Seascape context and urbanisation modify fish assemblages around rocky headlands

Seascape context is pivotal in shaping the abundance and diversity of fishes within coastal seascapes. However, pervasive human disturbances modify the composition of coastal seascapes, necessitating a thorough understanding of how these effects interact to influence ecosystems, which is critical for implementing effective conservation and management plans. In coastal ecosystems such as exposed rocky headlands and their abutting rocky reefs, these influences remain largely unquantified, thereby limiting effective management of this crucial coastal landform. We sampled fish assemblages around 12 rocky headlands across 300 km of coastline over two seasons (austral spring and winter) in eastern Australia with baited remote underwater video systems. We aimed to determine how seascape context, benthic habitat composition, exposure, and human disturbance shape fish community composition, and the abundance of harvested species, functional feeding groups and key indicator species around rocky headlands. Seascape context and human disturbance were important in shaping fish assemblages around rocky headlands. Sites that were less than 2.5 km from estuaries contained a greater species richness and a higher abundance of piscivores. Sites more than 0.9 km from urban land supported a greater species richness and a higher total fish abundance. Sites that had more than 2.5 km2 of reef nearby supported a greater species richness and herbivore abundance, while those with 2-3.5 km2 of reef nearby supported a higher abundance of omnivores and harvested fishes. In contrast, sites with less than 1 km2 of reef nearby supported a higher abundance of zoobenthivores. These results highlight the combined effects of human disturbance and seascape context on the abundance, diversity, and functional group composition of coastal fishes. Minimising the extent of urbanisation and prioritising the conservation of rocky headlands and their abutting reefs near estuaries with greater reef area, is, therefore, essential for maintaining biodiversity and fisheries productivity in coastal seascapes.