New Zealand Journal of Marine and Freshwater Research abstracts
Relationships between drifting and benthic invertebratesin three New
Zealand rivers: implications for drift-feeding fish
Karen A. Shearer
John D. Stark
John W. Hayes
Roger G. Young
Cawthron Institute
Private Bag 2
Nelson, New Zealand
email: karen.shearer@cawthron.org.nz
Abstract We assessed whether taxonomic structure and
density of aquatic drift could be predicted from the benthos in three New
Zealand rivers. The three main orders contributing to both the benthos and
drift were Ephemeroptera, Diptera, and Trichoptera. Drift and benthic densities
for all taxa and all rivers combined were not significantly correlated (adults
inclusive and exclusive). There were significant positive correlations between
benthic and drift densities for the three main drifting orders-Ephemeroptera,
Diptera, and Trichoptera when data from all rivers were combined. However,
these relationships were not always detected in individual rivers. The propensity
for Deleatidium to drift was negatively related to chlorophyll a concentration;
suggesting density-dependent drift mediated by food limitation. Drift was
reduced when periphyton chlorophyll a concentration was high in relation
to benthic Deleatidium density. This highlights an unexpected effect
of periphyton proliferation on invertebrate drift and drift-feeding fishes.
Despite finding some correlations between benthic and drifting communities,
defining general relationships between benthic and drifting communities is
challenging given the complexity of density-dependent and density-independent
mechanisms that influence invertebrate drift.
Keywords aquatic invertebrate; benthos, density-dependent;
drift, drift-feeding; fish; periphyton
M02079 Received 3 October 2002; accepted 15 July 2003; Online publication
date 31 October 2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37:
809-820
0028-8330/03/3704-0809 $7.00 © The Royal Society of New Zealand
2003
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