TRaCK: Tropical Rivers and Coastal Knowledge

Science and knowledge that governments, communities, industries for sustainable use of Australia's tropical rivers and estuaries

Extreme conditions structure meiofauna communities in the arid tropics of Australia

TitleExtreme conditions structure meiofauna communities in the arid tropics of Australia
Publication TypeConference Participation
Year of Publication2010
AuthorsDuggan, M, Burford, MA, Connolly, R, Whittle, M
Keywords5: Foodwebs and biodiversity

This study examined meiofauna populations in an estuary of the Gulf of Carpentaria (Australia), a remote and largely unmodified region of the arid tropics. It also presents the first insights into the long and short-term effects of a major flood on meiofauna populations in this region. For most of the year the Norman River estuary receives no freshwater flow, followed by extensive flooding in the wet season (December–March). High salinity (~35 or higher) in the dry season as well as freshwater conditions during flooding both appear to havedetrimental effects on meiofaunal abundance, with optimal salinities around 25. Flooding of the river in January 2009 was the second largest on record, resulting in freshwater conditions (salinity 0-1) in the estuary that lasted for three months. Meiofauna abundance dropped to zero at the peak of the flood but recovery was rapid after the flood and exceeded pre-flood numbers. It is proposed that the more tolerable salinity (25) and the input of nutrients and organic matter to the estuary post-flood are the reason why meiofauna abundance and taxa richness is greatest at this time of year. This study found a density of 0-78 ind.10cm2 for all meiofauna taxa in the Norman River estuary throughout the study, which is far lower than other estuarine studies. We propose that the extreme highs and lows in salinity of the Norman River Estuary have resulted in substantially lower meiofauna abundance and taxa richness compared with other tropical estuaries. This has implications for the productivity of the whole estuary, and other estuaries in the arid tropics.