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copepodite stage and reproduces in spring. For reproducing, however, the animals require a
supply of energy which is not available before primary production has begun to take place.
A time lag ensues before they can respond to the onset of phytoplankton outgrowth, which
enables the spring phytoplankton bloom to occur. The food supply is accordingly large when
the offspring of the overwintering animals eventually develop, so that they can mature fast and
reproduce in summer. This second generation feeds mainly on regenerated production
(effected mainly by flagellates) before migrating to deep waters for overwintering. The lack
of diatoms in their diet is a likely reason why they do not accumulate sufficient reserves,
especially in the form of lipids, to reproduce early and suppress the next spring bloom.
According to Parsons and Lalli (1989), the relatively high winter temperature at OWS I would
also cause significant metabolic losses in the overwintering copepod popUlation and contribute
to their being in poor condition at the beginning of the productive season. A time lag between
phytoplankton outgrowth and the increase in herbivore biomass seems to be general in Atlantic
temperate waters, even in shelf areas that remain well-mixed throughout the year and where
a single phytoplankton biomass peak is found in summer (e.g. Wafar et al., 1984).
An annual cycle of this type leaves ample room for the export and sequestration of biogenic
carbon. As long as the herbivore stock is too low to graze them, the diatoms from the spring
bloom will largely sink, as will part of the material from the subsequent coccolithophore
bloom. In autumn, recycling of the summer biomass pool by microheterotrophs may result
in the buildup of large pteropod populations which will export carbon in their calcareous
shells. Similar processes can also take place at other times of the year in hydrodynamic traps,
where ageing organisms or detrital material accumulate (e.g. summer tidal fronts on the
European continental shelf). Annual cycles of this type are largely driven by variations in
hydrodynamic conditions, which initiate a response at the level of primary producers that may
take time to be reflected in the secondary producers. The succession of blooms and biomass
peaks in animal populations thus corresponds to a dynamic imbalance and, given interannual
variations, the system probably never reaches steady state conditions.
Such systems with high amplitude production cycles (Le. blooms of large cells, followed by
peak production of herbivores) favour a food web leading to large animals and fish (see
copepodite stage and reproduces in spring. For reproducing, however, the animals require a
supply of energy which is not available before primary production has begun to take place.
A time lag ensues before they can respond to the onset of phytoplankton outgrowth, which
enables the spring phytoplankton bloom to occur. The food supply is accordingly large when
the offspring of the overwintering animals eventually develop, so that they can mature fast and
reproduce in summer. This second generation feeds mainly on regenerated production
(effected mainly by flagellates) before migrating to deep waters for overwintering. The lack
of diatoms in their diet is a likely reason why they do not accumulate sufficient reserves,
especially in the form of lipids, to reproduce early and suppress the next spring bloom.
According to Parsons and Lalli (1989), the relatively high winter temperature at OWS I would
also cause significant metabolic losses in the overwintering copepod popUlation and contribute
to their being in poor condition at the beginning of the productive season. A time lag between
phytoplankton outgrowth and the increase in herbivore biomass seems to be general in Atlantic
temperate waters, even in shelf areas that remain well-mixed throughout the year and where
a single phytoplankton biomass peak is found in summer (e.g. Wafar et al., 1984).
An annual cycle of this type leaves ample room for the export and sequestration of biogenic
carbon. As long as the herbivore stock is too low to graze them, the diatoms from the spring
bloom will largely sink, as will part of the material from the subsequent coccolithophore
bloom. In autumn, recycling of the summer biomass pool by microheterotrophs may result
in the buildup of large pteropod populations which will export carbon in their calcareous
shells. Similar processes can also take place at other times of the year in hydrodynamic traps,
where ageing organisms or detrital material accumulate (e.g. summer tidal fronts on the
European continental shelf). Annual cycles of this type are largely driven by variations in
hydrodynamic conditions, which initiate a response at the level of primary producers that may
take time to be reflected in the secondary producers. The succession of blooms and biomass
peaks in animal populations thus corresponds to a dynamic imbalance and, given interannual
variations, the system probably never reaches steady state conditions.
Such systems with high amplitude production cycles (Le. blooms of large cells, followed by
peak production of herbivores) favour a food web leading to large animals and fish (see