FULL REPORT

Tidal Wetlands









Lead Author: 

Catherine E Lovelock 1

Co Authors: Greg Skilleter 2, Neil Saintilan 3

Download this report in PDF format: Click here

What is happening?

The red mangrove Rhizophora stylosa is expanding within its range at its southern limits; the expansion is still to be attributed to climate change however knowledge of thermal limits suggests warming plays a role.

What is expected?

Increasing levels of atmospheric CO2 will increase tidal wetland productivity over the coming century. Sea-level rise will affect tidal wetlands, however spatial variation in sea-level rise, large and variable tidal ranges, and data gaps for large portions of the Australian coastline reduce our confidence in predictions for some regions.

What we are doing about it?

Systems to monitor surface height have been deployed in Moreton Bay, south-east Qld and in tidal wetlands in southern Australia The network will provide greater knowledge of possible thresholds of sea-level rise that exceed the adaptive capacity of coastal mangrove and saltmarsh ecosystems to keep pace.

Summary

Climate change is likely to have a strong impact on mangroves, salt marshes and other tidal wetlands. Their position in the intertidal exposes them to a multitude of ocean and atmospheric climate change drivers which leads to high vulnerability to climate change. Tidal wetlands are extremely sensitive to sea level rise. For example, too much flooding and mangroves will “drown”, too little and their productivity will be reduced and they may be replaced with salt marsh or cyanobacterial communities. The strong regulation of productivity and species composition by soil salinity and humidity (influenced by rainfall, river flows and groundwater) in tidal wetlands also makes these ecosystems highly sensitive to changes in rainfall. At the southern edge of their distribution mangroves are likely to often be limited by minimum temperatures and thus rises in air and sea temperatures is likely to increase growth rates and may allow their movement even further south where they will expand into salt marsh habitats.

Despite their vulnerability to climate change the adaptive capacity of tidal wetlands to climate change is also high. For example, mangroves have persisted on the coast of Australia through past variations in past sea level. Where there are no landward barriers, mangrove forests and other tidal wetlands can move inland as sea level rises. We also know that mangrove forests can grow rapidly on newly deposited sediments and that recovery from storms and other disturbances can be rapid if there are not major geomorphological changes, although some species are more resilient than others.


Citation: Lovelock CE et al. (2012) Tidal wetlands. In Marine Climate Change Impacts and Adaptation Report Card for Australia 2012 (Eds. E.S. Poloczanska, A.J. Hobday and A.J. Richardson). Retrieved from www.oceanclimatechange.org.au [Date]

Contact Details: 
1 Centre for Marine Studies, University of Queensland, St Lucia, QLD, 4072, Australia. .(JavaScript must be enabled to view this email address)
2 School of Biological Science, University of Queensland, St Lucia, QLD, 4072, Australia
3 Rivers and Wetlands Unit, Department of Environment, Climate Change and Water, NSW, Australia

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Authors

Cath Lovelock

Catherine lovelock

Cath Lovelock is Professor at the School of Biological Sciences at the University of Queensland. Her research is focused on the ecology and...
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Neil Saintilan

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Dr Neil Saintilan is Principal Research Scientist and head of the Rivers and Wetlands Unit in the NSW Office of Environment and Heritage. His...
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Greg  Skilleter

Greg skilleter

Greg Skilleter is an Associate Professor with School of Biological Science, UQ. He also holds the 2008 Australian Research Council (ARC) - OzReader....
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Scientific Review:

Definition and importance of tidal wetlands

Tidal wetlands in Australia occur on our sheltered coasts and are comprised of mangroves, salt marshes, cyanobacterial mats and salt flats. These different tidal wetland types have strong climatic affinities. Diversity of the plants and animals within these differing wetland types are also strongly influenced by climatic factors.

Mangroves forests dominate the tropical and sub-tropical coasts. The southern limit of mangrove vegetation is set by low temperatures (Morrisey et al. 2011) with temperate mangroves excluded from coastal areas where mean temperatures in winter months fall below 4oC (Harty, 1997), but they extend southward where sufficiently warm ocean currents permit and frost damage is reduced (Saintilan et al. 2009). Mangrove forests have highest diversity in the wet tropics with diversity decreasing on southern coasts and in arid regions (Duke et al. 1998, Victorian Saltmarsh Study 2011). On mangrove dominated coasts salt marshes and desiccation tolerant cyanobacterial mats occur landward of mangroves, with their species composition and structure dependent on the level of tidal inundation and freshwater inputs from the terrestrial environment. In arid regions and those with strongly seasonal rainfall succulent salt marsh species and cyanobaterial mats dominate the high intertidal zone, while in high rainfall regions or where freshwater mixed in the intertidal zone salt marsh species that are less tolerant of high salinity (e.g. Juncus and Phragmites) can be found, often transitioning to freshwater wetlands. In southern latitudes salt marshes are the dominant habitat of the intertidal zone (Adam 2002, Victorian Saltmarsh Study 2011). These marshes are dominated by the succulent species Sarcocornia quinqueflora at low tidal elevations and by grasses, rushes and sedges (e.g. Sporobolus virginicus, Juncus kraussii) at higher elevations.



Figure 1. Left: Forest of Ceriops tagal, Hinchinbrook Channel, Queensland, courtesy: C. Lovelock. Right: Southernmost mangroves in Australia located in Corner Inlet, Victoria, courtesy: C. Harty

Mangroves, salt marshes and other tidal wetlands contribute a wide range of ecosystem services. Although they are ecosystems dominated by low diversity plant communities they are highly productive and are habitat for a high diversity of animals, algae and microbes. Many animals are residents, spending part of their lifecycle within the wetlands while others access tidal wetland habitats opportunistically, when tides allow, to forage and escape predation. Commercially important fish and crustacean species are strongly linked to the area of mangroves and salt marsh in Australian estuaries (Saintilan 2004, Manson et al. 2005) and connectivity among habitats (Skilleter et al. 2005, Meynecke et al. 2008). Tidal wetland ecosystems are at the boundary of terrestrial and marine environments and thus they are regions of high biogeochemical activity. Materials from both the marine environment and terrestrial environment are deposited and processed. Some materials from mangroves are contributed to marine waters thereby supporting ocean productivity (Alongi 2009). Mangroves and salt marshes provide protection for our coastal zone against storms and waves, reducing erosion.


Observed Impacts:


Temperature

There are no published accounts of how increasing global temperature has affected the organisms within mangrove forests and tidal wetlands. But we know that temperature affects fundamental physiological processes and that low temperatures limit mangrove reproduction and distributions (Duke 1990, Duke et al. 1998, Stuart et al. 2006).


Two key processes that determine plant productivity; photosynthetic carbon gain and respiration, are highly sensitive to temperature. Photosynthesis in mangroves over much of the tropics is limited by high midday leaf temperatures which give rise to high vapour pressure deficits between leaves and air, resulting in stomatal closure (Clough and Sim 1989, Cheeseman 1994, Cheeseman et al. 1997). In contrast, photosynthesis is limited by low temperature at southern latitudes (Steinke and Naidoo 1991). However, in one of the few studies of a mangrove species at its extremes, Rhizophora stylosa grew successfully at its latitudinal limits (Wilson and Saintilan 2012) Low temperatures also strongly limit reproductive success in Avicennia marina (Duke 1990) although R. stylosa reproduces successfully at its southern limit (Wilson 2009).. Respiration (CO2 efflux) from plants and microbial communities in soils approximately double with every 10ºC increase in temperature (Davidson and Janssens 2006, Lovelock 2008) we therefore expect the balance between carbon gain and respiratory losses to be less positive with increasing air temperature. 


Mangroves decrease in diversity with increasing latitude, and population dynamics of individual species at their southern limit may be influenced by temperature and, for the southernmost species, the occurrence of frost. A recent survey of age-structure of Rhizophora stylosa at the southern extent of its range in northern NSW demonstrated strong recruitment and growth of juveniles over the past few decades, which may have been related to higher temperatures over the period, although any trigger to a biogeographical shift might predate the stronger recent warming trend (Wilson 2009). A few studies have pointed out that demographic factors such as dispersal limitation may be a factor at latitudinal limits and extending climatic suitability may not necessarily result in latitudinal extension (e.g. de Lange and de Lange 1994, Steinke 1999). At the least the situation might prove to be more complex than simple range extension, including the possible influence of changing ocean currents (Wilson 2009).


Saltmarsh floristic diversity increases with increasing latitude in Australia (Victorian Saltmarsh Study 2011). Mean minimum temperature explains nearly 80% of variability in species diversity between coastal bioregions in Australia, with diversity inversely related to temperature (Saintilan 2009). Saltmarsh physiological responses to temperature are poorly understood, though one study has indicated that germination of some species may be inhibited by higher temperatures (Greenwood and MacFarlane 2006).


