continent out to the subtropical
convergence (STC) at around 40°S is in a sense also a set of “westerlies” provinces.
The persistent winds are westerlies, and water flow, the Antarctic Circumpolar
Current (ACC), is from west to east around the entire ring and essentially all the way
down the water column. North-to-south and south-to-north velocity components are
added at different depths by density-driven flows. South of about 65°S, the winds
reverse to easterly, forcing westward flow alongshore of Antarctica, augmented by
buoyancy from ice melt, and generating cyclonic (clockwise in the southern
hemisphere) gyres at the boundary with the ACC, particularly in the Ross Sea south
of the Pacific and Weddell Sea south of the Atlantic. Westward flow inshore is not
continuous; the southern edge of the east-bound ACC sweeps along the coast from
120°W to the tip of Palmer Peninsula, and is quite close in to the continent across the