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September - October 2018
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boatingonthehudson.com
Report of Nature Conservancy Billion
Oyster Project, (For those folks really
wanting to study Billion Oyster Project here
is a perfect place to start!)
DESIGNING FOR DEEP WATERS
Different reef projects require different materials. For the
Hudson reefs system, it was important to consider the
fact that these waters are deep and fast moving. Pictured
below, the steel gabion structures provide a strong, current-
resistant 3D environment that facilities reefing. Since this
project is geared toward wild oysters already in the water,
note that shells are empty and will provide homes for wild
oyster babies (larvae).
PHASE 1
The original gabion deployed in 2015 was designed
by Pete Malinowski, New York Harbor School Ocean
Engineering instructor Rick Lee, and Harbor School student
Marisol, and constructed by Harbor School Marine Systems
Technology instructor Clarke Dennis. While the structure
effectively prevented oysters from sinking into the mud (a
common cause of mortality in murky waters), we found that
it could be improved to serve more oysters per foot.
PHASE 2
During the summer of 2017, the Billion Oyster Project
initiated a re-design of the reef gabions, with the goal of
providing more space on the structure where larvae could
set and grow. Ocean Engineering and Marine Systems
Technology students from New York Harbor School
collaborated with Billion Oyster Project to consider various
configurations of materials and submit a proposal to the
Thruway Authority.
The main modifications were:
• A hollow column was added to the middle of the structure,
maximizing surface area available to oysters and other
animals. This is important for three reasons: (1) Oysters will
grow on all available outer surfaces (2) We have seen that
baby oysters (larvae) swim only 4–5 inches into shells as
they’re seeking a shell to attach to (3) One of the profound
benefits of reefs is the 3D habitat that they create. More
surface area means more habitats for oysters and for other
marine species.
• A full-unit steel mesh enclosure replaces eight inner
cubes, which were held in place with zip ties that sometimes
came loose and shifted. Note that the mesh (galvanized
steel) holds the shells in, and outer (raw) steel is for stability
and ease of lifting and moving the structures.
• The original design used a PVC-coated wire mesh insert.
Within three years time, the oysters had reefed up around
this material, growing right through the 1” x 1” openings.
In an attempt to reduce the amount of unnatural materials
added to NY Harbor, we proposed a switch to uncoated
steel mesh, which over several years will break down
without adding pollutants to the water. (And in the long run,
the oysters will cement together and the mesh will no longer
be needed to maintain the structure of the reef.)
River Project
Photo Huge
Oyster