This follows a two-year study of 31 major rivers across the region by the Department of Water and researchers from Western Australia’s Centre of Excellence in Natural Resource Management in Albany.

CENRM associate professor Dr Barbara Cook said the study was the first of its kind and revealed how unique aquatic systems were on the South Coast.

“Many of the rivers we had never sampled before and had no idea of the plants or animals there,” she said.

“As a result of the study, we’ve now come up with a ranking scheme according to the ecological value of our rivers which will indicate to our decision-makers just which rivers are worth investing in.”

The study involved undertaking an ecological “snapshot” of South Coast rivers, including several which had never been sampled before.

The new species included a shrimp-like amphipod in the Family Paramelitidae, and a caddisfly species in the Family Hydroptilidae, among others.

Other surprises included a build-up of mosquito fish and east coast yabbies in some rivers, which pose a threat to biodiversity.

Apart from identifying “hotspots” for species richness and endemism, the study also noted the presence and relative abundance of invertebrates, fish and aquatic vegetation and algae at each of the selected sites, while also assessing foreshore condition and habitat type.

The rivers with the highest level of ecological value in the west of the region include the Shannon, Deep and Gardner Rivers, and the highest ranking rivers in the east of the region are the Bremer, Oldfield and Jerdacuttup Rivers.

The study identified two distinct aquatic bio-regions, with the eastern part of the South Coast region significantly more saline, slightly more alkaline and containing higher levels of total nitrogen and different macro-invertebrate communities than those in the west.

Rivers in the west of the region revealed more species diversity.

South Coast NRM chief executive Rob Edkins said the information provided a valuable benchmark for future conservation activities and reinforced the importance of initial research, and ongoing funding into the protection of river systems.

“This is a great example of the type of work CENRM has been doing in the South Coast region. South Coast NRM is looking forward to using the findings to update the South Coast Regional Strategy for NRM.”

South Coast NRM will be hosting a presentation of the river report on Tuesday, October 20, from 2pm to 3.30pm at its Mercer Road office.