"Can newly fertilized oyster eggs be reared to successfully metamorphose in New York Harbor water by New York High School students?" That’s been the question at the heart of Pete Malinowski’s work with Harbor School students over the past seven years.
The answer, as he reported to the Harbor community this past Friday, is yes.
His report follows:
One way to find out.
In 2007, when Murray and I first met and started talking about growing oysters at Harbor School, he asked me if I thought it was possible to run an oyster hatchery on Governors Island. I told him I didn’t know if the water quality would allow it but there was only one way to find out.
Generally speaking, when siting an oyster hatchery, the number one concern is water quality. Bivalve larvae are extremely sensitive to impurities or toxins in the water and will not develop normally if they are present (the younger the oyster the more sensitive it is to water quality). The best indicator that water quality is acceptable in an area is the presence of a robust oyster population. Absent that, there should be solid evidence that the site is free from pollution sources, heavy boat traffic and industrialization.
They grew like popcorn.
Knowing that we did not have an ideal site we decided to run some tests. In 2009, we installed a floating upweller system right in front of the current MAST center and stocked that with 100,000 2mm oyster seed. While these were 8 times the size of oysters at their final larval stage and 50 times the size of fertilized eggs they are still a decent bio-indicator.
They grew like popcorn, doubling in size each week.
Next, in 2010 we built a remote setting system on Lima pier on the south end of the island to see if 3-week old larvae could survive and successfully metamorphose in East River water. They did, and we spent a couple of years happily importing millions of oyster larvae and building up our numbers in the water and on our reefs.
The ultimate question…
With the MAST center we finally have New York Harbor in our classroom and can begin answering the ultimate question: Can newly fertilized oyster eggs be reared to successfully metamorphose in New York Harbor water by New York high School students? A few weeks ago, we spawned our oysters and stocked our tanks with 11 million fertilized eggs. If everything had gone perfectly we could have expected to get about 250,000 set oysters out of that group.
Gradually, over two weeks they were culled down to about 200,000 growing larvae. A subset of these were retained on a 200 micron screen (indicating that they are large enough to metamorphose) and placed in a 5-gallon bucket with some oyster shells as substrate.
Then the power went out for 30 hours or so.
This cut off aeration and heat to our tanks. I was sure that all the oysters would be dead on Wednesday when we came in. We lost the remaining smaller larvae but our bucket yielded surprising results.
What we are trying to do is actually possible.
2,873 oysters attached to the shells, rearranged their internal organs and began to build their own shells. It’s not the 250,00 we were hoping for from that group, and it’s a far cry from the billion we hope to produce, but it is the best indicator so far that what we are trying to do is actually possible. The following students conducted the spawn and were responsible for almost all the care that went into these tiny little guys. Please give them your congratulations.