Tidal wetlands are among the most productive systems in the world; they function as both a transition zone between terrestrial and aquatic systems and as a coastal buffer of pollution filtration, sediment accretion, and erosion control. Despite their importance, salt marshes have experienced a long history of destruction and alteration by human activities. In fact, since colonial times nearly 50% of Connecticut salt marshes have been destroyed. Those remaining often function under stressful conditions as the land around them is altered and developed. Across the state, symptoms of this degradation such as changes in diversity and dominance in salt marsh vegetation have been observed. The most notable change has been the increase in the dominance of the common reed Phragmites australis.

Studies have found that the construction of roads, causeways, bridges and other impervious surfaces near salt marshes lead to a loss in the functional connection with surrounding estuaries. Such disturbances will result in decreased water quality, changes in marsh surface elevation, and vulnerability to invasive vegetation. Many speculate that increases in impervious surfaces may be responsible for the dramatic growth increase and dominance of Phragmites along the East coast; however, few have quantified the relationship between the changes in tidal marsh vegetation composition and land development. This study is aimed at developing a method for filling this gap through quantifying the increase in the invasive vegetation, Phragmites, and development (defined as impervious surface), and calculating the rates in spatial increase of the two parameters in one Connecticut salt marsh Meadows End Marsh, over the past 20 years.

Calculations show that, despite extensive restoration efforts, Phragmites has increased in the marsh at a very high intrinsic rate of 0.05/yr during the period from 1968 to 1995. Development around the marsh has also increased at a rate of 0.006-1, augmenting the effects of an already restricted tidal flow and elevated landscape. If the high growth rates are sustained, growth calculations predict that in twenty years 56% of the marsh will become a less productive, monoculture ecosystem of Phragmites. This high growth rate emphasizes the negative effects that marsh alteration and surrounding development can have on tidal marsh ecosystems. Fortunately, management plans are underway to prevent this occurrence in Meadows End Marsh.

The Meadows End Marsh represents an extreme case of salt marsh degradation but one that is not uncommon in the Northeast. The quantitative method of measuring degradation indicators used in this study can be useful in assessing and predicting tidal wetland conditions over temporal and spatial scales.