Research: Seabed mapping in NSW

Scientists in NSW want to gain a better understanding of the marine ecosystem in NSW by identifying the many different habitats that exist on our seabeds.

Right now scientists are mapping seabed habitats along the whole length of the NSW coast. They use techniques such as satellite imagery and aerial photography (photos taken from out of a helicopter) and then go out to those areas and conduct habitat surveys to be sure that the habitats they think they see in the photos actually exist (this is called 'ground truthing'), to measure their size and to document the habitat structure along the NSW coast. These habitats include submerged rocky reefs, seagrass beds, mangrove forests and saltmarshes.

For the offshore environment, that is, the area more than about five kilometres from the coast, scientists are analysing water depth and the sediments to find out more about the structure of the seabed on the continental shelf.

Map showing the movements of a survey vessel in an estuary, documenting seagrass habitat types.

Left: A survey technician with a field computer, for entering habitat information.
Right: The end result of survey work. Different-coloured patches refer to areas with dense or patchy marine vegetation types.

This information will be used to understand how physical environmental changes might change the health and total area of seabed habitats. The physical changes are those associated with climate change, such as more dissolved carbon dioxide in the sea water, higher sea temperatures, changes in ocean currents, and the changes in nutrients in the waters that these currents bring.

Some habitats such as seagrass have different standards of health. A seagrass bed located in an area far away from busy vessel traffic, stormwater or sewage, with access to lots of light through clear, clean water, might be expected to have better health than a seagrass area that is located next to a spot where there is a lot of run-off from the land, or is adjacent to a marina, for example.

After assessments are made about the condition of a seagrass bed, the information can be used by local councils, for example when deciding whether to allow a new development such as a new sailing marina that may influence an already stressed seagrass bed. It is known that healthy seagrass beds support ongoing ecological functions, and tonnes and tonnes of fisheries production, by supporting juvenile prawn and fish species such as snapper, bream and whiting, and thus recreational or commercial fishing.

So a decision about whether to allow one new marina is complex. The seabed mapping project provides the information needed to make these difficult decisions with the best available knowledge.

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