Climate Change, Hurricanes and Tropical Storms, and Rising Sea Level in Coastal Wetlands

Abstract

Global climate change is expected to affect temperature and precipitation patterns, oceanic and atmospheric circulation, rate of rising sea level, and the frequency, intensity, timing, and distribution of hurricanes and tropical storms. The magnitude of these projected physical changes and their subsequent impacts on coastal wetlands will vary regionally. Coastal wetlands in the southeastern United States have naturally evolved under a regime of rising sea level and specific patterns of hurricane frequency, intensity, and timing. A review of known ecological effects of tropical storms and hurricanes indicates that storm timing, frequency, and intensity can alter coastal wetland hydrology, geomorphology, biotic structure, energetics, and nutrient cycling. Research conducted to examine the impacts of Hurricane Hugo on colonial waterbirds highlights the importance of long‐term studies for identifying complex interactions that may otherwise be dismissed as stochastic processes. Rising sea level and even modest changes in the frequency, intensity, timing, and distribution of tropical storms and hurricanes are expected to have substantial impacts on coastal wetland patterns and processes. Persistence of coastal wetlands will be determined by the interactions of climate and anthropogenic effects, especially how humans respond to rising sea level and how further human encroachment on coastal wetlands affects resource exploitation, pollution, and water use. Long‐term changes in the frequency, intensity, timing, and distribution of hurricanes and tropical storms will likely affect biotic functions (e.g., community structure, natural selection, extinction rates, and biodiversity) as well as underlying processes such as nutrient cycling and primary and secondary productivity. Reliable predictions of global‐change impacts on coastal wetlands will require better understanding of the linkages among terrestrial, aquatic, wetland, atmospheric, oceanic, and human components. Developing this comprehensive understanding of the ecological ramifications of global change will necessitate close coordination among scientists from multiple disciplines and a balanced mixture of appropriate scientific approaches. For example, insights may be gained through the careful design and implementation of broad‐scale comparative studies that incorporate salient patterns and processes, including treatment of anthropogenic influences. Well‐designed, broad‐scale comparative studies could serve as the scientific framework for developing relevant and focused long‐term ecological research, monitoring programs, experiments, and modeling studies. Two conceptual models of broad‐scale comparative research for assessing ecological responses to climate change are presented: utilizing space‐for‐time substitution coupled with long‐term studies to assess impacts of rising sea level and disturbance on coastal wetlands, and utilizing the moisture‐continuum model for assessing the effects of global change and associated shifts in moisture regimes on wetland ecosystems...

Can elevated CO2 modify regeneration from seed banks of floating freshwater marshes subjected to rising sea-level?

“…Except for P. hemitomon and the unknowns, these species are likely to use a C 3 carbon assimilation strategy Hydrobiologia (2012) 683:123-133 129 after emergence (i.e., germination not directly affected) (Nielsen et al, 2003). After storms, coastal freshwater wetlands may increase in salinity and become dominated by different species, even if the species involved do not change (Michener et al, 1997;Middleton, 2009a). The general characteristics of the seed bank in this floating marsh are roughly similar to those of an oligohaline marsh in Louisiana (Baldwin et al, 1996).…”

“…In coastal ecosystems, regeneration may be dictated by disturbances related to hurricanes, water fluctuation, and/or saltwater intrusion (Platt & Connell, 2003;Middleton, 2009a, b, c, d). These disturbances may increase in the future with climate change, particularly because of increased hurricane activity, sea-level rise (Michener et al, 1997), or declining freshwater input because of inland freshwater diversion or abstraction along rivers (Middleton, 1999). Experimental studies of species in freshwater wetlands indicate that water depth and salinity changes can greatly alter seed germination and seedling growth of species (Middleton, 1999(Middleton, , 2009aHoward & Mendelssohn, 2000;Brock et al, 2005).…”

“…Future environments for regeneration in freshwater may involve novel combinations of increased atmospheric CO 2 (IPCC, 2007), temperature, sea level, salinity (Michener et al, 1997), precipitation (Easterling et al, 2000), and hurricane activity (Webster et al, 2005). Careful assessment of any interactive effects of these environmental factors is important in projecting the future responses of freshwater wetland species to climate change.…”

Large wood debris recruitment on differing riparian landforms along a Gulf Coastal Plain (USA) stream: a comparison of large floods and average flows

“…From 1899 to 1992, 219 hurricanes including 89 major hurricanes (!category 3; Gray, 1990) affected the southeastern US (Michener et al, 1997). Tropical storm frequency, and in particular major hurricane frequency, is associated with cyclical variations in sea surface temperatures and patterns of precipitation in western Africa (Gray, 1990).…”

Coastal use accelerated the regional sea-level rise

“…Regional SLR has increased the risk of damage in low-lying coastal regions, such as densely populated deltas. Direct consequences include submergence, flooding, saltwater intrusion and shoreline retreat, as well as coastal habitat loss (Michener et al, 1997;Pilkey and Cooper, 2004;Hopkinson et al, 2008;Ranasinghe and Stive, 2009). These physical impacts in turn have resulted in significantly negative socioeconomic consequences, such as flooding of urban roadways and coastal lands (Nicholls and Cazenave, 2010).…”