μM, and nitrate was reduced from 11 to 4 μM. The SEEDS I experiment was similar,
but in the western gyre (48.5°N, 165°E) in July–August with a mixed layer of only
∼10 m, which kept the added iron concentrated and generated a bloom that reached 20
μg Chl liter−1, almost entirely accounted for by one centric diatom, Chaetoceros
debilis.
(^) The entire inshore rim of the subarctic Pacific gyre has a substantially different
production regime. The eddy-rich British Columbia and SE Alaska coast; the close-in
coastal waters of the northern Gulf of Alaska; the inshore Alaska Stream along the
Aleutians; and the Oyashio from Kamchatka to its offshore turn off Hokkaido, all
have strong, diatom-dominated spring blooms. These do draw down NO 3 −, PO 4 3− and
Si(OH) 4 to low levels, and evidently there is at most intermittent iron limitation, likely
because both sediment resuspension and river influx supply iron to the euphotic zone.
The boundary between bloom-supporting and HNLC zones occurs at various and
fluctuating distances from shore. The mesozooplankton community of these more
coastal waters is constituted of the same species as that of the oceanic area. The
Neocalanus species have faster developmental rates in coastal and fjord waters, more-
focused periods of active feeding in the surface layers, and more-focused times of
spawning, particularly in the Sea of Japan and in fjord areas like Georgia Strait and
Prince William Sound. Calanus pacificus and several species of Pseudocalanus are
more abundant than offshore, and the coastal copepod Calanus marshallae is added to
the mix. Several euphausiid species, for example Thysanoessa spinifera and
Thysanoessa raschii, tend to be much more abundant in or restricted to the coastal
zones.
(^) The subarctic Pacific is habitat to an array of endemic squid, fish, and marine
mammals, both in oceanic reaches and along the coast. Among schooling fish, the
Pacific saury (Collolabis sauri), an important food fish for salmon, is both oceanic
and coastal, migrating north and south across the region seasonally. The pomfret
(Brahma brahma) migrates north in summer from more subtropical waters, crossing
far into the subarctic. Offshore coastal waters are home to several species of anchovy
and sardine. Of course the totemic fish of the region are the five species of
Onychorhynchus, the Pacific salmon, anadromous fish that home to their natal streams
around the whole arc of the subarctic coastline. Some species are more coast-bound
than others, especially as the young enter the ocean, but sockeye, pink, and older
chinook salmon range across the entire oceanic reach, south in winter and north in
summer. Massive volumes of research results are available on the biology of salmon,
partly because of commercial importance, partly because their migrations and
physiology are so amazing.
(^) There are both large oceanic squid, Onykia robusta, and more coastal squid,
including the Japanese flying squid, Todarodes pacificus. The latter grows during