Authors: Dinethra Rodrigo, Thilini Gunathilake, Thimali Dharmakeerthi

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Coastal ecosystems are among the world’s most vulnerable ecosystems to the impacts of climate change. Anthropogenic activities contribute to rising greenhouse gas emissions which cause sea level rise and an increase in ocean temperatures, ocean acidification, and extreme weather events such as tropical cyclones. Additionally, the increase in plastic pollution, unsustainable tourism, illegal fishing practices, and domestic, industrial, and agricultural waste continues to increase the vulnerability of coastal ecosystems to the impacts of climate change and disrupt their ecology, transport of sediments, and morphology.

The impacts of climate change on coastal ecosystems including coral reefs, seagrass beds, and mangroves also affect the global fisheries and aquaculture sector which, in turn, impacts food security and the livelihoods of coastal communities. Given the current and future impacts of climate change, new, sustainable, multi-functional, and economically viable coastal protection strategies and solutions are needed to protect coastal ecosystems and livelihoods.

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Coastal Ecosystems as Nature-Based Solutions

The International Union for Conservation of Nature (IUCN) defines nature-based solutions as “actions to protect, sustainably manage and restore natural and modified ecosystems in ways that address societal challenges effectively and adaptively, to provide both human well-being and biodiversity benefits”. Nature-based solutions are essential for economic development. They are underpinned by benefits derived from healthy ecosystems and tackle challenges like climate change, disaster risk reduction, food and water security, and health. The resilience of a coastal ecosystem is its ability to withstand and adapt to the impacts of climate change and disasters. Coastal ecosystems can reduce the susceptibility of coastal communities to hazards. For example, mangroves in coastal zones and lagoons act as barriers to coastal erosion and buffer zones to attenuate the energy of harsh waves.

Coastal ecosystems evolve overtime and build resilience by adapting to changing physical, biological, chemical, and geological activities in coastal environments. The natural resilience of coastal ecosystems can be harnessed to provide nature-based solutions to adapt to climate change and mitigate climate and disaster risks especially for coastal communities in developing countries.

Nature-based solutions are greener and have a smaller carbon footprint than gray infrastructure such as dams and seawalls. They also have the capacity to repair themselves and recover after a hazard, giving them a significant advantage over gray infrastructure which can be expensive and time-consuming to rebuild.

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Types of Nature-Based Solutions for Coastal Protection

Dunes and beaches are found in border areas between the land and the sea. They are home to several types of flora and fauna and provide the foundation for extensive vegetation root systems. Dunes and beaches reduce the impact of coastal storms and provide resilience against other climate risks such as strong winds, large waves, and high tides. by. They also prevent coastal erosion by acting as a repository for sand. Sand dunes can be constructed and strengthened using geotechnical meshes and vegetation covers to stabilise their structure and better act as a physical barrier to reduce the inundation caused by tidal waves.

Salt marshes and wetlands similarly reduce coastal erosion and provide sediment stabilization and wave attenuation. Although some salt marshes have flexible vegetation structures, research has identified other salt marshes with rigid vegetation structures that can attenuate waves up to 70% more efficiently and be part of a nature-based coastal defence solution. Engineers often design artificial wetlands in a way that enhances risk reduction using inspiration from the components of natural wetlands, for example through thin layer placement (TLP). Raising the wetland by several inches allows existing vegetation to penetrate through the new sediment layer and exceed or match sea level rise caused by climate change. Seagrass beds or submerged aquatic vegetation are similar to salt marshes in their resilience to tidal waves and can be adjusted by TLP to combat sea level rise. They also slow down the inland transfer of water, reduce the volume of runoff, and provide habitats for many aquatic species.

As well as forming a sizable portion of the earth’s blue carbon sinks, the root systems of mangroves and other coastal vegetation anchor the plants into underwater sediment and allow them to slow down incoming tidal water and swell waves. This reduces the impact of disastrous waves, storm surges, and high winds on habitats, neighbouring coastal communities, and coastal infrastructure. Mangroves are ecologically important as they provide habitats, nursery grounds, and feeding grounds for many species of flora and fauna. They sequestrate carbon more than any other type of forest, which means that mangrove ecosystems play an important role in climate change mitigation.

The canopies of wild seaweed also dampen wave energy and protect coastal environments against coastal erosion. Seaweed ameliorates acidification, deoxygenation, and other impacts of global warming and climate change which threaten coastal and marine biodiversity as well as food security and livelihoods.

Shallow coral reefs, sometimes referred to as the “rainforests of the sea,” occupy less than 0.1% of the world’s ocean area but provide a home for at least 25% of all marine species and run along more than 150,000 km of coastline in over a hundred countries and territories. They are very effective at absorbing the energy of tidal waves and storm surges, thereby contributing to the protection of coastlines from erosion due to their massive sizes and position between shallow waters and the deeper sea. Coral reefs can reduce wave energy of tidal waves by 97% and wave height by 84%. They also protect other coastal ecosystems such as seagrass beds and human settlements from flooding. The protection afforded by reefs is so important that countries in atolls like the Maldives, Tuvalu, Kiribati, and the Marshall Islands would not exist without their coral fringes.

