Fine sediments, small creatures, big headaches

View story in H20 Thinking

Fine sediments accumulating in river beds have serious implications for river health. With some 30,000 km of streambed thought to be being ‘suffocated’ by a coating of fine mud or sand, this is no small problem in Australia.

PhD student, Evan Harrison, supported by the Institute for Applied Ecology at University of Canberra, and CSIRO and eWater CRC, has been investigating the relationship between fine sediments and the various species of macroinvertebrates that live on streambeds or amongst the stones and other rubble on the stream floor.

His results indicate that even a small increase in fine sediments on the streambed can have a dramatic impact.

Image: A streambed smothered by fine sediment in Jugiong Creek, NSW.

Image: Wire baskets were buried in the streambed to sample macroinvertebrates and fine sediment.

For land managers, the message seems to be that efforts to control soil erosion need to be quite thorough.

Small quantities of fine sediments in streambeds, even 3% by weight, degrade stream ecology more than might be expected.