Exmouth Gulf, north western australia
a review of environmental and economic values and baseline scientific survey of the south west region
An extensive literature review and additional field surveys have revealed the diverse environmental and socio-economic values of Exmouth Gulf. Exmouth Gulf contains globally significant features including: a humpback whale nursery, a globally signficant undisturbed arid zone mangrove ecosytems and fossil Pleistocene coral reefs. The gulf also encompasses a diversity of habitats including samphire wetlands, subterranean karst limestone waterways, modern coral reefs, seagrass beds, high intertidal cyanobacterial mats, macroalgae-dominated reef flats, intertidal sand flats, soft coral and sponge beds, oyster beds, undisturbed islands and sandy beaches. This diversity of habitats support a highly diverse assemblage of invertebrate and vertebrate fauna, including:
28 marine mammal species including the world’s largest Humpback Whale nursery, feeding and mating habitat for the world’s largest stable Dugong population, and populations of Australian Snubfin, Australian Humpback and Bottlenose Dolphins.
>63 species of elasmobranch (sharks and rays) including two Critically Endangered Sawfish, pupping habitats, shelter for juvenile Giant Shovelnose Rays and Leopard Whiprays, and significant Manta Ray aggregations.
>15 species of sea snakes including endemic and Critically Endangered species.
Globally unique subterranean stygofauna assemblage associated with underground subteranean karst limestone waterways.
Five species of sea turtles including juvenile feeding habitat for Critically Endangered,
Endangered and Vulnerable species (Hawksbill, Leatherback, Loggerhead, Flatback and Green Turtles).
790 species of teleost fish including critical juvenile habitat for commercial and recreational species and poorly understood seahorse and pipefish assemblages
1147 species of invertebrates including crustaceans, cephalopods, echinoderms, gastropods and bivalves. This includes an extremely valuable panaeid prawn, crayfish and crab fisheries, highly endemic holothurians (sea cucumbers), and numerous Endangered and Vulnerable species.
95 species of migratory and resident shorebirds, waterbirds and seabirds, including important nesting, feeding and roosting habitat for 36 Migratory, four Endangered, 11 Near Threatened and two Vulnerable species.
This ecosystem also sustains economically and socially important fishing, ecotourism and recreation sectors worth tens of millions of dollars annually. Despite this importance, relatively little is understood of the baseline conditions or processes maintaining this unique biodiversity, productivity and values. In particular we do not have adequate knowledge to assess the potential environmental impacts of industrial coastal development within this unique ecosystem. The lack of knowledge of the unique marine biodiversity and ecosystem values and potentially sensitive nature of the Exmouth Gulf ecosystem to disturbance suggests any large-scale coastal development will be likely to have deleterious environmental, social and economic impacts.
Previously proposed large scale coastal industrial developments within Exmouth Gulf have all been discontinued or rejected. It has generally been viewed that there is inadequate knowledge available for environmental assessments within Exmouth Gulf, with the implication that the potentially large and negative impacts of any large scale coastal industrial developments would not be consistent with conserving Exmouth Gulf as one of the last remaining undisturbed arid zone mangrove ecosystems globally. However, currently there are proposed a large scale industrial development, including a pipeline fabrication facility, at the southern end of the Gulf concurrent with proposed rezoning of land for industrial use along the western coast of the Gulf. This is in contradiction to the fact that in 1994 the WA Government Marine Parks and Reserves Authority recommended that the Gulf should be considered for marine park zoning and in 2004 the World Heritage Consultative Committee recommended the area should be proposed for world heritage status.
To ensure the maintenance of this unique ecosystems diversity, productivity and values, and to address the many knowledge gaps on ecosystem function, there is an immediate need for implementing a multidisciplinary Exmouth Gulf Marine Research Program. This should inform a Strategic Assessment, as defined under the Environmental Protection and Biodiversity Conservation Act, Commonwealth, 1999 (EPBC Act), of past, current and future cumulative impacts and set future limits for development within this ecosystem. Such a Strategic Assessment is necessary to determine the scope of cumulative impacts, implement appropriate spatial management and set future development limits to ensure the biodiversity and socio-economic values of the Gulf are maintained.