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Resilience Along Sri Lanka’s Coastline

Sri Lanka is an island nation with a coastal belt of 1,340 km that includes a number of diverse ecosystems including sand dunes, beaches, tidal flats, lagoons, estuaries, seagrass meadows, mangroves, and coral reefs. These ecosystems provide habitats for many species of flora and fauna and support the livelihoods of coastal communities. Similar to the global situation, they are facing increasing risks from climate change and climate-related disasters as well as from anthropogenic activities such as pollution, excessive resource extraction, illegal, unreported, and unregulated (IUU) fishing, and unsustainable tourism practices.

Sri Lanka’s government and other stakeholders have taken legislative, conservative, and restorative action to protect Sri Lanka’s angrove belts and coral reefs along the coastline. The main laws, policies, and plans relevant to the conservation of coastal and marine ecosystems in Sri Lanka are listed below:

• Forest Ordinance No. 16 of 1907
• Fauna and Flora Protection Ordinance No. 2 of 1937
• National Environmental Act No. 47 of 1980
• Coastal Conservation Act No. 57 of 1981
• National Forest Policy of 1995
• Fisheries and Aquatic Resources Act No. 2 of 1996
• National Biodiversity Strategy and Action Plan of 1999
• National Wildlife Policy of 2000
• National Environmental Policy of 2003
• National Policy on Wetlands of 2006
• National Fisheries Policy of 2006
• Marine Pollution Prevention Act No. 35 of 2008
• National Policy on Climate Change of 2012
• National Adaptation Plan for Climate Change Impact in Sri Lanka 2016
• Nationally Determined Contributions of Sri Lanka 2016
• Conservation of Fish and Aquatic Resources within Sri Lankan Waters Regulations 2016

Sri Lanka is also a signatory to international treaties that protect nature-based solutions for coastal protection. For example, Sri Lanka is a signatory to the Ramsar Convention on Wetlands of International Importance, which is an international treaty for the conservation and sustainable use of wetlands. As part of the Commonwealth Blue Charter, Sri Lanka is also the lead of the Mangrove Ecosystems and Livelihoods Action Group (MELAG). 

Furthermore, nature-based solutions for coastal protection contribute toward achieving Goal 14 of the Sustainable Development Goals (SDGs), to conserve and sustainably use oceans, seas, and marine resources, as well as a number of other related SDGs. More specifically, nature-based solutions can help in achieving target 14.2 to “sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans.”

Nature-based solutions can also be part of mitigation and adaptation commitments alongside the Nationally Determined Contributions (NDCs) and National Adaptation Plans (NAPs). For example, nature-based solutions can be part of NDC 3 of the coastal and marine sector in Sri Lanka’s NDCs, to restore, conserve, and manage coral, seagrass, mangroves, and sand dunes in sensitive areas. Nature-based solutions can also supplement adaptation actions such as coastal zone management, beach, stability, and coastal biodiversity in the coastal and marine sector, as well as coastal settlements and infrastructure in the human settlements and infrastructure sector in the NAPs.

Some of the gaps, needs, and challenges in conserving and protection coastal and marine ecosystems include the need to build knowledge and capacity of the public through awareness-raising campaigns, education, and better communication and outreach of relevant stakeholders; the need to strengthen and empower coastal communities; the need for a greater focus on priority actions to improve governance related to coastal and marine ecosystems; the need for more incentives to encourage sustainable business practices; and a lack of support for the development of sustainable funding mechanisms for environmental conservation and restoration actions.

Furthermore, there is a need for better collaboration and partnerships between the government, private sector, non-governmental organisations, and civil society to develop, improve, and implement restoration and conservation measures. An example of successful joint action would be SLYCAN Trust’s Blue Green Protectors project, which is being implemented in collaboration with the Marine Environment Protection Authority, the Department of Coast Conservation and Coastal Resource Management, the private sector, local authorities, the communities, and other stakeholders to protect mangroves and develop mangrove-related livelihoods.

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Conclusion

Coastal ecosystems can function as nature-based solutions to combat the impacts of climate change and protect coastal communities, but conservation and restoration efforts are needed to help them thrive and expand. To establish sustainable systems of ecosystem conservation and restoration, it will be crucial to form multi-actor partnerships and bring together government, the private sector, local communities, and civil society. Restoring natural systems and combining gray infrastructure with nature-based solutions to create hybrid systems can help mitigate greenhouse gas emissions and often results in environmental, economic, and social co-benefits for humans, ecosystems, and infrastructure resilience.