A recent edition of NewScientist has a small article on the world's largest surviving mangrove ecosystem, which is also home to the endangered royal Bengal tiger. According to the article, in February, the state government of West Bengal and the Indian government approved plans for a petrochemicals hub on the island of Nayachar, located in the Hooghly River.
If finalized, the plan would refine crude oil and produce petroleum by-products. The island is nearly 10 km from the Sunderbans, a biodiversity hotspot containing a UNESCO World Heritage Site. Noxious effluents would flow into the coastal waters and spread into the network of rivers and creeks. Sunderban, home to a range of marine, coastal and estuarine lifeforms, would be subjected to the pollution.
This article caught my eye, since I just visited Belize this past week, a place that Mangrove Action Project (MAP) says is also in danger of losing its mangroves due to construction.
In this case, the South Beach Belize Project, a private gated resort, would cut down the mangroves that border the island of Ambergris Caye to make way for the development. The biggest casualty would be the nearby Hol Chan Marine Reserve (where I just spent a whole day snorkeling!). The reserve is the single most visited site in Belize and encompasses more than 21 square miles of ecologically linked coastal mangrove swamp, sea grass meadows and coral reef habitats, including a portion of the Belize Barrier Reef, the Western Hemisphere's longest coral reef.
According to MAP:
Many marine species, particularly reef fishes and certain invertebrates, rely on mangroves and seagrasses for the feeding and protection of their young. Numerous bird and reptile species nest, rest and feed among mangroves, safe from predators. The food chain for Hol Chan's marine life begins in the mangroves with the algae that grow on mangrove roots and the bacteria and fungi that feed on decomposing mangrove leaves. When mangroves are destroyed, the effects are felt by all the species dependent on them, including bird and fish populations far away from the site of the damage.
Mangroves trap sediment washed into the water by rain and serve as a filter, keeping the water clear and protecting Hol Chan's reef and seagrass beds. Dredging, even when it does not directly destroy corals and seagrasses, adds sediments to the water. These sediments harm corals and seagrasses by reducing the light that can reach them, smothering them and altering the area's nutrient levels and sources. While dredging for South Beach Belize is slated for the back lagoon, westerly winds are known to send currents from the back lagoon towards the reef with drastic increases in suspended sediment.
You can find the full article on MAP's website by clicking here.
These two scenarios demonstrate the current threat that mangroves throughout the world are facing due to development projects that do not take into account their important role. To get a good background on mangroves, click here.