An eelgrass restoration program is underway in Boston Harbor to provide important shallow water eelgrass habitat to juvenile crustaceans, shellfish, and finfish which commonly inhabit sea grass meadows. Restoration of these beds would serve as partial mitigation for assumed impacts to marine resources identified relative to the HubLine gas pipeline construction which transits Boston Harbor. This proposal is intended to restore eelgrass habitat in order to improve abundance of juvenile marine resources and larger forage species.
Tautog in an eelgrass bed.
Tautog in an eelgrass bed.

Eelgrass meadows form the foundation for primary production which supports numerous species. These meadows are very important to the coastal marine ecosystem. Loss of eelgrass habitat due to anthropogenic impacts on the Massachusetts coastal marine ecosystem has been extensive. Eelgrass meadows were once prolific in Boston Harbor and elsewhere along our coast. Boston Harbor beds now can be found in only a few isolated locations. Coastal development, severe organic loading, and siltation in many areas of the inner and outer Harbor have resulted in loss of eelgrass meadows.

In order to enhance finfish or invertebrate species abundance, we need to create an environment with adequate food and shelter. Sea grasses are important to the flow of energy and nutrients. They play a vital role in controlling local food web productivity, both indirectly and also directly, because not only are eelgrass meadows used as habitat in the form of shelter and foraging area, but they also serve as a food source for some grazing species. These meadows are vital to sediment trapping and sediment stabilization which in turn is important to the ecology and life history of finfish, crustaceans, shellfish and a variety of benthic invertebrates.

Eelgrass has the ability to spread from healthy environments to adjacent sediments, but loss of eelgrass can result in significant changes in physical and biological characteristics at a site. This can prevent natural recolonization; whereas transplantation can expedite the process by decades. The removal of wastewater inputs, heavy organic loads, and siltation is very important to successful eelgrass restoration efforts. Water quality improvements from re-direction of the Boston Harbor sewage outfalls to an offshore site have resulted in a measurable reversal of environmental degradation within the Harbor. These conditions decrease nutrient loading, particularly nitrogen levels, which increase water clarity and eelgrass survival by decreasing epiphytic growth and algal blooms. Macroalgal growth within the meadows, which can shade out newly developing eelgrass shoots, is thus diminished. Therefore the Boston Harbor environment is a prime candidate for eelgrass restoration. The Atlantic States Marine Fisheries Commission developed a Submerged Aquatic Vegetation Policy which supports states' goals to preserve aquatic vegetation beds, minimize further loss, improve water and habitat quality, regularly monitor beds to assess status, and implement scientifically-based planting activities to restore historical distribution of beds.

Sea grass researchers have generated a number of restoration techniques which have proven successful. These will be applied where feasible in this restoration effort. Acquisition and review of available water quality databases for Boston Harbor has been underway to help in the process of selecting suitable sites for transplanting eelgrass. These data are being augmented by on-site monitoring of pertinent environmental parameters. Water quality, sediment type, depth, relative exposure, historical and current SAV distribution data layers were included in a preliminary GIS analysis with the help of MarineFisheries' Research Analyst Micah Dean. This analysis will be a valuable asset to the Eelgrass Restoration Project. It assigns a suitability rating to all data, combines them by calculating a multiplicative index to accept or eliminate a potential site, and it can be updated as new environmental data are collected.