Mangroves are salt-tolerant trees and shrubs that thrive in coastal zones, acting as natural barriers against adverse events such as tsunamis. India has a significant mangrove cover, totalling 4,992 sq km, which represents 0.15% of the country's total geographical area. These incredible ecosystems protect the coast against storms and erosion and are crucial for a wide range of biodiversity, protecting and providing for millions of people. With rising sea levels and changing weather patterns, the vital mangrove forests that hug India's shores are now under immense pressure. A new study now shows that the pressure isn’t distributed evenly.
Researchers from the CSIR-National Botanical Research Institute, the Academy of Scientific and Innovative Research (AcSIR), and Panjab University have discovered a significant difference in how India's mangrove forests on the east and west coasts are responding to climate change. They found that while the east coast, with its vast river deltas, might have a slight edge in adapting to changing conditions in the short term, both coasts face serious threats.
Did You Know? Mangroves are incredibly important for storing "blue carbon," which is carbon captured from the atmosphere and stored in coastal and marine ecosystems. They can store up to five times more carbon than tropical rainforests! |
The study used Species Distribution Models (SDMs), which are computer models used to predict where mangrove species are likely to thrive or struggle in the future based on climate, soil, and land features. The researchers gathered a vast amount of data, including information on the current distribution of 20 different mangrove species along India's coast. They combined this with details about temperature, rainfall, soil type, and the shape of the land. Then, they fed this information into their computer models, which were designed to understand how these factors influence mangrove survival.
The team used an ensemble of eight different models to ensure that the predictions are more reliable and account for different perspectives on the problem. They then projected these conditions into the future, considering two main scenarios: one where we manage to reduce greenhouse gas emissions (called SSP1-2.6) and another where emissions continue to rise significantly (called SSP5-8.5).
The findings revealed a stark contrast between the two coasts. The west coast, squeezed between the Western Ghats mountains and the sea, has mangroves that are more vulnerable. These areas are often narrow fringes with less freshwater, making them more susceptible to heat and salt stress.
On the other hand, the east coast boasts expansive deltaic systems, like the Sundarbans and the deltas of the Godavari and Mahanadi rivers. These areas receive more sediment and freshwater from large rivers, which helps the mangroves cope with climate impacts. However, the east coast is also more prone to cyclones, which can cause significant damage.
Interestingly, the study found that while the east coast generally has more mangrove species, the west coast might have more concentrated areas of high species richness, meaning more species are found together in specific spots. This is because the west coast's conditions, though more constrained, have been relatively stable, allowing hotspots to develop.
Looking ahead, the models predict that by the end of the century, the areas suitable for mangroves will shrink significantly on both coasts, but the west coast is expected to suffer more severe losses. Even the east coast, which shows some resilience in the mid-century under a low-emission scenario, is projected to see its suitable habitats decline substantially under a high-emission scenario.
The researchers acknowledge that their models didn't explicitly include factors like changes in river flow due to dams or the direct impact of cyclones, which could further refine the predictions. Nevertheless, the study's findings are a wake-up call for conservation efforts. It emphasizes the urgent need for tailored strategies to protect these vital ecosystems.
For the east coast, this means focusing on maintaining and expanding existing mangrove patches, especially in areas prone to cyclones, and restoring connections between these patches to help them adapt. For the west coast, the focus should be on protecting the existing biodiversity hotspots from human development and ensuring that the flow of freshwater to these areas is maintained. By understanding these regional differences and implementing targeted conservation measures, we can work towards safeguarding India's precious mangrove forests and the essential services they provide to millions of people.
This article was written with the help of generative AI and edited by an editor at Research Matters.