Zooplankton of the open Baltic: Extended Atlas - IOW

intimately linked ever since fish evolved from macrophagy to microphagy
(Kerfoot & Lynch, 1987). Various studies of the stomach contents of young
fish show from 1% to 95% Cladocera by volume, and very few studies show
less than 10% (Pennak, 1978). However, some cladoceran species (e.g. a
large-bodied predatory cladoceran of the Ponto-Caspian origin, Cercopagis
pengoi, one of the recent invaders in the Baltic Sea), being a suitable food
item for planktivorous fish, may also demonstrate structural and functional
impact on zooplankton community thus performing competitive interactions
for food (smaller crustaceans) with fish populations as shown recently for the
Baltic Proper (Gorokhova, 1998), Gulf of Riga (Ojaveer & Lumberg, 1995),
and Gulf of Finland (Antsulevich & Välipakka, 2000; Telesh et al., 2000;
Telesh & Ojaveer, 2002).
In general, the role of zooplankton for the earlier juvenile fish is critical
to high fish survival so that they can take advantage of an abundance of
phytoplankton and detritus when available (Fernando, 2002).
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