Mangroves are trees that grow on the shores, rivers and estuaries of tropical and subtropical land masses. They are a unique species that can grow in far saltier conditions than other plants by filtering and excreting salt to provide fresh water for photosynthesis.
The greatest mangrove diversity in the world can be found in South-east Asia, with one third of this in Malaysia alone. Mangroves provide refuge, and act as nurseries and feeding grounds for entire food chains, from commercially important fish to wading birds, monitor lizards and even crocodiles.
Not only are they great habitats for the creatures, they also supply ecosystem services to people living nearby. These services are vital to local communities whose livelihoods directly or indirectly rely on healthy mangrove systems, which have an estimated economic value of US$194,000 per hectare of mangrove every year.
Over 35% of mangrove habitats around the world have been destroyed between 1980 and 2000 alone, primarily to provide space for coastal development and intensive aquaculture. The rate of mangrove loss is likely to increase with rising sea levels and urban sprawl.
Another modern-day threat to the health of mangrove forests is pollution from man-made litter, which enters mangroves with ocean currents, wind, ships, tides and land-based sources. Of all marine debris, plastics are the most common – and the most threatening – due to its persistence in the environment.
Plastics have been produced on a global scale since the 1950s as a cheap, durable material used in almost all industries. In 2016, 335 million metric tonnes of plastic were created, half of which was produced in Asia alone. A total of 8.3 billion metric tonnes of plastic have been produced since 1950. Of this, only 9% has been recycled; the rest were dumped in landfills or the natural environment.
Asian countries produce high quantities of waste, but they also import waste from other countries around the world. In 2017 Malaysia imported 316,600 tonnes of waste, but as a result of the waste import ban in China this number was exceeded in just the first half of 2018.
The threats of marine litter to mangroves and associated wildlife are vast. Entanglement of marine life is reported in mussels, fish, turtles, monitor lizards and birds. Ingestion of plastics by marine organisms results in bioaccumulation – plastic passing through the food chain and ultimately to human stomachs by eating the commercial fish stocks in these habitats.
The weight and shading of large items of debris can alter the structure of the sediment below, preventing the growth of native species while creating opportunities for invasive species. This obstruction can prevent species that rely on these habitats from being able to access and use the mangroves as normal. Over the decades, much of Penang’s mangroves have been cleared for coastal development; an estimated 30% of the coastline is now artificial.
Apart from providing ecosystem services and aquatic habitat, mangroves also function as a form of coastal defence: during the 2004 Indian Ocean tsunami, which claimed over 250,000 lives worldwide – 52 in Penang alone – the mangrove forests surrounding the island were recognised for mitigating the tsunami waves and reducing potential loss of life and economic damage. With an increase in extreme weather events due to climate change and rising sea levels, it is vital that such defensive habitats are not destroyed.
On top of that, Penang’s mangroves provide income for local people through ecotourism, fishing and other associated resources for medicine, fuel and food. The forests also hold cultural, spiritual and recreational significance for the people of Penang. Today, the most extensive mangrove forests on the island can be found in Balik Pulau and Pantai Acheh on the west coast of the island.
Mangroves – more than mud.
Tropical and subtropical nations around the world are beginning to take action to safeguard their coastal forests. The Reduced Emissions from Deforestation and Forest Degradation (REDD+) is a mechanism that creates financial value for the carbon stored in forests by offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development – when mangroves are better managed and protected, REDD+provides financial payment based on the carbon dioxide that would have been released without management.
Mangroves can also be used as sites for sustainable tourism to promote the awareness of conserving and reducing degradation and deforestation. Tourism creates jobs and provides incentives for communities to protect mangrove forests as part of their livelihoods; however, it is crucial that ecotourism is created on sustainable principles to ensure resources do not become over-exhausted.
Penang has an example of a successful ecotourism scheme: Matahari Cycle Tours provides educational cycles through the mangroves of Balik Pulau, introducing visitors to the ecosystem services they provide. With improvements and maintenanceof mangrove reserves, more ecotourism activities could be implemented in Penang – this would increase income in rural areas and create a sense of stewardship within the communities towards mangrove forests.
Malaysia needs to protect its mangrove forests, which are essential to the reduction of our carbon footprint. A step forward is to set strong policies that protect mangroves and encourage schemes to reward communities for better management of these forests, such as REDD+. The benefits of doing so – be they environmental, economic or societal – are enormous and far-reaching.
Danielle Carey was born in Wales and studied BSc Environmental Science at University of Plymouth, England. She spent most of 2018 exploring South-east Asia, including three months completing research on plastic pollution in Penang’s mangroves. She is passionate about protecting coastal habitats and communicating science to wider audiences.
Dr Chee Su Yin is a senior lecturer at the Centre for Marine and Coastal Studies. Born and bred in Penang, she has made it her goal to discover novel approaches to develop coastal areas in a sustainable way in order for the ecosystem and the community to co-exist in equilibrium.