Importance of Regional, System-Wide and Local Spatial Scales in Structuring Temperate Estuarine Fish Communities

• Published in: Estuaries and coasts 2014-05, Vol.37 (3), p.525-547
• Main Authors: Valesini, F. J, Tweedley, J. R, Clarke, K. R, Potter, I. C
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal and plant ecology; animal communities; Animal scales; Animal, plant and microbial ecology; Biological and medical sciences; Brackish; Brackish water ecosystems; Brackishwater fishes; Coastal Sciences; Coasts; decision support systems; Earth and Environmental Science; Ecology; Environment; environmental factors; Environmental Management; Estuaries; estuarine fish; Fauna; Fish; Fish scales; Fresh water; Freshwater & Marine Ecology; Freshwater fishes; Fundamental and applied biological sciences. Psychology; Marine biology; Marine fishes; prediction; Synecology; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Water and Health
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-013-9720-2

An extensive literature base worldwide demonstrates how spatial differences in estuarine fish assemblages are related to those in the environment at (bio)regional, estuary-wide or local (within-estuary) scales. Few studies, however, have examined all three scales, and those including more than one have often focused at the level of individual environmental variables rather than scales as a whole. This study has identified those spatial scales of environmental differences, across regional, estuary-wide and local levels, that are most important in structuring ichthyofaunal composition throughout south-western Australian estuaries. It is the first to adopt this approach for temperate microtidal waters. To achieve this, we have employed a novel approach to the BIOENV routine in PRIMER v6 and a modified global BEST test in an alpha version of PRIMER v7. A combination of all three scales best matched the pattern of ichthyofaunal differences across the study area (ρ = 0.59; P = 0.001), with estuary-wide and regional scales accounting for about twice the variability of local scales. A shade plot analysis showed these broader-scale ichthyofaunal differences were driven by a greater diversity of marine and estuarine species in the permanently-open west coast estuaries and higher numbers of several small estuarine species in the periodically-open south coast estuaries. When interaction effects were explored, strong but contrasting influences of local environmental scales were revealed within each region and estuary type. A quantitative decision tree for predicting the fish fauna at any nearshore estuarine site in south-western Australia has also been produced. The estuarine management implications of the above findings are highlighted.