in Sri Lanka - Ministry of Environment

and eutrophication (due to agricultural fertilizers and pesticides, and residues from illegalbreweries) are major threats identified for the Muthurajawela marshes (IUCN Sri Lanka andCEA, 2006). This marsh is a habitat for threatened aquatics, Aponogeton natans (L.) Engler& Krause, Murdannia gigantea (Vahl) G. Bruckn. and Nympoides aurantiacea (Dalz.) Krutze.Construction of dams across major rivers, especially the Mahaweli, has affected the downstreamvegetation. Due to further diversion and impoundments in the upstream areas of the Mahaweliriver, the water flow has been reduced causing the drying up of about one third of the villus inthe Mahaweil villu system and affecting the aquatics. Further, this has facilitated the spreadof alien plants such as Eichhornia crassipes, Xanthium indicum Koenig and Salvinia molestaaffecting the natural villu vegetation (IUCN Sri Lanka and CEA, 2006). These villus also harborwild relatives of rice such as Oryza rufipogon Griffith and O. eichingeri Peter.Apart from these threats, construction of mini-hydropower plants at a rapid rate during thepast few years has added to deterioration of many habitats of aquatic plants. One of the mostaffected groups being the family Podostemaceae, a group of flowering plants that only growson stones in rapidly flowing streams and rivers with changing water levels. Due to this habitatpreference, it occurs only in few specific localities and is difficult to be conserved under in situconditions. The richest site for these members at Gannoruwa-Hallolluwa area of the Mahaweliriver is presently being disturbed by the construction of a mini-hydropower plant. Farmeriametzgerioides (Trimen) Willis ex Hook.f. and Polypleurum elongatum (Gardner) J.B.Hall areendemic members of the seven species of Podostemaceae recorded in Sri Lanka while sixof them, including the two endemics, are found at this location. The blasting of large rocksin the river has directly affected the aquatic vegetation while the resulting reduction of waterflow will affect the downstream vegetation. In addition four Cryptocoryne species have beenrecorded as occurring in the rapids at this location. Cryptocoryne parva de Wit grows closestto the water where the course is rapid. Cryptocoryne walkeri Schott grows in a little further up,but is also rather exposed, while C. beckettii Trimen and C. undulata Wendt. are found evenfurther up on the banks. The hybrid, C. x willisii Reitz is found in several locations, both lowand high, in the shade and the sun (Jacobsen, 1986). The construction of the Upper Kotmalehydropower project and restriction of downstream water flow have affected many downstreamplants including Zeylanidium subulatum (Gardner) C. Cusset and Z. olivaceum (Gardner) Engl.of the Podostemaceae.Further, illegal constructions and dumping of soils along water courses, including the mainrivers, cause a serious threat to riverine vegetation, including species such as Lagenandra andHygrophila. The Mahaweli river along Peradeniya to Katugastota, on both sides of the bank,could be identified as one of the severely affected areas due to development activities alongthe river bank. This stretch once again includes the Gannoruwa-Hallolluwa area, one of therichest aquatic floral habitats providing home to three Critically Endangered (two endemics andone native), three Endangered (one endemic and two native), three Vulnerable (endemic) andone native Endangered species. Encroachments for settlement, building of hotels borderingthe river, and utilising of the river banks for waste disposal and dumping could be witnessedand are still continuing at an alarming rate.Over-exploitation of species: Many aquatic plants, especially the species with an ornamentalvalue, are being extracted from the wild. Over-exploitation of species has led to a decline in191