Environmental threats in wetland ecosystems
One important natural resource in wetland ecosystems is diversity of species. Because wetlands connect land with water, they are the most productive ecosystems in the world. Wetlands can be natural or artificial, such as marsh, fen, and peat land; wetland water may be permanent or temporary, static or flowing, and fresh or brackish, including the areas of marine water, where the depth of at low tide does not exceed six meters. The biodiversity of wetland ecosystems is variable throughout the world; it encompasses the range of living things, the degree of genetic variation, and the wealth of different habitats within a particular ecosystem.
The wetland habitat is distinct from any other land-based terrestrial habitats, and the organisms of these ecosystems face specific environmental problems. However, most of these problems are overcome through the development of plant or animal's distinctive behaviour.
The wetland species are visible in different climatic regions due to their typical characteristics; they are not confined to certain areas or particular zones of latitude as are the most of the great global biomes, such as rain forest, savanna, and desert area. As a consequence, wetlands are a great source of global biodiversity within the major climatic belts due to the evolved collection of fish, animals and plants.
Therefore, human activities have tremendously altered the habitats in wetland ecosystems. As a result, a quarter of mammals and aquatic species, including those reliant upon wetlands for habitat, have been threatened by human activities over the last 100 years. Recently, wetland species in Bangladesh have experienced rapid degradation as a result of high population density, unplanned industrialization and urbanization, habitat destruction, and waste water disposal, as well as natural hazards. Biodiversity within the ecosystems has been lost, creating further negative impacts on natural resources. In response to this, human beings have been struggling to maintain a sustainable livelihood due to the decline in wetland species.
About 150 animal species are isolated from wetland habitats, and 33 are at risk within their habitats; 125 species are critically endangered; 220 are vulnerable; and 98 are threatened in wetland ecosystems. In the USA, 131 species are stated red listed, 67 are federally endangered species, and 835 species are considered rare within the state of Florida's wetland ecosystem. Similarly, the Hakaluki wetland at Sylhet in Bangladesh faces species scarcity. It contains more than 238 interconnecting wetlands, but most of the species are rare, endangered, threatened, or vulnerable in this wetland ecosystem. As a consequence, the relationship between wetland biodiversity, ecosystem services, and human benefits have received much more attention for the protection of biodiversity in the wetlands.
Bangladesh is rich in wetland biodiversity, with 280 fresh water and 490 marine species present in different wetland ecosystems. These wetlands provide natural ecosystem services, such as water, fish, edible animals, wood, energy, and recreational activities. However, the vulnerability of wetland species and ecosystem services have elevated in Bangladesh due to the agricultural land conversion, forest clearing, climate change, harvesting of natural resources, and the introduction of alien species. The depletion of the wetland biodiversity also depends on the wetland type and ecosystem services, and how valuable they are to human beings. For this reason, substantial investments are urgently needed to systematically record wetland species for full documentation.
Human sustainability has been widely dependent on wetland resources. Wetland species improve resilience of human habitats by stabilizing environmental factors, such as climate, nutrient and carbon cycles, hydrological cycles, and soil-forming dynamics. They support natural-resource-driven livelihoods and reduce vulnerability of crops to pests, disease, drought, and ?ooding, thereby alleviating poverty through enhanced food security. For this reason, species distribution in wetland ecosystem have accounted for the substantial gain in human well-being and economic development over the past century. Therefore, continuous monitoring with thorough documentation of wetland species in relation to environmental threats could be helpful for the protection of biological diversity and a sustainable environment in wetland ecosystems.
The writer is an Associate Professor, Department of Environmental Science, Faculty of Agriculture, Bangabandhu Sheikh Mujibur Rahman Agricultural, University (BSMRAU)