Contrasting beta-diversity patterns of temperate coastal fish species and their functional traits

Useful measurements of biodiversity for the purpose of conservation planning are dependent on describing appropriate biological characteristics of assemblages at a representative spatial scale. Defining ecological connectivity and composition over the extents of a management region can provide insights on the spatial ecology of assemblages intended for protection. Here we investigated the biogeographic patterns in both taxonomic and functional beta-diversity of fish assemblages from two depth strata (infralittoral and circalittoral reefs) across 800 km of exposed coastline on the south-east Australian continental margin, including six no-take marine protected areas. A general increase in both functional and taxonomic beta-diversity from west to east was observed using a null modelling approach. Notably, patterns in functional beta-diversity were largely attributed to the nestedness component of beta-diversity between sites in contrast with taxonomic beta-diversity which showed patterns related mostly to species turnover. Defining functional and species beta-diversity of marine fish revealed these metrics didn’t always follow analogous patterns, despite the ecological niche similarities in the assemblages sampled across sites. This investigation of functional and taxonomic diversity can inform the inherent ecological resilience of assemblages across differing bio-regional scales. Furthermore, the application provides a unique and comparable representation of functional and taxonomic characteristics using existing biological datasets. • We investigated patterns on reef in fish taxonomic and functional beta diversity • Two depth strata across 800km of coastline were sampled in south-east Australia • We identified a west to east gradient in taxonomic and functional beta diversity • Patterns in functional beta-diversity identified assemblages were highly nested • Functional approaches are useful in understanding the significance of change