Southwestern Sri Lanka Rivers and Streams - A Global Ecoregion
More than one-fourth of the freshwater fish are endemic
Snapshot: Ecoregion 172
Size:
15,500 sq. km (6,000 sq. miles)
Habitat type:
Small Rivers
Asia: Sri Lanka, an island southeast of India
Conservation Status:
Vulnerable
Quiz Time!
How does this ecoregion harbour such a high number of endemic fish species?
Answer:
Many of Sri Lanka's so-called "rivers" are really small, narrow brooks that are dry except during the rainy season. On the other hand, the rivers and streams that flow through the southwestern Wet Zone are full year-round and carry half of all the freshwater on the island.
About the Area
Much of Sri Lanka is arid and has only a few permanent rivers. However, the southwestern region's "wet zone" is characterised 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. Local Species
Sri Lanka's known freshwater species include 90 fish (with twenty-six endemics) and 21 crabs, yet ongoing studies suggest that the number of undescribed species is potentially quite large.
Most of these fish are small and highly specialised to their habitat. Several fish species of an endemic barb genus, Puntius, are considered vulnerable, these include P. cumingii, P. nigrofasciatus, P. martenstyni, P. pleurotaenia, and P. titteya. One species, P. bandula, is critically endangered.
Rare endemic species include the Jonklaas loach (Lepidocephalichthys jonklaasi), Rasporas (Rasbora wilpita, R. vaterifloris), and the spotted Gourami (Malphuhutta kretseri).
Threats
Deforestation for fuel wood and agriculture, in stream habitat alteration, introduced species, pesticide use, and collection of fish for aquarium trade has damaged parts of the freshwater ecosystem.
A number of species adapted to still or slow-water environments are threatened by conversion of habitats for rice cultivation.
Resources
• NationalGeographic.com
