Loss of eelgrass in Casco Bay, Maine, linked to Green Crab disturbance

Northeastern Naturalist



Over half of the Zostera marina (Eelgrass) cover disappeared from Casco Bay, ME, largely between 2012 and 2013. Eelgrass decline coincided with a population explosion of the invasive crab Carcinus maenas (European Green Crab). Green Crabs have been found to damage Eelgrass in Atlantic Canada through foraging activity, but destruction of established beds had not been documented in Maine. My objective was to determine whether loss of Eelgrass from Casco Bay was related to Green Crab disturbance. In September 2013, I transplanted Eelgrass shoots inside and outside of replicate Green Crab exclosures in a formerly vegetated area of upper Casco Bay. Following 26 d, mean survival of Eelgrass inside the exclosures was 82% and outside the exclosures was 24%. The mean plastochrone interval (time between formation of 2 successive leaves) of undamaged shoots was the same inside and outside the exclosures, and was comparable to published values from healthy Eelgrass beds in New England. Results implicate Green Crab bioturbation as a leading cause of Eelgrass loss from this system.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Loss of eelgrass in Casco Bay, Maine, linked to Green Crab disturbance
Series title Northeastern Naturalist
DOI 10.1656/045.022.0305
Volume 22
Issue 3
Year Published 2015
Language English
Publisher Eagle Hill Institute
Contributing office(s) Patuxent Wildlife Research Center
Description 23 P.
First page 478
Last page 500
Time Range Start 2013-08-23
Time Range End 2013-10-01
Country United States
State Maine
Other Geospatial Casco Bay, Maquoit Bay
Online Only (Y/N) N
Additional Online Files (Y/N) N
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