Atmospheric CO2

CO2 concentrations in the atmosphere have already increased from 350 ppm to 370 ppm in the last 20 years and are predicted to approximately double by 2080, with potentially profound effects on physiological and ecological processes in plant communities and their consumers. CO2 is the substrate for photosynthesis and influences respiration. Because of the sensitivity of these key physiological processes to elevated CO2, primary production and foodwebs in mangrove forests and salt marshes are likely to be sensitive to atmospheric CO2 concentrations.


There are few direct studies of the effects of elevated CO2 on mangroves and salt marshes and only one in Australia (Ball et al. 1997). In many plant species photosynthesis and growth is often enhanced at doubled atmospheric CO2 concentrations; however the level of enhancement is dependent on other interacting environmental factors (Drake et al. 1997, Poorter and Perez-Soba 2001). Growth enhancements are also attributed to declines in respiration under enhanced CO2 concentrations that are in the order of approximately 20% (Drake et al. 1999). In mangroves, elevated CO2 conditions (twice ambient) had little effect on growth rates when growth was limited by salinity, but increased growth by up to 40% when growth was limited by humidity (Ball et al. 1997). Faster growing, less salt tolerant species are more responsive to elevated CO2 conditions, having enhanced growth rates compared to slower growing more salt tolerant species. This may suggest that productivity and expansion of mangroves into fresh and brackish wetlands could occur at an accelerating pace (see sea level section below).


Elevated CO2 also decreases the temperature at which plants freeze making them more susceptible to frost, which could counteract increases in productivity due to enhanced temperatures (Woldendorp et al. 2008). In salt marshes in the USA, elevated CO2 resulted in increased salt marsh surface elevation through positive effects on root growth which was proposed to counterbalance the negative effects of sea level rise on these communities (Cherry et al. 2009, Langley et al. 2009)


Another common plant adaptation to elevated CO2 concentrations is decreased nitrogen invested in leaves and a concomitant increase in the carbon:nitrogen ratio of plant tissues. Changes in the ratio of carbon and nutrients in plant tissue have been observed to have flow on effects on consumers (Stiling and Cornelissen 2007 and on decomposition processes (Bosire et al. 2005). Elevated CO2 concentrations are therefore likely to affect food webs, carbon and nutrient cycling and the quality of material exported from mangroves to nearshore waters.


Sea Level

Mangroves, salt marsh and salt flats are within the intertidal zone of low energy coasts and are thus highly sensitive to rising sea level. During the past 10,000 years mangroves in some situations were unable to withstand rates of sea level rise that exceeded 1.4 mm yr-1 (Bermuda: Ellison 1993), but the sea level rise threshold for mangrove loss and for changes to intertidal wetland communities will vary depending on a range of interacting factors, including geomorphological setting, tidal range, accretion (e.g. from sediment inputs), subsidence (Ellison 1993, Cahoon et al. 1999), tree growth rates and species composition (Cahoon et al. 1999, Cahoon et al. 2003, Krauss et al. 2003). Current rates of sea level rise in Australia range from 1.3 to 8.0 mm y-1. In many mangrove forests rates of surface accretion (increase in the elevation of the soil surface) matches or exceeds the local rate of sea level rise (Lovelock et al. 2011a). There is no evidence yet to suggest that seaward fringing mangroves are being lost in Australia (although see Lucas et al. 2002). Modelling indicates mangrove areas will increase with sea level rise, mostly through expansion landward and at the expense of salt marsh (Traill et al. 2011).  Palaeoecological studies from northern Australia suggest rising sea levels after the last ice age were associated with the largest mangrove areas (Crowley et al. 1990; Grindrod et al. 1999).  Increases in mangrove forest cover, primarily through recruitment into landward salt marshes, have been documented in southern Australia (Saintilan and Williams 1999, Rogers et al. 2005, Eslami-Andergoli et al. 2009) and encroachment of mangroves into fresh water wetlands has been observed in northern Australia (Applegate 1999, Mulrennan and Woodroffe 1998, Winn et al. 2006).


Extreme events

Mangroves have an important role in protecting coasts from storm and tsunami damage (Smith et al. 1994, Massell et al. 1999, Mazda et al. 2002, Dahdouh-Guebas et al. 2005, Danielsen et al. 2005, Granek et al. 2007) and from coastal erosion (Thampanya et al. 2006, Swiadek 1997). Storms can have a large impact on mangroves, with catastrophic destruction being observed in Florida, the Caribbean,  Bangladesh (Smith et al. 1994, Mastaller 1996, Cahoon et al. 2003) and Australia (Paling et al. 2008) often with very slow recovery (Sherman et al. 2001, Piou et al. 2006), or none at all (Cahoon et al. 2003). Intense storms can strongly influence the surface elevation of wetlands through erosion, deposition and subsurface processes which can subsequently influence rates of recovery (Cahoon 2006). In the North West of Western Australia a large rain-bearing cyclone increased productivity of trees due to increases in availability of nutrients in flood waters (Lovelock et al. 2011b). Quantitative data from Australia on impacts of cyclones on mangroves and their recovery are rare (Bardsley 1985, Woodroffe and Grime 1999, Paling et al. 2008).


Mangroves can recover from severe storm damage providing patches of reproductive trees remain and hydrology and sediments are not altered to an extent where re-establishment is prevented (Smith et al. 1994, Ellison 1998, Sherman et al. 2001, Paling et al. 2008). Tree species differ in their responses to cyclones, with species from the Rhizophoraceae being particularly vulnerable as they are unable to resprout (Baldwin et al. 2001). Although in Exmouth, defoliation of Avicennia marina resulted in tree deaths, while R. stylosa was less affected (Paling et al. 2008). The effects of cyclones on fauna associated with mangroves in Australia are not known, but loss of mangroves from human disturbances in Kenya and Malaysia resulted in declines in diversity and abundance of fauna (reviewed in Manson et al. 2005).


Rainfall

Changes in rainfall will have major effects on tidal wetlands. The predicted changes in rainfall with climate change are complex, with increases in rainfall predicted in some regions and decreases in others. Additionally, increases in the intensity of rainfall events are predicted. These are likely to influence erosion and other processes in catchments potentially having flow on effects on tidal wetlands due to altered delivery of sediments to estuaries.


Rainfall influences species composition, diversity and productivity of intertidal wetlands. Freshwater inputs into intertidal wetlands reduces salinity, increases the water content of soils and delivers sediments and nutrients creating conditions that are favourable for plant physiological function (Smith and Duke 1987, Ball 1998). Rainfall also influences groundwater inputs, which can lead to the maintenance of soil surface elevation through subsurface swelling of soils (Whelan et al. 2005, Rogers et al. 2005). Connectivity of ecosystems through fresh flows, e.g. with flushing accumulated material from salt flats to mangroves and near shore waters, is also strongly influenced by rainfall (Ridd et al. 1988).


In tropical and subtropical environments in Australia, the proportion of the intertidal zone colonised by mangrove is correlated with annual rainfall (Bucher and Saenger 1991). Rainfall will modulate the size of the seasonally hypersaline zone from which mangroves are excluded and thus alter the abundance of different habitat types.


Sediment delivery to estuaries increases with increasing rainfall (Davies and Eyre 2005) and increases with human development of the catchment (Furnas 2003). Sedimentation within wetlands results in increases in the surface elevation of wetland soils relative to sea level, as well as increasing habitat for mangrove colonization (e.g. Trinity Inlet, Cairns; Duke 1997, Duke and Wolanski 2001). In addition to increasing soil surface elevation, delivery of sediments has a direct positive effect on wetland plant growth (Pezeshki et al. 1992, Hemminga et al. 1998, Ellis et al. 2004, Lovelock et al. 2007), although it can lead to reduced diversity of fauna (Ellis et al. 2004) and tree mortality if sedimentation is excessive (Ellison 1998). Increases in the frequency of intense rainfall events combined with land use change in catchments has increased sedimentation which has increased the availability of suitable mangrove habitat and enhanced mangrove growth (Duke et al. 2003,  Lovelock et al. 2007).

Potential Impacts by the 2030s and 2100s: 


Temperature

Plant, soil and fauna will be affected by increases in water and air temperatures. The predicted 2ºC increase in temperature may increase growth of mangroves at their southern limits through enhanced photosynthesis over longer growing seasons and because of increased reproductive potentials. This may have large effects on southern coastal ecosystems as mangroves have different faunal associations to salt marshes. Saltmarsh diversity may also decrease, both in competition with mangroves but also due to the potentially negative effects of higher temperatures on germination.


