Restoration of Eelgrass to Upper Casco Bay: Feasibility Tests in 2015 Hilary A. Neckles US Geological Survey Augusta, ME hneckles@usgs.gov
Robert J. Orth Eelgrass: Zostera marina * marine flowering plant *
Eelgrass grows in Casco Bay from the low intertidal zone to depths of approximately 3m below Mean Low Water
Eelgrass beds are among the most productive plant communities on the planet!
Eelgrass Values Provides essential habitat for commercially valuable fish and shellfish Dense canopy provides protection from predators Some fish, such as winter flounder, Atlantic cod, and striped bass, use as nursery habitat Many fish, such as pollock, feed on abundant invertebrates in eelgrass Small forage fish, such as sticklebacks, silversides, and grubby, occur in very high densities Eelgrass leaves are preferred settlement substrate for larval blue mussels Juvenile lobsters find refuge by burrowing in eelgrass beds Provides habitat for waterfowl, wading birds, and shorebirds that concentrate on food resources Reduces water pollution by absorbing nutrients Improves water clarity and stabilize shorelines Leaves dampen waves and slow currents so that suspended sediments settle out of water column and energy is reduced at shoreline Roots and rhizomes bind bottom muds Mitigates effects of anthropogenic carbon dioxide enrichment Serves as natural carbon sink Photosynthesis drives up ph, thus lessening coastal acidification
Eelgrass Change in Casco Bay Mapping by Seth Barker Produced by: Maine DMR (2001) Maine DEP & Casco Bay Est. Partnership (2013) The map at left shows the distribution of eelgrass based on aerial photography acquired in 2001 and 2013 Where 2013 coverage is mapped, it overlays and largely coincides with the 2001 distribution 56% of the eelgrass area in Casco Bay disappeared between the two mapping intervals, largely between 2012 and early 2013
Intertidal Flats at Head of Maquoit Bay 2001
Intertidal Flats at Head of Maquoit Bay 2013
Green crab damage to eelgrass: Eelgrass shoots collected from the shoreline of upper Casco Bay in 2013 showed clipped and frayed bases characteristic of damage caused by green crabs as they forage for benthic prey Exclosure experiment off Little Flying Point in 2013 identified green crabs as a leading cause of eelgrass loss: Neckles, H. A. In Press. Loss of Eelgrass in Casco Bay, Maine, Linked to Green Crab Disturbance. Northeastern Naturalist.
Feasibility Tests in 2015 1. Natural recovery is beginning in Freeport waters, but upper Maquoit and Middle Bays are largely still unvegetated 2. Small-scale tests can determine the feasibility of jump-starting eelgrass recovery through restoration: Determine whether green crab control is required to restore eelgrass in Casco Bay; Identify eelgrass transplanting methods that yield the highest success rate in Casco Bay; Identify environmental factors contributing to measured rates of eelgrass restoration success.
Project Partners Federal US Geological Survey USFWS Gulf of Maine Program State Maine Dept. of Environ. Protection Maine Coastal Program Municipal Town of Brunswick Marine Resources Division Conservation Organizations Casco Bay Estuary Partnership Friends of Casco Bay Maine Nature Conservancy Academic and Research Entities Bowdoin College University of New Hampshire Southern Maine Community College Resource Access International Independent seagrass mapping experts Concerned citizens Shoreline residents of Flying Point, Freeport, ME
Test Sites: Flying Point and Simpson Point
Testing Different Planting Techniques Wooden grid MDI Bio Lab Shell as anchor Lee & Park 2008 Burlap disk Cornell Coop. Extension Bamboo staple -- Davis & Short 1997
Timeline June 17: Flying Point planted July 7: Simpson Point planting Aug 15 July 16: monitor response Fall-winter 2016: Report