Research and Monitoring Projects

North Australia Marine Biodiversity Survey
NT Seagrass Survey
Beagle Gulf Bioregion Survey
Fog Bay – Bynoe Harbour Habitat Survey
NT Marine Debris Monitoring Program

North Australia Marine Biodiversity Survey

Image of blue swimmer crab in seagrass habitat

Blue swimmer crab in seagrass habitat
(jpg 68Kb)

In November 2004 researchers from the Marine Biodiversity Group and NT Museum of NRETA, and sea rangers, commenced the North Australia Marine Biodiversity Survey (NAMBS). This collaboration between scientists and Indigenous landowners attempted to combine both scientific and cultural knowledge approaches and the survey was notable in this regard. NAMBS was co-funded by the NT Government, the National Oceans Office (NOO), the Director of National Parks and supported by the Northern Land Council.

NAMBS aimed to collect baseline environmental data in the Northern planning Area (NPA). The NPA covers almost 700,000 square kilometres, encompassing waters in both the Northern Territory and Queensland. In the NT, the area stretches from Kakadu National Park across Arnhem Land to the Gulf of Carpentaria and the Torres Strait.

NAMBS focussed on seagrass habitats as they are a widespread and integral component of these waters, stabilising sediment and providing habitat for many commercial and endangered species. The aims of this survey were to broadly map seagrass habitat and then to describe associated marine communities.

Helicopter surveys were used to map the distribution, structure and composition of inter-tidal and shallow sub-tidal seagrass communities from Kakadu National Park to the tip of Cape York. Consultation and partnership with Aboriginal people proved invaluable in this process as additional deep water seagrass habitats were located though local knowledge of traditional hunting grounds.

A range of methods were used to describe seagrass communities, including small beam trawl, gill nets, grabs, dredge, light traps and underwater video. This sampling revealed a diverse and species rich seagrass community, possibly due to the wide range of bottom types in the area (muddy, sandy and rocky). The survey uncovered approximately 15 previously undescribed species. Approximately 30 species were found in the territory for the first time, extending known ranges of these species. Additionally, the survey greatly improved our understanding of seagrass habitat in Northern Australia and established a solid foundation for future collaborations.

Report available Feb 2007.

NT seagrass survey

The NT seagrass survey was a joint tender to the National Oceans Office (NOO) by the Queensland Department of Primary Industries and Fisheries, the CRC Reef Research Centre and the Marine Biodiversity Group, NT. The key aims of the project were to map the distribution, structure and composition of seagrass habitats and map discarded fishing gear on the Northern Territory and Gulf of Carpentaria coasts. This survey was conduced just prior to the North Australia Marine Biodiversity Survey in November 2004 and provided valuable broad-based information for the more detailed NAMB Survey.

The survey described intertidal and shallow sub-tidal seagrass communities from Van Diemen Gulf to Castlereagh Bay, Northern Territory, and from Gove to Horn Island, Queensland, an area representing almost 10% of Australia’s mainland coastline .The survey addresses a gap in biological knowledge identified in the NOO key species report as being important to the northern marine regional planning process.

A combination of helicopter survey techniques and sophisticated GPS systems were used to provide a snapshot of seagrass distribution and abundance at two different spatial scales. An area of just over 42,000 hectares of intertidal seagrass was mapped. Combined with data from previous surveys it is estimated that at least 70,000 hectares of intertidal and shallow sub-tidal seagrass are present in the survey region.

Seagrass meadows were extremely patchy in their distribution and individual meadow structure. Almost all seagrass meadows observed showed evidence of turtle activity and/or dugong feeding. Some small patches were heavily grazed and may be vital for dugong travelling along the coast.

While the survey was primarily designed to map seagrass habitat, large numbers of discarded nets were found. The highest density of nets were found within the western Gulf and area to the north of Aurukun. Large numbers of abandoned crab pots were recorded in the south western Gulf. Net and trap type and location have been recorded in a GIS database.