Increasing temperature may increase plant and soil respiration by approximately 20%, resulting in reduced net carbon gain, increased methane emissions and decreases in soil carbon storage (Davidson and Janssens 2006). As mangroves and salt marshes have large carbon and nutrient stores in soils and in their plant biomass (Robertson et al. 1992, Twilley et al. 1992, Chmura et al. 2003, Mcleod et al. 2011) increases in temperatures and associated increases in respiration may have negative effects on carbon balance that may not be matched by increases in primary production, which in some cases, particularly in northern regions may be reduced (e.g. see Clark 2004 for terrestrial forest ecosystems).


Atmospheric CO2

The available data suggest that under future elevated CO2 primary production is likely to be enhanced although not uniformly over the range of tidal wetlands. Increases in CO2 concentrations may partially reduce the negative effects of reduced humidity and rainfall expected where temperatures increase in northern regions. Increasing levels of CO2 may also change patterns of species dominance in wetlands, accelerating mangrove encroachment into adjacent brackish and freshwater wetlands, and alter the competitive interactions between saltmarsh species which are comprised of species that use both C4 and C3 photosynthetic pathways. The dominant saltmarsh grass, Sporobolus virginicus, is C4, and is a more important source of organic carbon in intertidal foodwebs than the C3 saltmarsh plants (Guest and Connolly 2006; Saintilan and Mazumder 2010). C4 species are predicted to be less responsive to enhancements in photosynthesis under elevated levels of CO2 compared to C3 species. Elevated CO2 may exacerbate the negative effects of freezing temperature on mangroves (Woldendorp et al. 2008) which may limit their expansion into southern regions.

Sea Level

The effect of sea level rise will be moderated by coastal geomorphology. Many of the mangrove areas of northern Australia are associated with broad, flat coastal plains that often have large areas of intertidal salt flat and high intertidal salt marsh (e.g. Fitzroy River, Duke 1997). Around 5500-7500 years ago salt flats and salt marsh areas were covered in mangrove forests in what Woodroffe (1990, 1992, 1995) has called the ‘big swamp’ phase of estuary development. In northern Australia sediment deposition raised the level of soils and sea level has dropped (by approximately 1 m in the last 6000 years) resulting in mangrove forests that currently occupy the edges of coastal plains with the development of salt marsh and salt flats behind them (landward), and in areas of high rainfall, the development of extensive fresh water marshes. Landward migration of mangroves into salt marshes, fresh water wetlands or agricultural lands (where there are no significant human barriers to prevent this) is highly probable. Significant changes in faunal diversity and ecosystem function, often necessitating changes in the human utilization of the coast is likely (Eliot et al. 1999, IPCC 2002a,b, Millenium Ecosystem Assessment 2005, Nicholls 2004).  Impacts of sea level rise will also depend on tidal range. For coasts with similar slopes we expect areas with smaller tidal ranges to be more vulnerable to sea level rise compared to those with larger tidal ranges (Semeniuk 1984, Woodroffe 1986).


Whether mangroves and saltmarshes will persist in their current distribution and abundance will depend on the rate of sea-level rise. Preliminary results from the SE Australian surface elevation table (SET) network indicate that mangroves have been able to increase elevation primarily as a result of sediment accretion, at a rate comparable to the rate of sea-level rise over the past decade, of 1-3 mm per year. Saltmarshes have not been able to maintain this rate of vertical accretion and have been colonised by mangroves.  The Fourth Assessment Report of the IPCC has projected acceleration in the rate of sea-level rise to 2100, with rates of rise exceeding 10 mm yr-1 towards the end of this period. It is unlikely that mangroves will persist in their current position in the landscape given these rates of sea-level rise (Traill et al. 2011).The nascent SET network in Australia and globally should provide knowledge of processes determining the resilience of tidal wetlands and thresholds over the coming decades.

Extreme events

Increases in the frequency and intensity of cyclones and intense storms will increase the destructive effects on mangroves and salt marshes. Decreases in frequency of events, which is predicted for the Southern Hemisphere (Knutsen et al. 2010) may reduce overall productivity (Lovelock et al. 2011b). There are gaps in our knowledge of effects of both the predicted changes in the frequency and intensity of cyclones and intense storms as well as few data documenting the extent of damage and recovery of mangroves and salt marshes in Australia.


Rainfall

Where rainfall is reduced productivity and diversity of mangroves will decline and increases in the area of salt marsh and salt flats are likely (Smith and Duke 1987). Reduced rainfall will lead to reductions in plant growth and rates of sedimentation. Both of these factors will result in reduced tidal wetland surface elevation increments and thus increase the susceptibility to sea level rise. Sedimentation in mangroves has been observed to vary between -11 mm y-1 (erosion) to 10 mm y-1 (Furukawa and Wolanski 1996, Bird and Barson 1977, Spenceley 1977, 1982, Bryce et al. 2003). At the higher end, sedimentation is higher than projected sea level rise, but there is not sufficient data to determine what levels of sedimentation occur over most of Australia and whether these exceed tidal wetland surface subsidence (Syvitski et al. 2009). In a study of sedimentation in southern Australia, sedimentation was higher in mangroves compared to salt marsh (approx 5 mm y-1 in mangroves and 2.5 mm y-1 in salt marsh, Rogers 2005). Sedimentation increased linearly with tidal range (Rogers 2005) and with depth in the intertidal (Lovelock et al. 2011). Thus areas with low tidal ranges, low rainfall and limited sediment supply are more likely to experience a landward retreat of tidal wetlands with sea level rise compared to those areas with high tidal range, high rainfall and an ample sediment supply, which are conditions under which tidal wetland maintenance or even expansion is likely to occur.

Multiple stressors

Climate change factors interact with each other, and with direct human influences on the coast, to affect outcomes for tidal wetlands.  For example, nutrient enrichment and elevated CO2 have positive influences on wetland plant root growth (McKee et al. 2007, Cherry et al. 2009) which may decrease vulnerability to sea level rise (Langley et al. 2009). However, nutrient enrichment also results in increased mortality when mangroves experience drought (Lovelock et al. 2009), thereby increasing vulnerability to climate change factors. Similarly, elevated CO2 increases vulnerability to low temperatures (Woldendorp et al. 2008) potentially limiting the effects of increased temperatures. Increases in the area of mangroves may be particularly likely if high sediment deposition rates due to land-use change in the catchments are sustained or increased with increasing rainfall resulting in the creation of new habitat for mangrove colonisation.


Losses in mangrove and salt marsh area may occur if high temperatures and aridity depress productivity and if sediment delivery is reduced. Pollution and storm damage could accentuate these losses (Duke et al. 2005). Under scenarios of negative human influence (e.g. pollution and impoundment by building of barriers) reductions of fringing mangroves may be substantial, and forests establishing landward may have reduced productivity.


The largest threat to the resilience of intertidal wetlands with climate change is the presence of barriers (e.g. Figure 2) that will prevent the landward migration of intertidal wetland communities. Barriers to landward migration of intertidal communities can be imposed by natural features e.g. steep slopes, but urban, agricultural and other human developments that build berms, bunds, seawalls and roads on coastal plains impose significant threats to resilience of mangroves, salt marsh and salt flats with sea level rise. Barriers also reduce connectivity between ecosystems and overall productivity (Skilleter et al. 2005). Landward barriers to wetland migration will have particularly negative consequences for salt marsh and salt flat communities that are compressed between human imposed landward barriers and encroaching mangroves (Saintilan and Williams 1999, Adam 2002, Saintilan et al. 2009). Landward retreat is currently inhibited in NSW by in excess of 4000 impediments to tidal flow (Williams and Watford 1997). One third of these impediments, if removed or regulated, would provide opportunities for wetland restoration (Williams and Watford 1997).


Figure 2. Mangrove shoreline and adjacent sea wall, South East Queensland.

