Over just this past year, Mordecai Island has seen more activity and undergone more changes than it has in decades. Watch this video for more info.
The mission of the Mordecai Land Trust (MLT) is to protect the ecologically valuable flora and fauna species on Mordecai Island. This includes stopping shoreline loss due to erosion from wind and nearby boat wakes. The southeastern corner has been most vulnerable due to fetch and its closeness to intracoastal vessel wakes.
Conventional technologies using coir fiber biologs were first tried. Their rigid anchoring system failed due to the poor soil conditions and destructive wave vibrations from the bay. Undeterred, the MLT tried again and succeeded in 2010 with a breakwater using polypropylene geotextile tubes filled with 1000 tons of sand. Integral with their permit, the MLT is responsible for the maintenance of the breakwater, what the Army Corps of Engineers refers to as “maintenance of a legally permitted structure”. The tubes attenuate wave forces and accrete sand and sediment behind them, in time building the island section back to its 1977 tidal boundaries. The ideal maintenance program is to let Mother Nature heal itself. It is not only cost effective; it is one of the guiding concepts in the design of Living Shorelines.
Protecting the tubes with a colony of living organisms that can withstand the forces of nature and boating damage and which can heal itself is insurance against costly repairs. Doing it with a natural covering of shellfish and marine biota that grows with sea level rise addresses the spirit and goals of sustainability. This is the definition of a Living Breakwater. It is New Jersey’s relative to a tropical reef which performs many beneficial functions, not the least of which is attenuating the force of waves. It’s nature’s resilient way of protecting an adjacent beach from erosion. A Living Breakwater is an integral component of a Living Shoreline.
A combination of oysters and ribbed mussels native to Barnegat Bay has been selected as a first choice cost effective solution. Oysters grow to a finite elevation based on climatic conditions. However ribbed mussels grow higher than oysters due to their unique air-gaping capability when the tide recedes. They even grow on top of the tidal salt marsh. For our purposes in protecting the geotubes we intend to ultimately use the oysters as a subtidal foundation and grow ribbed mussels on top of them to their maximum height.
The challenge is that although ribbed mussels have been protecting marshlands from erosion for eons, they have never been farmed by man to do this. For the past three years the MLT, and our partners at ReClam the Bay have been experimenting with oysters and ribbed mussels at our local upwellers and at the geotubes. We have been evaluating the performance of live individual oysters, bagged oyster shells, and bagged oyster spat on shells at various locations around the geotubes and anchor tubes. We also harvested individual ribbed mussels and have been observing their attachment capabilities with substrates.
Transplanting ribbed mussels from existing colonies in the volumes required to cover 600 feet of geotube surface is impractical from ecological and material handling standpoints. Therefore our research is directed toward developing lab spawning and remote setting techniques.
This spring and summer we plan to continue evaluating ribbed mussels and oysters for suitability as a structural component of our Living Breakwater project. We expect to carry out these pilot tests at the Long Beach Island Foundation (LBIF) laboratory facilities, the adjacent LBIF tidal salt marshes, the various ReClam the Bay (RCTB) upwellers, and at strategic points on the geotubes themselves.
This year our ribbed mussels will come in two forms: clumps and eyed larvae. The clumps can be found nearby. Initially, clumps will be relayed and installed in upweller tanks or test facilities for study. Data on elevation growth, survivability, substrate adaptability, attachment strength, spawning compatibility, etc. are some of the basic data we’ll seek. Before they can be relayed, we will survey their location and determine timing and methods of relaying, transporting, storing and nurturing them. Tides and weather dictate scheduling this work. A timetable would span thru the summer months.
Much of the testing program schedule will be dependent on temperature and spawning times. Ribbed mussel larvae will be available from the Rutgers Aquaculture Innovation Center in late June/ early August. Ideal larval temperature is around 28 degrees Celsius which could complicate timing. Since bagged shell will be used as a foundation for the ribbed mussels, they will be installed at the tubes beforehand. Alternately, various substrate materials will be evaluated in the upwellers at the Coast Guard Station and Little Egg Harbor Yacht Club.
One expeditious approach has always been to attach the bivalve colonies onto the geotube surface itself. We initially tried this with oysters and failed. However the attachment mechanisms that oysters and ribbed mussels have are completely different. Ribbed mussels attach to oyster and clam shell with byssal threads. We would repeat testing multiple substrates in the upwellers as in the past, or the Foundation lab. If spat setting was successful, we’d continue with pilot testing on the tubes.
