Diversity surrogates for estuarine fish assemblages in a temperate estuary in New South Wales, Australia

The efficacy of fish diversity surrogates is central to their utility in conservation planning and management. Here we examine the linkages among a range of biotic and abiotic surrogates for estuarine fish diversity within the Port Stephens estuary in NSW, Australia. We examine the effectiveness of using biotic habitats as surrogates for diversity, and examine whether this surrogacy persists through time. The study was conducted using fish assemblage data gathered across eight a priori identified biotic habitat types. Significant differences in fish assemblages, species richness, and functional richness were detected among 26 out of 28 biotic habitats pairs, and these differences persisted for over 1 year within key Dendronephthya australis (soft coral) and filter feeder habitats, demonstrating the potential for biotic habitats to be used as surrogates for estuarine fish diversity. Significant correlations between abiotic variables (i.e. depth, location, substrate type, and substrate complexity) and fish assemblages were also established. Overall, the results demonstrate that both abiotic variables and biotic habitats can be used as surrogates for fish diversity in the study estuary, and combining both these types of predictor variables can provide a high level of discrimination among estuarine fish assemblages. The use of both abiotic variables and biotic habitats in conservation planning can, therefore, improve representation of estuarine fishes within marine protected areas.