Key Points: 


• Tidal wetlands provide valuable ecosystem services, including supporting high biodiversity and productivity of the coastal zone.
• Effects of increasing temperature have not been documented but may include changes in reproductive phenology of mangrove trees, enhanced respiration (CO2 efflux) and increased productivity of forests in southern latitudes.
• Elevated CO2 is likely to result in increased productivity of trees, particularly where growth is not limited by high salinity or low humidity. But decreased quality of food for consumers and increased susceptibility of trees to freezing damage are also likely.
• Reductions in rainfall will decrease diversity and productivity of forests while increases in rainfall will increase diversity and productivity.  Pollution with nitrogen fertilizers increased the negative effects of lower rainfall.
• Overall, total area of mangrove forest in Australia is likely to increase with sea level rise as low lying coastal areas become inundated. Salt marsh area is likely to decline as mangroves invade and landward migration is prevented by human and natural barriers.
• Changes in rainfall, catchment development, elevated CO2, sea level rise and nutrient availability interact to modify outcomes as all factors affect processes that maintain wetland surface elevation and thus vulnerability to sea level rise



Figure 3. Coastal saltmarsh (Beaded Glasswort) courtesy: C. Harty

Confidence Assessments

Observed Impacts: 


Temperature

Evidence: There is weak evidence for tidal wetland response to warming temperatures. There is no direct evidence that mangroves are moving south with climate change though there is evidence that the red mangrove Rhizophora stylosa is expanding within its range at its southern limits. There is strong evidence that mangrove forest productivity and reproduction is limited by low temperature in temperate regions, although R. stylosa grows and reproduces at its limits. Mangroves are highly frost sensitive. There is strong global evidence of changes in the phenology of plant and animal species with increased temperature. There is a strong inverse relationship between saltmarsh diversity and temperature. There is a medium level of agreement that warming temperatures are affecting tidal wetlands. There is little direct evidence that climate change is resulting in increases in productivity and abundance of mangroves at southern latitudes.  Factors such as enhanced sedimentation may explain mangrove expansion where it has occurred (e.g. Lovelock et al. 2007).

Confidence: We have MEDIUM confidence that warming temperatures are impacting tidal wetlands. Knowledge of thermal limits to mangrove and salt marsh flora and fauna is balanced against a lack of direct evidence of change.


Atmospheric CO2

Evidence: We have evidence from experimental studies that elevated atmospheric CO2 levels increases plant productivity under some conditions. One USA salt marsh study documents increased surface elevation with elevated CO2 suggesting high CO2 will mitigate effects of rising sea level. There is weak evidence of impacts on Australian tidal wetlands. There are no field studies in mangrove forests and none in Australian salt marshes. There is a low level of agreement that elevated atmospheric CO2 levels will benefit tidal wetlands. Enhancements in growth with elevated CO2 can be reduced with high salinity, low humidity and low nutrient availability. Positive effects of root growth on tidal wetland surface elevation may only occur in ecosystems with highly organic soils and not those with mineral soils.

Confidence: We have LOW confidence that elevated atmospheric CO2 levels are impacting tidal wetlands due to insufficient evidence.


Sea Level

Evidence: There is strong evidence globally that sea level rise will affect wetlands. Loss of wetlands in the USA is well documented. Models indicate tidal wetland loss should be expected where surface elevation of wetlands does not keep pace with sea level rise (Cahoon et al. 2007). There is a high level of agreement that sea level rise is an important factor affecting wetlands in Australia and globally.


There is evidence of impacts in Australia. Published accounts of wetland loss and change due to sea level rise are not common in Australia (with exceptions, e.g. Winn et al. 2006; Rogers et al. 2006), although invasion of marsh communities by mangroves is documented in Australia. Monitoring in Australia is geographically limited with some regions lacking information. There is limited information of short term adaptive capacity to sea-level rise of tidal wetlands in Australia, although changes in mangrove distribution during sea level change in the Holocene are known. There is a low level of agreement that sea-level rise is a factor causing mangrove invasion of marshes in Australia.  Other hypotheses, e.g. subsidence due to groundwater loss, changes in rainfall regimes and the disturbance of salt marsh vegetation are also proposed.


We have high confidence that sea-level rise is affecting Australian tidal wetlands. Although there is ample international evidence of wetland loss and change, spatial variation in sea level rise in Australia, large and variable tidal ranges and data gaps for tidal wetlands for large portions of the Australian coastline reduce our confidence. 


Rainfall

Evidence: There is evidence that alteration of rainfall regimes is affecting Australia tidal wetlands. Variation in tidal wetlands over climatic gradients within Australia provides strong evidence that patterns in rainfall affect tidal wetland diversity and productivity. Changes from salt marsh to mangroves were linked to both low rainfall, where sediments compacted as water was removed from the soil profile, resulting in greater tidal inundation (Rogers et al. 2005) and to high rainfall which increased recruitment of mangroves into salt marsh (Eslami-Andergoli et al. 2009). Drought resulted in mangrove mortality (Lovelock et al. 2009). There is a high level of consensus on the importance of increasing and decreasing rainfall on the composition and productivity of tidal wetlands despite few experimental studies and the complexity of results.

Confidence: There is high confidence that changes in rainfall influences tidal wetlands. Despite few experimental studies there is a high level of consensus that increasing and decreasing rainfall will strongly influence tidal wetlands because of fundamental importance of tidal inundation, salinity and water availability to plant and animal communities.

Potential Impacts by the 2030s and 2100s: 


Temperature

Evidence: There is evidence that warming temperatures will influence tidal wetland distributions. There is fossil evidence of more extensive tropical mangrove forest communities at lower latitudes in the past in Australia (Hashimoto et al. 2006) ), but opportunity for these areas might be now limited by geomorphological infilling of river valleys and current land use. Mangrove forest productivity and reproduction is limited by low temperature in temperate regions. Mangroves are highly frost sensitive. There is strong global evidence of changes in the phenology of plant and animal species globally with increased temperature. There is a medium level of consensus that warming temperatures will affect tidal wetlands. There is a lack of evidence of change but there is high confidence in physiological models. Dispersal barriers and faunal dependencies are not known.

Confidence: There is medium level of confidence that warming temperatures will affect tidal wetlands over the coming century. Knowledge of thermal limits to tidal wetland flora and fauna is balanced against a lack of direct observations.


Atmospheric CO2

Evidence: There is evidence from experimental studies that CO2 increases plant productivity under some conditions. One USA salt marsh study documents increase in surface elevation with elevated CO2. There is weak evidence that Australian tidal wetlands will be affected. There are no field studies in mangroves and none in Australian salt marshes. There is a low level of agreement that increasing elevation of atmospheric CO2 levels will benefit tidal wetlands.  Enhancements in growth with elevated CO2 can be reduced with high salinity, low humidity and low nutrient availability. Enhancement in root growth and the positive effects expected for tidal wetland surface elevation gain may only occur in ecosystems with highly organic soils and low nutrient availability and not those with mineral soils or higher nutrient availability (where decomposition of organic matter may be enhanced). It is highly likely that elevated CO2 will reduce the quality of organic matter available to consumers

Confidence: There is a low confidence that increasing elevation of atmospheric CO2 levels will benefit tidal wetlands over the coming century. There is insufficient evidence to be confident of predictions.


Sea Level

Evidence: There is strong evidence that accelerating sea-level rise will impact tidal wetlands.  Models predict loss of wetlands, particularly of salt marsh, as sea level rise accelerates (Traill et al. 2011). Loss of salt marsh is expected as landward barriers restrict wetland upland migration. Changes in tidal wetland fauna are expected. Medium confidence arises due to uncertainty in sea level rise predictions and lack of information on adaptive capacity. There is a HIGH level of agreement that sea level rise is an important factor that will affect tidal wetlands in Australia and globally.

Confidence: There is medium confidence that sea level rise over the coming century will affect tidal wetlands. Spatial variation in sea-level rise in Australia, large and variable tidal ranges and data gaps of wetlands for large portions of the Australian coastline reduce our confidence in predicted outcomes. 


Rainfall

Evidence: There is evidence that changing rainfall over the coming decades will affect tidal wetlands. Variation in tidal wetlands over climatic gradients within Australia provides evidence that patterns in rainfall will have a strong impact on tidal wetland diversity and productivity. Subsidence within salt marsh and increased vulnerability to mangrove encroachment has been linked to low rainfall (Rogers et al. 2005). Drought resulted in mangrove mortality (Lovelock et al. 2009).  There is a MEDIUM consensus, despite few experimental studies, on the strong effects of increasing and decreasing rainfall on tidal wetland communities.

Confidence: There is MEDIUM confidence that alteration of rainfall patterns and intensity will affect tidal wetlands this century. Despite few experimental studies there is consensus on effects of increasing and decreasing rainfall because of fundamental importance of salinity and water availability to plant and animal communities.



