Ecosystems on the Brink
- Many of the predators that were once dominant in Peter Lake were eaten by largemouth bass
- The remaining of the few survivors hid in the shallows
- Water fleas and other tiny animals that the small fish once devoured were now free to flourish
- The grazing of algae by diminutive animals led to the result of the lake water becoming more clearer
- The dramatic alterations of Peter Lake's food web was an experiment designed on purpose to look at how those factors made persistent changes to the mix of organisms eating and being eaten by one another
- In recent decades, food webs across the globe have also been flipping out, often unexpectedly, on far greater scales
- Whether by fishing, converting land into farms and cities, or warming the planet, humanity is putting tremendous stresses on the world's ecosystems
- Models were developed to enable scientists to pick up early-warning signs of any incoming changes to the ecosystems
- This helped the scientists to have the ability to decipher some of the rules that determine whether a food web will remain stable or cross a threshold and change substantially
- Ideally, these early-warning systems would alert us when to alter human activities that are pushing an ecosystem towards breakdown or even allow us to pull ecosystems back from the brink
- Ecologists turned food webs into mathematical models
- Most food webs consist of many weak links rather than a few strong ones
- Two species are strongly linked if they interact a lot, such as a predator that consistently devours huge numbers of a single prey
- Food webs may be dominated by numerous weak links because that arrangement is more stable over the long term
- Weak links may keep species from driving one another to extinction
- In the ocean, we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves
- We introduced invasive species such as rats to islands and gave a variety of other shocks to the world's ecosystem
- The results of these actions vindicated the key role of predators and the cascading effects they can have from the top of a food web on down
- Ecologists realized that changes in certain predators had massive impacts on food webs
- Returning a food web to its original state is hard
- Climate Change is also altering food webs, in some cases by shifting the ranges of predators and their prey
- Some scientists say that preventing food webs from switching is a more effective strategy than trying to restore ones that have flipped
Ecologist Stephen Carpenter and a group of scientists ran an experiment on Peter Lake in which they brought themselves there with invasive species that were largemouth bass. This was done on purpose to see the differences in the lake in reference to how interference to the ecosystems can cause an outbreak of collapsing food webs and affecting the species that inhabit. When these organisms were set in the lake, changes have begun to spark substantially as to water fleas and other tiny animals that was once devoured, are now free from harm. In addition, the grazing of algae by these little ones made a positive impact to the lake by the water becoming clearer. By the removal of the top predator, many species that were associated to this can now venture off freely. It also illustrates that even one variable of the ecosystem taken away can lead to dramatic outcomes and sometimes it can be very worse like the overfishing of cods. Therefore, scientists created models such as the early-warning system to help them in the search for particular signs of changes in an ecosystem and being prepared to keep it from flipping. When an ecosystem's food web is damaged, it is difficult to reverse it back to its original state.
Seeing how the disappearance of the top predator can bring massive impacts to the food web was compelling. Sometimes the changes can be either positive or negative. In this study, the change was rather a positive one as how it provided the organisms that were once being the prey for predators are now released to be able to go wherever. However in the case of the cods, it was a negative cause. Overfishing and the equipment of advanced technology overriden the territory of these delicate species and the environment that contains them are no longer stable. Similarly, in today's society, where many human activities like fishing, converting land into farms and cities, and pollution that is altering our climate, hence affecting many species at large scales, which then will also hurt us as well. Producing better ways for our activities is a step that we can make to aid and prevent further catastrophes and paving the way for a brighter future where our environments are greatly intact.