Implications of spatial variability of fish assemblages for monitoring of Australia’s tropical estuaries

Sheaves, Marcus, and Johnston, Ross (2010) Implications of spatial variability of fish assemblages for monitoring of Australia’s tropical estuaries. Aquatic Conservation: marine and freshwater ecosystems , 20 (3). pp. 348-356.

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1. Although often seen as ideal targets for monitoring environmental change because of their high public profile, fish assemblages rarely appear as indicators in monitoring and reporting.

2. Published data were evaluated to develop a simple approach to quantifying the temporal consistency in assemblage structure suitable for routine monitoring and assessment. Data were examined as catch per unit effort (CPUE) and probability of encounter (PoE), and compared using three approaches with the potential to produce simple indices quantifying the patterns of similarity within an estuary over time: species richness, Bray-Curtis Similarities and a new approach, DeltaPoE. Indices derived from published data were then tested against a time series of data from two estuarine lakes with a history of fish kills.

3. Multidimensional scaling based on PoE emphasizes the temporal consistency of fish assemblages within estuaries at least as well as one based on mean CPUE while providing operational advantages. Similarities based on PoE were more sensitive to change from ‘natural’ assemblage structure than the simpler indices and showed comparable results with Similarities from (log) CPUE data. The one drawback to Similarities is that their complex statistical formulation often makes them less effective vehicles for reporting and communication. Where this is the case the conceptual simplicity of DeltaPoE and its performance relative to Similarities suggests it is a good candidate from which to develop monitoring indices suitable for routine reporting.

4. The performance of each of the indices were considered against the known fish kills. Species richness tracked the observed changes, an expected outcome in this case because a major impact directly removed species. Both indices based on Similarities also tracked the changes faithfully. Of the two, Similarities based on PoE seemed to react more strongly to assemblage changes.

Item ID: 15195
Item Type: Article (Research - C1)
ISSN: 1099-0755
Keywords: fish; estuary; monitoring; assessment; environmental change; CPUE; probability of encounter; similarities
Date Deposited: 13 Jan 2011 06:31
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 90%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 10%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 80%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960305 Ecosystem Adaptation to Climate Change @ 20%
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