A new study is underway to determine how a rarely thought of group of organisms — marine invertebrates — are bouncing back after recent severe flooding across northern New South Wales.
Southern Cross University Professor Kirsten Benkendorff, Director of the National Marine Science Centre, is leading the research in collaboration with the Department of Primary Industries.
She said very little was known about how flooding affected invertebrates, which played a key role in marine ecosystems.
"An invertebrate is an organism without a backbone, including insects, slugs and snails and a lot of marine life, corals, sponges, crabs, snails.
"The invertebrates living in our estuaries are important as fish food, so if we don't have the food there, we don't get the fish, and then we can't fish them for ourselves to eat either.
"So it's really important to study how the floods have impacted these invertebrates and how well they recover after flood events."
Assessing biodiversity
Professor Benkendorff said the new study would focus on invertebrates in six estuaries across the NSW Mid North and North Coast, which were impacted by flooding in late February and March this year.
Surveys of the river systems will be done at least six different times, over a two-year period.
Rivers will include the Bellinger, Clarence, Richmond and Brunswick.
"We will have water running to wash fine sediment through to catch the critters without too much damage.
"We will then look at them under the microscope, identify them and assess the biodiversity of these different areas."
Planning for the future
Professor Benkendorff said she expected results would vary depending on how severely river systems were impacted by flooding, and the extent of surrounding farm and urban development.
"The invertebrates have adapted to live in many different types of environments, with flexible body forms that let them live in different places, like worms in the sediment and snails on the rocks," she said.
"That includes the amount of freshwater coming down, and the amount of terrestrial runoff, particularly where we have flood gates and there's potential acid sulphate soil impact … so we don't know what we will find in the sediment of these rivers.
"I suspect that there could be some significant impacts in systems like the Richmond and the Clarence where there have been really prolonged and severe effects."
The results will be presented in a scientific study and will help direct future land and river management plans.
"I think it is a really important component of management, understanding the capacity of these systems to recover and what sort of fish populations can be supported by these invertebrate communities and thus how much we can actually take from the environment," Professor Benkdendorff said.
"Comparing systems where we have agriculture, with and without flood gates, and whether some types of systems recover better than others, is important information for future management."
