Biodiversity
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BIODIVERSITY 3.4.1 INTRODUCTION species of indigenous fish, 13 exotic fish, 56 prawns, about 26 freshwater molluscs, and 150 birds. “Biological Diversity” means the variability among living organisms from all sources including, inter alia, The marine water bodies (200 nautical miles along the terrestrial, marine and other aquatic ecosystems, and coast) are also remarkable for being habitat of 442 the ecological complexes of which they are part; it species of fish. There are at least 36 species of marine includes diversity within species between species, and shrimps. About 336 species of molluscs, covering 151 of ecosystems (Article II, CBD, 1992). Literal genera have been identified from the Bay of Bengal. meaning of biodiversity is the diversity of all life In addition, several species of crabs, and 31 species of forms on earth. This includes the various races and turtles and tortoises, of which 24 live in freshwater, species of all microbes, plants, and animals that live are found in Bangladesh (Sarker and Sarker, 1988; and Ali, 1997). Ahmed and Ali (1996) published a species on earth, including their genetic differences, i.e., the list of 168 seaweeds, 3 sponges, 15 crabs, 3 lobsters, gene pool of each species. 10 frogs, 3 crocodiles, 24 snakes, 3 otters, 1 Bangladesh is a transitional zone of flora and fauna, porcupine, 9 dolphins, and 3 species of whale found in Bangladesh (Table 3.4.1). because of its geographical settings and climatic characteristics. As mentioned in the overview section There are numerous invertebrates in the country that of the report that there are many rivers and streams are yet to be identified. Various authors have recorded existing in the country covering a length of 22,155 about 70 species of bees, and many species of wasps km. In addition to the regular inland waters, (Alam, 1967). seasonally a large part of the country remains submerged for 3-4 months during monsoon. In Bangladesh only about 8-10 per cent of the land area is under good canopy cover. It supports This country is rich in fish and aquatic resources, and approximately 5000 species of angiosperms, out of other biodiversity (Table 3.4.1). Bangladesh’s inland which about 300 species are being cultivated. The list water bodies are known to be the habitat of 266 of medicinal plants is currently being revised at the Bangladesh National Herbarium (BNH), and is Table 3.4.1 Flora and Fauna Recorded in Bangladesh expected to exceed 5000 species. Mia and Haque Category Total Number of (1986) showed there are 224 species of timber- Species yielding plants found in Bangladesh. Khan and Mia Flora (1984) described 130 species of indigenous fiber Angiosperms 5000 plants. Gymnosperms 5 The IUCN Bangladesh Red Data Book (2000) has Algae/seaweed 168 described 266 species of inland fishes, 442 marine fishes, 22 amphibians, 109 inland reptiles, 17 marine Fauna reptiles, 388 resident birds, 240 migratory birds, 110 Sponges 3 inland mammals, as well as 3 species of marine Corals 66 mammals in Bangladesh. (Marine + freshwater) Molluscs (336+26) 362 Insects 2493 According to the Red List of IUCN, there are 54 species of inland fishes, 8 amphibians, 58 reptiles, 41 Mites 19 resident birds, and 40 mammals, which are threatened Shrimp/prawns 56 throughout the country. Among the marine and (Marine + freshwater) Crabs (11+4) 15 migratory species of animals, 4 fishes, 5 reptiles, 6 Lobsters 3 birds, and 3 mammals are threatened. So far, the Red Echinoderms 4 Data Book on plants, which is under preparation at BNH, lists 96 seed-bearing plant species that are (Marine + freshwater) Fish (442+266) 708 threatened. Amphibians 22 (Marine + inland) Reptiles (17+109) 126 The depletion of biodiversity is the result of various Birds 628 kinds of human development interventions and activities, especially in the areas of agriculture, (Marine + inland) Mammals (3+110) 113 forestry, fisheries, urbanization, industries, chemicals, Source: Khan, 1991; Ahmed and Ali, 1996; Alam 1967; minerals, transport, tourism, and energy (Table 3.4.2). IUCN, 2000 77 BANGLADESH : STATE OF THE ENVIRONMENT 2001 3.4.2 PRESSURES ON BIOTA Both flora and fauna are threatened by the loss of habitat resulting from increasing human populations, and unwise bio-resource utilization (Table 3.4.2). Increasing demand for timber and fuel-wood, encroachment for other purposes, and Jhum (shifting) cultivation in the hilly districts, might be the aggravating factors in the annual rate of deforestation and degradation. The unplanned rapid urbanization and industrialization are leading to waste and pollution problems that affect natural ecosystems. As the land and water-based ecosystems are environmentally compromised, the flora and fauna populations are being