Published and unpublished accounts of the zooplankton community of Loc
h Lomond are reviewed. Loch Lomond's zooplankton community is unique a
mongst those of Scotland's other large lochs. Holopedium gibberum appe
ared in Loch Lomond in the years between the studies of Slack & Hamilt
on in the 1950s and zooplankton surveys in the late 1970s. The annual
cycles of Eudiaptomus gracilis, Cyclops strenuus abyssorum and Mesocyc
lops leuckarti are described for the mid basin of Loch Lomond. E. grac
ilis overwinter mainly as adults with variable egg production during t
heir lifespan of 5-8 months. The cyclopoid copepods have variable life
history characteristics. C. str. abyssorum produce a single generatio
n per year, overwinter by means of resting eggs and a small population
of planktonic adults, while M. leuckarti is present in the plankton t
hroughout the year, but in low numbers during winter. Zooplankton popu
lations in Loch Lomond are predated by the diverse fish community whic
h includes a facultative planktivore in the powan, Coregonus lavaretus
. Powan feed heavily on zooplankton from late spring until late autumn
. Powan display selectivity in the prey species taken, in the size dis
tribution and morph types taken within prey species. Zooplankton speci
es, morphs and forms in Loch Lomond tend to reflect this predation.