Surveys
Automated Underwater Vehicles (AUVs) are ideally suited to undertaking repeat surveys that will be necessary to monitor changes in the benthos. Changes in community structure and benthic cover derived from precisely registered maps collected at regular intervals by AUVs will provide researchers with the baseline ecological data necessary to make quantitative inferences about the long term effects of climate change and human activities on the benthos. Consequently, the Automated Underwater Vehicle facility in collaboration with regional IMOS nodes have established a number of benthic observing programs located around Australia’s continental shelf that are regularly surveyed with AUVs to monitor changes in the benthic environment. In the short term, the facility will also provide stakeholders with data useful for the effective management of marine parks and fisheries where the benthos provides a food source or plays a role in the lifecycle of a target species. A particular focus of the benthic observing programs is reef habitats, as these systems are most sensitive to environmental change because of the sessile nature of organisms and because reef systems have a disproportionate contribution to marine economic activity. Benthic observing programs have been established for both temperate and tropical reef systems.
- Locations of the benthic monitoring programs that involve regular surveys by AUV.
- AUV being retrieved aboard the RV Challenger offshore of the Tasman Peninsula, Tasmania.
Temperate reef observing programs
A key aspect of the monitoring of temperate reef systems, particularly in Victoria and Tasmania but also in NSW, is to determine rates of change of benthic habitat. Kelp forest habitats on these reefs are predicted to undergo significant change related to changes in boundary current characteristics, contracting at their northern end due to warming and thickening of mixed layer depth, and in the south through the formation of ‘barrens habitat’ as a result of overgrazing by the long-spined sea urchin, Centrostephanus rodgersii. Repeated and precisely registered AUV surveys at key sites will enable scientists to describe the extent of kelp habitats, from inshore to deep water areas, and determine changes within these habitats over time. Currently, benthic observing programs on temperate reefs are undertaken at 4 main areas;
- Eastern Australia and the East Australian Current
- Tasmania
- South-East Queensland
- Western Australia and the Leeuwin Current
- AUV surveying at Scott Reef, Western Australia (Photo: Australian Centre for Field Robotics).
Tropical reef observing programs
In Australia’s northwest the oceanography is complex and seabed monitoring of offshore and coastal habitats influenced by a mix of regional and local currents has been very limited. At Ningaloo Reef (21º50'S to 23º35'S), where the Leeuwin current is of particular note on the adjacent shelf, and at Scott Reef (14 º04'S), which is under the influence of the Indonesian Throughflow, long term data exists in the respective shallow reef habitats, but until recently data has been virtually non-existent in the majority of waters (>30 m) because of constraints on scientific diving depths. Recent deeper-water seabed surveys at Ningaloo Marine Park and Scott Reef, including missions with AUVs have demonstrated that in both areas extensive and diverse benthic habitats exist that contribute significantly to the known biodiversity values of the system. Repeated AUV surveys at key sites will enable monitoring of these habitats but also provide an excellent global reference site to monitor the status of deeper water reef habitats over time in the face of large scale climate related change. Currently, benthic observing programs on tropical reefs occur at two main areas;
Other programs that have utilised the facilities’ AUV include surveys to document the nocturnal camouflage behaviour of cuttlefish in South Australia.
