The chiton fauna of the Swan River Estuary and their potential role as indicators of environmental contamination
Shaw, J.A., Maker, G.L., Brooker, L.R. and Clode, P.L. (2009) The chiton fauna of the Swan River Estuary and their potential role as indicators of environmental contamination. In: Swan Canning Research and Innovation Program Showcase, 19 August, Perth, Western Australia.
Chitons are marine molluscs that typically feed on algae living on and within the surface layer of hard intertidal substrates. They exploit this ecological niche by hardening their teeth with the iron oxide magnetite and a range of other biominerals. In order to facilitate this mineralisation process, chitons have large reserves of iron in their blood and soft tissues. While iron is an essential metabolic requirement, large amounts can be toxic, and chitons have developed a number of strategies for preventing the free radical damage normally associated with this highly reactive element.
Molluscs are well known for their ability to accumulate other heavy metals, such as tin, cadmium and lead, and it is this fact that has led researchers to query whether such metals are incorporated within the iron mineralised teeth of chitons.
Recently, it was discovered that chitons were living in the Swan River Estuary, which was unexpected as they are normally restricted to coastal marine habitats. This discovery provided an ideal opportunity to investigate whether chiton teeth could act as indicators of environmental contamination. Accordingly, an underwater survey was conducted to determine the number of chiton species in the Swan River Estuary and the extent of their colonisation upriver from Fremantle Harbour.
A total of 9 river sites and 1 coastal site were investigated. Radulae and sediment samples were collected from inhabited river sites and analysed for tin and other heavy metals using a combination of energy dispersive X-ray microanalysis, inductively coupled plasma-mass spectrometry and secondary ion mass spectrometry. The levels of heavy metal contamination in these samples will be discussed in context with equivalent samples collected from a fully marine system.
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|Murdoch Affiliation:||School of Pharmacy|
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