seriously affected. This biodiversity section described mostly on A view of mono culture, destroying habitat destruction of habitat, overexploitation of flora and fauna, and illegal trades. Other issues such as water inland fisheries. But the availability of many species pollution section of the report deals with industrial that were very popular locally has been drastically decreased, and some are no longer found in the Table 3.4.2 Major Threats to Biodiversity country. On the migration journey to the floodplains, · Destruction of habitat and the return to safe sanctuaries, populations of fish · Overexploitation of flora and fauna now face many obstacles and hazards, which seriously · Indiscriminate use of agro-chemicals disturb reproduction in the open water and ponds. · Industrial waste disposal. · Oil spills The physical loss, shrinkage, and modification of · Encroachment into the natural forests aquatic habitats for fish, prawn, turtle and other · Change in land use pattern and land use conflict aquatic organisms are said to be the major factors involved in depleting fish varieties. Such loss or pollution and oil spillage, and land degradation section shrinkage of aquatic habitats has been the result of deals with agrochemicals, encroachment in the natural thousands of physical structures, dikes, and drainage forest and changes of land use pattern. systems that have been constructed in Bangladesh in Several wildlife species have become extinct in an effort to control floods, cyclones, and other Bangladesh, and many more are threatened. Most of natural calamities. These structures have disrupted the economically important local plants, medicinal the natural flow of waters in closed rivers, diverted plants, etc., are also under equally great pressure, and rivers, and have dried up water bodies. Such physical are likely to be lost due to habitat destruction, and constructions have also changed or damaged the local ecosystems and hydrological features, resulting unsustainable harvesting. in irreparable damages to fisheries resources. Studies done under the Flood Action Plan (FAP) declared 3.4.2.1 Habitat Depletion and Over Exploitation that all Flood Control Drainage (FCD) and Flood Control Drainage and Irrigation (FCDI) projects Fish contributed to the decline of fish stocks and fisheries The people of Bangladesh largely depend on fish to by creating obstacles in the fish migration routes. As meet their protein needs, especially the poor in rural a consequence, fish production have declined. Land areas. Several decades ago there was an abundance of reclamation required for the implementation of these fish in this country. But recently, capture fish projects has also reduced the permanent water production has declined to about 50 per cent, with a bodies. negative trend of 1.24 per cent per year (Ahmed, 1995b). Despite the constant depletion of the river, The extensive irrigation schemes for agricultural canal, and flood plain habitats for years, Bangladesh fields, and indiscriminate use of agrochemicals are still holds the world’s most diverse and abundant changing the feeding and breeding grounds of 78 BIODIVERSITY many indigenous fish species. Discharge of the country is yet to formulate appropriate policies pollutants into water bodies (rivers, canals, ponds, and guidelines to manage the utilization of these etc.) from industries, and over-fishing (especially biological resources in a sustainable manner. Most of juvenile and brood fishes) are highly responsible of them are exploited in an unsustainable way, and for the destruction of fish species throughout the hence, a number of wildlife species have become country. Short term leasing of haors and baors to threatened. individuals for commercial exploitation has led to many species becoming locally extinct. This can be Flora attributed to the practice of almost total intake of fish stocks by dewatering the water bodies while Natural forests throughout the country are increasingly harvesting fish. Moreover, there has been a being depleted. Various types of development activity, reduction of sanctuaries for natural replenishment such as dikes, highway, road construction, and other of fish species throughout the country, which is infrastructure development have further intensified another factor leading to shrinkage and destruction deforestation, and destruction of natural forests in of aquatic habitats. Bangladesh. Briefly, the other causes of deforestation are listed below. The degradation of forestland is Amphibians described in detail in the Land Degradation section of In Bangladesh, 22 species of Amphibians have been this report. recorded (Table 3.4.1). Some of these are · Shifting cultivation (Jhum), and inappropriate economically important and thus are being exploited utilization of forest