Characterising natural values and identifying indicators and metrics in South-west Corner Marine Park

Parks Australia has developed management plans for the five regional AMP Networks (North, North-west, South-west, South-east and Temperate East) and the Coral Sea Marine Park. Associated science plans will set monitoring and research priorities to guide the collection of information for evidence-based management.

Surveys conducted under the NESP Marine Biodiversity Hub (a forerunner of the Marine and Coastal Hub) inventoried natural values and ecosystem components in selected AMPs. They also developed and tested standardised survey techniques. This new knowledge and capability allows scientists and park managers to identify and measure the status of natural values and ecosystem components. These are essential elements of AMP monitoring.

A Marine Biodiversity Hub survey in the Capes region of South-west Corner Marine Park off Western Australia conducted bathymetric and visual sampling of key seafloor habitat and fish assemblage natural values and ecosystem components. This Marine and Coastal Hub project analysed the survey data, characterised and predicted the broader distribution of significant features and natural values, and outlined the underlying techniques and processes.

The new knowledge is presented together with a summary of existing knowledge of park natural values, socio-economic values, cultural values and pressures. Recommendations for future work include the creation of national and international benchmarks, and survey guidance from Traditional Owners.

Approach and findings

Within the National Park Zone of South-west Corner Marine Park, the survey revealed one of the best-preserved examples of submerged ancient coastlines and lowlands seen across the AMP network. Distinct endemic fish assemblages were found at depths associated with four ancient shorelines, from 18,000 years ago in ~120 m depths, to 9000–10,000 year old submerged lowlands and granite outcrops in 39 m depths indicating ancient coastal wetlands.

Highlights included:

• extensive rocky reef habitats, with kelp, seagrass and sponge gardens out to the last interglacial paleo shoreline in ~120 m depths, including the deepest seagrass and kelp recorded in the South-west Network;
• extensive sand plains with isolated reefs out to the shelf break in 220 m depths with extensive sponge gardens;
• aggregations of Hapuku, a deep-water grouper valued by commercial and recreational fishers in 220–250 m depths at the shelf break, likely to benefit from increased productivity along the shelf break created by nutrient rich Mentelle upwelling;
• a potential aggregation of the Critically Endangered Grey Nurse Shark on isolated reefs in 140 m depths among the mid-shelf sand plains; and
• submerged granite outcrops now covered in kelp and deep water seagrass supporting aggregations of the endemic Western Australian Dhufish.

The survey report outlines the methods used for the survey design, sampling, analysis, modelling, quality control, data visualisation and access. These include:

• survey design and sampling methods (baited remote underwater stereo-video systems, drop camera, autonomous underwater vehicle):
• statistical analysis (relief modelling and prediction, habitat distribution modelling, fish assemblage abundance and distribution modelling);
• instructions on how to use available open data from portals in web apps for data exploration and immersive exploration of imagery; and
• open-access and reproducible data analysis workflows to create models and spatial extent predictions for both benthic and fish assemblage metrics.

Wadandi guidance for future studies and surveys of submerged wetlands

Cultural values information summarised in this project was drawn from the NESP Marine Biodiversity Hub report, ‘The Cultural Seascape of Wadandi Boodja’. This cultural knowledge provided through partnership with Wadandi Traditional Owners and Custodians guided the discovery of remarkable biodiversity across the park’s submerged ancient coastline features, providing future guidance for managing the cultural and natural values of the marine park.

Wadandi, People of the Sea, are the Custodians for the far southwest region of this continent, with obligations to protect, manage and monitor their Sea Country. The Wadandi-led team recognise how these surveys have shown us the submerged wetlands that would have existed along and behind the ancient shorelines. These wetlands would have been where the old people camped, and freshwater springs would have been located within them. Future surveys should visit these areas and identify the freshwater springs so they can be better understood and protected.

Following the animal prints

Outside of the current survey area, the submerged ancient softlands and wetlands have shown us animal prints. The Wadandi project team proposes that future surveys will follow these animal prints to find the old country that is now submerged in the Australian Marine Parks.

Bolghinup

Bolghinup (Black Rock) lies on the Ngingaraa Kaala (Lava flow). Bolghinup means the shaking or rumbling of the land as it moved and rose. After the shaking, this is where the people went out from and is the source of different languages. There is now a National Park Zone offshore from Bolghinup in the South-west Corner Marine Park. This area is shallow and will hold submerged coastal areas that would have been frequently visited by our ancestors and should be a place for future surveys to be led in collaboration with the Wadandi project team.

A suggested potential focus for future research and monitoring is the creation of suitable national and international benchmarks that enable meaningful comparison, evaluation and reporting of the status and trend of AMP natural values and ecosystem components.

This approach would overcome the inherent difficulty of identifying comparable reference sampling areas across areas of interest, such as control areas to evaluate change in a National Park Zone. It also obviates the need to have had substantial data collected before the implementation of zoning, which, due to the design and implementation legacy of AMPs and their constituent zones, is rarely available.

Creating such national and international benchmarks would involve the synthesis and maintenance of national-scale data sets of the appropriate breadth and scope (depth extents) for metrics that can be compared across bioregions.

For example, establishing a benchmark with condition categories (such as Good, Good with some concerns, Significant concern, Poor) could be investigated through an extension of the existing Australian national BRUV synthesis dataset maintained through GlobalArchive.org. By adding newer datasets it would be feasible to extend national benchmarks to include rariphotic depths (70–200 m) where important fish assemblages may occur in AMPs.

Outcomes

This project provided Parks Australia with an improved knowledge base for identifying, managing and monitoring natural and cultural values in South-west Corner Marine Park.

Natural values surveys revealed the extensive submerged ancient coastline features in the National Park Zone, extensive mesophotic and rariphotic reefs, the occurrence of large-bodied key target species in the National Park Zone, a potential Grey Nurse Shark aggregation site in the National Park Zone and aggregations of Hapuka, a highly targeted deeper water species, on the shelf break in the National Park Zone.

The partnership between hub researchers and Wadandi Traditional Owners was strengthened through the experience of sharing traditional ecological and scientific knowledge that helped to guide bathymetry data collection and associated components of the survey.

In addition, this survey demonstrated the application of a novel panoramic drop-camera system and its use to rapidly ground truth the benthic composition of relatively large survey areas. This drop-camera is now being evaluated as a national standard for benthic composition surveys and tested further for broad-scale benthic habitat characterisation in Marine and Coastal Hub Project 2.1.

Recommendations on the development of data products to enable the benchmarking of fish assemblage natural values and ecosystem components are also important to developing AMP monitoring approaches, as well as to national reporting.

Project location

South-west Corner Marine Park