| Summary: | Progress Code: completed Purpose To determine if climate change variables will increase the sensitivity of subantarctic marine invertebrates to copper. Study location and test species Subantarctic Macquarie Island lies in the Southern Ocean, just north of the Antarctic Convergence at 54 degrees 30' S, 158 degrees 57' E. Its climate is driven by oceanic processes, resulting in highly stable daily and inter-seasonal air and sea temperatures (Pendlebury and Barnes-Keoghan, 2007). Temperatures in intertidal rock pools (0.5 to 2 m deep) were logged with Thermochron ibuttons over two consecutive summers and averaged 6.5 (plus or minus 0.5) degrees C. The island is relatively pristine and in many areas there has been no past exposure to contamination. To confirm sites used for invertebrate collections were free from metal contamination, seawater samples were taken and analysed by inductively coupled plasma optical emission spectrometry (ICP-OES; Varian 720-ES; S1) The four invertebrate species used in this study were drawn from a range of taxa and ecological niches (Figure 1). The isopod Limnoria stephenseni was collected from floating fronds of the kelp Macrosystis pyrifera, which occurs several hundred meters offshore. The copepod Harpacticus sp. and bivalve Gaimardia trapesina were collected from algal species in the high energy shallow, subtidal zone. Finally, the flatworm Obrimoposthia ohlini was collected from the undersides of boulders throughout the intertidal zone. We hypothesised L. stephenseni would be particularly sensitive to changes in salinity and temperature due to its distribution in the deeper and relatively stable subtidal areas, while O. ohlini would be less sensitive due to its distribution high in the intertidal zone and exposure to naturally variable conditions. We reasoned that the remaining two species, G. trapesina, and Harpacticus sp. were intermediate in the conditions to which they are naturally exposed and hence would likely be intermediate in their response. Test procedure The ...
|
|---|