In this post Associate Editor Joseph Bennett discusses a paper he recently handled by Chris Ware and colleagues ‘Biological introduction risks from shipping in a warming Arctic’
It is well known that the Arctic is one of the most vulnerable regions to the impacts of climate change (IPCC 2014). Climate change will not only have direct impacts, it will also magnify the effects of existing threats (Bennett et al. 2015). If we do not manage these existing threats – while working toward reducing anthropogenic warming – we will see irrevocable changes in Arctic ecosystems.
Species invasions are one of the most compelling examples of the interactions among climate change and other threats. As ambient conditions are altered via climate change, native species can become maladapted to their environments. This creates niche opportunities for any newly arriving non-native species. Increased development and shipping in the Arctic – which is partly facilitated by climate change – is providing the vectors for species transport. One of the major questions, at this early stage of Arctic species invasions, is how many new species we are already bringing into the Arctic, and how likely these species are to survive.
A new paper by Ware et al. helps to answer this question, for marine invaders in particular. Ware et al. sampled ballast water in 26% of the bulk shipping vessels traveling to the Norwegian Arctic archipelago of Svalbard. Using both traditional taxonomy and DNA barcoding techniques, they assessed the composition of ballast water communities, the thermal and salinity thresholds of individual taxa, and whether taxa were native to Svalbard. They then modeled future environmental conditions using the RCP 8.5 emissions scenario (which predicts growing greenhouse emissions based on a status-quo approach to mitigation), to determine how many new species would be able to live in Svalbard waters by the years 2050 and 2100.
They found non-native taxa in ballast water from every ship they sampled. In total, they found 23 taxa that were non-native to Svalbard. Of the eight species for which there was sufficient information to model habitat suitability, one was projected to be capable of colonizing under current conditions, and six were projected to be capable of colonizing by 2100.
These findings are particularly troubling because vessels entering Norway are required to exchange ballast water at sea, in an effort to reduce species invasions. In fact, Ware et al. found that vessels that had complied with this regulation harbored more non-native species. This suggests a need to rethink ballast water management on Arctic shipping routes, and an immediate need to examine the performance of additional ballast water treatment technologies (including those involving chlorination, e.g. Paolucci et al. 2015) in Arctic conditions. Otherwise, there will almost certainly be increasing establishment of non-native marine species in the Arctic. Ware et al. caution that we need to consider the way we manage vectors of species introduction against a backdrop of inevitable natural species invasions in the Arctic – that is, those temperate species which will extend their ranges to Arctic waters under future favourable conditions. Nevertheless, due to the efficiency with which ships transfer large volumes of diverse species (in ballast water and through biofouling), there is clear risk of ship-mediated invasions causing profound ecological changes.
It should be noted that this study represents a sample of shipping to a relatively small portion of the Arctic. Additional studies (e.g. Chan et al. 2013, 2015) suggest that the synergistic threats of marine species introductions and climate change will bring big changes to Arctic marine ecosystems. Scientists need to react quickly to this, by further studying abatement technologies in polar environments. And regulators need to implement stricter regulations while there is still time to prevent many species invasions.
Bennett, J.R., Shaw., J.D., Terauds, A., Smol, J.P., Aerts, R., Bergrstrom, D., Blais, J., Cheung, W., Chown, S., Lea, M.-A., Nielsen, U., Pauly, D., Reimer, K. J., Riddle, M., Snape, I., Stark, J., Tulloch, V., & Possingham, H. (2015). Polar lessons learned: informing long-term management based on shared threats in Arctic and Antarctic environments. Frontiers in Ecology and the Environment, 13, 316-324.
Chan, F.T., Bailey, S.A., Wiley, C.J., & MacIsaac, H.J. (2013) Relative risk assessment for ballast-mediated invasions at Canadian Arctic ports. Biological Invasions, 15, 295–308.
Chan, F.T., MacIsaac, H.J., & Bailey, S.A. (2015) Relative importance of vessel hull fouling and ballast water as transport vectors of nonindigenous species to the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences, 72, 1230-1242.
IPCC (Intergovernmental Panel on Climate Change). 2014a. Summary for policymakers. In: Field CB, Barros VR, Dokken DJ, et al. (Eds). Climate change 2014: impacts, adaptation, and vulnerability. Part A: global and sectoral aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press.
Paolucci, E.M., Hernandez, M.R., Potapov, A., Lewis, M.A. & MacIsaac, H.J. (2015) Hybrid system increases efﬁciency of ballast water treatment. Journal of Applied Ecology, 52, 348–357.