Adaptation Responses

Management options for adaptation

• Limit construction of future barriers and remove barriers, thereby managing the landward retreat of wetlands (Gilman et al. 2008, Shoo et al. 2012).
• Detailed elevation mapping of coastal wetland and hinterland environments, using remote sensing platforms such as Light Detection And Ranging (LiDAR). This will determine areas where landward migration of critical coastal wetland communities can be accommodated.
• Improved models of coastal wetland migration based on quality elevation models and dynamic elevation responses derived from the SET data and landscape scale process models
• Retain intertidal and coastal floodplain habitats to allow readjustment of natural boundaries.
• Leave and introduce appropriate buffers either through land acquisition, restrictive zoning or planned retreat that prevents new development from encroaching upon tidal wetlands (Gilman et al. 2008, Harty 2004, Shoo et al. 2012).
• Prohibit filling of land adjacent to mangrove/saltmarsh wetlands that would prevent landward migration to adapt to tidal inundation changes (Harty 2004).
• Regulate groundwater management to avoid cumulative groundwater depletion and maintain recharge (Harty 2004).
• Provide economic incentives for coastal wetland restoration, for example, by development of approved methodologies for carbon sequestration assessment, fisheries or coastal protection values.
• Remove and limit additional drivers that have negative effects, e.g. pollution, nutrient enrichment, delivery of upstream sediments, clearing and cutting in catchments and introduced predators (e.g. Traill et al. 2011).
• Manage catchments for processes that modify surface elevation (e.g. groundwater extraction, erosion, fertilization and river flows).
• Restore degraded tidal wetlands.
• Protect and restore tidal wetlands that have a high capacity for adaptation, such as those with suitable topography, and where human barriers are absent or can be removed.
• Management actions for wetlands with climate change are likely to affec adaptation in other sectors (e.g. affordable housing, pest management). Management of tidal wetlands should occur within a broad cross-sectoral context (Burley et al. 2011).


Knowledge Gaps

Much of what we know about how tidal wetlands are being and will be influenced by climate change comes from paleontological research over past climatic fluctuations and from comparisons over sites at different latitudes and climatic conditions, not from direct experimental manipulations or long term observations, although there are exceptions (see Further information section). We have few direct evaluations of adaptations to climate change drivers and little data on which to predict rates of adaptation or limits to adaptation.

• There are few locations with adequate data to describe coastal topography at a sufficiently fine scale to model inundation with sea level rise.
• There are data on wetland surface elevation dynamics (rates of accretion and subsidence of wetland soils) from temperate and subtropical estuarine systems, but none from the tropics.
• There are parts of Australia where little is known of the current state of tidal wetlands, e.g. the Kimberley and other parts of northern Australia.
• Although large tidal ranges are proposed to decrease vulnerability of wetlands to sea level rise there are no direct tests of this hypothesis.
• Although much discussed, there is little specific work undertaken on mangrove and saltmarsh biota at the limits of their range and how will they will shift with changing climate.
• Most of what we know about how tidal wetlands respond and adapt to climate change is focussed on the plant communities. Very little is known of how animal and microbial communities of tidal wetlands will adapt to climate change. Microbial communities are vital for many of the ecosystem services provided by mangroves. Faunal communities are important to human livelihoods and cultural values of the coastal. These are significant knowledge gaps that require research. Although changes are anticipated in vegetation structure and coverage of intertidal wetlands with sea level rise, understanding of the functional consequences of these changes, or how ecosystem services will change, remains qualitative. The impacts on climate change on tidal wetland faunal abundance, sediment trapping, nutrient and carbon fluxes are currently not known with any certainty.
• Further work similar to Traill et al 2011 is required to model tidal wetland changes to SLR in combination with land use and development conditions and changes and accounting for the effects on tidal wetlands from changes to atmospheric CO2 concentrations, rainfall patterns and temperature.
• There is a lack of quantifiable information over the extent and timing of change to tidal wetlands to assist in strategic planning for managing the effects of sea level rise and responding with strategies to support ecological resilience and adaptation.


Observations and Modelling

Sea Level
Mangrove forests and other tidal wetlands will encroach landward and may adapt to rising sea level and remain stable on seaward edges if the rate of vertical accretion of the soil surface of the wetland equals or exceeds the rate of sea level rise (Cahoon et al. 1999, Morris et al. 2002). This simple idea underpins many of the current models used to assess wetland resilience to rising sea level (e.g. Craft et al. 2009). Wetland soil surface elevation and its response to sea level are influenced by a suite of interacting processes and feedback mechanisms (Figure 4) that occur on both the surface and subsurface of soils. Elevation of the wetland soil surface is directly influenced by soil volume, which is related to several interrelated processes. Tidal floodwaters deliver sediments to wetlands, where aerial roots and pneumatophores of mangroves enhance sediment deposition, adding to soil volume (Krauss et al. 2003, Kumara et al. 2011, Lovelock et al. 2011). In addition, soil volume is related in part to soil organic matter accumulation, which is the net result of root growth (positive soil volume) and root decomposition (negative soil volume) (Cahoon and Lynch 1997, Cahoon et al. 2003, 2006, McKee et al. 2010). Groundwater drainage and storage result in shrinking and swelling of soils (negative and positive soil volume) (Whelan et al. 2005; Rogers and Saintilan 2008), and soil compaction (reduced soil volume) also influence soil elevation. As soil elevation increases the frequency, depth, and duration of tidal flooding decreases (negative feedback) (Cahoon and Reed 1995). When sea level rises, hydroperiod increases. So as long as soil elevation gain matches sea level rise, the wetland will maintain the same relative elevation within the tidal frame, migrating upslope if need be. This model (Figure 4) and the instrumentation devised to test the model, the rod surface elevation table (RSET, Cahoon 2002; Figure 5) have been used to understand the vulnerability of wetlands to sea level rise and capacity for adaptation by describing the trajectory of the elevation of coastal wetlands in responses to a range of environmental conditions. In Australia RSETs (or earlier version SETs) have been deployed in southern salt marshes and mangroves (Rogers et al. 2006) and in Moreton Bay, South East Queensland (Lovelock et al. 2011). The RSET and SET network will provide greater knowledge of possible thresholds of sea-level rise that exceed the adaptive capacity of coastal mangrove and saltmarsh ecosystems to keep pace with sea level rise, and increase our knowledge of the processes that contribute to variation in adaptation among tidal wetlands in different geomorphic and biogeographic settings. Adaptation can also be enhanced by management of tidal wetlands and adjacent ecosystems.


Figure 4. Diagram showing direct and indirect biotic controls on vertical accretion and elevation change. From Cahoon et al. 2006.


Figure 5. Left: Measuring wetland soil surface elevation, North Stradbroke Island, Queensland. Right: Installing surface elevation tables for measuring changes in soil elevation in salt marsh, South East Queensland.


Further Information

• A vulnerability assessment of tidal wetlands in the Great Barrier Reef to climate change http://www.gbrmpa.gov.au/corp_site/info_services/publications/misc_pub/climate_change_vulnerability_assessment/climate_change_vulnerability_assessment
• Details of how to measure wetland surface elevation change and the network of uses of this technique are found at: http://www.pwrc.usgs.gov/set/
• Assessment of coastal change in some locations in Queensland can be found at:
Duke, N.C., P. Lawn, C.M. Roelfsema, S. Phinn, K.N. Zahmel, D. Pedersen, C. Harris, N. Steggles and C. Tack 2003. Assessing historical change in coastal environments. Port Curtis, Fitzroy River Estuary and Moreton Bay regions. Final Report to the CRC for Coastal Zone Estuary & Waterway Management. Historical Coastlines Project, Marine Botany Group, Centre for Marine Studies, The University of Queensland, Brisbane. 258 pages plus appendices. http://www.marine.uq.edu.au/marbot/research%20highlights/historiccoastlines.htm
• Change in mangroves in South Australia can be found in Burton 1982.
Burton, T. 1982. Mangrove development north of Adelaide, 1935-1982. Transactions of the Royal Society of South Australia 106: 183-189.
• Information on wetland loss and elevated CO2 in the USA can be found at: http://soundwaves.usgs.gov/2009/05/
• An assessment of enhancing the resilience of mangrove systems to climate change stressors, mostly in a tropical developing world context, but including management strategies including enhancing site selection is in McLeod, E. and Salm, R.V. (2006) Managing mangroves for resilience to climate change. IUCN, Gland, Switzerland.
• Adaptation to climate change for coastal wetlands and other ecosystems and sectors in South East Queensland are discussed in a special issue of the journal Regional Environmental Change. This work was supported by the South East Queensland Climate Adaptation Research Initiative: http://www.csiro.au/Organisation-Structure/Flagships/Climate-Adaptation-Flagship/seqcari.aspx
• Resources that discuss “blue carbon” or carbon sequestration in mangrove, saltmarsh and seagrass can be found at: http://bluecarbonportal.org/


