Development and evaluation of a PCR-based test for detection of Asterias (Echinodermata : Asteroidea) larvae in Australian plankton samples from ballast water

The northern Pacific seastar, Asterias amurensis, spread to Tasmania in the 1980s from its native range in the North Pacific. The seastar has subsequently established in Port Phillip Bay on mainland Australia. Transportation of larvae in ballast water is one vector for these introductions and is likely to contribute to additional range expansion of this species. Larval identification methods are critical to assess risks of further transport to uninvaded ecosystems; however, morphological identification of larval asteroids is impractical and unreliable. Therefore, we have developed a sensitive PCR-based method that specifically detects Asterias DNA. The method works on isolated seastar larva, mixed plankton and ballast water samples. Trials using uninfected ballast water samples spiked with known numbers of A. amurensis larvae indicate that the technique can detect single larva in 200 mg of plankton. The test also detects other Asterias species; therefore, discrimination between seastars within the genus Asterias was accomplished using denaturing gradient gel electrophoresis (DGGE). Currently, this method is being used to facilitate research on ballast water transport, distribution and the ecology of A. amurensis larvae. The general approach can be expanded to provide a rapid and cost-effective approach for detecting a suite of marine species in ballast water and environmental samples

Port of Hastings National Demonstration Project - Verification of the Type II error rate of the Ballast Water Decision Support System (DSS).

In July 2001, Australia introduced a risk-based Decision Support System (DSS) to manage ballast water on international shipping. Up until now, however, the accuracy of the risk assessments made by the DSS have never been evaluated or tested. It was not until the DSS was considered as a mechanism to assist the management of domestically sourced ballast water, coupled with advances in genetic technologies, that the opportunity arose to evaluate the accuracy of the predictions of the DSS. The results of that evaluation are reported here..

Estimating diet composition in sea lions: which technique to choose?

Reliable estimates of diets are vital to monitor impacts of sea lion popu-lations on their ecosystems and their interactions with fisheries, and to understand the role of food to animal nutrition and health. Approaches include using (1) prey remnants in stomach contents, spews and scats; (2) prey DNA in scats; (3) fatty acid signatures in blubber; and (4) stable isotope ratios in predator’s tissue. Each methodology has particular ad-vantages and limitations, many of which can be assessed and improved through controlled captive feeding trials. Analysis of prey remnants from captive sea lion scats have shown significant variability in diges-tion between and within prey species, which, coupled with preferen-tial regurgitation and enumeration biases, can confound accurate diet quantification, but does not prevent spatial or temporal comparisons. Correction for partial digestion and use of additional structures besides otoliths can provide reliable prey size estimates. Prey DNA can be con-sistently isolated from soft remains in scats from captive sea lions, and with further development this approach may allow quantification of diet. Genetic methods can be expensive and representative of only one to tw