Editing Salt marsh (section)

===Sea level rise===
Due to the [[Arctic sea ice decline|melting of Arctic sea ice]] and thermal expansion of the oceans, as a result of global warming, sea levels have begun to rise. As with all coastlines, this rise in water levels is predicted to negatively affect salt marshes, by flooding and eroding them.<ref>{{cite journal |last1=Valiela |first1=Ivan |last2=Lloret |first2=Javier |last3=Bowyer |first3=Tynan |last4=Miner |first4=Simon |last5=Remsen |first5=David |last6=Elmstrom |first6=Elizabeth |last7=Cogswell |first7=Charlotte |last8=Robert Thieler |first8=E. |title=Transient coastal landscapes: Rising sea level threatens salt marshes |journal=Science of the Total Environment |date=November 2018 |volume=640–641 |pages=1148–1156 |doi=10.1016/j.scitotenv.2018.05.235 |pmid=30021280 |bibcode=2018ScTEn.640.1148V |hdl=1912/10488 |s2cid=51703514 |hdl-access=free }}</ref><ref name="Scott, D. B. 2014"/> The sea level rise causes more open water zones within the salt marsh. These zones cause erosion along their edges, further eroding the marsh into open water until the whole marsh disintegrates.<ref>{{Cite journal|last1=Ganju|first1=Neil K.|last2=Defne|first2=Zafer|last3=Kirwan|first3=Matthew L.|last4=Fagherazzi|first4=Sergio|last5=D’Alpaos|first5=Andrea|last6=Carniello|first6=Luca|date=2017-01-23|title=Spatially integrative metrics reveal hidden vulnerability of microtidal salt marshes|journal=Nature Communications|language=en|volume=8|pages=14156|doi=10.1038/ncomms14156|issn=2041-1723|pmc=5264011|pmid=28112167|bibcode=2017NatCo...814156G}}</ref>

While salt marshes are susceptible to threats concerning sea level rise, they are also an extremely dynamic coastal ecosystem. Salt marshes may in fact have the capability to keep pace with a rising sea level, by 2100, mean sea level could see increases between 0.6m to 1.1m.<ref name=Best2018>{{Cite journal |doi = 10.1016/j.envsoft.2018.08.004|title = Do salt marshes survive sea level rise? Modelling wave action, morphodynamics and vegetation dynamics|journal = Environmental Modelling & Software|volume = 109|pages = 152–166|year = 2018|last1 = Best|first1 = Ü. S. N.|last2 = Van Der Wegen|first2 = M.|last3 = Dijkstra|first3 = J.|last4 = Willemsen|first4 = P. W. J. M.|last5 = Borsje|first5 = B. W.|last6 = Roelvink|first6 = Dano J. A.|doi-access = free| bibcode=2018EnvMS.109..152B }}</ref> Marshes are susceptible to both erosion and accretion, which play a role in a what is called a bio-geomorphic feedback.<ref>{{cite journal |last1=Bouma |first1=T. J. |last2=Van Belzen |first2=J. |last3=Balke |first3=T. |last4=van Dalen |first4=J. |last5=Klaassen |first5=P. |last6=Hartog |first6=A. M. |last7=Callaghan |first7=D. P. |last8=Hu |first8=Z. |last9=Stive |first9=M. J. F. |last10=Temmerman |first10=S. |last11=Herman |first11=P.M.J. |title=Short-term mudflat dynamics drive long-term cyclic salt marsh dynamics |journal=Limnology and Oceanography |date=2016 |volume=61 |issue=2016 |pages=2261–2275|doi=10.1002/lno.10374 |bibcode=2016LimOc..61.2261B |doi-access=free |hdl=10067/1384590151162165141 |hdl-access=free }}</ref> Salt marsh vegetation captures sediment to stay in the system which in turn allows for the plants to grow better and thus the plants are better at trapping sediment and accumulate more organic matter. This positive feedback loop potentially allows for salt marsh bed level rates to keep pace with rising sea level rates.<ref name=Best2018/> However, this feedback is also dependent on other factors like productivity of the vegetation, sediment supply, land subsidence, biomass accumulation, and magnitude and frequency of storms.<ref name=Best2018/> In a study published by Ü. S. N. Best in 2018,<ref name=Best2018/> they found that bioaccumulation was the number one factor in a salt marsh's ability to keep up with SLR rates. The salt marsh's resilience depends upon its increase in bed level rate being greater than that of sea levels' increasing rate, otherwise the marsh will be overtaken and drowned.

