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Groundbreaking study reveals biodiversity decline in Noosa River

Groundbreaking study reveals biodiversity decline in Noosa River

A groundbreaking study of the Noosa River ecosystem has found significant declines in estuarine biodiversity.

The study was the third component of the Bring Back the Fish research program, a joint initiative of the Noosa Biosphere Reserve Foundation, Noosa Parks Association and The Thomas Foundation, aimed at understanding how to improve biodiversity in the Noosa River.

Chair of the NBRF, Rex Halverson said that although water quality in the Noosa River is rated an A-, these reports don’t measure biodiversity nor provide a complete picture of ecological health.

“The Noosa River is the lifeblood of the Noosa community. It supports us economically and has significant cultural and environmental value, so it’s important we preserve it,” said Mr Halverson.

“The Bring Back the Fish program addresses the core components to building resilience in the Noosa River ecosystem – sediment, structure and fish food source – the latter the focus of this study,” he said.

Professor Greg Skilleter from the University of Queensland led the research team and said prawns were to be used as an indicator of the condition of the system. However, the study took an unexpected turn in direction when there weren’t enough prawns for their analysis.

“We were surprised to find very low numbers of prawns and other small animals in comparison to 20 years ago, particularly in Spring when numbers should normally be high,” he said.

Researchers studied the benthic layer, measuring the small animals that live in the sand and mud and make up a key component in the diet of many fish and crabs. Prof. Skilleter’s report revealed a 30-65 percent decline in the number of species since levels were recorded in 1998.

“The overall conclusion was that the abundance and diversity of the benthic animals in the Noosa River is now severely depleted compared with historical levels,” said Prof. Skilleter.

Michael Gloster, President of Noosa Parks Association said, “NPA seeks a Noosa River that runs blue not brown, has increasing not decreasing prawns and fish, and is a source of shared community pride not division. Professor Skilleter’s rigorous scientific study of a Noosa River in decline steels our resolve.”

Professor Skilleter’s research points to the most likely impact on these animals is due to fine sediment building up in the system.

Director of The Thomas Foundation, Rowland Hill said “the report further confirms the biodiversity decline in the Noosa River system, making the Noosa Council’s recent endorsement of The Nature Conservancy’s management plan for the Oyster reef project even more timely.

“The Thomas Foundation has worked for the past six years to establish this Noosa Council/TNC partnership, confident of the benefits TNC’s involvement will bring to resolving the river system’s environmental challenges,” said Mr Hill.

Dr Simon Walker, a marine ecologist who has studied the Noosa River for the past six years says Prof. Skilleter’s work provides a highly valuable baseline and framework for the future.

“The Noosa River estuary is a unique and complex ecosystem that requires local and nuanced management. We now have a rare opportunity to monitor and measure the impact of our management response on the condition of the estuary through a variety of indicators other than just water quality,” said Dr Walker.

Mr Halverson said this study is a timely example of how biosphere reserves can act as living laboratories.

“This report provides a benchmark for evaluating the results of initiatives like the oyster reef restoration and Keep it in Kin Kin sediment mitigation projects. It will also help to inform Noosa Council’s river management planning and monitoring into the future.

“I thank the project partners, the University of Queensland research team and Noosa Council for working together on this project,” he said.

A public information forum to discuss the results of the Report will be held at a later date.

Read the Report: Biodiversity in the Noosa River System – Executive Summary

Background: Noosa River Biodiversity Study – Fact Sheet

Project page: Bring Back the Fish