Abstract:

Macroalgal meadows are a prominent, yet often maligned component of the tropical seascape. Our work at Ningaloo reef in WA demonstrate that canopy forming macroalgae provide habitat for adult and juvenile fish of ecological and fisheries importance. The abundance and diversity of fish in macroalgae habitats is related to the canopy height, density and cover, the persistence of these structural features linked to fish survival over winter. A synthesis of 12 studies that surveyed fish on both coral and macroalgae reefs found most species (62%) are observed on both habitats and 17% of species were unique to macroalgae. By combing information on fish habitat associations with species specific catch data from >90 locations around the globe we estimate that macroalgae habitats support 25% of the catch from tropical reefs. However, at some locations macroalgal associated fishes dominate the catch and in the Seychelles these fish have sustained fisheries following regime shifts from coral to macroalgae. Fisheries heavily dependent on macroalgae habitats are characterized by high abundance of species with life history traits that make them less susceptible to overfishing. Catch diversity of these fisheries is however low, the reduced portfolio of fished species leaving these fisheries vulnerable to natural fluctuations stock size. These findings improve understanding of how macroalgae habitat contribute to tropical fish assemblages, and demonstrate that the composition of fish assemblages and fisheries are reliant on contributions from multiple habitats within the seascape.

Bio:

Shaun Wilson is a Principal Research Scientist with the Marine Science Program, DBCA, where he conducts and facilitates research to inform management of Western Australia’s marine parks and threatened species. This involves working closely with DBCA regional staff across that state and collaborating with scientists from both universities and research institutes. Shaun’s main research interests revolve around ecological research and monitoring of tropical marine systems, particularly coral reefs.  Much of this work is focused on how environmental disturbances and pressures influence marine systems, associated communities, processes, and ecosystem services.