Background
Coastal plain ponds are bodies of freshwater found in lowland coastal areas of sand and gravels which were deposited as outwash when glaciers melted, and often occur in former lake beds ^6,8 Many ponds are shallow, while others are known as deeper “kettle” ponds. These naturally occurring systems are often oligotrophic (low nutrients, high oxygen) as a result of their glacial history and well-drained sandy and gravel soils, and typically have high acidity levels ^1,3. This is particularly important for native shoreline vegetation communities that are adapted to low-nutrient, acidic conditions. Even though these ponds are naturally nutrient-poor, human activities have increased nitrogen and phosphorous loading in many areas, leading to overstimulation of primary production and increasing eutrophic conditions ¹ (high nutrients, low oxygen) . Many coastal plain ponds do not have inlets or outlets, and are controlled by groundwater fluctuations, as well as precipitation and evaporation ^4,5.

Due to periodic flooding and changes in water levels, coastal plain ponds maintain a diverse community of shoreline vegetation, which is a high priority for conservation ^3,8,9. Coastal pond shore vegetation community structure depends on the magnitude, duration, frequency, and timing of flooding and exposure events ². In addition to providing important habitat for plants, coastal ponds are important spawning grounds for migratory fish, such as alewife and blueback herring ⁷. Coastal plain ponds are also important habitat for a variety of turtle species, freshwater mussels, dragonflies, as well as migrating and wintering waterfowl, such as common and hooded merganser, goldeneye, and bufflehead ². In Massachusetts, 40 species of greatest conservation need (SGCN) live in coastal plain ponds, thus making them a high priority for conservation ².

Climate Impacts
Climate change has many potential impacts on coastal plain ponds and dependent species. Increasing precipitation and temperatures will impact seasonal fluctuations in water levels. Increasing temperatures are expected to warm coastal pond waters, thereby increasing evaporation; these conditions may favor invasive species and be inhospitable to native species ². A projected increase in precipitation is expected to intensify terrestrial runoff and the transport of sediments, nutrients, and other pollutants to ponds, thus altering the biology and chemistry of pond habitats. Sea level rise and coastal storms are increasing threats to coastal plain ponds; sea level rise causes groundwater levels to rise, altering pond water levels, while salt water intrusion is expected to affect many low-lying freshwater habitats by increasing salinity and altering species communities.