Scientists on a mission to better understand the ecological biodiversity that thrives on the ocean floor in Australia’s remote northwest returned from the fourth of five field trips, this time to uncover what lives in the area of the proposed North Kimberley Marine Park.
Dr Andrew Heyward, from the Australian Institute of Marine Science, leads the Western Australian Marine Science Institution (WAMSI) Benthic Biodiversity project and provided this update.
The WAMSI Kimberley project continued to expand the seabed survey area, extending to waters of the far north in a recent voyage. Multibeam acoustics was used to map depth and geomorphology, while the biota growing on the seabed was studied using towed cameras and, in representative areas, a small sled was deployed to collect samples for the biota.
As with other regions surveyed by ship, a high number of species were observed and it is expected many will be new to science.
|The seabed sled comes aboard with a sample including sponges, algal covered rocks and sea whips (Image: Andrew Heyward)|
However, the sea life encountered, while somewhat different from place to place, was very similar in terms of ecosystem function.
The ship based research spent most of the time in navigable waters deeper than 10 metres and most sampling focused on the depth band between 15-50 metres. These areas are often turbid and organisms that need light were not major components of the seabed communities. Rather, animals that filter the water or eat detritus on and in the seabed were predominant. In all places visited to date, sponges have been the most common and largest organisms encountered. Echinoderms, soft corals and bryozoans also featured routinely.
The survey results are still being analysed but point to much of the deeper Kimberley waters often having low levels of large sessile marine life (those organisms that spend their lives attached to the substrate), but in places where rocks and ridges provide a place to settle and hold on, quite diverse and abundant benthic communities exist.
The role of light in supporting abundant benthic primary production, such as algae, seagrasses and stony corals, seems likely to be most important in the shallower margins, less than around 15 metres below low tide.
Shoreline areas and fringing reefs with abundant corals and plants are throughout the Kimberley, but are yet to be surveyed in any detail from the large ship-based field expeditions.
Future work is being planned, in collaboration with local Indigenous sea rangers, to gather additional nearshore data on some of these key shallow water habitats.
The results will be added to the data collected from the recent field trip aboard RV Solander to the islands of the Bonaparte Archipelago to investigate the coral reefs, sponges and other marine life inhabiting this remote area of the Kimberley.
|Scientists on the back deck of RV Solander sorting a sled catch into biological groups prior to processing as voucher specimens destined for the WA Museum. (Image: Andrew Heyward)|
The Solander voyages include researchers from AIMS, the Western Australian Museum, CSIRO and Curtin University.
The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.