Salt marshes are dynamic systems that can and do respond to changes induced by natural and unnatural disturbances. For example, salt marshes can respond to rising sea level by expanding vertically, if there is sufficient sediment and organic matter, or by migrating inland, if there is sufficient land behind the marsh. Salt marshes hemmed in by human infrastructure (roads, buildings, etc.) and intervention (e.g, infilling, breakwaters, dykes, etc) are less able to adapt. This phenomenon is referred to as ‘coastal squeeze’. The consequences of coastal squeeze can be a loss of salt marsh and other coastal habitat.
In addition to direct human disturbances, salt marsh (and other coastal) habitat in eastern New Brunswick is threatened by the effects of indirect human impacts, specifically the increasing rates of sea-level rise associated with climate change.
Estimated relative sea-level rise (2000-2100) between Escuminac and Cape Jourimain (Environment Canada 2006)
According to a report published by Environment Canada (2006), the highest relative rate of sea-level rise will be experienced along the southeastern coast of New Brunswick. Hanson et al. 2006 found that, despite a sea level rise in the region of 25-32 cm over the last century, coastal areas like Shemogue, which are considered underdeveloped, experienced the least change in salt marsh habitat compared to adjacent developed areas like Aboiteau, Shediac and Cocagne. Their research suggested that salt marshes which exhibit less human disturbance or coastal squeezing have a greater potential to adapt to sea-level rise.
Coastal habitat changes for the Shemogue and Aboiteau areas of southeastern New Brunswick (Hanson et al. 2006)
New Brunswick’s Wetland Conservation Policy is designed to protect wetland habitat like salt marshes. Based on information gathered through the Conservation Council’s survey, certain regulations in the policy, such as the requirement for a 30-metre buffer between wetland features and development activities, are not being respected or enforced. It is also apparent from the survey that a 30-metre buffer is inadequate to protect salt marsh habitat and adjacent development from predicted sea-level rise, particularly along the eastern coast of New Brunswick.