13.5: Invasive Species
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The impact of increased average global temperature due to global warming on terrestrial ecosystems has been prevalently studied and the commonly accepted result is that there will be increased domination of invasive who alter the habitat and disturb the species associations by outcompeting the native species. And this concept also applies to the marine ecosystems, as well. The study was conducted at the marine fouling community of Bodega Harbor, Bodega Bay, CA, where human-mediated colonization is frequent. The species composition of this particular site has been known to have nonnative species representing 71% of cover in the dock fouling community. The researchers took 10 sessile species (4 native and 6 invasive) and put them on tile and placed them into 1L tank. Then they raised the temperature gradually, observing total of 6 intervals between the temperature 14 to 32 degrees Celsius. The result concluded that the invasive species were more tolerant to higher temperature and that native species showed taunted growth or death by stress.
Ever since humans had the ability to sail from one continent to the other, they have unintentionally transported marine organisms, an introduction of invasive species to new community. Once invasive species are introduced to new community, they can outcompete the native species and disrupt the species associations that may result in less biodiversity and migration of upper predators. The reduced number of fish which fisheries rely on can then take huge economic damage and overall socioeconomic benefits degrade to some degree. The solution to mitigate such a problem is then to cooperate both the regional and the global trading partners, approaching the most effective management system.
An invasive species can be defined as an introduction of any non native living organism
to an environment resulting in some type of harm to the environment/native inhabitants. In fact,
“invasive species are one of the leading threats to native wildlife,” (www.nwf.org) since they are
able to reproduce and spread so rapidly as a result of having no predators or natural controls.
This proves to be the reason why disturbances such as timber harvesting, tree falls, and
flooding along creeks can encourage these invasive species. Native species have not yet
evolved any defenses against these invaders which leads the natives susceptible to preying,
out-competing, disease, and prevention of reproduction. (www.nwd.org). In addition to these
direct threats, there are also a plethora of indirect threats that invasive species bring to native
species, including but not limited to, changing food webs, decreasing biodiversity, and altering
Invasive species can spread through a number of mediums including ships, pet trade,
wood products, and ornamental plants. These mediums are primarily made possible through
unintentional human activity. Corridors such as forest roads, trails, and creeks prove to be
excellent routes for spread of these species to new areas because they’re wide open areas that
allow for speedy travel (www.indiana.edu). There are thousands of types on invasive species
which can include, but are not limited to, Asian carp, West Nile Virus, Brown marmorated stink
bugs, and feral pigs.
- Cascade J. B. Sorte, Susan L. Williams, and Robyn A. Zerebecki 2010. Ocean warming increases threat of invasive species in a marine fouling community. Ecology 91:2198–2204. dx.doi.org/10.1890/10-0238.1
Nicholas Bax, Angela Williamson, Max Aguero, Exequiel Gonzalez, Warren Geeves. 2003. Marine invasive alien species: a threat to global biodiversity. Marine Policy 27: 313-323. doi:10.1016/S0308-597X(03)00041-1