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Spatial and temporal variation in the stucture of estuarine macroinvertebrate assemblages: implications for assessing the health of estuaries


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Hirst, AJ and Kilpatrick, R (2007) Spatial and temporal variation in the stucture of estuarine macroinvertebrate assemblages: implications for assessing the health of estuaries. Marine and Freshwater Research, 58 (9). pp. 866-879. ISSN 1323-1650

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As human impacts in estuaries are often pervasive (estuary-wide) and/or pre-existing, the identification of
suitable reference points, from which to assess the extent of impacts, is problematic. One solution is to compare potentially
degraded estuaries with estuaries deemed to be largely unmodified by human activities. However, there is a perception
that individual estuaries are too spatially and temporally dynamic to allow valid comparisons to be made using such
an approach. We tested this idea for a commonly used indicator, benthic macroinvertebrates, using a factorial design
incorporating both temporal and spatial scales between and within three adjacent meso-tidal river estuaries in northern
Tasmania. Variation in macroinvertebrate assemblage structure was analysed using permutational multivariate analysis
of variance. Most variance occurred within estuaries (68–82% variance) relative to spatial differences between estuaries
(24–14%) corresponding with a strong upstream estuarine gradient and small-scale spatial patchiness. Seasonal variation
accounted for 9–4% of total variance indicating that temporal differences were relatively insignificant when contrasted
against spatial variability within and between estuaries. We suggest that with sufficient spatial replication at the within
estuary-scale, entire estuaries may act as whole reference systems, allowing studies to examine potential impacts within
estuaries with spatially diffuse, pre-existing human impacts.

Item Type: Article
Keywords: environmental gradients, multivariate variance components, salinity, sediment, Tasmania.
Journal or Publication Title: Marine and Freshwater Research
Publisher: CSIRO
Page Range: pp. 866-879
ISSN: 1323-1650
Identification Number - DOI: 10.1071/MF06219
Date Deposited: 07 Apr 2008 14:05
Last Modified: 18 Nov 2014 03:33
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