Download the Seagrass Survey:

Introduction (pdf 583Kb)
Study area (pdf 1.1Mb)
Discussion and references (pdf 1.8Mb)

Beagle Gulf Bioregion Survey

Bubble snail
(jpg 107Kb)

In 1991 the Northern Territory Government proposed the formation of the Beagle Gulf Marine Park (BGMP). The park was expected to occupy 4700m 2 in the Anson-Beagle bioregion, south-west of Darwin. A paucity of data about marine habitats in the region has been an obstacle in the development of a comprehensive management plan for the BGMP.

A broad-scale baseline study was conducted in 1993 by the Parks and Wildlife Commission of the Northern Territory and the Museum and Art Galleries of the Northern Territory and funded by Ocean Rescue 2000. The study aimed to describe patterns in species diversity, abundance and distribution of soft bottom communities in the region.

Soft bottom communities were sampled using an Ockelman sledge with a mesh size of 1.5 cm that was towed for one minute. In a systematic survey, 162 stations were sampled from the1st to the 13th October 1993. Most samples consisted primarily of sand-sized particles and a total of 8 substrate types were identified: mud/sandy mud, muddy sand, fine sand, sand, unsorted sediments, coarse-sandy gravel and gravel. The distribution of sediment was determined mainly by current strength, the existence of reefs in the neighbourhood, and terrigenous input.

The most abundant taxonomic groups in the BGMP were crustaceans, molluscs and echinoderms. Species richness was high (874 taxa) and it is estimated that the total number of species in the region is approximately 1200. Sediment grain-size played an important role in species distributions and species richness was highest in coarse-sandy gravel and gravel habitats. Other environmental parameters such as depth, latitude, longitude, carbonate content also contributed to species distributions, however these parameters did not affect overall species richness.

The status of the BGMP will be reviewed and clarified during the development of the NT Marine Protected Areas Strategy.

Report

Summary / Introduction / Table of Contents / Methods (pdf 838Kb)
Results (pdf 4.9Mb)
References and appendices (pdf 280Kb)

Fog Bay – Bynoe Harbour Habitat Survey

Batfish in rocky reef habitat
(jpg 61Kb)

The Fog Bay – Bynoe Harbour region, located about 145km south west of Darwin, has conservation, commercial, recreational and cultural significance. Home to a number of Aboriginal language groups, the region has both coral reef (pdf 53Kb) and seagrass ecosystems. Increased levels of recreational and commercial activity such as shark fishing, prawn trawling, mud crab fishing and reef fishing have created an urgent need for baseline data about the extent and type of marine communities in this area.

The Fog Bay project was funded by the National Heritage Trust (NHT) and conducted between 1999 and 2002 by researchers from the Marine Biodiversity Group of the NRETA. The project aimed to broadly map habitats in the Bay, to identify juvenile fish habitat and describe fish communities within these habitats.

Habitats were identified through satellite and aerial photography and acoustic surveys. These habitats were then characterised using underwater video. The project revealed a range of different environments (reefs, intertidal flats, subtidal flats and seagrasss meadows) and associated marine communities.

Coral reef assemblages were generally found on fringing and subtidal rocky reefs with low turbidity and relatively good light levels. In high turbidity, algal and sponge communities dominated. Seagrass meadows were not widespread and were patchy in nature, dominated by the pioneer species Halophila sp. and Halodule sp. However, some meadows had extensive dugong feeding trails, indicating that the area may be an important feeding ground.

More than 200 species of fish were collected using a small beam trawl, grabs and top- and bottom-set trammel nets. Approximately 87 of these species did not occur in the neighbouring embayment of Darwin Harbour. Endangered green sawfish were found on muddy bottoms in the southern Fog Bay area. Data collected during this survey will be important for the assessment of the Bynoe Harbour Marine Protected Area. A full report is expected to be completed during 2007.

NT Marine Debris Monitoring Program

Image of fishing nets washed up on Cape Arnhem

Fishing nets washed up on Cape Arnhem
(jpg 56Kb)

Marine debris is a major threat to marine wildlife in northern waters and is linked to the mortality of turtles, cetaceans, dugongs, crocodiles, sharks, seabirds and fish (Kiessling 2003). Injury and fatality can occur through ingestion or entanglement. The Australian Government identified marine debris as a ‘key threatening process’ in August 2003 and is currently in the process of developing a Marine Debris Threat Abatement Plan. Fishing nets that have been lost or abandoned at sea are of particular concern as derelict nets have the capacity to continue fishing for many years, capturing and killing threatened species such as marine turtles.

