Mangroves are also very important to society, the economy and ecology as habitats for many fish and molluscs and a source of raw materials for communities in the surrounding area. And they, too, are affected by the oil industry. Its activities interrupt the flow of both freshwater and seawater into mangroves and within them, affecting drainage patterns, plant life and the soil, and causing a general lack of stability. Results include large-scale erosion, death of plant life, stunting of seedlings, suffocation and poisoning of anchoring roots, and a reduction in absorptive ones. The top canopy of the mature trees that do survive deteriorates, producing fewer leaves and buds.
Mangroves can take several decades to regenerate.
Moreover, no way is known of cleaning polluted sediment from the forest floor without destroying the forest itself. Seagrass beds found in shallow water, especially along tropical coastlines, can also suffer, with widespread impacts on both the immediate and surrounding environments. They stabilize the seabed, trap sediments, improve water quality, and directly nourish more than 340 species of marine fauna, which suffer when the food chain is disrupted. Some seagrass species are extremely fragile, dying on contact with crude oil and finding it very difficult to regenerate. Those with limited means of dispersal and low reproductive rates are particularly hard-hit in the long term, whereas species with higher reproductive rates recover more quickly.