New Zealand Journal of Marine and Freshwater Research abstracts
Longitudinal changes in biota along four New Zealand streams: declines and
improvements in stream health related to land use
Dev K. Niyogi*
Mark Koren
Chris J. Arbuckle
Colin R. Townsend
Department of Zoology
University of Otago
Dunedin, New Zealand
*Present address: Department of Biological Sciences,
University of Missouri-Rolla, Rolla, MO 65409-1120, United States. email:
niyogid@umr.edu
Abstract We studied four streams in southern New Zealand
in 2002 to document downstream changes in water quality, habitat, and stream
biota in relation to land use. Two streams were in catchments that had increasing
intensity of agricultural development downstream from relatively pristine headwaters.
A third stream had the most intense land use in the headwaters and a riparian
corridor of regenerating native forest along its middle reaches. A fourth stream
had low intensity pasturing in its lower reaches, but also downstream increases
in sedimentation from natural and historic mining sources. Four to six sites
were sampled along each stream. Pastoral land cover in catchments was positively
related to nutrient concentrations and fine sediment cover in the streams.
At the most agricultural sites, dissolved inorganic nitrogen reached concentrations
of 2 mg/litre, and fine sediment covered 33% of the stream bottom. Several
biotic indices for invertebrates, including the Macroinvertebrate Community
Index (MCI), were lower at the agricultural sites, which had MCI scores around
100. The indices were negatively related to fine sediment cover. The site with
the intact riparian zone had declines in sedimentation downstream, which were
paralleled by increases in invertebrate richness and biotic indices. Our findings
support the notion that the restoration of riparian zones can improve stream
habitat and invertebrate health.
Keywords streams; land cover; riparian; macroinvertebrates;
stream health; sedimentation
New Zealand Journal of Marine and Freshwater Research, 2007, Vol. 41:
63–75
0028–8330/07/4101–0063 © The Royal Society
of New Zealand 2007
M06044; Online publication date 2 March 2007. Received 19 July 2006;
accepted 26 January 2007
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