Monday, September 24, 2012

Oyster Shell Recycling Taking Off

Benefits of Oyster Shell

Oyster shell on the ocean floor provides a host of benefits. The first is as a shelter. It's nooks and crannies provide shelter for up to 100 other species, and many of the commercially harvested fish and sport fish species spend a portion of their life in coastal waters. When small they hide from the larger predators. In our oysters, we have seen shrimp, crabs, pogeys, eels,lobsters and a myriad of other creatures.

The second is as a scaffold for live oysters to grow on. Young oysters float in the water and then settle into the post where they will spend their lives filtering. They prefer to settle on calcium containing substances such as oyster shell. If there is not appropriate substrate to attach to the spat can die without a suitable location to anchor. 

The third is in maintaining the acid-base balance of the sea. Mark Green,of St. Joseph's College of Maine has studied this issue extensively. He was the first scientist to prove tiny juvenile clams were dying primarily because their shells were dissolving in less alkaline conditions. Now, the National Science Foundation has honored his pioneering contributions by awarding the marine science professor a third grant to continue his research related to the adverse effects of ocean acidification on clams.Interestingly, he has had good results reversing these effects using oyster shell. 

Mark Green

MOP and Oyster Shell Recycling

As part of our oyster restoration activity the oyster project has begun recycling used oyster shell. We have used it as a substrate for spat-on-shell placements and provided it to restoration programs such as that in Wellfleet. With a growing base of experience, we have now moved beyond accepting it from The B&G Oyster Invitational and our own events (shell will be recycled at the Mayflower event on October 7) to accepting it from fine establishments such as the Langham Hotel and the Boston Seafood Festival on October 6.

Where did the oyster shell go?

The estuaries of Massachusetts and the Eastern Seaboard once contained enormous amounts of shell. The reefs in the Charles and Neponset Rivers were once so large as to be a hazard to ships navigation. But today it is almost devoid of it.

Oyster shell was often lifted from the bottom as by-catch when oysters were dredged. It was then used for a variety of purposes, such as mortar for buildings including the old Massachusetts State House, fill for roads and sidewalks, or even spread on fields to offset soil acidity. 

old Statehouse with oyster shell mortar
Massachusetts Old State House
Unfortunately, most oysters today are grown commercially with minimal shell cultch so many oyster farms are not adding to the mass of oyster shell in the water. And oyster shell recycling is not an easy endeavor. If you are interested in learning more, or starting a program- you can click here, which will take you to the presentation below if it does not display well.

As far as other programs go North Carolina has a terrific shell recycling program. They have restored multiple reefs and are moving shell by the tractor trailer load.

oyster shell recycling for oyster restoration in NC
Volunteers build an oyster reef sill. Photo courtesy of NC Coastal Federation.

1 comment:

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