Marine Systems

The waters off the Western Australian coast, are influenced by the Leeuwin Current. The current transports warm and low saline waters from the tropical north to southern Western Australia. The Leeuwin Current is of extreme importance to the marine environment, of particular importance to the NAR is its influence on the recruitment of the Western Rock Lobster (Panulirus cygnus) and the survival of corals in the Houtman Abrolhos Islands.

The coastal waters of the NAR is open and exposed, with substantial current and wind-driven water movements. The population is also small, with only about 60,000 people living in the NAR, half of whom are resident in the Geraldton area. There is little heavy industry along the coastline. These features combine to ensure that, while relatively few measurements have been made, overall water quality is thought to be non-impacted (NACC, 2005).

The coast of the NAR contains many offshore islands. The islands are grouped into 12 nature reserves managed by the Department of Parks and Wildlife to conserve their ecological, recreational, commercial, educational and cultural, and research values. The islands are host to a number of endangered fauna and are important examples of island habitats within the Central West Coast marine bio-region (NACC, 2005). The Houtman Abrolhos islands in particular, has a unique mixture of tropical, temperate and Western Australian endemic marine species.

Jurien Bay Marine Park and a few nearby islands form the only major breeding area for Australian sea lions along the western coast of Australia. The park also has the highest diversity of seaweed species in Australia and its extensive seagrass meadows provide shelter and nursery habitat for many fish and other marine creatures such as western rock lobster (DPaW, 2014b).

The west coast of Western Australia, between Ningaloo and Rottnest Island, is a key center of biodiversity. Eighteen hotspots of coral reef biodiversity have been found. The Abrolhos are one of four reef systems that constitute the hotspot. The Abrolhos’ total diversity is second to Ningaloo Reef, but has far more restricted range species (NACC, 2005).

The waters surrounding the Abrolhos islands have an incredible abundance of coral, macroalgae, invertebrates and fish which provide a spectacular setting for diving and snorkelling. These waters have been given special status as a Fish Habitat Protection Area for the conservation of fish and fish breeding areas and the aquatic ecosystem, and for the management of aquatic tourism and recreational activities. The Abrolhos and Jurien are classified as a Commonwealth Marine Reserve, due to major conservation values (i.e. important foraging areas for sea lions). These Commonwealth Marine Reserves also both comprise National Marine Park zones.

Along the continental coastline, subtidal reefs, limestone drop-offs, macroalgae and seagrass beds in sandy areas also provide outstanding submerged seascapes. Wreck diving is popular, and dive trails are being set up in some areas (Jurien Bay and Abrolhos) to highlight local features.

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