Bioaccumulation monitoring of the mud crab, Scylla serrata, from Queensland estuaries

Mature male mud crabs were collected by commercial fishers from 11 rivers and creeks spanning 1500 km of the Queensland coast, following the 2004/2005 and 2005/2006 wet seasons. The sites, sampled between March and July, were located at the mouths of the Normanby River, Barron River, Johnstone River, Tully River, Herbert River Gordon Creek, Burdekin River, Pioneer River (post 2005/2006 wet season only), O'Connell River, Fitzroy River and Burnett River.

On arrival at the laboratory, the live crabs were placed in a seawater/ice slurry. Each crab was weighed, the carapace width was measured and urine and hemolymph samples taken. Hepatopancreas, muscle and gill samples were collected. Most of the hepatopancreas was frozen at -20°C. Sub-samples of hepatopancreas, muscle gill, urine and hemolymph were also snap frozen in liquid nitrogen and stored at AIMS at -80°C for future bioindicator assays.

The hepatopancreas from each of 12 crabs from each site was subsampled and pooled to form four hepatopancreas samples (each sample derived from three individual crabs). These samples were extracted and analysed for pesticides and persistent organic pollutants (POPs). Individuals from the pooled samples were further analysed when contaminants were detected in the pooled samples. Analyses, were conducted for organochlorine pesticides (OC), organophosphate pesticides, polychlorinated byphenyls (PCBs) as selected congeners and polyaromatic hydrocarbons (PAHs). Pesticide analyses were carried out by Queensland Health and Scientific Services (QHSS).

A freeze dried subsample of the hepatopancreas from 12 replicate crabs from each site was digested using HNO3/HClO4 and analysed for metals and metalloid concentrations (total Ca, Mg, Cu, Fe, Sr, Zn, Mn, Cd, Be, Co, Ni, Ba, Mo, Al, Cr, Pb, Sn, V and Se) using a Varian Liberty 220 inductively coupled plasma-atomic emission spectrometer (ICP-AES). Arsenic (As) was analysed on the Liberty 220 ICP-AES by hydride generation and mercury (Hg) by cold vapour generation.