Climate Change and Intertidal Wetlands

Abstract

Intertidal wetlands are recognised for the provision of a range of valued ecosystem services. The two major categories of intertidal wetlands discussed in this contribution are saltmarshes and mangrove forests. Intertidal wetlands are under threat from a range of anthropogenic causes, some site-specific, others acting globally. Globally acting factors include climate change and its driving cause—the increasing atmospheric concentrations of greenhouse gases. One direct consequence of climate change will be global sea level rise due to thermal expansion of the oceans, and, in the longer term, the melting of ice caps and glaciers. The relative sea level rise experienced at any one locality will be affected by a range of factors, as will the response of intertidal wetlands to the change in sea level. If relative sea level is rising and sedimentation within intertidal wetlands does not keep pace, then there will be loss of intertidal wetlands from the seaward edge, with survival of the ecosystems only possible if they can retreat inland. When retreat is not possible, the wetland area will decline in response to the “squeeze” experienced. Any changes to intertidal wetland vegetation, as a consequence of climate change, will have flow on effects to biota, while changes to biota will affect intertidal vegetation. Wetland biota may respond to climate change by shifting in distribution and abundance landward, evolving or becoming extinct. In addition, impacts from ocean acidification and warming are predicted to affect the fertilisation, larval development, growth and survival of intertidal wetland biota including macroinvertebrates, such as molluscs and crabs, and vertebrates such as fish and potentially birds. The capacity of organisms to move and adapt will depend on their life history characteristics, phenotypic plasticity, genetic variability, inheritability of adaptive characteristics, and the predicted rates of environmental change.

Observed and Projected Impacts of Climate Change on Marine Fisheries, Aquaculture, Coastal Tourism, and Human Health: An Update

“…Climate-induced local (i.e., landward) and global (i.e., poleward) range shifts are also likely to occur for shallow tropical water systems and coastal mangroves, which support fisheries by providing nursery grounds and sheltered habitats that are critical for many species. Mangrove habitats are expected to respond to higher temperatures and CO 2 concentrations through poleward range shifts and faster growth rates, with species richness increasing at higher latitudes (Ross and Adam, 2013). Southern and eastern range expansions have already been reported in Australia (Ross and Adam, 2013).…”

Impact of fire and the recovery of molluscs in south‐east Australian salt marsh

“…Nyman & Chabreck 1995;Adam 2002). The ability to shift or readily adapt to changing conditions is largely dependent upon their physiological tolerance and behavioural capacity (Ross et al 2009;Ross & Adam 2013). Mollusc specieslevel responses to fire in salt marsh are dependent upon the life history, functional traits of the species present, environmental factors and disturbance characteristics.…”

“…Coastal salt marshes have experienced a range of threats from anthropogenic disturbance (McGuinness 1990;Pennings & Bertness 2001;Ross et al 2009;Ross & Adam 2013) which creates opportunities for non-indigenous plants to successfully colonise and invade (Ruiz et al 1999). Coastal salt marshes have experienced a range of threats from anthropogenic disturbance (McGuinness 1990;Pennings & Bertness 2001;Ross et al 2009;Ross & Adam 2013) which creates opportunities for non-indigenous plants to successfully colonise and invade (Ruiz et al 1999).…”

“…Many organisms in salt marsh have larvae which disperse into the water column with late stage larvae returning to the habitat of the adult. The ability to shift or readily adapt to changing conditions is largely dependent upon their physiological tolerance and behavioural capacity (Ross et al 2009;Ross & Adam 2013). Environmental factors associated with a post-burn disturbance including water depth, salinity, rainfall and the frequency, intensity and season of burn are all known to differentially influence species-level composition and dominance (Pennings & Bertness 2001;Mitchell et al 2006).…”

“…Southern Hemisphere salt marshes have a long history of exploitation for urban, agricultural and aquacultural, industrial and recreational pursuits. Coastal salt marshes have experienced a range of threats from anthropogenic disturbance (McGuinness 1990;Pennings & Bertness 2001;Ross et al 2009;Ross & Adam 2013) which creates opportunities for non-indigenous plants to successfully colonise and invade (Ruiz et al 1999). In coastal salt marshes of south-east Australia, the non-indigenous Spiny Rush (Juncus acutus) native to the Mediterranean is increasingly colonising the upper border of coastal salt marshes (e.g.…”