The Effects of Overfishing has on the Coral Reef Ecosystem

By PSU EcoMerge Capstone - 2:56 PM

Coral reefs are the homes of some of the most diverse ecosystems and biologically productive habitats. One of the largest biological organisms in the world is the Great Barrier Reef. Considering that the Great Barrier Reef’s ecological system is so vulnerable that even the slightest influence by human activity can intensify the level where coral reefs are threatened globally. This activity has not only affected the coral reefs, but also the surrounding biodiversity that coexist within these systems.
The major disruptions to the food web as had a negative domino effect due to aggressive overfishing. The over exploitation of marine life has disrupted the entire stability of oceanic life due to over depletion of keystone plant and animal life.  This happens in the following ways:
·        Overfishing – reefs suffer directly and indirectly from the increasing pressure of mans’ resource exploitation. This has been a devastating impact on coral reefs. It damages many coral reefs around world, specifically to the Great Barrier Reef and has caused a shift in the reef ecosystem. This affects the ecological balance and biodiversity of the coral reef.
·        Overfishing of important herbivores has only been increasing over the past few decades. Direct overexploitation of different fishes and invertebrates by recreational, subsistence, and commercial fisheries has resulted in the rapid decline in populations.
·        Overfishing effects fish size, abundance, species composition and genotypic diversity. Also, overexploitation of marine organisms contributes to the degradation of coral reef ecosystems as a whole. (Puglise, K.A)

Effects of Overfishing on the Food Chain
·       Plant and animal species have an important role in the coral reef ecosystem, which requires certain environments, nutrients and dependency on other organisms, which is crucial for their survival.
·         Food chain organization.
o   Producers, which are photosynthetic organisms.
o   Zooxanthellae – plant like organisms that photosynthesis for the reef.
o   Producers are eaten by consumers, which are either herbivores or carnivores.
·        Fishing for a particular species affects that species directly, but it also affects the animals and/or plants in both directions along the food chain - the predators and the prey of the fish will both be affected, and changes to them will also affect their predators and prey, and so on.
·        Overfishing of grouper in some cases has led to an increase of damselfish, which is a major food supply for the Grouper fish. Damselfish help create pockets in corals that are important for coral reef life.
·        If the damselfish population isn’t controlled by natural predation, these algae can take over a reef, eventually killing it. Overfishing of other herbivorous fishes can also lead to high levels of algal growth in different cases.
Impacts of Overfishing
·        Destructive fishing techniques can have direct physical impacts on reef environments or create a deceit of certain species in the ecosystem.
·         Unauthorized fishing causes further destruction to coral reefs.
·         The vulnerability of coral-reef species is partly because of their life-history adaptations to uncertainty in survival of recruits and juveniles in diverse communities where predation and competition are intense. With low rates of survival of recruits, multiple attempts at reproduction are favored through longevity and large size. These traits lead to low rates of population turnover and special vulnerability to overfishing.
·        Overfishing can devastate the marine ecology of the coral reef. Since certain amounts of nutrients, oxygen and salt content the fishes in the coral reef ecosystem help maintain the balance needed by the corals, without these fishes the coral reef will collapse.

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