The marine debris monitoring program in the NT was initiated by the WWF in 2000, in response to the concerns of coastal Indigenous communities, land councils, government agencies, conservation organisations and the fishing industry. In 2006, NRETA (Marine Biodiversity Group) took over co-ordination of the debris program (and the National Marine Debris Database) from WWF-Australia, who remains an advisory partner. The project has received funding through the Natural Heritage Trust and continues to be a community based, collaboration between Indigenous people, community groups, sea rangers and scientists.

Image of map showing the locations of monitoring in the NT

Monitoring locations

The marine debris monitoring program aims to scientifically quantify and monitor the amount, composition, source (and wildlife impacts) of marine debris washing ashore on selected beaches in the NT. Surveys will continue to be conducted on an annual basis at seven locations (Tiwi Islands, Cobourg Peninsula, Elcho Island, Cape Arnhem, Groote Eylandt, Blue Mud Bay and Vanderlin Island). Surveys are conducted according to methods established by WWF (White 2005). Fishing nets are identified according to the WWF Net Kit which provides a manual for identifying the type and probable country of origin of nets.

The debris monitoring program complements the Carpentaria Ghost Nets Programme, which is primarily focused on the collection and disposal of nets and the prevention and rescue of entangled wildlife within the Gulf of Carpentaria.

In 2006, fishing nets and plastic were the major components of marine debris, comprising approximately 81% of the total. Other components included rubber (6%), metal (2%), glass (6%) and paper (5%). The amount of marine debris on beaches ranged from around 50 kg to over 175 kg per km. Preliminary results suggest that much of the fishing related debris comes from foreign fishing and shipping fleets operating in the Arafura and Timor Seas outside the Australian Exclusive Economic Zone. For a full copy download the NT Marine Debris Monitoring Report 2006. (pdf 1.38Mb)

Thongs collected from
Cape Arnhem

These results, and also results from previous surveys (White 2003, 2004, 2006), suggest that reduction of marine debris will require an international management strategy. Recommendations include improving waste disposal facilities and providing educational material at ports in the Arafura and Timor Seas (Kiessling 2003 pdf 3.5Mb).This project will continue to monitor trends in marine debris and its wildlife impacts in the NT and will provide crucial data to help develop solutions to the problem.

Program partners

Dhimurru Land Management Aboriginal Corporation
Tiwi Land Council
Laynhapuy Rangers
Anindilyakwa Rangers
Marthakal Homeland Resource Centre
Lianthawirryarra Sea Rangers
World Wildlife Fund - Australia
Conservation Volunteers Australia
Department of Environment & Heritage

Download Marine Debris fact sheet (pdf 634Kb).

References

Kiessling, I. (2003) Finding Solutions: Derelict Fishing Gear and Other Marine Debris in Northern Australia. (pdf 3.5Mb) National Oceans Office, Hobart.

White, D. (2003) Marine Debris in Northern Territory Waters 2002 (pdf 4Mb). WWF Australia, WWF-Australia, Sydney.

White, D. (2004) Marine Debris in Northern Territory Waters 2003 (pdf 618Kb). WWF Australia, WWF-Australia, Sydney.

White, D. (2005) Marine Debris Survey Information Manual 2nd edition (pdf Kb). WWF Marine Debris Project, Arafura Ecoregion Program. WWF Australia.

White, D. (2006) Marine Debris in Northern Territory Waters 2004 (pdf 634Kb). WWF Australia, WWF-Australia, Sydney.

Related links

WWF Interactive Debris Map: Illustrates the percentage of each debris category (plastic, glass, rubber etc) found in the regions around Australia.
WWF Net Kit: A Fishing Net Identification Guide for Northern Australia - This kit helps to identify discarded fishing nets collected during marine debris surveys or found at sea. The Net Kit details net colour, mesh size, twine size and, where possible, the probable country of origin of fishing nets collected in WWF's marine debris surveys.
Gulf of Carpentaria Ghost Nets Program
Marine and Coastal Biodiversity of the NT
Marine Environmental Issues of the NT

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