An Update, written by Ron Zweig, member of the Falmouth Water Quality Management Committee:
The Town of Falmouth is committed to cleaning up the nitrogen from Little Pond, using a variety of decentralized methods such as oyster aquaculture, in addition to the planned sewering of the Little Pond lower watershed. This Shellfish Aquaculture Demonstration Project started in 2013 and is expected to span at least three years.
SHELLFISH FROM LITTLE POND ARE NOT SAFE TO EAT!
The town is implementing the project in a two-acre area of Little Pond in the vicinity of Narragansett Street. The Affsa and Shea families, abutters to the pond at the west end of the street, agreed to allow access across their properties to the pond. There, all Little Pond neighbors and the many volunteers’ ongoing support has contributed enormously to the success of project implementation.
The street is being used for short periods to prepare the equipment and materials for the project. A small boat is moored at the end of the street to service the aquaculture activity during the growing season.
Oysters were selected because they are highly efficient filter feeders. Oysters eat the microbes (plankton or microscopic plant cells) growing on the dissolved nitrogen and other nutrients in the water. Because there is too much nitrogen entering Little Pond, there is too much plankton. The nitrogen reached these excessive levels mainly from septic system effluent that enters groundwater and constantly moves into the pond. Nitrogen also enters the pond from Little Pond Stream, precipitation and surface runoff.
The plankton proliferates because of the high concentration of nitrogen in the pond. These microbes then die and decompose – causing odors, cloudiness and, in some instances, fish kills. By feeding on the plankton, oysters manage the plankton concentration that continues to regenerate and grow on dissolved nutrients. In this way, oysters improve water quality.
For 2013, two batches of 1.25 million juvenile oysters each for a total of 2.5 million are being grown in Little Pond. . The first batch was put in an upweller in Falmouth Harbor in June. By July, they grew to a size suitable and were transferred to floating nursery bags in Little Pond in July. The other batch was put in upwellers in July and is awaiting standard pathogen test results from the state before being transferred to Little Pond. As growth in the nursery bags reaches a large enough size, they are transferred to larger mesh bags for growout also in Little Pond. The larger seed from both batches will be transferred to other estuaries in Falmouth for clean-out, further growth and recreational and commercial harvest in 2014. The remainder will be overwintered by submerging them in Little Pond for further growth there in 2014. Oyster growing in 2014 and 2015 will also use the late batches of oysters overwintered from the previous year, supplemented by a single batch of early seed each year.
A water quality monitoring program is complementing the aquaculture activity to determine water quality changes in Little Pond. Water samples are being taken twice monthly; and, during July and August, two continuous monitoring buoys collected data for some factors in the pond. The purpose is to develop an estimate of the amount of nitrogen that can be removed from the water through plankton consumption and incorporation into oyster growth. In addition, oyster aquaculture has also been found to remove nitrogen through microbial activities in the oyster wastes that settle to the bottom and burial of some of that material. Since the main water quality problem manifests only during the warmer months of the year, preliminary analyses and estimates indicate that shellfish aquaculture might have the potential to manage and resolve the water quality issues facing Little Pond. Secondary, longer term goals of this project are to open Little Pond to recreational and commercial shellfishing and to restore historical eelgrass habitats. The project has included periodic public information sessions to seek input, particularly from residents in the Little Pond area, during the design, set-up and production stages. It is anticipated that the project design will be modified as information becomes available from the analysis of the data and feedback from neighbors.
This project is operated by the Department of Marine and Environment, with support from the Department of Public Works and Water Quality Management Committee. If you have any questions or see any unusual activity in the vicinity of the floating units, please contact Sia Karplus, Technical Consultant to the Water Quality Management Committee at 508.457.4557 or WQMC@falmouthmass.us.