PREP Reports & Publications


Eelgrass (Zostera marina) is an essential habitat for the Great Bay Estuary (GBE) because it provides food for wintering waterfowl and habitat for juvenile fish. Eelgrass is the basis of an estuarine food chain that supports many of the recreational, commercial and ecologically important species in the estuary. Additionally, eelgrass filters estuarine waters, removing both nutrients and suspended sediments from the water column. Eelgrass in the Great Bay Estuary is the largest monoculture in the State of New Hampshire and is considered a vital resource to the State’s marine environment. The UNH Seagrass Ecology Group has mapped the distribution of eelgrass in Great Bay every year from 1986 to 2001 (Short, unpublished data). Eelgrass in the entire Great Bay Estuary system (Great Bay, Little Bay, tidal tributaries, Piscataqua River, and Portsmouth Harbor) was mapped in 1996, 1999, 2000, and 2001.

Eelgrass cover in Great Bay has been relatively constant for the past 10 years at approximately 2,000 acres. Earlier, in 1989, there was a dramatic decline in eelgrass beds to only 300 acres (15% of normal levels). The cause of this crash was an outbreak of a slime mold Labryrinthula zosterae, commonly called “wasting disease”. Recently, the greatest extent of eelgrass in the GBE was observed in 1996.

In 2002, the NH Estuaries Project provided financial support to the University of New Hampshire to digitize eelgrass distribution information in Great Bay Estuary for the years 1999-2001. That project was completed and those historic eelgrass coverages are now in the NHEP database.

In 2003, the NHEP committed to support the annual monitoring program for eelgrass starting with aerial photography of eelgrass coverage for 2003 and mapping of eelgrass distribution from information gathered in 2002. The present report presents eelgrass distribution information for 2002.


Piscataqua Region Estuaries Partnership

Publication Date



Piscataqua Region Estuaries Partnership

Document Type