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Introduction: Coastal Wetlands’ Adaptation and Ecosystem Services Analysis
Coastal wetlands are considered to be one of the most productive ecosystems of the terrestrial globe, and they can be seen as having strategic significance in terms of global ecological organisation and human beings’ life. But these essential habitats are getting pressure from climate change,e specially through the rise in the levels of the seas. Mangrove forests are among the habitats that have been worst impacted by the rise in aggregate global temperatures and especially by the relatively enhanced sea levels across the globe. Relative to that, this essay shall examine how coastal wetlands may manage or do not manage to adapt to changes in sea levels. However, the responses also have impacts on the ecosystem services, and the features and implications of these effects will be under discussion; further, it will also discuss the ways to minimise and adapt to the effects of sea level rise for ecosystem services.
Background
The ecosystems are located at the coast, and being located in the coastal region, the ecosystem of salt marshes, mangroves, and tidal flats can be affected by the sea level fluctuations (Cahoon, McKee and Morris, 2020). These systems are used in the protection of coastal regions, water purification, sequestration of atmospheric carbon and acting as habitat to several animal species. Normally, people have identified that the coastal wetlands have inherent coping strategies for the changes in sea levels that go hand in hand with aspects of sediment accretion and the growth of wetland vegetation (Fagherazzi et al., 2020). However, the current rate of sea level rise is not determined by natural factors, but rather by the impact of climate change, so it poses new challenges. Wetlands are capable of adapting to the increasing rates of sea level rise in accordance with the rate of sediment supply, tidal excursions, and the rate of sea level rise. Wetlands are being flooded at rates that are faster than their ability to adapt, and hence are lost or have their services degraded. This paper aims to analyse the interactions between these factors to be able to foresee the future of coastal wetlands and to elaborate appropriate strategies for their protection and management.
Mechanisms of Response
Sediment Accretion: The other important feature that comes as a direct result of sea-level rise in wetlands is sedimentation, which causes the wetland’s surface to rise (van Dobben, de Groot and Bakker, 2022). It is transported by tidal currents, river water, and coastal drift, and its deposition assists in the upward movement of wetlands in relation to sea level. Nonetheless, the rate at which sediments accumulate on the wetland's floor has to match the rate of sea-level rise; otherwise, wetlands get flooded.
Vegetation Growth and Peat Formation: Wetland vegetation, for instance, mangroves and salt marsh grasses, are known to determine the rate of sedimentation (Ballut-Dajud et al., 2022). Also, the deposition of organic matter from decomposing plant material may result in the formation of peat, and this enhances the vertical development of wetlands. This process, however, is dependent on the salinity level, the degree of inundation and nutrient supply.
Lateral Migration: When the sea level is increasing, some of the coastal wetlands may shift inland, occupying new higher grounds and new territory which was not wetland before (Van Dolah, Mille, Hesed and Paolisso, 2020). This kind of lateral movement is quite natural as a way of escaping submersion. But such a migration can be successful only if there are appropriate upland habitats available and no barriers in the form of cities or coastal protection structures.
Tidal Prism Adjustment: Wetlands may also change their tidal prism, that is, the amount of tidal water that flows into and out of the wetland in the course of a tide, in relation to sea level rise (Khojasteh et al., 2022). Alterations of the tidal prism affect the spatial distribution of sediments and nutrients in the wetland, which in turn affect its potential to deal with sea level changes.
Erosion and Submergence: When the rate of sea level rise is higher than the rate of wash deposition or wetland lateral movement, erosion and submergence dominate the wetland dynamics (Bruun, 1962). It has the effect of reducing the area of wetland and the quality of the habitat through erosion, and the process of submergence causes wetland vegetation to drown and die, thus converting the wetland to open water (Cooper and Pilkey, 2004).
Case Studies
Chesapeake Bay, USA: The seas in the Chesapeake Bay region have been rising in the course of the twentieth century, and many tidal marshes have been inundated as a result. Some marshes are still able to build vertically upwards with the rising water table through sediment accretion, while others fail to trap enough sediment; hence, they are submerged and converted to shallow water habitats. This has an Impact several-fold on the local biodiversity and the ecosystem functions of these marshes.
Sundarbans, India and Bangladesh: Sundarbans, the biggest mangrove forest in the world, is located in the delta of the Padma, Brahmaputra and Meghna Rivers in the India/ Bangladesh border and is likely to submerge in the face of the rising sea levels (Islam and Gnauck, 2008). Mangroves in this region have also been strongly resistant and sensitive. Many regions of the Sundarbans have been able to withstand the process of sediment accretion and further spreading of mangroves to new regions, while other parts of the Sundarbans are suffering from severe erosion and a resultant decrease in the availability of viable habitats due to upstream sediment trapped by dams and embankments. Its deforestation poses problems to coastal barrier systems, the sourcing of fish staple foods, as well as income for residents (Tibbetts, 2002).
Venice Lagoon, Italy: Venice Lagoon is a special coastal wetland complex that has experienced threats from natural sea-level fluctuation and anthropogenic constructions (Taramelli et al., 2021). From today to the recent past, the salt marshes in the lagoon have been similarly threatened by subsidence and reduced sediment supply resulting from engineering projects, hence fast erosion and loss of marshland. Some of the management strategies that have been attempted to rehabilitate the lagoon include artificial sediment nourishment together with marsh creation, and these have had limited success at attempting to counter the encroaching sea level rise (van der Meulen, IJff and van Zetten, 2022).
