Search

The increasing focus of marine biosecurity agencies on transferring management responsibilities to citizens and industry begs the question whether devolved responsibility is a viable option for creating biosecurity outcomes. We examined recreational marine users’ self-declared awareness of non-indigenous marine species (NIMS) at six locations in Tasmania, Australia and evaluated the accuracy of their awareness through recognition of four well-known NIMS with active awareness campaigns. We also investigated whether the activities of recreational marine users influence the accuracy of their NIMS recognition skills. We generally found that respondents declare NIMS awareness (70.45%), yet we found their recognition accuracy was variable ranging from low to fair (<10% to 54.95%) and recreational activity did not influence accuracy. Based on our results, we conclude that marine users’ awareness does not predict accuracy and therefore devolved management of biosecurity without additional resources may pose a risky biosecurity management strategy. [ABSTRACT FROM AUTHOR]

Petrolisthes elongatus (Milne-Edwards, 1837) was first introduced into southern Tasmania in the late 19th century putatively associated with live-oyster transfers from New Zealand. In the last century P. elongatus populations have expanded, inoculating rocky intertidal zones around Tasmania. We initially identified the scope of P. elongatus introduced range around Tasmania by visiting 57 sites to identify presence. Density of P. elongatus and populations of two native grapsid crab species was assessed at 12 sites around Tasmania to identify any biotic resistance. Abiotic factors including substrate availability and preference, and wave stress, were identified at each of the 57 sites. Our results indicate that P. elongatus has successfully invaded a large proportion of the southern and northern coasts of Tasmania, with a small number of sites on the east and none on the west coast supporting P. elongatus populations. Densities were found to be higher in southern Tasmania compared to the eastern and northern coastlines. Petrolisthes elongatus presence was found to be positively correlated with native grapsid crab presence, however, no statistically significant relationship was found between densities at scales of site or quadrat. Abiotic factors have been identified as the primary drivers of Petrolisthes distribution patterns. [ABSTRACT FROM AUTHOR]

Abstract: The northern Pacific seastar, Asterias amurensis, was first collected in southeast Tasmania in 1986. Mistaken for the endemic asteroid Uniophora granifera, its true identity was not realised until 1992. It is now a conspicuous predator in soft sediment habitats in this region, and is considered a major threat to native assemblages and commercial species. We examined the structure of soft sediment assemblages at different spatial scales in southeast Tasmania, and correlated spatial variation in community composition with seastar abundances. We found that the structure of soft sediment assemblages is highly variable at a range of spatial scales from metres to tens of kilometres. Clear differences in the composition of assemblages and abundances of major taxa were detected between areas with and without seastars and between areas with low and high seastar densities. However, the nature of these patterns suggests that they are more likely due to differences in sediment characteristics than due to impacts of the seastar. Thus, spatial differences in soft sediment assemblages might have been erroneously attributed to seastars without detailed information on important physical factors such as sediment characteristics. A second survey, using larger sampling units (1m2) but across a more limited spatial extent, targeted bivalves and heart urchins that were identified as important prey of the seastar in observations of feeding and in experimental studies. Large-scale patterns of abundance and size structure were consistent with seastar effects anticipated from small-scale experimental and feeding studies for some, but not all, species. While the field survey ultimately provided evidence about the presence or absence of seastar impacts at large-scales, the identification of key ecological variables in experimental and feeding studies proved crucial to both the design and interpretation of patterns observed in the large-scale surveys. Overall, this work highlighted the necessity to consider multiple lines of evidence rather than relying on a single ‘inferential’ test, in the absence of pre-impact data. [Copyright &y& Elsevier]