Northern Australia has the world’s largest remaining network of natural free flowing rivers. These rivers support an amazing array of fish, water birds, turtles and other species that are important to local communities and industries.

With increasing interest in developing regions of Northern Australia for irrigated agriculture and other activities, it is important to understand the distributions and ecological requirements of freshwater biodiversity and how extracting water for development could affect it.

In a video launched this month, Hub researcher Dr Mark Kennard from the Australian Rivers Institute at Griffith University explains how the diversity of fish species in the Daly River is richer than first thought.

Genetic analysis has found that some fish that look the same are actually separate species. This is known as cryptic species diversity.

These fish generally would have started as the same species but have been evolving separately for tens to hundreds of thousands of years. The split may have occurred due to historical changes in the landscape which separated populations, such as much higher sea levels separating some freshwater catchments.

Knowing where you have this added species diversity is very important for management. For example a species that was previously thought to be common and widespread, may actually be two different species one in the upper and one in the lower reaches of a river, each with different habitat or migration needs. Sustaining natural patterns of cryptic diversity can give species the best opportunities to cope with future environmental changes.

By identifying the true levels of cryptic biodiversity, this research is informing the identification of conservation priorities to protect and restore freshwater fish in the Daly River.