Tidal marshes are highly productive ecosystems located at the interface between freshwater and marine environments. Maine has over 19,500 acres (79 km²) of tidal marshes, far more than any other New England state, New York, or Canadian province in the Bay of Fundy/Gulf of Maine region. Tidal marshes provide habitat for a unique suite of organisms as well as playing an important role in the life cycle of a large number of migrating fish and birds with regional economic and recreational significance.

Despite strong state and federal wetland laws that have virtually eliminated most filling and draining of tidal marshes, many factors continue to threaten the long-term ecological integrity of these ecosystems. Typically located in areas of concentrated coastal development, tidal marshes are threatened by fragmentation of the upland fringe, polluted runoff, rising sea level, invasive plant species such as Common Reed (Phragmites australis), and legacies of past activities that include ditching, fragmentation by roads, and restriction of tidal flows. Tidal restrictions and their effects on tidal flow, salinity, available sediment, and plant communities are the greatest threat facing many Maine marshes. However, systematically collected data on the numbers of tidal restrictions and their effects are nearly non-existent for most Maine tidal marshes.

Maine Audubon Society recently developed the Maine Citizens Guide to Evaluating, Restoring, and Managing Tidal Marshes (Bryan et al. 1997), based on a similar manual used in New Hampshire. During 1997 Maine Audubon hosted a series of workshops on the use of the manual and trained over 50 potential volunteers on the use of the manual. During 1998 we began a volunteer-based tidal marsh monitoring project in the Town of Scarborough to provide baseline information to the scientific community, resource management agencies, and the citizens of Scarborough. The goal of the monitoring was to evaluate the impacts of past and current tidal restrictions and extent of Phragmites growth on Scarborough Marsh, Maine’s largest salt marsh.

A web of roads and other human barriers restrict tidal flows in many portions of the Scarborough Marsh estuary. A network of ditches, past fill, and development along the marsh fringe all affect the ecological integrity of the marsh system. The rapid encroachment of Phragmites in parts of Scarborough Marsh may indicate restricted tidal flows and lower salinity levels. However, the effects of tidal restrictions and other alterations to the marsh have not been quantified on most of the marsh. State and federal agencies as well as local communities have expressed increasing interest in restoring Scarborough Marsh but good baseline data on potential restoration sites is not available.

• Raise citizen awareness of threats facing tidal marshes and increase local grassroots support for tidal marsh conservation and restoration
• Collect baseline data on tidal restrictions and invasive plants in Scarborough Marsh for use by cooperating agencies and organizations
• Prioritize restoration opportunities within the Scarborough Marsh estuary

This report summarizes the findings of the volunteer monitoring effort. The audience for this report includes local groups as well as state and federal conservation agencies. Local citizens and schools will also find the information of interest. Conservation organizations with a current interest in Scarborough Marsh include:

The Maine Audubon Society coordinated the project, provided technical expertise, lead field studies, and prepared the final report. Volunteer Tidal Marsh Stewards were used to the greatest extent possible, depending on their availability and the tasks to be performed. Several of the Tidal Marsh Stewards attended training workshops hosted by Maine Audubon and the Wells National Estuarine Research Reserve in 1997. In addition, volunteers received training for the specific monitoring protocol used in this project in 1998. Depending on the task, volunteers either worked independently or worked as field assistants with the Maine Audubon wetland ecologist. The purpose of using volunteer stewards was to increase the amount of data that could be collected within the available budget and to create local investment in and support of the study.