IMPACTS OF CLIMATE CHANGE ON NON-NATIVE SPECIES
Paul Elliott
Aquatic ecology Group, University of Cambridge
Executive Summary
Non-indigenous species are becoming increasingly common in marine habitats, and are causing major ecological changes on both local and global scales (Ruiz et al., 1997; 2000). Most species have reached new localities by anthropogenic dispersal such as deliberate introduction, fouling on the bottom of ships, or through the release of organisms in ballast water (Ruiz et al, 1997, Eno et al., 1997). Many factors can then affect the successful establishment of the species, such as the presence of predators, availability of unfilled niches, and the presence of food (Eno et al., 1997, Hawkins et al., 2004). There is also a growing body of evidence that most aspects of global climate change favour the successful establishment of invasive alien species (Dukes & Mooney, 1999; Carlton, 2000; Stachowicz et al., 2002).
Climate change has been proposed to affect marine invasions in a number of ways. Firstly, warm water-indigenous species may expand ranges to the warming higher latitudes and out-compete cold-adapted species through their greater growth and recruitment (Carlton, 2000; Stachowicz et al., 2002). Secondly, climate change may alter primary trophodynamic regimes and oceanography, indirectly facilitating invasions (Carlton, 2000; Hulme, 2005). Thirdly, successful invaders tend to be more resilient to disturbances than native species, and thus climate change could combine with other stresses to allow invaders to out-compete native species (Rogers & McCarty, 2000).
Unfortunately, evidence and models of the effects of climate change on invasive spread are rare. However, many studies have revealed a correlation between water temperature and success of marine invaders. For instance, Stachowicz et al. (2002) found that three invasive species of ascidians in the USA can out-compete native species in warm years. Also, in the UK, many of our marine invasive species are thought to be limited in distribution by water temperature Examples include the tubeworm, Ficopomatus enigmaticus (Zibrowius & Thorp 1989), the barnacle Elminius modestus (Eno et al., 1997), and the algae, Codium Fragile (Hardy 1981). It is likely that increasing water temperatures will further facilitate the spread of these species, and possibly allow introductions of new and notorious warm-water invaders such as the Northern Pacific Sea Star, Asterias amurensis, or the Caulerpa Seaweed, Caulerpa Taxifola.
Level of Confidence
Medium
Key sources of Information
Please acknowledge this document as: Elliot, P. (2006). Impacts of Climate Change on Non-Native Species in Marine Climate Change Impacts Annual Report Card 2006 (Eds. Buckley, P.J, Dye, S.R. and Baxter, J.M), Online Summary Reports, MCCIP, Lowestoft, www.mccip.org.uk