Friday, October 19, 2007

Wild Water, Urban River

There are wonderful water-based programs taking place right under our noses and we might not even be aware of them. The Ecosystem Health Monitoring Program of local waterways and the Healthy Waterways project for SE Queensland are looking after the environment and working together across community, industry and science to create purposeful strategies for waterwise development and water sustainabiltiy.

What happens upstream is reflected in what's going on downstream, especially the upstream events along the Brisbane River and the end point of the flow into Moreton Bay and then further afield. How the land and water are treated along the river's trajectory reflect not only the health of Moreton Bay but also the health of the creatures that live there - Dugongs, Turtles, Fish and Seagrass.

The EPA explains that seagrass is central to the marine web of life, and dead or alive, seagrasses are protected under the Queensland Fisheries Act, 1994. Many animals from big mammals like the Dugong and Green Turtle forage the seagrass, while these leafy meadows are home to an ecology of fish, prawns, seaweeds and other marine species.

The EPA comments that 'Seagrasses are very sensitive to changes in water quality and are used to measure ecosystem health.' So practices like land clearing, use of fertilisers and pesticides, sewerage and septic overflow and dredging have changed the river's water quality and turbidity and also affected the health of Moreton Bay.

Early accounts of river quality talk of clear water and easy fishing. But landclearing leaves arenas of denuded soil which, when it rains, flows in a muddy plume down to the river, eventually running into the sea, smothering the seagass meadows and the food for the sea mammals. In an information session on the future for Moreton Bay held during the week, renowned Dugong researcher Dr Janet Lanyon from the University of Queensland mentioned that after very heavy rains and flooded rivers a few years ago, the Dugong were found to weigh less and did not appear to be as healthy.

She indicated the likely cause was the reduction in seagrass meadows (See Lanyon, 2003). In her talk she pointed out that an increase in the human population over the next few years intent on finding home along the waterways of SE Queensland will bring increased pressure on the Moreton Bay environment, particularly the mammals, some of whom like the various turtle species, are already threatened.

She also mentioned that researchers in Florida monitoring the health of the Manatee have suggested that global warming might not be such a bad thing for these large sea mammals. Warmer water might lead to a greater spread of sea meadows and thus more Manatee and Dugong-friendly pastures for undersea grazing. But she stressed the need for urgent action now to protect the delicate and interconnected marine, coastal and riverine ecologies.

Lanyon JM, 2003, 'Distribution and Abundance of Dugongs in Moreton Bay, Queensland, Australia,' Wildlife Research, 30, 397-409.