|New Jersey Division of Fish, Game and Wildlife|
For more information contact:
Bill Figley at 609-748-2020
Preliminary results from a recent artificial reef colonization study conducted by the Department of Environmental Protection's Division of Fish, Game and Wildlife indicate that New Jersey's reefs have hundreds of times more marine life than areas of sea floor with no reefs. The study was conducted to determine the types and amounts of marine life that colonize ocean reefs and to compare that information with what is normally found on the sandy sea floor.
The study began two years ago when 30 experimental reef habitats were placed on the Barnegat Light Artificial Reef Site. Each habitat consisted of a 3' x 1' square plastic coated wire box embedded in a concrete base. The boxes were filled with a variety of materials to imitate the hiding places found on reefs and to duplicate common reef building materials. Each box contained 10 corrugated fiberglass panels, 40 whelk (large snail) shells and two 6-inch diameter plates each of four different materials -- steel, concrete, rock and tire rubber.
Part of the study focused on comparing the biomass on reefs with that found on the sandy sea floor. Biomass is a biologist's measure of the weight of all the organisms living in a particular habitat. In this study, biomass referred to the weight of all marine life inhabiting a square foot of sea floor.
More than 99-percent of New Jersey's sea floor consists of sand. Since sand is constantly shifting and does not provide a foothold for marine life, the biomass of sand bottom is low. Sand bottom life includes burrowing animals such as surf clams, snails, crabs and sand worms.
The first experimental reef habitat was raised from the sea floor in October of 1998. After spending two years on the sea floor, it was retrieved by scuba divers from the U.S. Environmental Protection Agency. Division biologists then spent the next three months in a lab removing, sorting, counting, identifying and weighing the marine life living within the experimental habitat. The results were impressive. In just two years, the habitat was colonized by 39,938 marine animals, including 25,000 blue mussels, 8,500 barnacles, 2,000 snails, 1,300 worms, 350 crabs, 12 fish, 2 lobsters and much more. The total biomass (weight) of these organisms amounted to 9.5 pounds.
In another phase of the study, 60 square-foot samples were taken with a scientific sampling dredge on the sandy sea floor around the Cape May Artificial Reef. Marine organisms were separated from the sand using sieves. The biological samples were then analyzed by the Center for Coastal and Marine Studies at Rutgers University. These samples yielded an average of 58 marine organisms with a biomass of .2 ounces per square foot of sea floor. In comparison, the reef habitat had 689 times the number of organisms and 760 times more biomass than the same area of sandy sea floor. The increased biomass of the reef habitat is significant because it represents a far greater food source for marine life and a greater number of food and game species (fish, lobster, crabs, mussels) available to anglers.
New Jersey reefs are colonized entirely by marine animals. The depths (generally over 60 feet) on reef sites are too great for the penetration of sufficient light to sustain plant growth. Instead of plants, the basic level of the reef food web consists of many species of filter feeding animals that live attached to reef structures and feed by straining the plankton that is carried past them by ocean currents. The filter feeders (i.e., mussels, barnacles, tubeworms and others) are in turn eaten by fish, crabs and lobsters. The stationary filter feeders also serve another function on the reef by providing a carpet of cover or hiding place for small mobile invertebrates such as shrimp, snails and worms. These animals too, may end up as food for larger predators.
The goal of building reefs, which provide firm, stable substrate for the attachment of marine organisms, is to enhance the biological productivity of the sea floor. Based on the preliminary results of this study, building reefs does enhance New Jersey's marine environment. As an extension of this research, the survey will be continued in future years to determine how the species and biomass of reef communities change over time.