Climate Change Impacts on Marine Invasive Species, C. Nall

Abstract 

This chapter presents evidence and predictions regarding the impacts of climate change on marine invasive species, with specific relevance to the seas of northern Europe. Invasive species have a drastic impact onmarine ecology and can be a nuisance to industries that operate in marine environments. In some cases they can also have a negative effect on human health, for instance when invasive algal blooms cause shellfish poisoning. Invasive species tend to be rapid colonisers that are tolerant of a wide range of environment conditions and this has allowed them to thrive in many locations throughout the world. Native species however tend to be less tolerant of environmental changes. It is predicted that the impact of invasive species will be exacerbated by climate change as it could promote the spread of invasive species and also increase their ability to out-compete native species. The components of climate change likely to have this effect include increased seawater temperature, increased frequency of extreme weather events, ocean acidification, and alterations to ocean circulation and salinity. There is already evidence to suggest increased seawater temperature over the last few decades has facilitated introductions of invasive species. Examples of the northward range expansion of invasive species in northern Europe that can be attributed to warming seas do exist. These include the introduction of Crassostreagigas (Pacific oyster) and Styelaclava (Leathery Sea Squirt) at more northerly locations in Europe than previously observed. Future increases to seawater temperature are likely to further promote the spread of invasive species and could cause native species to go extinct from various locations. Warm-water species previously unable to colonise habitats in northern Europe may be introduced via human-mediated pathways (such as shipping) or by natural dispersal from warmer locations in the south of Europe. So far only increased seawater temperature has been observed to have an effect on invasive species abundance and distribution. However, other changes associated with climate change are predicted to facilitate marine invasions in the future. A predicted increase in precipitation at northerly latitudes will result in a decrease in salinity in the enclosed Baltic Sea, and as a result of this, it is forecasted to enhance the abundance of euryhaline invasive species in the region. Ocean acidification is also predicted to favour some invasive species. Changes in human maritime activity in response to climate change could further impact marine invasions. This is of particular relevance to the Atlantic and Baltic region because new arctic shipping routes are opening up between the Atlantic Ocean and Pacific Ocean due to sea ice melt. This represents a huge opportunity for marine invasions from the Pacific because shipping is a major vector for non-native species introduction. The addition of coastal sea defences in order to adapt to increased risk of coastal flooding and erosion is also likely to enhance marine invasive species because they provide habitat for these species and can aid dispersal.

Keywords

alien species, increasing sea surface temperature, species range shifts, decreasing salinity, ocean acidification, extreme weather events, arctic shipping routes, coastal sea defence.

Key questions and concepts

What are invasive non-native species?
Why do we care about them?
Do they have environmental, economic or societal impacts?
How has climate change already influenced the spread and establishment of invasive non-native species?
In the future, will continued environmental changes caused by climate change further influence the impact of invasive non-native species?

This scientific article was prepared as the basis for pedagogical material which is being developed by the EduCO2cean project team. The magazine articles are not intended for use as teaching material in their own right.