Louisiana, USA: Lowlands and coastal marshes in Louisiana, especially those found in the Mississippi River Delta, have been significantly degraded by the impacts of sea-level rise, chiefly on account of sinking land along the coastline and human interference that includes the setting up of levees and drilling for oil and natural gas (Jung et al., 2024). Wetlands have been degraded in the region over the past few decades, and the rate of loss has increased as sea levels have risen. Programs to rebuild and safeguard coastal Louisiana have incorporated massive sediment diversion and marsh construction projects, the permanency of which is in question.
Implications for Ecosystem Services
It is crucial to understand how coastal wetlands respond to sea-level rise as this has significant implications for ecosystem services (Li et al., 2022). Coastal wetlands provide habitat, shoreline regulation of shorelines, carbon storage, and water purification services. However, as seas start to rise and wetlands are unable to do so in the same measure, the demise or loss of these habitats causes effects.
Among these, the most important is that they lead to reduced biological diversity. They are important feeding and breeding grounds for fish, birds and numerous invertebrates. When such wetlands are flooded or eroded, the space for these species is reduced and, therefore, their stock may be affected and reducing the number and variety of species. This loss can affect the interconnections between species within the food chain, leading to decreased stability of the coastal systems.
The other major effect is on the capacity of wetlands to defend coasts from natural calamities such as storms, hurricanes, and flooding (Sun and Carson, 2020). People use wetlands to absorb storm surges, waves, as well as to protect inland areas from flooding. This protective function is greatly reduced due to the loss of wetlands resulting from a rising sea level, and thus exposing the coastal communities to adverse effects of such weather situations as storms. Because of this, coastal communities experience higher economic costs in the occurrence of storms and higher dependency on artificial measures in the form of coastal structures (Dedekorkut-Howes, Torabi and Howes, 2020).
Another remarkable influence on the coastal wetlands ability to sequester carbon is the capability of the wetland in responding to changes in sea level. Estuaries, especially mangroves and salt marshes are some of the most productive ecosystems and the potential carbon storage in the wetland soils and above-ground vegetation is extremely high (Alongi, 2020). When these wetlands are converted to a different use or are degraded, the carbon is then released into the environment and increases greenhouse gas emissions hence affecting climate change. Also, such a loss affects wetlands’ potential to sequester carbon in the future, which is counterproductive to combating climate change.
Figure 1: Map showing the location of the coastal wetlands in the text
(Source: Newton et al., 2020)
The occurrence and cycling of nutrients are also affected when coastal wetlands are deformed. Coastal wetlands are known to act as a buffer to filtering out pollutants and nutrients from flowing through the water systems and into the ocean. When the areas of wetlands decrease or disappear, the capacity of wetlands for water purification is also reduced, as a result of increased pollution and eutrophication in the neighbouring marine areas (Newton et al., 2020). This tend to ripple into fisheries, tourism and human health implications within provinces and countries therein.
Mitigation and Adaptation Strategies
As a result of Sea-Level Rise on coastal wetlands, measures for mitigation and adaptation can be applied. There is the management and enhancement of sediment supply which is among the major techniques used in the process. Implementation can be done by the sediment management projects headed by diverting the sediments in the river to the wetlands or else by adding the sediments directly to the wetlands and elevating its height (Khojasteh et al., 2022). These approaches assist to keep up or reinstate the melodic change vertical development of wetlands concerning to the escalating sea level.
Figure 2: Strategies of close-to-natural wetland restoration
(Source: Cai et al., 2021)
Another aspect that should be considered is the restoration of natural hydrological processes to maintain the stability of wetland ecosystems (Islam and Gnauck, 2008). This may include eradicating structures that hinder the sediment flow and water levels for instance; levees, dams, and drainage channels among others. Because wetlands can again function as recipients of natural tidal exchange, they are in a position to incorporate long-term alterations in sea levels (Cooper and Pilkey, 2004).
Where wetlands are concerned, whether through reduction of their size or even destruction; any possibility of regeneration of new wetlands in the areas that have been lost or in the enhancement of lost or degraded wetlands may be of great help to use in avoiding implications of sea-level rise (Li et al., 2022). This may include sowing cover, dividing real marshes or returning the tidal that was earlier moved in other regions. This paper underlines the necessity of carefully planning the undertaken poststorm restoration interventions so that the results are sustainable as well as capable of withstanding permanent sea-level rises.
In some cases, the only thing that one can do is to let the wetland systems move inland seeking higher ground as sea levels rise (Davidson-Arnott, 2005). This process is called managed retreat and implies the purposeful removal of the infrastructure, and in some cases, communities; preservation of higher ground for the purpose of future wetland migration. The objective of managed retreat is to make sure that wetlands are employed to extend services in different area as seas continue to rise (Davidson-Arnott, 2005). Stakeholder awareness and sensitisation are critical steps in any strategy on mitigation and adaptation. The involvement of local communities in the conservation of wetlands and management of adaptation activities from climate change enhances support for wetlands and supports ecological-friendly initiatives. Promoting education and awareness can also enable communities to participate in the protection of their local wetlands, and management of impacts arising from the sea-level rise effects.
Conclusion
Coastal wetland response to sea-level changes is a dynamic process that has wide-ranging ramifications for aggregative species and ecosystem and human welfare assets. Another intervention is the coordination of measures envisaged and pursued to minimize and mitigate the impacts of sea-level rise on the coastal wetland including sediment control and restoration, and polices and approaches to the management of coastal wetland populations.
