Torres Strait baseline study

Abstract

A baseline study has been carried out in Torres Strait, separating northern Australia from Papua New Guinea, to investigate concentration levels of various metals within the sediments and their biota and a range of organisms either consumed locally or exported. The study was initiated as a result of the concern by the Torres Strait Islanders in the mid-1980s regarding the possible effect of copper and gold mines which had been established adjacent to the Fly River and its catchment in Papua New Guinea. During the monsoon season the prevailing winds tend to direct the river outflows from the Fly River into northern Torres Strait. A pilot study was initially carried out and showed that sediments in Torres Strait are a mixture of those deposited from the Fly River and those derived from marine sources. Northern Torres Strait sediments appear to be derived primarily from the Fly River whereas sediments in other parts of the Strait are marine-derived sediments. Trace metals were elevated in some seafoods consumed by the Islanders, and levels of copper might be a result of discharge from the mines. However, trace metal levels in biota varied both spatially and seasonally in some areas. Basically the pilot study has shown that the Fly River is a periodic source of fine sediments containing a suite of trace metals and a number of species have been shown to be potentially useful as indicators of variations in trace metals. This study has allowed a more extensive study to be carried out and the complex results are currently being analysed. In addition they recommend that another survey should be carried out concentrating on rates of consumption of those foods shown to have high levels of some trace metals. The study is also important as local Islanders were involved in all stages of the development and undertaking of the survey.