Northern Australia Hub researchers have uncovered the fish species most at risk of sea level rise in Kakadu National Park.

Wet season beam trawl sample. Photo: Brad Pusey

New research has found that the world heritage listed park supports an outstanding array of fish diversity, but climate change, especially sea level rise, threatens to put some of this unique biodiversity at risk.

To help better understand this threat and its potential impacts on fish, tropical river scientists extensively surveyed Kakadu’s estuaries, as part of the Australian Government’s National Environmental Research Program (NERP).

Griffith University Principal Research Fellow Mark Kennard says fish play an important role in the aquatic habitats of northern Australia.

“This is especially true in Kakadu National Park, which is only around 1% of the total area of northern Australia, but is home to a third of all freshwater fish species recorded in the region,” said Dr Kennard.

“There are 62 species of freshwater fish in Kakadu. Many of these live within Kakadu’s freshwater wetlands. Over the next century, climate change will cause sea level rise and more extreme high tides, which will bring salt water from the ocean into lower lying freshwater wetlands killing plants that the fish rely on.”

The research identified 11 species of freshwater fish that are considered to be vulnerable to the impacts associated with increased salinity.

“The species that were most vulnerable were those that cannot tolerate saltier water or that will have a large proportion of their habitat changed. Those most at risk include the popular angling species northern saratoga, as well as other small but ecologically important species such as pennyfish, poreless gudgeon, two species of blue-eyes and the black-banded rainbowfish.”

Dr Kennard presented the findings of his research to park managers, Traditional Owners and the general public during research seminars in Kakadu National Park today and will make the same presentation in Darwin tomorrow. Several other NERP researchers will also speak about the results of their projects during the seminars, as the program draws to a close.

“Fish are essential to the riverine food web dynamics in the park and are of great recreational and cultural significance,” said Dr Kennard.

“By identifying the fish species most at risk from future environmental changes, our research can help park managers to create strategies and prioritise resources to help these species persist into the future.”

Dr Kennard’s research has also helped to shed light on the true variety of fish in Kakadu estuaries.

“We collected small fish in the estuary of the South Alligator River in both the wet and dry seasons, and compared the results with previous dry season research in the river,” said Dr Kennard.

“We found 26 species which had not previously been recorded from Kakadu, most of which were sampled during the wet season. This is a significant number, which leads us to believe that we could expect to discover more species in the future, especially during the wetter months.”

Read more about the sea level rise research here and fish inventory research here