Biomass accumulation can be measured in the form of above-ground organic biomass accumulation, and below-ground inorganic accumulation by means of sediment trapping and sediment settling from suspension.<ref name=Li2018>{{Cite journal |doi = 10.1016/j.ecss.2018.08.027|title = The relationship between inundation duration and Spartina alterniflora growth along the Jiangsu coast, China|journal = Estuarine, Coastal and Shelf Science|volume = 213|pages = 305–313|year = 2018|last1 = Li|first1 = Runxiang|last2 = Yu|first2 = Qian|last3 = Wang|first3 = Yunwei|last4 = Wang|first4 = Zheng Bing|last5 = Gao|first5 = Shu|last6 = Flemming|first6 = Burg|bibcode = 2018ECSS..213..305L|s2cid = 135052098|url = http://resolver.tudelft.nl/uuid:098a0959-f449-4c14-9276-ee1cf810b36c}}</ref> Salt marsh vegetation helps to increase sediment settling because it slows current velocities, disrupts turbulent eddies, and helps to dissipate wave energy. Marsh plant species are known for their tolerance to increased salt exposure due to the common inundation of marshlands. These types of plants are called halophytes. Halophytes are a crucial part of salt marsh biodiversity and their potential to adjust to elevated sea levels. With elevated sea levels, salt marsh vegetation would likely be more exposed to more frequent inundation rates and it must be adaptable or tolerant to the consequential increased salinity levels and anaerobic conditions. There is a common elevation (above the sea level) limit for these plants to survive, where anywhere below the optimal line would lead to anoxic soils due to constant submergence and too high above this line would mean harmful soil salinity levels due to the high rate of evapotranspiration as a result of decreased submergence.<ref name=Li2018/>
Along with the vertical accretion of sediment and biomass, the accommodation space for marsh land growth must also be considered. Accommodation space is the land available for additional sediments to accumulate and marsh vegetation to colonize laterally.<ref>{{cite journal |last1=Schuerch |first1=M. |last2=Spencer |first2=T. |last3=Temmerman |first3=S. |last4=Kirwan |first4=M. L. |last5=Wolff |first5=C. |last6=Lincke |first6=D. |last7=McOwen |first7=C. J. |last8=Pickering |first8=M. D. |last9=Reef |first9=R. |last10=Vafeidis |first10=A. T. |last11=Hinkel |first11=J. |last12=Nicholla |first12=R. J. |last13=Brown |first13=S. |title=Future response of global coastal wetlands to sea-level rise |journal=Nature |date=2018 |volume=561 |issue=7722 |pages=231–247|doi=10.1038/s41586-018-0476-5 |pmid=30209368 |bibcode=2018Natur.561..231S |s2cid=52198604 |url=http://eprints.bournemouth.ac.uk/31232/1/Accepted_manuscript_25.07.18.pdf }}</ref> This lateral accommodation space is often limited by anthropogenic structures such as coastal roads, sea walls and other forms of development of coastal lands. A study by Lisa M. Schile, published in 2014,<ref>{{cite journal |last1=Schile |first1=L. M. |last2=Callaway |first2=J. C. |last3=Morris |first3=J. T. |last4=Stralberg |first4=D. |last5=Parker |first5=V. T. |last6=Kelly |first6=M. |title=Evaluating the Role of Vegetation, Sediment, and Upland Habitat in Marsh Resiliency |journal=PLOS ONE |volume=9 |issue=2 |page=e88760|doi=10.1371/journal.pone.0088760 |pmid=24551156 |pmc=3923833 |year=2014 |doi-access=free }}</ref> found that across a range of sea level rise rates, marshlands with high plant productivity were resistant against sea level rises but all reached a pinnacle point where accommodation space was necessary for continued survival. The presence of accommodation space allows for new mid/high habitats to form, and for marshes to escape complete inundation.