Between 2010 and 2012, we were engaged in a project, funded by the Swan River Trust (SRT), to monitor the effects of artificial oxygenation on benthic macroinvertebrate communities in the Upper Swan River region of the Swan Estuary. Previously, assessment of the Swan and Canning Rivers oxygenation program focused on the ability to add oxygen to the water column. Monitoring biotic responses is part of the longer term strategy to include ecosystem responses as a measure of success of the oxygenation program.
What has been done?
Macroinvertebrate samples were taken from five sites in the Swan River on a monthly basis between January 2010 and December 2011, and the community composition of benthic macroinvertebrates within these samples was analysed.
Benthic macroinvertebrates are suitable organisms for use in identifying ecosystem responses to oxygenation because of their:
Spatial and/or temporal patterns observed as a result of the monitoring may thus provide signals of the impact of the oxygenation program and/or of severe hypoxic (low dissolved oxygen) events on the ecology of the Swan River. The findings of this project are envisaged to have science and management implications concerning our broader understanding of the ecology of the system and its responses to hypoxia and other stressors.
A draft report on this project (Tweedley, J.R., Hallett, C.S. 2012. 'Monitoring the effects of artificial oxygenation on biota.' Draft report to the Swan River Trust. Murdoch University) has been submitted. The results of this project will be communicated not only within the peer-reviewed scientific literature (Tweedley, J.R., Hallett, C.S., Warwick, R.M., Clarke, K.R., Potter, I.C. The hypoxia that developed in a microtidal estuary following an extreme storm produced dramatic changes in the benthos. Submitted, Marine and Freshwater Research), but also to the broader community and stakeholders in the form of non-technical reports and presentations at the Swan River Forum and other community events. See here for a presentation of the aims and early results from this study, or read a recent local news article about the work.