Purpose
The lab attempts to determine the effect of invasive species on the ecosystem and the implications of having invasive species being introduced into the ecosystem.
Introduction
A species can be classified as invasive in an ecosystem if it is not native to the ecosystem in question and it causes harm to the other organisms in it. An invasive species can cause damage in an ecosystem by preying on other species, competing with other native species for food and resources, or keeping other native species from reproducing in the first place. Since invasive species do not face limiting factors in the ecosystem they were introduced, they grow rapidly and can thereby introduce other problems (“Invasive Species”, n.d.).
One example of a case of invasive species is the presence of zebra and quagga mussels in the Great Lakes. They are thought to be brought by the ballast water in other places. The environment of the Great Lakes, along with the lack of environmental resistance, gives the mussels ample room to grow. They filter phytoplankton in the water, thus reducing the primary producers in the ecosystem’s food chain. Furthermore, they increase the algae Cladophora in the water, leading to an increase of birds whose droppings make the water contaminated (“Zebra and quagga mussels”, n.d.).
Hypothesis
It is hypothesized that an increase of the population of the zebra and quagga mussels will lead to the decline of phytoplankton, zooplankton, and lake trout and other fish while increasing the population of Cladophora.
Methods
A lab animation was used to determine the population of zebra and quagga mussels, phytoplankton, zooplankton, Cladophora, foraging fish, and lake trout over the course of 20 years. The results were then collected and analyzed.
Results
Discussion/Analysis
As shown in Table 1, the increase of the population of zebra and quagga mussels has led to the increase of the Cladophora population as well, along with the decrease of the plankton and fish in the ecosystem. Conversely, its decrease has also led to the decline of Cladophora while increasing the population of plankton and fish. In other words, the hypothesis stated above is correct.
It is also interesting to note that the population of mussels does not increase over time; it reached its maximum growth at year 13 and then declined. One plausible explanation is that it the factors that favor its growth were at its lowest during that time, in which mussels have to compete with other mussels for nutrition. As a result, many of their population died in the subsequent years.
References
Invasive Species. (n.d.). Retrieved from https://www.nwf.org/Wildlife/Threats-to-Wildlife/Invasive-Species.aspx
Zebra and quagga mussels. (n.d.). Retrieved from http://www.greatlakesmapping.org/great_lake_stressors/2/zebra-and-quagga-mussels
