New Zealand Journal of Marine and Freshwater Research abstracts
Influence of substrate type and physico-chemical conditions
on macroinvertebrate faunas and biotic indices
of some lowland Waikato, New Zealand, streams
KEVIN J. COLLIER
ROBERT J. WILCOCK
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11 115
Hamilton, New Zealand
ADRIAN S. MEREDITH*
Environment Waikato
P. O. Box 4010
Hamilton, New Zealand
*Present address: Canterbury Regional Council, P. O. Box 550,
Timaru, New Zealand.
Abstract Lowland streams in agricultural areas are often
considered degraded because of high turbidity, high biomass of adventive
macrophytes, and a predominance of fine bed substrates. Invertebrate faunas in
these streams are being increasingly used in biomonitoring, and an
understanding of factors affecting their distribution and abundance is
important for interpreting the results of these studies. We measured
physico-chemical parameters and sampled macro-invertebrate faunas on inorganic
substrates, wood, and macrophytes to investigate factors influencing
invertebrate distribution and abundance in Waikato, New Zealand, lowland
streams, and to evaluate six biotic indices and a rapid bioassessment protocol
for lowland stream environments. At most sites, invertebrate faunas were
dominated numerically on all substrate types by the hydrobiid snail
Potamopyrgus antipodarum (Gray), the eusirid amphipod
Paracalliope, and Diptera (mostly the chironomid Neonella
forsythii Boothroyd and the blackfly Austrosimulium spp.). Stepwise
regression analyses indicated that densities of some common taxa on inorganic
substrates (0.1 m-2) and macrophytes (g-1 wet weight)
were correlated with combinations of reach water depth, percentage of bed
covered by macrophytes or sand/silt, and water quality factors including
conductivity, water temperature, and measures of dissolved oxygen (DO)
concentration and magnitude of diel fluctuation. These factors and also the
amount of wood present explained 36-87% of the variation in several of the
biotic indices examined on different substrate types. Some taxonomic (no. of
taxa) and compositional (% dominant taxon) indices appeared sensitive to
measured habitat conditions, and this may affect their utility for detecting
water quality impacts in lowland streams. Percent Ephemerop-tera, Plecoptera,
and Tricoptera (EPT), and the Macroinvertebrate Community Index (MCI) and its
quantitative analogue (QMCI) reflected factors thought to be more associated
with direct and indirect effects of riparian and catchment land use on water
quality (DO, conductivity, temperature, macrophyte cover). Comparison of
indices derived from intensive and rapid bioassessment sampling yielded
significant regressions with slopes that were not significantly different to 1
for % EPT and MCI. These indices appear to be particularly useful for rapid
bioassessment of lowland stream environments.
Keywords macroinvertebrate; macrophyte; wood; water quality;
biotic index; rapid bioassessment; lowland stream; New Zealand
New Zealand Journal of Marine and Freshwater Research, 1998, Vol. 32:
1-19
0028-8330/98/3201-0001 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (1240K); (scanned from paper original: notes about this process)
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