An eco-narrative of Perth Canyon Marine Park - South-west marine region

This report is one in a series of eco-narrative documents that synthesise our existing knowledge of Australia’s individual Marine Parks. This series is a product of the National Environmental Science Program Marine Biodiversity Hub Project D1, which seeks to collate, synthesise and visualise biophysical data within the parks. These documents are intended to enable managers and practitioners to rapidly ascertain the ecological characteristics of each park, and to highlight knowledge gaps for future research focus.

Perth Canyon Marine Park encompasses a diversity of benthic environments, ranging from gently sloping soft sediment plains to near-vertical towering cliffs of exposed bedrock. This geodiversity extends from the head of Perth Canyon at the shelf break to the slope-confined submarine canyons that dissect the lower continental slope. Spanning almost 4.5 km of ocean depths, Perth Canyon dominates the park and has a significant influence on the local ecosystem across the food chain. The size and location of the canyon is such that it promotes upwelling from the deep ocean, leading to plankton blooms that attract seasonal aggregations of larger pelagic fish, including whales. Over geological time, the canyon has evolved to provide extensive areas of benthic habitat suitable for deep-sea corals and sponges. The park is not without environmental pressures, however, with evidence that marine heat waves can affect the health of the ecosystem at upper trophic levels.

The information in this eco-narrative forms an initial characterisation of Perth Canyon Marine Park. Our knowledge of the park and of Perth Canyon in particular, is such that we can now better understand its ecosystem structure, which can be used to inform management and monitoring into the future. The key gap in our scientific knowledge of the park ecosystem is in the deepest areas, particularly for benthic communities on the lower continental slope to abyss. Targeted oceanographic and biological surveys covering these deep-water locations and to understand links between the deepest areas and the Perth Canyon in particular would contribute to an improved overall understanding of the park ecosystem. The importance of Perth Canyon Marine Park to seabird communities is also a recognised gap in our knowledge of this ecosystem.

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