References

Adam, P. (2002) Saltmarshes in a time of change. Environmental Conservation 29: 39-61.
Alongi, D.  (2009). Energetics of mangrove ecosystems. Springer Science + Business Media B.V.
Applegate, R.J. (1999) Saltwater intrusion and the Mary River Wetlands of the Northern Territory. In: Streever W.J. (ed), An International Perspective on Wetland Rehabilitation, Kluwer Academic Publishers, Dordrecht, The Netherlands, pp 113–120.
Baldwin, A., Egnotovich, M., Ford, M. and Platt, W. (2001) Regeneration in fringe mangrove forests damaged by Hurricane Andrew. Plant Ecology 157: 149–162.
Ball, M.C. (1998) Mangrove species richness in relation to salinity and waterlogging, a case study along the Adelaide River floodplain, northern Australia. Global Ecology and Biogeography Letters 7: 73-82.
Ball, M.C., Cocharane, M.J. and Rawson, H.M. (1997) Growth and water use of the mangroves Rhizophora apiculata and R. stylosa in response to salinity and humidity under ambient and elevated concentrations of atmospheric CO2. Plant Cell and Environment 20: 1158-1166.
Bardsley, K. (1985) The effects of Cyclone Kathy on mangrove vegetation. In, Bardsley, K., Davie, J., Woodroffe, C. (eds) Coasts and tidal wetlands of the Australian monsoon region, Canberra, Australian National University North Australia Research Unit, pp 167-185.
Bird, E. and Barson, M. (1977) Measurement of physiographic changes on mangrove fringed estuaries and coastlines. Marine Resources Indonesia 18: 73-80.
Bosire, J.O., Dahdouh-Guebas, F., Kairo, J.G., Kazungu, J., Dehairs, F. and Koedam, N. (2005)  Litter degradation and CN dynamics in reforested mangrove plantations at Gazi Bay, Kenya. Biological Conservation 126: 287-296.
Bryce, S., Larcombe, P. and Ridd, P.V. (2003) Hydrodynamic and geomorphological controls on suspended sediment transport in mangrove creek systems, a case study, Cocoa Creek, Townsville, Australia. Estuarine, Coastal and Shelf Science 56: 415-431.
Bucher, D. and Saenger, P. (1991). An inventory of Australian estuaries and enclosed marine waters: an overview of results. Australian Geographic Studies 29: 370-381.
Burley, J., McAllister, R., and Lovelock, C.E. (2011) Integration, synthesis and climate change adaptation: A narrative based on coastal wetlands at the regional scale. Regional Environmental Change, in press DOI: 10.1007/s10113-011-0271-4
Burton, T. (1982) Mangrove development north of Adelaide, 1935-1982. Transactions of the Royal Society of South Australia 106: 183-189.
Cahoon, D.R. (2006) A review of major storm impacts on coastal wetland elevations. Estuaries and Coasts 29: 889-898.
Cahoon, D.R., Day, J.W. and Reed, D.J. (1999) The influence of surface and shallow subsurface soil processes on wetland elevation, a synthesis. Current Topics in Wetland Biogeochemistry 3: 72-88.
Cahoon, D.R., Hensel, P., Rybczyk, J.,  McKee, K.L., Proffitt, E.D. and Perez, B.C. (2003) Mass tree mortality leads to mangrove peat collapse at Bay islands, Honduras after Hurricane Mitch. Journal of Ecology 91: 1093-1105.
Cahoon, D., Hensel, P., Spencer, T., Reed, D.J., McKee, K.L. and Saintilan, N. (2006) Coastal wetland vulnerability to relative sea-level rise: Wetland elevation trends and process controls. In Ecological Studies, Vol. 190 (Eds, Verhoeven, J.T.A., Beltman, B., Bobbink, R. and Whigham, D.F.) Wetlands and natural resource management, Springer-Verlag, Berlin, pp. 271-292.
Cahoon, D.R. and Lynch, J.C. (1997) Vertical accretion and shallow subsidence in a mangrove forest of southwestern Florida, U.S.A. Mangroves and Salt Marshes 1: 173-186.
Cheeseman, J.M. (1994). Depressions of photosynthesis in mangrove canopies. In, Baker, N.R. and Bowyer, J.R.  (eds.), Photoinhibition of Photosynthesis, From Molecular Mechanisms to the Field. Bios Scientific Publishers, Oxford. pp. 377-389.
Cheeseman, J.M., Clough, B.F., Carter, D.R., Lovelock, C.E., Eong, O.J. and Sim, R.G. (1991) The analysis of photosynthetic performance in leaves under field conditions, A case study using Bruguiera mangroves. Photosynthesis Research 29: 11-22.
Cheeseman, J.M., Herendeen, L.B., Cheeseman, A.T., and Clough, B.F. (1997) Photosynthesis and photoprotection in mangroves under field conditions. Plant Cell and Environment 20: 579-588.
Cherry, J.A., McKee, K.L., and Grace, J.B. (2009) Elevated CO2 enhances biological contributions to elevation change in coastal wetlands by offsetting stressors associated with sea level rise. Journal of Ecology 97: 67-77.
Chmura, G.L., Anisfeld, S.C., Cahoon, D.R. and Lynch, J.C. (2003) Global carbon sequestration in tidal, saline wetland soils. Global Biogeochemical Cycles 17: 1111-1120.
Clough, B.F. and Sim, R.G. (1989) Changes in gas exchange characteristics and water use efficiency of mangroves in response to salinity and vapour pressure deficit. Oecologia 79: 38-44.
Craft, C., Clough J., Ehman J., Joye S., Park R., Pennings, S., Guo, H., Machmuller M. (2009) Forecasting the effects of accelerated sea-level rise on tidal marsh ecosystem services. Frontiers in Ecology and the Environment 7: 73–78.
Crowley, G.M., Anderson, P., Kershaw, A.P. & Grindrod, J. (1990) Palynology of a Holocene marine transgressive sequence, lower Mulgrave River, north-east Queensland. Australian Journal of Ecology 15: 231-40.
Dahdouh-Guebas, F., Jayatissa, L.P., Di Nitto, D., Bosire, J.O., Lo Seen, D. and Koedam, N. (2005) How effective were mangroves as a defence against the recent tsunami ? Current Biology 15: R443-447.
Danielsen, F., Sørensen, M.K., Olwig, M.F.,  Selvam, V.,  Parish, F.,  Burgess, N.D., Hiraishi, T., Karunagaran, V.M., Rasmussen, M.S., Hansen, L.B., Quarto, A. and Suryadiputra, N. (2005) The Asian Tsunami, A Protective Role for Coastal Vegetation. Science 310: 643.
Davidson, E.A. and Janssens, I.A. (2006). Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature 440 doi:10.1038
Davies, P.L. and Eyre, B.D. (2005) Estuarine modification of nutrient and sediment exports to the Great Barrier Reef Marine Park from the Daintree and Annan River catchments. Marine Pollution Bulletin 51: 174–185.
de Lange, W.P. and de Lange, P.J. (1994) An appraisal of factors controlling the latitudinal distribution of mangrove (Avicennia marina var. resinifera) in New Zealand. Journal of Coastal Research 10: 539-48.
Drake, B.G., Gonzalez-Meler, M.A., and Long, S.P. (1997) More efficient plants, a consequence of rising atmospheric CO2? Annual Review of Plant Physiology and Plant Molecular Biology 48: 607-737.
Duke, N.C., Ball, M.C. and Ellison, J.C. (1998) Factors influencing biodiversity and distributional gradients in mangroves. Global Ecology and Biogeography Letters 7: 27-47.
Duke, N.C. (1997) Mangroves in the Great Barrier Reef World Heritage Area: current status, long-term trends, management implications and research. In: Wachenfeld, D., Oliver, J., Davis, K. (Eds.), State of the Great Barrier Reef World Heritage Area Workshop. Great Barrier Reef Marine Park Authority, Townsville, pp. 288–299.
Duke, N.C. (1990) Phenological trends with latitude in the mangrove tree Avicennia marina. Journal of Ecology 78: 113-133.
Duke, N.C., Bell, A.M. Pedersen, D.K. Roelfsema, C.M. and Bengston-Nash, S. (2005) Herbicides implicated as the cause of severe mangrove dieback in the Mackay region, NE Australia — serious implications for marine plant habitats of the GBR World Heritage Area. Marine Pollution Bulletin 51: 308-324.
Duke, N.C. and Wolanski, E. (2001) Muddy coastal waters and depleted mangrove coastlines – depleted seagrass and coral reefs. In, Wolanski, E. (ed.). Oceanographic Processes of Coral Reefs, CRC. Boca Raton. pp. 77-91.
