The primary focus of this experiment was to

The primary focus of this experiment was
to observe the cause of marshes dying off. This could be seen from shifts on
the dense grass in the marsh to the unvegetated mud flats in the marsh. In the
experiment, the top-down and bottom-up effects were monitored to investigate
the cause of shift or die-off. This experiment is significant because it would be
considered the first experiment to explain the die off factors that are caused
by top-down and bottom-up control instead of physical factors. There were cage
treatments implemented across the marsh to see if the hypothesis that
questioned whether or not top predators would affect marsh productivity through
regulating herbivores was accurate. The cages did not allow entry from top
predators but did allow herbivores to go in and out. This was a way for the
author to see total effects on predator exclusion. Based on the results, it was
observed that the unvegetated space in the cage treatments went up by over 150%
when compared to the control treatments within one growing season. Due to the
results, the author concluded that top predators do control the marsh productivity
by predation on the herbivore. The top predators have a positive impact on
productivity so when the Sesarma reticulatum are freed from predation, the
marshes will die off in a matter of time.

The paper can be considered a reliable
source of information because the methods involved in this experiment were
deliberate. Every factor that could possibly alter or affect the results were
accounted and measured for. An example would be the physical factors of
nitrogen composition and wave exposure, which were tested to see their effects.

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The data showed that eutrophication and wave exposure were not effect
experienced in this marsh, the authors results that revolved around the top
down controls affecting die off were reinforced. This study is applicable to
ecology since it is the first published experiment to provide evidence that
trophic cascade control is responsible for die-off. Based on the results, they
disproved the thought that physical factors determined the die-off present in
the marshes. The paper is overall written in a concise manner because there are
points stated and explained thoroughly without leaving the reader confused. The
figures and photos provided in the paper also allow the reader to attain an
understanding on the concept, which expand the effectiveness of the paper. The
results are what make this paper strong since the results prove that the
hypothesis is accurate by stating how herbivory increased by more than 100%,
the biomass of the grass declined by more than 60%, stating how disturbances
from herbivory on the marsh increased by more than 95%, and how the unvegetated
space went up by more than 150%. Overall, the results provided in this paper
show that marsh die off has an important relationship with the rejection of top

Even though this paper is strong, there
are also weak parts to it that can be adjusted accordingly. At one point in the
paper, the author states that marsh recovering from die off resulted from the
marsh where treatments were placed. This could have affected the results in the
experiment because it was not an entirely recovered area. It would’ve been
better to look at the die-off in a marsh that was not affected by die-off to
grasp an idea that die-off would’ve took place just as rapidly in marshes that
are pristine. There could have been more experiments on other marshes to set
right this predicament but it would be a strenuous experiment to duplicate a
marsh that is different compared to the one that was used by the author. Both
the methods and cage systems in this experiment were calculated for the marsh
that was used so it wouldn’t be easy to copy anywhere else. Other than that,
these weaknesses don’t take away the significance of this experiment and the
conclusions about marsh die off being impacted by trophic cascade.