The composition and structure of shallow benthic reef communities in the Kimberley, north-west Australia

WA Museum Records and Supplements | Updated 6 years ago

ABSTRACT – The diversity, productivity and health of tropical reef ecosystems are at risk from cumulative anthropogenic and climate stressors. To provide insight into natural patterns of community structure and to set benchmarks to detect change, it is important to establish baselines for common community metrics, such as benthic cover, while ecosystems are near-pristine. Here we report the findings from six years of shallow-water marine benthic surveys (0–15 m depth) in the Kimberley, Western Australia. This dataset provides the first broad-scale quantification of the general composition and structure of reefs in this little known region. We show that the Kimberley reef system is heterogeneous, with distinct inshore-offshore, intertidal-subtidal and subregional patterns of community structure. The dominant category of live benthos in the Kimberley is hard coral (23.81% ± 1.28%), followed by turf algae (14.40% ± 1.51%) and macro-algae (7.05% ± 1.00%). At the regional scale, soft corals and sponges were minor contributors to benthic cover accounting for less than 3%. Benthic composition and structure was significantly different between all five subregions, with the exception of Inshore North and Inshore South, which share traits, such as a higher level of macroalgae and lower level of turf and coralline algae, than the level recorded in the Inshore Central subregion. Offshore, the southern subregion (Rowley Shoals) had the highest level of hard coral cover (27.92% ± 2.51%), and inshore the highest level of hard coral cover was recorded in the northern subregion (25.39% ± 3.00%). Overall, this dataset provides a reference for future marine conservation planning in the region and confirms that shallow benthic communities of the Kimberley are an important part of Australia’s tropical reefscape.