Eliot, C., Finlayson, M. and Waterman, P. (1999) Predicted climate change, sea-level rise and wetland management in the Australian wet-dry tropics. Wetlands Ecology and Management 7: 63–81.
Ellis, J, Nicholls, P., Craggs, R., Hofstra, D. and Hewitt, J. (2004) Effects of terrigenous sedimentation on mangrove physiology and associated macrobenthic communities. Marine Ecology Progress Series 270: 71-82.
Ellison, J.C. (1998) Impacts of sediment burial on mangroves. Marine Pollution Bulletin 37: 8-12.
Ellison, J. C. (1993) Mangrove retreat with rising sea-level, Bermuda. Estuarine Coastal and Shelf Science 37: 75-87.
Ellison, J.C. and Stoddart, D.R. (1991) Mangrove ecosystem collapse during predicted sea-level rise - Holocene analogues and implications. Journal of Coastal Research 7: 151-65.
Eslami-Andargoli, L, Dale, P., Sipe, N. and Chaseling, J. (2009) Mangrove expansion and rainfall patterns in Moreton Bay, Southeast Queensland Australia. Estuarine, Coastal and Shelf Science 85: 292-298.
Furnas, M., (2003) Catchments and Corals. Terrestrial Runoff to the Great Barrier Reef. Australian Institute of Marine Science, Townsville.
Furukawa, K. and Wolanski, E. (1996) Sedimentation in mangrove forests. Mangroves and Salt Marshes 1: 3–10.
Gilman, E.L., Ellison, J., Duke, N.C. and Field, C. (2008) Threats to mangroves from climate change and adaptation options. Aquatic Botany 89: 237-250.
Guest, M.A. and Connolly, R.M. (2006) Movement of Carbon among estuarine habitats: the influence of saltmarsh patch size. Marine Ecology Progress Series 310: 15-24.
Granek, E.F. and Ruttenberg, B.I. (2007) Protective capacity of mangroves during tropical storms: a case study from ‘Wilma’ and ‘Gamma’ in Belize. Marine Ecology Progress Series 343:101-105.
Grindrod, J., Moss, P. and van der Kaars, S. (1999) Late Quaternary cycles of mangrove development and decline on the north Australian continental shelf. Journal of Quaternary Science 14: 465-70.
Greenwood, M.E. and MacFarlane, G.R. (2006) Effects of salinity and temperature on the germination of Phragmites australis, Juncus kraussii, and Juncus acutus: implications for estuarine restoration initiatives. Wetlands 26: 854-61.
Harty, C. (1997) Mangroves in New South Wales and Victoria. Vista Publications, Melbourne.
Harty, C. (2004) Planning strategies for mangrove and saltmarsh changes in southeast Australia. Coastal Management 32: 405-415.
Harty, C. (2009) Mangrove planning and management in New Zealand and South East Australia – a reflection on approaches. Ocean & Coastal Management 52: 278-286.
Hashimoto, T.R., Saintilan, N. and Haberle, S.G. (2006) Mid-holocine development of mangrove communities featuring Rhizophoraceae and geomorphic change in the Richmnod River estuary, New South Wales, Australia. Geographical Research 44: 63-76.
Hemminga, M.A., Slim, F.J., Kazungu, J., Ganssen, G.M., Nieuwenhuize, J. and Kruyt, N.M. (1994) Carbon outwelling from a mangrove forest with adjacent seagrass beds and coral reefs (Gazi Bay, Kenya). Marine Ecology Progress Series 106: 291-301.
Houston, W.A. (1999) Severe hail damage to mangroves at Port Curtis, Australia. Mangroves Salt Marshes 3: 29-40.
Krauss, K.W., Allen, J.A. and Cahoon, D.R. (2003) Differential rates of vertical accretion and elevation change among aerial roots types in Micronesian mangrove forests. Estuarine Coastal Shelf Science 56: 251-259.
Kumara, M.P., Jayatissa, L.P., Krauss, K.W., Phillips, D.W., Huxham, M. (2010) High mangrove density enhances surface accretion, surface elevation change, and tree survival in coastal areas susceptible to sea-level rise. Oecologia 164: 545-553.
Langley, J.A., McKee, K.L., Cahoon, D.R., Cherry, J.A. and Megonigal, J.P. (2009) Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise. Proceedings of the National Academy of Science, USA 106: 6182-6186.
Lovelock CE. 2008. Soil respiration in tropical and subtropical mangrove forests. Ecosystems 11: 342–354.
Lovelock, C.E., Feller, I.C., Ellis, J., Hancock, N., Schwarz, A.M. and Sorrell, B. (2007) Mangrove growth in New Zealand estuaries: The role of nutrient enrichment at sites with contrasting rates of sedimentation. Oecologia 153: 633-641.
Lovelock, C.E., Ball, M.C., Martin, K.C. and Feller, I.C. (2009) Nutrient enrichment increases mortality of mangroves. PLoS ONE 4: doi:10.1371/journal.pone.0005600
Lovelock, C.E., Bennion, V, Grinham, A, and Cahoon, D.R. (2011a). The role of surface and subsurface processes in keeping pace with sea-level rise in intertidal wetlands of Moreton Bay, Queensland, Australia. Ecosystems 14: 745-757
Lovelock, C.E., Feller, I.C., Adame, M.F., Reef, R., Penrose, H.M., Wei, L., and Ball, M.C. (2011b). Intense storms and the delivery of materials that relieve nutrient limitations in mangroves of an arid zone estuary. Functional Plant Biology 38, 514–522
Lucas, R.M., Ellison, J.C., Mitchell, A., Donnelly, B., Finlayson, M., and Milne, A.K. (2002) Use of stereo aerial photography for quantifying changes in the extent and height of mangroves in tropical Australia. Wetlands Ecology and Management 10: 161–175.
Manson, F.J., Loneragan N.R., Harch, B.D., Skilleter, G.A. and Williams, L. (2005) A broadsclae analysis of links between coastal fisheries production and mangrove extent, A case-study for northeastern Australia. Fisheries Research 74: 69-85.
Massel S.R., Furukawa K. and Brinkman R.M. (1999) Surface wave propagation in mangrove forests. Fluid Dynamics Research 24: 219–249.
Mazda, Y., Magi, M., Nanao, H., Kogo, M., Miyagi, T., Kanazawa, N. and Kobashi, D. (2002) Coastal erosion due to longterm human impact on mangrove forests. Wetlands Ecology and Management 10:1–9.
McLeod, E, Chmura, G.L, Bouillon, S., Salm, R., Bjork, M., Duarte, C.M., Lovelock, C.E., Schlesinger, W.H., and Silliman, B. (2011) A Blueprint for Blue Carbon:  Towards an improved understanding of the role of vegetated coastal habitats in sequestering CO2. Frontiers in Ecology and the Environment 9: 552–560
McLeod, E. and Salm, R.V. (2006) Managing mangroves for resilience to climate change. IUCN, Gland, Switzerland.
McKee K.L., Cahoon D.L., and Feller I.C. (2007) Caribbean mangroves adjust to rising sea level through biotic controls on change in soil elevation. Global Ecology and Biogeography 16:545-556.
McKee, K.L. (2010) Biophysical controls on accretion and elevation change in Caribbean mangrove ecosystems. Estuarine Coastal and Shelf Science doi:10.1016/j.ecss.2010.05.001
Meynecke, J.O., Lee, S.Y., and Duke, N.C. (2008) Linking spatial metrics and fish catch reveals the importance of coastal wetland connectivity to inshore fisheries in Queensland, Australia. Biological Conservation 141: 981 – 996.
Millenium Ecosystem Assessment 2005. Available at http//www.millenniumassessment.org/en/index.aspx
Morris, J.T., Sundareshwar, P.V., Nietch, C.T., Kierfve, B. and Cahoon D.R. (2002) Responses of coastal wetlands to rising sea level. Ecology 83: 286-287.
Morrisey, D.A., Swales, A., Dittmann, S., Morrison, M.A., Lovelock, C.E., and Beard, C.M. (2010). The Ecology and management of temperate mangroves. Oceanography and Marine Biology: An Annual Review 48, 43-160
Mulrennan, M.E. and Woodroffe, C.D. (1998) Saltwater intrusion into the coastal plains of the Lower Mary River, Northern Territory, Australia. Journal of Environmental Management 54: 169–188.
Nicholls, R.J., Hoozemans, M.J., and Marchand, M. (1999) Increasing flood risk and wetland losses due to global sea-level rise, regional and global analyses. Global Environmental Change 9: S69-S87.
Nicholls, R.J. (2004) Coastal flooding and wetland loss in the 21st Century, Changes under the SRES climate and socio-economic scenarios. Global Environmental Change 14: 69-86.
