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An eco-narrative of Geographe Marine Park - South-west marine region

Abstract:

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.

Geographe Marine Park contains areas of high biodiversity and benthic productivity, although much of the Marine Park has not been surveyed. The Park contains some of the largest continuous seagrass meadows in Australia. These act as feeding, breeding, resting and nursery grounds for migratory and threatened seabirds, whales and numerous fish species. Because seagrass communities are particularly susceptible to changes in water quality, they are under constant threat from a range of potential stressors. These include an increase in human population on the adjacent coastline, high levels of regional nutrient flow from runoff, growth in tourism, recreational and commercial fishing, introduced marine pests, and global climate change. While our existing knowledge of these threats is insufficient to detect the full extent of current impacts or to predict future ones, an overall loss in the shallow water seagrass cover from 2004 and 2007 has occurred. The information in this eco-narrative collates all the existing information to form an initial characterisation of Geographe Marine Park to help better understand its ecosystem structure. However, most of our knowledge of ecosystems in the marine park are those based on seagrass. We know very little about other ecosystems, particularly deeper offshore habitats which represent approximately 50% of the marine park.


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An eco-narrative of Gifford Marine Park - Temperate East marine region

Abstract:

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.

The Gifford Marine Park is dominated by two submerged flat-topped seamounts (guyots) that rise up to three kilometres above the surrounding abyssal plain and provide a diversity of benthic environments. These range from gently sloping plains atop the seamount plateaus to near-vertical towering cliffs of exposed bedrock that encircle both seamounts, and abyssal plains that characterise the northern third of the park. Depositional cones and mass movement scars alternate around the upper to mid slopes of the seamounts, and illustrate the processes by which these extant volcanic features are undergoing escarpment retreat.

The information in this eco-narrative forms an initial characterisation of Gifford Marine Park. The key gaps in our knowledge of the park are its specific oceanographic processes and its ecological significance; only limited ecological and oceanographic sampling has been undertaken within the park. Surveys have revealed lower than expected species richness and abundance, likely linked to the nutrient-poor waters over the Gifford guyot. Nevertheless, the extensive escarpment surfaces and the relatively shallow plateau surfaces do provide important habitat for sparse epibenthic communities. Sea surface temperatures within the park display only a slight warming trend since 2002, at an annual rate of 0.016oC. Targeted oceanographic and more extensive biological surveys over both seamounts are needed to develop a more informed overall assessment of the biological significance of the park ecosystem and identify potential anthropogenic threats to park health.


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

Abstract:

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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