New Zealand Journal of Marine and Freshwater Research abstracts
Effect of substrate stability and canopy cover on stream invertebrate
communities
Erna M. Zimmermann
Russell G. Death
Institute of Natural Resources-Ecology
Massey University
Private Bag 11 222
Palmerston North, New Zealand
email: R.G.Death@massey.ac.nz
Abstract Disturbance can be an important determinant
of stream benthic invertebrate community structure. Whether this is a result
of the direct loss of invertebrates, an alteration to the food base of the
community by the disturbance, or a combination of both, is never clear. We
examined this question by conducting a disturbance experiment under artificial
cover where low light limited periphyton growth and minimised the effect
of disturbance on periphyton abundance. The experiment was conducted using
baskets of natural substrate in a spring-fed Taranaki Ring Plain stream,
Taranaki, New Zealand during February and March 2000. Baskets were placed
in the open or under cover and half were disturbed every week for 4 weeks.
The artificial cover dramatically reduced periphyton biomass. Presence or
absence of cover was the primary determinant of what invertebrate taxa dominated
in the baskets, most likely as a result of differences in food resources.
The filter feeding Coloburiscus humeralis dominated numerically in
the covered baskets, whereas the generalist grazers Deleatidium spp.,
Beraeoptera roria, Orthocladiinae, and Diamesinae dominated numerically
in the open baskets. However, cover had no effect on the overall abundance
and species richness of the experimental baskets but disturbance reduced
abundance and to a lesser extent species richness.
Keywords community structure; cover; disturbance;
diversity; macroinvertebrates; periphyton; substrate stability
M01050 Received 22 June 2001; accepted 25 March 2002; published 17 September 2002
New Zealand Journal of Marine and Freshwater Research, 2002, Vol. 36:
537-545
0028-8330/02/3603-0537 $7.00 © The Royal Society of New Zealand
2002
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