| Summary: | The three gastropod species in this study were collected from the subantarctic Macquarie Island (54.6167 degrees S, 158.8500 degrees E), which is located in the Southern Ocean, just north of the Antarctic Convergence. Sea temperatures surrounding Macquarie Island are relatively stable throughout the year, with average temperatures ranging from ~4-7 degrees C (Reynolds and Banzon, 2008). Seawater samples were taken from collection sites of this study and verified as free from metal contamination by analysis by inductively coupled plasma optical emission spectrometry (Varian 720-ES) (ICP-OES). The three gastropod species were collected from a range of habitats within the intertidal and subtidal zone (Figure 1). Individuals of Laevilittorina caliginosa were often located in pools high on the intertidal zone, but can occur throughout the intertidal zone. Collections of this species were not specific to any one habitat. Macquariella hamiltoni, endemic to Macquarie Island, was collected from macroalgae in the high energy areas of the subtidal zone. Finally, Cantharidus capillaceus coruscan, was collected from the undersides of boulders in deep tide pools as well as from crevices in the shallow subtidal. This species was also abundant on the floating fronds of Macrocystis pyrifera in deep water which is up to several hundred meters from shore. Toxicity tests Toxicity tests were conducted at Macquarie Island, over the 2013/14 austral summer, and at the Australian Antarctic Division (AAD) in Tasmania, Australia, in 2015. The first round of tests with Laevilittorina caliginosa and Macquariella hamiltoni as well as both tests for Cantharidus capillaceus coruscan were done on Macquarie Island, while the second test for L. caliginosa and M. hamiltoni were done in Australia. Gastropods for use in tests in Australia were transported by ship to the Marine Research Facilities at the AAD where they were housed in purpose-built recirculating aquariums at 6 degrees C for 2 months prior to being used in tests. For tests done at the ...
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