CSIRO PUBLISHING Marine and Freshwater Research, 2008, 59, 1048–1060 www.publish.csiro.au/journals/mfr Selenium bioaccumulation and biomagnification in Lake Wallace, New South Wales, Australia J. F. Jasonsmith A,C , W. Maher A,D , A. C. Roach B and F. Krikowa A A Institute for Applied Ecology, University of Canberra, Belconnen, ACT 2601, Australia. B Centre for Ecotoxicology, New South Wales Department of Environment and Climate Change, Lidcombe, NSW 1825, Australia. C Current address: Earth and Marine Sciences, Australian National University, Acton, ACT 0200, Australia. D Corresponding author. Email: bill.maher@canberra.edu.au Abstract. Selenium concentrations were measured in water, sediments and organisms inhabiting a freshwater coal power station cooling reservoir. Se concentrations found were: water, 1.9 ± 2 μgL −1 ; sediment, 7 ± 1 μgg −1 ; phytoplankton, 3.4 μgg −1 ; zooplankton, 5.3 μgg −1 ; epiphytic algae, 1.3 ± 0.2 μgg −1 ; benthic algae, 8 ± 2 μgg −1 ; macrophyte leaves, 2.7–2.8 μgg −1 ; macrophyte roots, 0.5–6.5 μgg −1 ; detritus, 10 μgg −1 ; Oligochaeta, 11 μgg −1 ; Corbiculidae, 1.1 μgg −1 ; Insects, 3.7–8.3 μgg −1 ; Gastropoda, 3.2 μgg −1 ; Crustacea, 3.1–6 μgg −1 ; whole fish, 2.2–13 μgg −1 ; and fish liver, 134– 314 μgg −1 . Bioconcentration factors were similar to those found in aquatic ecosystems with comparable Se concentrations in the water column.A food web was constructed with four main food chains (phytoplankton, epiphytic algae, benthic algae and sediment/detrital), with fish fed from multiple pathways. Biomagnification only occurs along food chains for flathead gudgeons and rainbow trout. Se concentrations in food sources were above the 3 μgg −1 dietary Se level considered to induce teratogenesis in fish spawning. Flathead gudgeons were found to be suffering teratogenesis and rainbow trout showed no evidence of teratogenesis. Additional keyword: ecotoxicology. Introduction The ability of selenium (Se) to act as a toxicant was first noted in the 1930s, when seleniferous soils were linked to fatalities in cat- tle and horses (Seiler 1998). With the discovery in the 1950s that Se also had nutritional benefits, the perception of Se as a toxicant slowly faded from view (Milne 1998). The issue of Se toxicity arose again in the late 1970s, when 12 of 16 fish species in a coal power plant cooling basin – Belews Lake, North Carolina, USA – disappeared. Se was found to be the sole cause of the fish kills (Lemly 1985; Skorupa 1998). Extensive studies of Se bioac- cumulation, biomagnification and toxicity have been undertaken on freshwater ecosystems in the USA, with additional stud- ies occurring in Sweden and the UK (Lemly 1999b; Hamilton 2004). In Australia, research on Se bioaccumulation and bio- magnification in aquatic ecosystems has been confined mostly to marine systems (Maher and Batley 1990; Peters et al. 1999a, 1999b; Kirby et al. 2001a, 2001b; Barwick and Maher 2003). Few studies have been undertaken on freshwater ecosystems in an Australian setting. Se biomagnifies through food chains in aquatic ecosys- tems receiving elevated Se inputs (Lemly 1993; Barwick and Maher 2003). Where remediation has been carried out to lower Se concentrations in water, aquatic flora and fauna continue to contain high Se concentrations 10–20 years after remedia- tion (Lemly 1997a). Se concentrations in food sources above 2–3 μgg −1 dry mass are considered to induce teratogenesis in fish spawning and deformities in fish larvae (Lemly 1993; Can- ton andVan Derveer 1997). Organisms at lower trophic levels, such as phytoplankton and invertebrates, can accumulate high Se concentrations (100 μgg −1 ) without exhibiting any observable effects (Foe and Knight 1986; Lemly 1993). However, consump- tion of organisms containing Se at these levels is certain to affect predators. Food chain studies help to understand pathways of exposure, giving insights into how Se moves through aquatic ecosystems, and allows identification of vulnerable components of the ecosystem. Coal-power stations currently supply 49% ofAustralia’s elec- tricity, with energy demand projected to increase to 57% by 2040 (Australian Bureau of Statistics 2006; Saddler et al. 2007). Cooling basins and ash dams are widely used in the manage- ment of selenifierous wastes from coal-fired power stations. These wastes are known to produce Se concentrations that can be threatening to the health of some aquatic ecosystems. The growing demand for energy increases the likelihood that Se may enter the environment via cooling basins and ash dams. As such, regulatory authorities need a better understanding of the environmental significance of Se in potential receiv- ing waters. This study was undertaken in part to meet these research requirements in one such reservoir, Lake Wallace, New South Wales. © CSIRO 2008 10.1071/MF08197 1323-1650/08/121048