Piou, C., Feller, I.C., Berger, U. and Chi, F. (2006) Zonation patterns of Belizean offshore mangrove forests 41 years after a catastrophic hurricane. Biotropica 38: 365-372.
Poorter, H., and Perez-Soba, M.  (2001)  The growth response of plants to elevated CO2 under non-optimal environmental conditions.  Oecologia 129: 1-20.
Ridd, P.V., Sandstrom, M. W., and Wolanski, E. (1988) Outwelling from tropical tidal salt flats. Estuarine Coastal and Shelf Science 26: 243-253.
Robertson, A. I., Alongi, D.M. and Boto, K.G. (1992) Food chains and carbon fluxes. In Tropical Mangrove Ecosystems., Vol. 41 (Eds, Robertson, A. and Alongi, D.) American Geophysical Union, Washington DC, pp. 293-326.
Rogers, K. (2005) Mangrove and saltmarsh surface elevation dynamics in relation to environmental variables in Southeastern Australia. PhD Thesis. Earth and Environmental Sciences. University of Wollongong.
Rogers, K., Saintilan, N. and Heijnis, H. (2005) Mangrove encroachment of salt marsh in Western Port Bay, Victoria, the role of sedimentation, subsidence, and sea level rise. Estuaries 28: 551-559.
Rogers, K., Saintilan, N. and Wilton, K. (2006) Vegetation change and surface elevation dynamics of the estuarine wetlands of southeast Australia. Estuarine Coastal and Shelf Science 66: 559-569.
Rogers, K. and Saintilan, N. (2008) Relationships between groundwater and surface elevation in SE Australian wetlands. Journal of Coastal Research, 24: 63-69.
Saintilan, N., Rogers, K. and McKee, K.L. (2009) Salt marsh– mangrove Interactions in Australasia and the Americas. In: Gerardo M. E. Perillo, Eric Wolanski, Donald R. Cahoon, Mark M. Brinson, editors, Coastal Wetlands: An Integrated Ecosystem Approach. Elsevier, 2009, pp. 855-883.
Saintilan, N. (2004) Relationships between estuarine geomorphology, wetland extent and fish landings in New South Wales estuaries. Estuarine Coastal and Shelf Science 61: 591-601
Saintilan, N. (2009). Biogeography of Australian Saltmarsh Plants. Austral Ecology 34, 929-937
Saintilan N. and Mazumder D., (2010). Fine scale variability in the dietary sources of grazing invertebrates in a temperate Australian Saltmarsh. Marine and Freshwater Research.61 615-620
Saintilan, N. and Williams, R.J. (1999) Mangrove transgression into saltmarsh environments in south-east Australia. Global Ecology and Biogeography 8: 117–123.
Semeniuk, V. (1994) Predicting the effect of sea-level rise on mangroves in North western Australia. Journal of Coastal Research 10: 1050-1076.
Sherman, R.E., Fahey, T.J., and Martinez, P. (2001). Hurricane impacts on a mangrove forest in the Dominican Republic, damage patterns and early recovery. Biotropica 33: 393–408.
Shoo. L, O’Mara, J., Perhans, K., Rhodes, J.R., Runting R., Schmidt, S.,. Traill LW, Weber LC, Wilson KA, Lovelock C.E., Adaptation for the maintenance of biodiversity with climate change. Regional Environmental Change, in review
Simas, T., Nunes, J.P. and Ferrier. J.G. (20010 Effects of global change on coast salt marshes. Ecological Modeling 139: 1-15.
Skilleter, G.A., Olds, A., Loneragan, N., and Zharikov, Y. (2005) The value of patches of intertidal seagrass to prawns depends on their proximity to mangroves. Marine Biology 47: 353-365
Smith, T.J. III and Duke, N.C. (1987). Physical determinants of inter-estuary variation in mangrove species richness around the tropical coastline of Australia. Journal of Biogeography 14: 9–19.
Smith, T.J., III, Robblee, M.B., Wanless, H.R., and Doyle T.W., (1994) Mangroves, hurricanes and lightning strikes. BioScience 44: 256-262.
Snedaker, S.C., Meeder, J.F., Ross, M.S. and Ford, R.G. (1994) Discussion of Ellison, Joanna C. and Stoddart, David R. 1991. Mangrove ecosystem collapse during predicted sea-level rise: Holocene analogues and implications. Journal of Coastal Research, 7 , 151-165
Spencely, A. (1977) The role of pneumatophores in sedimentary processes. Marine Geology 24: 31-37.
Steinke, T.D. (1999) Mangroves of South African estuaries. In Estuaries of South Africa. (Eds Allanson, B.R. & Baird, D.). Cambridge University Press, Cambridge: 119-40.
Stiling, P., Cornelissen, T., 2007. How does elevated carbon dioxide (CO2) affect plant–herbivore interactions? A field experiment and meta-analysis of CO2-mediated changes on plant chemistry and herbivore performance. Global Change Biology 13: 1823–1842,
Stuart, S.A., Choat, B., Martin, K.C. Holbrook, N.M. and Ball, M.C. (2006) The role of freezing in setting the latitudinal limits of mangrove forests. New Phytologist 173: 576-583.
Syvitski, J.P.M. (2008) Deltas at risk. Sustainability Science 3: 23-32.
Syvitski, J.P.M., Kettner, A.J., Overeem, I., Hutton, E.W.H., Hannon, M.T., Brakenridge, G.R., Day, J., Vörösmarty, C., Saito, Y., Giosan, L. and Nicholls, R.J. (2009) Sinking deltas due to human activities Nature Geoscience 2: 681–686.
Thampanya, U., Vermaat, J.E., Sinsakul, S. and Panapitukkul, N.  (2006) Coastal erosion and mangrove progradation of Southern Thailand. Estuarine, Coastal and Shelf Science 68: 75-85.
Traill, L.W., Perhans, K., Lovelock, C.E., Prohaska, A., Rhodes, J.R. and Wilson, K.A. (2011) Managing for global change: wetland transitions under sea level rise and outcomes for threatened species Diversity and Distributions, 17: 1225–1233
Twilley, R.R., Chen, R., and Hargis, T. (1992) Carbon sinks in mangroves and their implication to carbon budgets of tropical ecosystems. Water, Air and Soil Pollution 64: 265-268.
Victorian Saltmarsh Study* (2011) Mangroves and coastal saltmarsh of Victoria: distribution, condition, threats and management. Institute for Sustainability and Innovation, Victoria University, Melbourne. *Paul I Boon, Tim Allen, Jennifer Brook, Geoff Carr, Doug Frood, Chris Harty, Jasmine Hoye, Andrew McMahon, Steve Mathews, Neville Rosengren, Steve Sinclair, Matt White and Jeff Yugovic.
Whelan, K.R.T., Smith, T.J. III, Cahoon, D.R., Lynch, J.C. and Anderson, G.H. (2005) Groundwater control of mangrove surface elevation, Shrink and swell varies with soil depth. Estuaries 28: 833–843.
Williams R.J. and Watford F.A. (1997) Identification of structures restricting tidal flow in New South Wales, Australia. Wetlands Ecology and Management 5: 87-97.
Wilson, N.C. and Saintilan, N. (2012) Growth of the mangrove species Rhizophora stylosa Griff. at its southern latitudinal limit in eastern Australia. Aquatic Botany (2012), doi:10.1016/j.aquabot.2012.03.011
Wilson, N. (2009) Growth, reproduction and population genetics of Rhizophora stylosa in NSW. PhD Thesis, School of Arts and Sciences, Australian Catholic University.
Winn, K.O., Saynor, M.J., Eliot, M.J., and Eliot, I. (2006) Saltwater intrusion and morphologicvla change at the mouth of the East Alligator River, Northern Territory. Journal of Coastal Research 22: 137–149.
Woldendorp, G., Hill, M.G., Doran, R. and Ball, M.C. (2008) Frost in a future climate: modelling interactive effects of warmer temperatures and rising atmospheric [CO2] on the incidence and severity of frost damage in a temperate evergreen (Eucalyptus pauciflora). Global Change Biology 14: 294-308.
Woodroffe, C.D. (1990) The impact of sea-level rise on mangrove shore lines. Progress in Physical Geography 14: 583-520.
Woodroffe, C.D. (1992) Mangrove sediments and geomorphology. In, Robertson, A.I., and Alongi, D.M. (eds.), Tropical Mangrove Ecosystems. Coastal and Estuarine Studies. vol 41. American Geophysical Union. Washington DC. pp. 7-42.
Woodroffe, C.D., and Grime, D. (1999) Storm impact and evolution of a mangrove-fringed chenier plain, Shoal Bay, Darwin, Australia. Marine Geology 159: 303-321.


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