Copper pollution enhances the competitive advantage of invasive ascidians
In: Management of Biological Invasions. Regional Euro-Asian Biological Invasions Centre (REABIC): Helsinki. e-ISSN 1989-8649, more
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metal toxicity, marine, benthic, invertebrates, competition, tolerance |
| Authors | | Top |
- Osborne, K.L.
- Poynton, H.C.
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| Abstract |
Invasive species dominate and often outcompete native species in marine harbors. The abundance of introductions due to shipping activity combined with artificial substrates and poor water quality helps to facilitate invasion success in these areas. Colonial ascidians, in particular, have broad environmental tolerances that allow them to invade novel ecosystems including urban harbors. While the effects of invasive species and poor water quality on native species have been explored, the relative influence and how these pressures may interact to degrade biodiversity is not well characterized. The purpose of this study was therefore to understand the role of interspecific competition and pollution on the native Aplidium glabrum and the invasive Botrylloides violaceus. Colony surface area has been previously identified as a sensitive toxicity endpoint and was measured weekly to assess impacts both separately and together at 0, 1, 10, 20, and 40 μg/L copper concentrations. A. glabrum was significantly impacted at 1 μg/L in the presence of interspecific competition and at 10 μg/L with no competition; however, the copper EC50 revealed increased sensitivity in the presence of B. violaceus (11.3 μg/L versus 6.9 μg/L while in competition). Conversely, significant impacts to B. violaceus growth did not occur until much higher copper concentrations with an EC50 of 37.1 μg/L while alone and 31.7 μg/L when in competition. Interspecific competition was found to significantly impact A. glabrum surface area growth at 1, 10, and 40 μg/L, while there was no significant effect on B. violaceus at any of the concentrations tested. Finally, an interaction effect was found between copper pollution and competition status only for A. glabrum. The results of this study support the hypothesis that invasive species are more tolerant of pollution while also revealing the interactive effects of pollution exposure and interspecific competition. |
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