Importance of an oyster

IndiaVisionExclusive - Every time you buy a pearl, you have killed an oyster. Every time you eat an oyster you will have contributed to the destruction of the ocean.

The word oyster is a common name for a number of groups of bivalve molluscs which live in marine or brackish habitats. Some oysters are eaten, cooked or raw, by humans. Others are made to produce pearls from their own skin and then torn apart when the pearl is extracted.

Six species of oysters, namely the Indian backwater oyster Crassostrea madrasensis, Chinese oyster C. rivularis, West coast oyster C. gryphoides, Indian rock oyster, Saccostrea cucullata, Bombay Oyster, S. cucullata, and giant oyster Hyostissa hyotis are found in India. 

The Indian backwater oyster C. madrasensis is the dominant species, and inhabits backwaters, creeks, bays and lagoons and occurs in the coastal areas of Orissa, Andhra Pradesh, Tamil Nadu, Kerala, Karnataka and Andamans. C.gryphoides  occurs along north Karnataka, Goa and Maharashtra coast. C. rivularis is found along Gujarat and Maharashtra coast while Saccostrea cucullatais found all along the main land coast and Andamans and Lakshadweep islands. Pictada fucata (another important pearl oyster) varies , is abundant in some years and missing in others.

Oysters are harvested by simply gathering them from their beds. Fortunately oysters are still not a very popular food item in India (except in some coastal communities) or they would have been extinct ages ago. But they are exploited hugely for pearls and nacre (mother of pearl, the substance that lines the shell from inside).

Now, government wants to increase oyster extraction.

Oyster fishermen take thousands of oysters from the ocean everyday. Even if they didn’t , 50 % of oysters die of disease, water temperature changes, rejection of the foreign body that has been inserted into it .

Oysters should not be exploited at all. We are just creating our own doom.

Scientists have found they are a keystone species - which means they have a critically large effect on their environment. Such species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community. An ecosystem, like a part of the ocean, may experience a dramatic shift if a keystone species is removed, even though that species was a small part of it.

What is the importance of an oyster? An oyster reef can more than double the surface area of a flat bottom.

The hard surfaces of oyster shells and the nooks between the shells provide places where a variety of small creatures can live. Hundreds of animals such as sea anemones, barnacles, and hooked mussels inhabit oyster reefs. Many of these animals are prey to larger animals, and fish.
 
Oysters consume nitrogen-containing compounds (nitrates and ammonia), removing them from the water. Nitrogen compounds are important phytoplankton nutrients. Phytoplankton increase water turbidity or fogginess and lessen the amount of oxygen in the water. Limiting the amount of phytoplankton in the water improves water quality and other marine life by reducing competition for dissolved oxygen.

A larger oyster population effectively filters more water in the estuaries.  The improvements in water quality leads to more sea grass growth (which cannot grow in cloudy waters as there is not enough sunlight) and this becomes the habitat for a fish nursery.

Oyster reefs along with mangrove and other plantings are effective shoreline stabilizers, helping to combat erosion.

Isn’t that far more important than wearing pearls?

In India, with the increase in commercialisation, there is a definite possibility that the oyster populations will hit an all-time low. This is disastrous and not just for the oyster industry. Oysters provide the underwater equivalent of condominiums for small creatures like minnows and worms that love the protection offered by the hard oyster shells. Those are some pretty important tasks for such a tiny bivalve. However the most important function oysters perform in the bay, without a doubt, is that they clean the water. In a way, oysters are like small water purification plants, ridding their marine habitats of harmful chemicals and toxins. With the oysters almost gone, the bay suffers from the loss of all these important environmental functions. The more changes that occur in the bay the more unlikely it becomes that even given the chance the oysters will be able to make a comeback. As the health of the bay goes down, the remaining oyster population weakens with it, eventually becoming unable to fight off things like infection and disease.

Once the oysters in the seas around us are over exploited – which they are now in danger of - we will lose all the fish as well; and then the land.  Let us learn a lesson from the disaster of America’s Chesapeake Bay.

Oysters were once so plentiful on the Eastern Shore that it seemed the supply would never run out. The peak of the harvest came in 1880 and millions of oysters kept being taken out. Overharvesting took its toll and the numbers started declining drastically. People still took no notice. MSX and Dermo, two highly fatal oyster diseases, showed up in the Chesapeake and did a great deal of damage to the already diminished stock of oysters, decimating the population . 

Efforts were made to restore the balance. Rules were made to protect oysters. All mechanized fishing boats were stopped from dredging and no oyster gathering was allowed in months which had an ‘R’ in them (the mating months). Wild oysters were brought in to repopulate the disease-free parts of the bay bottom. They brought more disease in. An initiative that should have helped repopulate a dwindling oyster colony only served to spread the disease to new areas. All these attempts came too little too late.

Do we want to reach this point? We could reach there within five years. All this to hang a dead scab round your neck or to eat raw so that you can prove you are sophisticated enough to eat the rubbish gatherers of the ocean.