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EUROPEAN CETACEAN BYCATCH CAMPAIGN |
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Dolphins in South Australia |
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The Port Adelaide River estuary is home to approximately 200-250 Bottlenose dolphins (Tursiops truncatus). |
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During the last decade, researchers have noticed an increase in the occurrence of newborn calf fatalities in this area. |
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A high incidence of neurological and physical abnormalities in first-born calves has led some researchers to conclude that the consistent ill health of neonates at birth may reflect the ailing health of the estuary. |
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PCB's (which are persistent and harmful synthetic chemicals), and other chemicals and heavy metals may 'bio accumulate' in the ecosystem, by building up inside the bodies of plants and animals progressively throughout the food chain, magnifying at each level. Long lived animals such as whales and dolphins accumulate high concentrations of pollutants due to their position at the top of the food chain. |
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Generally, such chemicals can not only cause birth defects, but disrupt hormones, reproductive, immune and nervous systems. |
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A researcher recently found PCB levels in a wild dolphin at 18 parts per million (ppm) - which is 300 times higher than other contemporary Australian studies (0.06ppm). This result has implications not just for the dolphins, but the overall health of the estuary and the safe consumption of fish caught from it. |
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Most recently significant levels of mercury have been detected in Pt Adelaide dolphins (a dolphin found dead as a result of gun shot wounds was found to have the highest levels (40 times higher) of mercury contamination every recorded for a bottlenose dolphin in Australia). |
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There are serious implications from this for human health (in humans, mercury attacks the brain, the immune system, can cause genetic mutations and newborn babies), as well as that of the dolphins and other marine life. |
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Once mercury is in sediments it is impossible to remove without major environmental damage, however, careful management can reduce the seriousness of the problem. Another reason for a sanctuary management framework to be in place at Barker Inlet, which is driven by both prevention as well as 'cure'. |
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It is worth noting that dolphins elsewhere in South Australian waters are also at risk from pollution - with high cadmium levels having been found Spencer Gulf dolphins. The main source of cadmium input into the Spencer Gulf is via the liquid effluent channel from the largest lead and zinc smelter in the world - at Port Pirie. |
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In humans, cadmium is known to cause kidney dysfunction and bone diseases. |
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Antifoulants (paints used to prevent marine organisms attaching themselves to the hulls of boats and fish-farms) contain toxic compounds - they leach slowly from the paint and bio-accumulate. They can remain in sediments for up to 50 years. In Australia - TBT (Tributylin) has been linked to abnormal growth, sterility and death of shellfish. |
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