Hello everyone! Hope you’re enjoying the last few days before term starts again!
In my opinion, arguably, two of the major drivers responsible for recent global biodiversity loss today are
invasive species and climate change. Previously, we have explored
how climate change has significantly altered species’ reproduction,
distribution and interactions. Similar to climate change, biological invasions have caused losses and distributional changes in native species, as well as significantly affecting species interaction within the ecosystem as a whole.
However
something more devastating to note is …
Invasive
species will also respond to the rapid changes in climate conditions. Climate change will increasingly work with other stressors to alter the distribution, size, spread, and heighten the consequences of invasive species. Individually,
they pose a great to biodiversity, but in
combination, the complex interaction between both threats is likely to increase drastically. There are increasing evidence on how climate change is adding/amplifying the devastating consequences of invasive species. Climate change impacts, including increases in temperatures and changes in carbon dioxide concentrations will likely aid the spread of
invasive species by increasing their chances of establishment and introduction into
a new area.
There are several ways
in which we can examine and consider how climate change may promote the
introduction and aid the establishment of invasive species, as well as its consequences
into a new area. For example, Hellman et al. (2008) suggested some of the following
mechanisms:
Invasive species are often likely introduced into a new area through transport by humans. Often they are transported accidentally or purposefully for a number of reasons: including tourism, biocontrol, sport fishing and horticulture. Starting with the factor I found most interesting, Hellman et al. (2008) suggests that climate change could connect geographic regions that were once separated, or it can alter geographic areas used for tourism and recreation, which can promote new invasive species to an areas. Nonetheless, climate change could also alter international shipping and transportation routes. For example, the loss of Arctic ice caps has already shortened the time and distance for certain ships. Consequently, this affects the survival chances of invasive species in ballast water. On the other hand, climate change has placed greater pressure on the survival rate of Monkey Goby (Neogobius fluviatilis), due to the longer shipping season at the Great Lakes, hence reducing their chances of survival.
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| Advertisement to remind people to clean and check their boats for invasive species after usage |
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The invasive species
Monkey Groby – Yes, not very pleasant to look at! |
2) Changes in climate constraints and distribution
Due
to climate change, non-native species that are currently unsuccessful in colonizing new areas will be able to overcome these environmental and biological constraints if these areas become more favourable and similar to the species’ current native habitat. Due to their invasive traits of being able adapt to rapid disturbances, and their ability to survive in a wide range of biogeographic conditions, this
will allow them to successfully outcompete native species for limited resources
available under climate change. This response as a result of climate
change has already been observed in some areas. Some examples are shown in the
table below:
Temperature Change
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The range that
North American Mountain Pine Beetle (Dendroctortus ponderosae) occupies has historically been constrained from temperature conditions. An increase in temperature globally have led to a higher latitude
and elevation shift in their range, and allowed the Pine Beetle to complete a
life cycle within one season. A range shift of 7º North will allow it to expand
into and invade the lodgepole pine habitat, which will create competition for
native Jack pines (Pinus banksiana) in
the new region.
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Changing Precipitation Patterns (Frequency and Volume) |
Lonsdale (1993) suggests that there is
a close correlation between precipitation levels and the dispersal range of the
invasive weed species Mimosa pigra in
Australia. Its range is closely related to the precipitation levels of the previous wet season. It has also been
suggested that the increase in precipitation may provide an explanation for the recent expansion of the Giant Sensitive Tree (Mimosa pigra) as an invasive species across tropical Africa.
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Nonetheless, changes in other environmental constraints like wildfire frequency, carbon dioxide concentration, salinity, soil moisture and ocean circulation may also promote invasive species into colonizing new areas. Speaking
of changes in ocean circulation, one of the short-term factors that alter circulation
patterns is extreme weather events.
Climate
change will most likely increase the intensity and chances of extreme weather
events (check out the example from my previous post!). Strong windstorms, hurricanes and ocean currents can promote and aid the movement of invasive species, such as birds, seeds and marine larvae away from their native habitat. For instance, the cactus moth (Cactoblastis cactorum) was likely transported from its native habitat in the Caribbean to Mexico during the 2005 hurricane. Its introduction posed serious threats to more than 104 species of Opuntia (a genus from the cactus family). Similarly, the Cyclone Demonia that hit Swaziland in 1984 was known to have blown the seeds of Demonia weed (Parthenium hysterophorus) across Southern Africa, which created
substantial impacts on the agricultural production in the region and other endemic
species present.
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| Cactus Moth (Cactoblastis cactorum) |
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| Demonia Weed (Parthenium hysterophorus) |
So far, I have only briefly covered the consequences of climate change on invasive species, and its devastating impacts on biodiversity. But I would like to finish this post off by mentioning a little known fact: invasive species can also have an impact on exacerbating climate change. For example, the Mountain Pine Beetle invading native tree species as mentioned, and other impacts such as increase wildfire events created from invasive grass species all have the ability to increase the chance of tree mortality and reduce native forest coverage. This will consequently reduce the amount carbon dioxide that can be sequestered, thus increasing the greenhouse gases in the atmosphere.
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| Invasive Species Meme! |
Concluding remarks
Unfortunately this will be my last post for quite a while (at least not until i finish my dissertation) :'( . Though I must say, its been hard to maintain a blog and updating it each week, but its been an incredible journey - from trying to come up with different topics each week to keeping myself updated via facebook posts on recent news and attending climate change seminars/events. I hope you enjoyed my posts and thank you so much for reading/commenting them throughout the past few months!
- Eva x
