Indo-Malayan
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i Jiang Rivers and Streams [170] – China, Vietnam
Geographic Location: Southeastern Asia
Biodiversity Features: The southern margin of China is characterized by a distinctive landscape of karst limestone, where hills, sinkholes, and caverns abound. This landscape is traversed by the Xi Jiang River, China’s second largest river. The ecoregion defined by the river and its tributaries contains over 380 freshwater, brackish, and anadromous fish species, and approximately 120 of these may be endemic. DISTINCTIVE FISH FAUNA EXHIBITING HIGH DEGREE OF RICHNESS FOR FISHES IN A TEMPERATE REGION, INCLUDING PRONOUNCED ENDEMISM.
Selected Species: This ecoregion’s migratory fish species include the rare Chinese sturgeon (Acipenser sinensis) and two shads (Tenualosa reevesii and Clupanodon thrissa).
General Threats: Over 3000 dams have been built on the Xi Jiang River and its tributaries, blocking the migration of freshwater and anadromous species. Over seventy-five percent of land in the basin is cropland and eighty percent of the original forest has been lost. Thus, the landscape around the rivers and streams has been severely changed, leaving little of the natural vegetation to buffer water flowing overland to the streams. One result is water pollution. Population in the delta of this river is expected to double over the next 25-50 years, and with an increasing population will come an increasing need for fresh water.
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estern Ghats Rivers and Streams [171] – India
Geographic Location: Southwestern Asia
Biodiversity Features: The small rivers and streams draining the old and relatively stable Western Ghats host a highly endemic aquatic biota. Over 100 fish and about 20 percent of the mollusc species are endemic to this ecoregion. Additionally, nearly 100 amphibian species may be endemic to this ecoregion. Isolated region Characterized by small coastal drainages with a high degree of endemism
Selected Species: Eighteen fish species in six families are recognized as threatened, including Malabar batasio (Batasio travancoria), Peninsular hilltrout (Lepidopygopsis typus), six species in the genus Hypselobarbus, and Indian blind catfish (Horaglanis krishnai). Two endemic genera of gastropods, Turbinicola and Cremnoconchus, also live here.
General Threats: Deforestation and its consequent effects on water quality and flow regimes pose the largest threats to freshwater systems in this ecoregion, particularly through increased sedimentation. Conversion of forest to agriculture (e.g., rubber plantations) is an additional threat. Fish are also harvested intensively by growing populations. Urbanization, construction of dams, and water diversion projects are expected to increasingly threaten the integrity of these systems.
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outhwestern Sri Lanka Rivers and Streams [172] – Sri Lanka
Geographic Location: Island to the Southeast of India, southern Asia
Biodiversity Features: Much of Sri Lanka is arid; consequently there are few perennial rivers. However, the southwestern region’s wet zone is characterized by numerous rivers that arise in the high mountains of the central part of the island. These diverse river basins support endemic populations of aquatic plants, bivalves, and fish. Sri Lanka’s known freshwater species include 90 fish and 21 crabs, yet ongoing studies suggest that the number of undescribed species is potentially quite large, especially given revision of earlier taxonomies. Distinctive island fauna with high levels of endemism
Selected Species: Several fish species of an endemic barb genus, Puntius, are considered vulnerable: P. cumingii, P. nigrofasciatus, P. martenstyni, P. pleurotaenia, and P. titteya. One species, P. bandula, is crictically endangered. A number of other endemics are found in these streams, including several species of concern: a loach (Lepidocephalichthys jonklaasi), rasporas (Rasbora wilpita, R. vaterifloris), and a gourami (Malphuhutta kretseri).
General Threats: Deforestation for fuelwood and agriculture, along with instream habitat alteration, has damaged many of the freshwater ecosystems. A number of species adapted to still or slow-water environments are threatened by conversion of habitats for rice cultivation. The introduction and dispersal of several exotic species has increased pressure on natives. Pesticide use and collection of fish for the aquarium trade pose additional threats.
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alween River [173] – China, Myanmar, Thailand
Geographic Location: Southeast Asia
Biodiversity Features: The Salween River originates in the eastern highlands of the Tibetan Plateau and flows through valleys that are at first steep and narrow, then increasingly broad as the river appraoches the tropical lowlands. Eventually it enters the Andaman Sea in eastern Myanmar. About 140 fish live in this river and approximately one-third of these are endemic. Minnows (Cyprinidae) are the most diverse group of fish. This area is also home to the world’s most diverse turtle community, with between 10 and 15 genera of turtles represented, many of which are riverine species. HABITATS IN THIS ECOREGION SUPPORT A RICH AND ENDEMIC FRESHWATER FAUNA
Selected Species: Endemic fish species include Hampala salweenensis and Hypsibarbus salweenensis. Freshwater turtles found in the Salween include stream terrapin (Cyclemys dentata), giant Asian pond terrapin (Heosemys grandis), and bigheaded turtle (Platysternon megacephalum). The Salween delta and associated wetlands also support populations of fishing cat (Prionailurus viverrinus), Asian small-clawed otter (Aonyx cinerea), and Siamese crocodile (Crocodylus siamensis).
General Threats: Intensive agriculture, fishing, and mining are all threats in this ecoregion. Until recently, hills in the drainage of the Salween were extensively logged, but this activity has been banned out of concern that siltation increases flooding downstream. In addition, the construction of dams and interbasin water transfers pose significant problems for the integrity of these freshwater systems, and in particular for migratory species. As this part of Southeast Asia is poised to undergo rapid economic development, a large increase in the number of dams on the Salween and its tributaries seems almost inevitable. Mitigation of the effects of dams will be an important conservation strategy for this region.
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undaland Rivers and Swamps [174] – Brunei, Malaysia, Indonesia, Singapore
Geographic Location: Southeast Asia
Biodiversity Features: This ecoregion contains a diversity of freshwater habitats, including hill streams, lowland floodplains, and peat swamps. The fish and decapod crustaceans of this ecoregion are remarkably rich and differentiated, with endemic species found in many individual river basins. Known freshwater fish species total 272 in Sumatra and 394 in Borneo. While many of these are common to both islands, Borneo has 149 endemic fish and Sumatra has 30. Likely the richest freshwater faunas in asia with much island and local endemism
Selected Species: Endemic freshwater fish include several shark catfish of the Pangasius genus; several bettas (Betta spp.), four species of hillstream loaches (Protomyzon spp.), and tapah (Wallago maculatus). Also present is the endangered Asian arowana (Scleropages formosus).
General Threats: Deforestation for logging, conversion to agriculture, overfishing, exotics, the aquaculture industry, and mining pollution threaten these habitats and their native species. Proposed hydropower dams on high-gradient streams would jeopardize the natural flow regime and species movements.
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