VITAL clues about what killed six Swan River dolphins may be known next month.
Murdoch University’s School of Veterinary Sciences Carly Palmer told the Melville Times that results from two dolphins’ samples could be known next month, while an inquiry set up by WA chief scientist Prof Lyn Beazley has indicated April findings.
Six dolphins from the river’s 24-strong family were found dead between June and October last year.
Tests of four showed suppressed immune systems, the banned termite poison dieldrin and severe skin lesions. The dieldrin was at some of the highest levels in marine mammals, the university’s Dr Hugh Finn said at the time.
Researchers also mooted cetacean morbillivirus – one of several marine mammal viruses – as having a potential effect.
More tests at New South Wales’ National Measurement Institute are looking for poly aromatic hydrocarbons from fuel and oil, organochlorins, such as dieldrin, and PCBs.
Perth’s The Chemistry Centre is searching for the heavy metals methyl-mercury, used to preserve seed, and tributyltin, a banned boat anti-foulant.
Which toxin being sought dictates which body parts are tested, Dr Palmer said. “Dieldrin, DDT, and its metabolites, are all fat-soluble contaminants, along with other organo-chlorine pesticides and PCBs.
“Therefore, the best tissue sample to test for their presence is blubber.”
Dolphins are vulnerable to toxins in fats because they are large eaters that live for many years.
“But their capacity to decompose organic contaminant molecules is low and their blubber, which is rich in fat, acts as a storage area for the accumulation of contaminants,” Dr Palmer said.
Liver, kidney and bone samples are at the chemistry centre for testing to reveal heavy metals.
Morbillivirus tests are being conducted at Melbourne University.