New Zealand Journal of Marine and Freshwater Research abstracts
Spatial patterns in the composition of shallow-water
macroinvertebrate communities of a large New Zealand river
Kevin J. Collier1,2
Adrian Lill1,*
1Environment Waikato
P. O. Box 4010
Hamilton, New Zealand
email: kevin.collier@ew.govt.nz
2Centre for Biodiversity and Ecology Research
The University of Waikato
Private Bag 3105
Hamilton, New Zealand
*Present address: Department of Zoology, University of
Otago, P. O. Box 56, Dunedin, New Zealand.
Abstract Identifying the environmental factors
influencing biotic patterns in large rivers will assist with
extrapolating biological monitoring results to broader scale
conclusions about river condition. In the present study, we collected
macroinvertebrates and physico-chemical data at 47 shallow-water
(<1-m deep) sites, including nine sites at major tributary
junctions, during summer along the lower Waikato River, North Island,
New Zealand. Macroinvertebrate communities were dominated by a few
relatively abundant and widespread taxa. Upper site samples were
characterised by high relative abundances of Diptera, but the
significance of this group declined further downstream where Crustacea
became more dominant. Overall, more taxa (36) were found at tributary
junctions than at mainstem sites within four hydrogeomorphic zones
(22–31 taxa per zone). Significant differences among faunal groups
identified in a cluster analysis on relative abundance data were
detected for the percentage of wood sampled, and for water conductivity
which increased downstream at mainstem sites and was high at some
junction sites. Non-metric multidimensional scaling of percentage
abundance data revealed differences in community composition among
zones, and among some mainstem and tributary junction sites. Geographic
position (easting and northing) was significantly correlated with taxa
richness and community evenness (Pielou) at mainstem sites (excluding
tributary junctions), reflecting an increase in sample diversity and
less equitable taxonomic dominance with distance down river. Overall,
these results point to an interplay between habitat patchiness and
successional and hydrogeomorphic processes influencing
macroinvertebrate community composition in the lower Waikato River.
Such multiscale variations need to be accounted for in the design of
invertebrate biomonitoring programmes if they are to represent the
ecological condition of large river environments.
Keywords Waikato River; tributary junctions;
biomonitoring; succession
New Zealand Journal of Marine and Freshwater Research, 2008,
Vol. 42: 129–141
0028–8330/08/4202–0129 © The Royal Society
of New Zealand 2008
M07053; Online publication date 29 April 2008;
Received 25 October 2007, accepted 18 January
2008
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