Influence of habitat condition on shallow rocky reef fish community structure around islands and headlands of a temperate marine protected area

Abstract

Rocky reef fish assemblages in coastal areas are under increasing pressure from a range of human activities, including extraction via recreational and commercial fishing. Within Australia, spatial management of fish assemblages aims to protect habitats and regulate harvest pressure via the use of no-take areas (NTAs), where no extraction is permitted, and partially protected areas (PPAs), where limited fishing is allowed but higher impact activities (e.g. trawling) are prohibited. We used a novel combination of mini-baited remote underwater video (mini-BRUV) systems and in situ microhabitat assessments to assess whether reef fish community structure on shallow (6-9 m) rocky reefs varied with spatial management zone (NTAs versus PPAs), sampling season (autumn, spring) and benthic habitat condition around coastal islands and headlands within the Port Stephens-Great Lakes Marine Park (established in 2007). While fish community composition and the relative abundance of fish species did not differ significantly across spatial management zones, there were significant differences among sampling season, and spatial variation at the site level that was partly explained by geomorphology (island/headland). Notably, there was a strong association between variation in fish community structure and site-level cover of canopy-forming macroalgae among islands and headlands, which transcended management zones. Our study suggests that balancing habitat condition and geomorpho-logical setting (islands, headlands) among management zones is key to the conservation and management of shallow-water reef fish assemblages. In particular, the percent cover of canopy-forming macroalgae may be a key habitat indicator for designing, monitoring and re-balancing spatial management zones.