The word “oyster” is a nickname for several different, extremely diverse family of marine bivalve molls that live both in fresh water and saltwater habitats worldwide. In certain species, the orogens are highly calcified, while others are less so. Most, if not all, oysters belong to the class Ostreoidea, though not all oysters that are found today are still reproducing within their own species.
Oryzanthos, or “oysters” (Greek word for “stone”) actually belong to the Bacteria class. Within the phylum Clostridiala, this group contains several species of tiny marine sponges that often infect other organisms with the disease that can kill an ocean-wide population of shrimp, clams, or other forms of marine life. These parasites in turn infect other oysters, which create a feedback cycle that destroys coastal ecosystems by reducing the productivity of oyster reefs. The death of these reefs also reduces the nutrient cycling environment inside the oyster shellfish itself, thereby increasing the acidity and alkalinity of its surrounding environment.
The destruction wrought by the crabs is caused by their attempt to increase the total number of shells they possess in their oyster bays. This means that they disturb the existing shell ecology by removing the existing shell structures as well as the supply of food inside those shells and thus significantly impacting the concentration of dissolved organic and inorganic compounds (NOCs) in those waters. These chemical compounds are essential for the ecosystem’s health, since they form a base from which NOCs can travel into and out of the shell.
If these chemicals were to enter into the bays directly, they would compete directly with the life inside the oyster reef. Destroying the natural organic condition of the bay through something as drastic as an overpopulation of oysters would be catastrophic. In turn, the reduction in productivity of the bay itself would dramatically decrease the shellfish population as well, since something has to give in order to maintain the ecosystem. However, this is exactly what happens when the oyster reef bay is disturbed by human activities.
Overharving, or over-exploiting, of a species occurs when humans remove the natural environment of a marine organism in order to better exploit it for human consumption. While oysters do not usually suffer at the hands of humans, they are often affected. The first, and most obvious, effect of overharvesting is death of the existing population of oysters. This is commonly referred to as “PCB death” in scientific literature. Unfortunately, while the primary cause of this is a loss of ocean productivity, another more insidious cause is the introduction of toxic chemical ants into the oyster shell beds.
One of the most common, and most dramatic, results of overcharging is what is called the “bleaching out of the oyster beds.” This refers to the gradual destruction of the oyster shells, which forms a thin white film on the inside of the oyster shell. This white film gradually develops over time until there is nothing left but a scar tissue and the ghost of an oyster. As with the other effects of overharvesting, this process is most likely to occur during the early stages of operations, when it is less feasible for operators to carefully remove the shells from the oyster beds.
A less obvious effect of overharvesting is what is sometimes referred to as the “ecological dead zone.” The dead zone is an area that has diminished and depleted the oxygen content of an ocean floor. A major source of confusion regarding this phenomenon is the use of the word “dead” itself. The dead zone is an oxygen enriched and polluted water mass, often including dead jellyfish and aborigines.
Although all three of these effects of overharvesting may be negative in terms of the future health of the marine ecosystem, collectively they will have a relatively minor impact. The future impact of Pacific oyster farming, however, is likely to be far more severe than either of the previous effects. The bottom line is that the continued harvesting of Pacific oyster beds will deplete the ocean of oxygen and threaten the sustainability of future eco-systems. In addition to the threat posed by overfishing, this type of activity adds to the problem of overpopulation of the wild population of Pacific oysters, which already exists in very low numbers.