Maintaining salt marshes in the face of sea level rise — review of literature and techniques

Abstract

Guidance relevant to the maintenance and restoration of coastal salt marshes in the face of sea level rise is limited and sometimes conflicting; an understanding of ecological considerations and best management practices are needed to inform restoration and management that is appropriate, timely, successful, and sustainable. A literature search was conducted to assess the severity of current and projected impacts of sea level rise on salt marshes throughout the coastal regions of the United States, to identify other stressors contributing to relative sea level rise, to assess and consolidate current practices in marsh management, and to identify knowledge gaps that are impediments to development of consistent best management practices for restoring or maintaining marshes exhibiting degradation due to relative sea level rise. Literature identified in this search is synthesized, organized by stressor type, relevant metrics, management actions, and adaptive management. The citations are presented in such a way as to be easily utilized by managers of marshes degraded by relative sea level rise. The results of this literature search will inform data acquisition efforts to address data gaps and uncertainties necessary to support development of a holistic approach to identifying, sustaining, and restoring impacted marsh areas. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

One Thousand Nesting Pairs Packed into One Hundred Square Metres: The Sad Story of the Sandwich Terns Thalasseus Sandvicensis of the Venice Lagoon

“…Dredge islands or other similar artificial sites are also commonly accepted and used for nesting by gulls and terns (Van Zoemeren et al ., 2019; Ritenour et al ., 2022). Indeed, construction of artificial islands has been used to compensate for the loss of previously used natural sites (Stienen et al ., 2005; Gamblin et al , 2022).…”

Coastal wetlands can be saved from sea level rise by recreating past tidal regimes

“…There is limited guidance relevant to the conservation of high value intertidal wetland communities threatened by accelerating SLR 26 . In this study, we applied an eco-engineering solution to a threatened intertidal ecosystem and demonstrated its outcomes 3-years post rehabilitation.…”

“…Current literature suggests that a major global environmental crisis in coastal ecosystems is underway, due to the loss of intertidal ecosystems, but offers limited practical solutions to prevent or mitigate the impacts 12 , 14 , 25 . The four most common options for managing the impacts of SLR on intertidal ecosystems are 26 – 29 : status quo (maintaining existing management strategy); retreat landwards (horizontal migration); sediment supply (vertical accretion) and protection/defence measures. …”

“…In intertidal wetlands, where ecosystems are aligned with tidal inundation patterns, future SLR will alter a site’s hydrology and impact existing vegetation communities 26 . One solution to this pressure, is to preserve the existing tidal hydrology by artificially manipulating the tidal regime.…”

Fluvial Transport of Suspended Sediments in the Apalachicola Basin to Apalachicola Bay: Implications to Salt Marsh Sustainability

“…Anthropogenic influences on sediment delivery to the coastal zone have been of concern to scientists for some time (GESAMP, 1994), particularly regarding the survival of salt marshes. Maintaining salt marshes in the face of sea-level rise is considered by the U.S. Army Corp of Engineers to be an important issue that deserves national attention (VanZomeren et al, 2019), and the decline in sediment supply to tidal wetlands is being addressed by an increasing number of researchers (e.g., Kirwan and Megonigal, 2013;Mudd, 2011;Weston, 2014;Windom and Palmer, 2022).…”