Marine life returning to Green Harbor River

Humans have controlled the flow of Marshfield’s Green Harbor River for centuries. In the 1800s, at the behest of farmers who wanted more grazing land, a dike was built to limit how much tidal water flowed upstream into the river.

It was the beginning of a slow loss of habitat as the river’s salt and oxygen dropped. But recently, plant and animal species that sharply declined or disappeared are returning. From tiny invertebrates to clams and fish, the marine life is coming back.

Worms that live in the sediment have been observed on the upstream side of the dike in the last two years. Environmental officials have found six species of worm and five species of amphipod, a diminutive crustacean.


The fish are coming back, too. Species found in the river in the last two years include Atlantic silverside, banded and striped killifish, flounder, northern pipefish, sculpin, and tautog. Officials have also recorded soft shell clams, various species of crab and shrimp, snails, sea grapes, and barnacles, as well as plants that thrive in salt marshes.

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Found in the Green Harbor River in 2010 and 2011:


Carcinus maenas - green crab

Crangon septemspinosa -


sevenspine bay shrimp

Dolichopodid larva - long-legged fly

Fundulus diaphanus - banded killifish

Fundulus heteroclitus - mummichog

Fundulus majalis - striped killifish


Gasterosteus aculeatus - threespine stickleback

Hemigrapsus sanguineus - Asian shore crab

Molgula - sea grapes

Mya arenaria - softshell clam

Pagarus longicarpus - longclawed hermit crab

Palaemonetes vulgaris - marsh grass shrimp

Palaemonetes pugio - daggerblade grass shrimp

Illyanassa obsoleta - Eastern mudsnail

Littorina littorea - common periwinkle

Menidia menidia - Atlantic silverside

Myoxocephalus - sculpin (species not identified)

Syngnathus fuscus - Northern pipefish

Tautoga onitis - tautog

flounder (species not identified)

6 species of worm

5 species of amphipod



Salicornia - a succulent found in salt marshes

Spartina alterniflora -

salt marsh cordgrass

Sources: Sara Grady, Massachusetts Bays Program; Jason Burtner, Office of Coastal Zone Management.