I’m happy to say that we’ve recently succeeded in attaching ribbed mussel seed to oyster and ribbed mussel shell as well as geotube material in our upwellers. Now we hope to grow them to maturity and test their byssal strength in our lab during the coming months.
Over the past 5 years an intertidal land bridge has been established between the tubes and island. We intend to plant clumps of ribbed mussels and Spartina together to prove the symbiotic relationship between the two species cited in the literature. The desired goal is that sediment would accrete faster and speed up island growth toward the tubes.
Mordecai Land Trust
August 22, 2016
We’re constantly bombarded by new terms. In the environmental field, concepts are given abstract names that are redefined daily depending on the view of the beholder. Sustainability is such a term used today to embrace our desire to maintain our environment for the future. Or as the definition goes “Sustainability is the ability to continue a defined behavior indefinitely.”
However, the definition of sustainability on Mordecai Island falls short in light of rising sea level rise. Our islands in Barnegat Bay are growing at a rate slightly lower than sea level rise. It follows that sustainability on Mordecai Island must go beyond maintaining status quo.
Our projects partner with Mother Nature in order to protect the island from man and sea level rise through leverage. Leverage happens when two or more activities synergize to create growth beyond the norm. It is well known that symbiotic relationships exist between species on our island. Our job is to nudge these relationships along.
Ribbed Mussels and Spartina Alterniflora – Ribbed mussels feast on Spartina detritus and Spartina feast on ribbed mussel feces. Both grow the saltmarsh.
Eelgrass and Bay Scallops – eelgrass is the favorite setting for scallop larvae. Eelgrass is a keystone species in Barnegat Bay.
Eelgrass and Black Skimmers – Eelgrass seeds are a favorite food for Black Skimmers.
Diamondback Terrapins and Periwinkles – Our geotubes have created a home for large masses of periwinkles. We recently established diamondback terrapin nests on the island. Periwinkles are one of their favorite foods.
Oysters and Ribbed Mussels – Both are filter feeders gobbling up eutrophicating nutrients and other suspended particulates from our bay waters. Oysters grow in the subtidal waters and form the foundation for ribbed mussels which grow at higher elevations. Together they form a living breakwater, attenuating wave forces to prevent shoreline erosion.
Beneficial use of dredged material – hurricane sandy caused shoaling in the Intracoastal Waterway adjacent to the island and needed dredging. Many years ago the island was cut in two by a storm. This cut was filled with this material and has since been planted with species native to the island.
These are examples of “synergistic sustainability projects” where the interactions of two activities cause additional positive long term results.
Jim Dugan 8/19/2016
What a difference a year makes. Last year at this time we were about to embark on a Capital Campaign to raise an additional $200,000 toward our local cost share for the Mordecai Island Coastal Wetlands Restoration Project (“Breakwater Project”). The contributions to the Capital Campaign had a terrific response. Our fundraisers were made possible by the support of an army of dedicated volunteers and the community at large. Last summer was the summer of Mordecai.
By April of this year, the NJDEP and MLT had both signed off on the form of the Continue reading NORTH END LIVING SHORELINE CLOSER TO REALITY
The Southwestern Mordecai Environmental Restoration II project incorporated the installation of 560 feet of geotubes filled with sand to act as a breakwater in the effort to protect the adjacent Mordecai island shoreline from further wave erosion. A secondary goal has been to allow accretion of material behind the tubes in order to rebuild that section of the island to its 1977 dimensions. To date, the geotubes are performing up to expectations with little or no maintenance required. Their intertidal surfaces are covered with a healthy growth of bladderwrack seaweed and barnacles with accompanying
periwinkles and small forage fish. In a way, a living breakwater already exists here, protecting the island, but not itself.
The geotubes are made of a heavy weave of polypropylene designed for many years of service. In marine environments they are often covered with sand or other materials to protect them from damage or wear from foreign objects, including boats and Continue reading OYSTER LIVING BREAKWATER PROJECT GOAL IS LIFE BEYOND GEOTUBES
Oyster spat will be growing in a new upweller this summer on Norwood Avenue in Beach Haven, thanks to the efforts of Mike Davis, past MLT president, and MLT member Wes Heilman.
A ReClam the Bay upweller will give us the opportunity to raise oysters from spat to a size where they can be placed around Mordecai Island in bags that will begin to create a natural reef. Why oysters rather than clams? Oysters filter far more water than clams and they do Continue reading NEW OYSTER UPWELLER FOR MORDECAI