Article: http://www.nytimes.com/2014/05/15/science/when-predators-vanish-so-does-the-ecosystem.html
Source: The New York Times
Author: Carl Zimmer
Date of Publication: May 15, 2014
An ecologist at Brown University, Mark Bertness, started studying salt marshes in New England in 1981. Now he has observed that the salt marshes are dying. In the place of lush green cordgrass is the bare ground. Salt marshes are very valuable because they shield coasts from flooding, pull pollutants from the water, and is a breeding area for many fish species. So, it is very important to find out what is causing the salt marshes to die off. Dr. Bertness has found an explanation for the decline of salt marshes. The cause is the act of fishing and crabbing. If the top predators of the salt marsh, such as striped bass and blue crabs, are repeatedly removed, then the predator population would significantly decrease. Therefore, the predator's prey species, particularly the ones that eat plants, thrive. For example, the marsh crabs eat the cordgrass of a salt marsh. If the population of the marsh crab grows, then more of the cordgrass is eaten. This causes the cordgrass to be completely wiped off . The size of the salt marsh would also decrease because the roots of the cordgrass provide as an anchor for the soil. Without the roots the salt marsh would erode, making it difficult for new plants to grow. In addition, Dr. Bertness surveyed healthy salt marshes to ones that were dying. He was able to observe that in the dying salt marshes, the there were more signs of marsh crabs eating the plants.
This topic relates to the ecosystem unit. It shows the connection of the predator and prey, and how one thing could lead to a decline of an ecosystem. It also shows that maintaining a good predator population is an important thing to keep in mind. Without any predators, the prey population would rapidly increase. In addition, there is a predator-prey relationship in this. The marsh crab is the predator because it is eating the cordgrass, which is the prey.
It seems as if there would be more than just the cordgrass holding the marsh's soil together. Were there other plants besides the cordgrass keeping the soil together, and if so, then how did they become impacted enough to cause the soil to be wasted away?
ReplyDeleteI searched for many other articles about cordgrass keeping the soil together, and it seems that cordgrass is the main plant. There may be other plants that are holding the soil together. I did not get a specific name because the article just called them "marsh plants". However, the marsh plants can be heavily impacted by oil spills. The roots of marsh plants are matted, and this literally holds and sticks the soil together. When the marsh plants die from oil spills, their roots don't function anymore. This loosens the soil dramatically. Since the soil is looser now, the water can easily erode it. This will result in a decrease of soil elevation, and soon the soil will be completely gone.
DeleteHere is the link that I used: http://www.wildflower.org/pastissues/?id=162
Since they concluded that fishing and crabbing has a large impact on these marshes, what is their next step to preserve and save the healthy marshes?
ReplyDeleteUnfortunately, after researching for quite some times, I could not find an answer to your question. However, I would think that ecologists and/or environmentalists would make an effort to decrease crabbing and fishing in salt water marshes. They might make a limit for each person. For example, the rule might be '1 fish and 1 crab for each person'. Also, environmentalists could limit the number of fishermen in the salt water marshes per day.
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