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to Parsons and Lalli (1988), is that these copepods have a single generation per year, they are
in particularly good condition at the end of the overwintering period, and their reproduction
is in phase with the annual increase in primary production (diatoms). One reason for their
good condition may be the low water temperature, which minimizes metabolic losses. The
protozoan biomass also provides an initial food supply that allows the animals to reproduce
at the very beginning of the production increase; the continued production will be exploited
later by their offspring. This strategy for survival and reproduction might also be favoured
by an accumulation of lipid reserves, derived from diatoms. According to Miller and SUPER
Group (1988), the actual picture could be somewhat more complex than described by Parsons
and Lalli (1988). The euphotic layer appears to be subdivided into two strata, with taxonomic
differences in both primary producers and large herbivores. One of the factors contributing
to the absence of blooms would be inefficient utilization of the nitrate pool by phytoplankton
(in both strata). Control by grazing is not disputed by Miller and SUPER Group (1988), but
their view is that microzooplankton playa more important role than previously acknowledged,
since protozoans consume at least as large a share of the annual primary production as do
major copepod grazers.
This type of ecosystem is apparently not restricted to the subarctic Pacific Ocean. Calanus
jinmarchicus, the dominant copepod grazer in subarctic and cold-temperate Atlantic waters,
may sometimes follow the same life-cycle strategy as the Neocalanus species in the Alaskan
Gyre (e.g Norwegian Current, Peinert et aI., 1989; Labrador Sea, Parson and Lalli, 1988).
Other species act in such a way that they are ready to take advantage of phytoplankton
outgrowths as soon as they occur, but may not always be efficient enough to suppress blooms
(e.g. Calanoides carinatus in the Somali upwelling, Indian Ocean; Smith, 1982).
In such an ecosystem, where the activities of producers and consumers, large and small, are
largely coupled in time, the export of new primary production will tend to be channelled
towards grazing and subsequent steps in the food chains rather than towards sedimentation.
Miller and SUPER Group (1988) report that phytoplankton losses to cell sinking seldom
exceed 10%, the major part being partitioned between microzooplankton and
macro zooplankton grazing, the latter (accounting for 10-51 % of phytoplankton losses)
producing some additional fallout of material to deep waters. In addition, most of the carbon
to Parsons and Lalli (1988), is that these copepods have a single generation per year, they are
in particularly good condition at the end of the overwintering period, and their reproduction
is in phase with the annual increase in primary production (diatoms). One reason for their
good condition may be the low water temperature, which minimizes metabolic losses. The
protozoan biomass also provides an initial food supply that allows the animals to reproduce
at the very beginning of the production increase; the continued production will be exploited
later by their offspring. This strategy for survival and reproduction might also be favoured
by an accumulation of lipid reserves, derived from diatoms. According to Miller and SUPER
Group (1988), the actual picture could be somewhat more complex than described by Parsons
and Lalli (1988). The euphotic layer appears to be subdivided into two strata, with taxonomic
differences in both primary producers and large herbivores. One of the factors contributing
to the absence of blooms would be inefficient utilization of the nitrate pool by phytoplankton
(in both strata). Control by grazing is not disputed by Miller and SUPER Group (1988), but
their view is that microzooplankton playa more important role than previously acknowledged,
since protozoans consume at least as large a share of the annual primary production as do
major copepod grazers.
This type of ecosystem is apparently not restricted to the subarctic Pacific Ocean. Calanus
jinmarchicus, the dominant copepod grazer in subarctic and cold-temperate Atlantic waters,
may sometimes follow the same life-cycle strategy as the Neocalanus species in the Alaskan
Gyre (e.g Norwegian Current, Peinert et aI., 1989; Labrador Sea, Parson and Lalli, 1988).
Other species act in such a way that they are ready to take advantage of phytoplankton
outgrowths as soon as they occur, but may not always be efficient enough to suppress blooms
(e.g. Calanoides carinatus in the Somali upwelling, Indian Ocean; Smith, 1982).
In such an ecosystem, where the activities of producers and consumers, large and small, are
largely coupled in time, the export of new primary production will tend to be channelled
towards grazing and subsequent steps in the food chains rather than towards sedimentation.
Miller and SUPER Group (1988) report that phytoplankton losses to cell sinking seldom
exceed 10%, the major part being partitioned between microzooplankton and
macro zooplankton grazing, the latter (accounting for 10-51 % of phytoplankton losses)
producing some additional fallout of material to deep waters. In addition, most of the carbon