Seascape diversity and configuration shape habitat selection across multiple coastal ecosystems

Many species move among habitats to feed, shelter, reproduce, and disperse, linking ecosystems across land and seascapes. In coastal ecosystems, fish movements throughout ontogeny connect habitats to form interlinked seascapes. The concepts of nursery habitats and ontogenetic habitat shifts are widely accepted, but how seascape features shape habitat use across coastal ecosystems during different life stages remains unclear. To address this, we surveyed fish from six habitat types with stereo-remote underwater video stations to examine how the spatial attributes of coastal ecosystems influence habitat use. Surveys were completed four times over two years and encompassed 180 sites along 200 km of the inshore Great Barrier Reef, Australia. Key fisheries taxa, including species of Lutjanus, Lethrinus, and Choerodon, exhibited clear ontogenetic shifts, moving from mangroves and back-reef habitats to coral reefs at larger body sizes. Variation in the spatial properties of coastal seascapes, principally the composition and configuration of habitats, was tightly linked to changes in the distribution and abundance of these species at different sizes. These strong seascape effects were evident across all habitats and sizes examined and were consistently more important than variation in habitat cover. Our findings strongly support the seascape nursery concept, demonstrating how the spatial diversity, composition and configuration of habitats can influence the abundance and distribution of coastal fishes and that interconnected habitats are critical for species undergoing ontogenetic shifts. Implementing effective management strategies for these species and their habitats will require protecting seascape features such as high habitat diversity and conserving well-connected patches.