In coastal regions around the world, sea walls have long been seen as fortresses against the relentless forces of the ocean, designed to prevent erosion and land encroachment. Although these man-made structures have been the primary line of defense, nature had already perfected a more sophisticated protection technology before human intervention—mangroves.
Credit: 4969_CFS2016_Mangroves-Factsheet_DR.pdf (waikatoregion.govt.nz)
Mangroves are woody plants or shrubs that grow in the shallow intertidal zones of protected coastal and estuarine environments. In New Zealand, there is only one species of mangrove (Avicennia marina subsp. australasica, also known as Manawa), native to the estuaries of the North Island. They are capable of thriving where most plants cannot, by filtering out most of the salt through their roots and expelling the excess through their leaves, thereby coping with daily inundations of seawater. They can survive in waterlogged muddy sediments because their roots obtain oxygen through vertical snorkel-like ‘breathing’ roots and their extensive lateral root system helps anchor them in soft mud.
Mangroves provide numerous environmental benefits. They support a complex food web by producing organic matter that serves as food for various creatures, ranging from grazing insects to small fish and crabs. This, in turn, attracts larger predators like fish and birds, creating a biodiverse ecosystem. Additionally, mangroves offer habitat to various species, including non-wading birds and marine organisms like oysters and mussels that attach to their roots. Crucially, mangroves protect coastlines by acting as a buffer against storms and improving water quality by trapping sediments and contaminants. These functions make mangroves vital for both ecological health and coastal protection. Unfortunately, due to climate change and human intervention, the global mangrove population has been drastically reduced, with a staggering 50% loss.
The limitations of traditional sea walls are becoming increasingly apparent. Unlike mangroves, these rigid structures often disrupt local ecosystems and do little to protect underwater biodiversity. In a shift towards seeking natural solutions, researchers are rethinking sea wall design, drawing inspiration from these coastal protection experts.
In an innovative shift, scientists have developed panels that mimic the root structure of mangroves. These panels are being integrated into new and existing sea walls, transforming them from mere barriers into life-supporting systems. Like the roots of mangroves, these panels help buffer the impact of waves and enhance the durability of sea walls. More importantly, they provide critical habitats for crustaceans and local coral species, fostering biodiversity that was nearly nonexistent.
Integrating mangrove-inspired biomimetic designs into modern coastal defenses represents a hopeful development in the environmental movement. This trend reflects our recognition of the value of replicating and preserving natural systems and their importance to our ecological well-being. As these innovative solutions become more widespread, they pave the way for building more resilient and environmentally harmonious coastal defenses.
By deeply understanding and mimicking the durability and multifunctionality of mangroves, these natural engineers of the environment, we can protect our coastlines and enhance biodiversity in coastal areas. This integration of natural wisdom represents is an improvement over traditional coastal defense methods and a fundamental reinvention of our approach to coexisting with the planet.
Reference: 4969_CFS2016_Mangroves-Factsheet_DR.pdf (waikatoregion.govt.nz)