Agusan marsh (9785)
Philippines, Asia
Site overview
KBA status: confirmed
Year of last assessment: 2006
National site name: Agusan marsh
Central coordinates: Latitude: 8.1500, Longitude: 125.9500
System: freshwater, terrestrial
Elevation (m): 40 to 50
Area of KBA (km2): 143.48727
Protected area coverage (%): 100.00
KBA classification: Global
Legacy site: Yes
Site details
Site description: Agusan Marsh is near Bunawan in the interior of north-eastern Mindanao Island, Agusan del Sur Province. It is a vast complex of freshwater marshes and watercourses with numerous small shallow lakes and ponds in the upper basin of the Agusan River and its tributaries. The rivers rise in the hills of eastern Mindanao and cause extensive flooding in the marshes from November to March. The main habitats of the marsh include freshwater swamp forest (c.49%), secondary scrub (c.14%), herbaceous swamp (c.7%), freshwater lakes, pools and rivers (c.10%), rice paddies and other agricultural land (c.6%) and small settlements (c.6%). Some parts of the marsh have been converted into fishponds. The main economic activities in the marsh are fishing, aquaculture and agriculture (mainly rice and cash crops), but the region is sparsely populated because of the annual flooding of the Agusan River. The marsh is an important source of water for irrigation. It has an important hydrological function, holding excess water at times of high flow, and ensuring adequate flow during dry periods. If the marsh were to be drained, the communities downstream would be prone to serious floods and droughts.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs. KBA identified in the CI/CEPF Conservation Outcomes booklet for the Philippines Hotspot (2006). Taxonomy, nomenclature and threat category follow the 2004 IUCN Red List.
Additional biodiversity: This IBA is important for a variety of waterbirds, notably herons and egrets. Several threatened species have been recorded in or near to Agusan Marsh in the past, mainly forest birds, but it is unclear whether they have significant populations in the remaining forests there. However, Silvery Kingfisher has recently been recorded in the marsh itself, and there may be a significant population of Philippine Duck there. Non-bird biodiversity: The marshes support the largest population of the Estuarine Crocodile Crocodylus porosus remaining in the Philippines, and it has been suggested that the endangered Philippine Crocodile C. mindorensis may also be present
Habitats
Summary of habitats in KBA: Agusan Marsh is near Bunawan in the interior of north-eastern Mindanao Island, Agusan del Sur Province. It is a vast complex of freshwater marshes and watercourses with numerous small shallow lakes and ponds in the upper basin of the Agusan River and its tributaries. The rivers rise in the hills of eastern Mindanao and cause extensive flooding in the marshes from November to March. The main habitats of the marsh include freshwater swamp forest (c.49%), secondary scrub (c.14%), herbaceous swamp (c.7%), freshwater lakes, pools and rivers (c.10%), rice paddies and other agricultural land (c.6%) and small settlements (c.6%). Some parts of the marsh have been converted into fishponds. The main economic activities in the marsh are fishing, aquaculture and agriculture (mainly rice and cash crops), but the region is sparsely populated because of the annual flooding of the Agusan River. The marsh is an important source of water for irrigation. It has an important hydrological function, holding excess water at times of high flow, and ensuring adequate flow during dry periods. If the marsh were to be drained, the communities downstream would be prone to serious floods and droughts.
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Artificial - Terrestrial | 20 | |
| Wetlands(Inland) | 40 | |
| Forest | 40 |
Threats
Summary of threats to biodiversity at KBA: Clear cutting of forests in the water catchment area of Agusan Marsh, including the Diwata Mountains of Surigao del Sur to the east and the mountains of Bukidnon and Davao del Norte to the south, has resulted in severe flooding and increased rates of sedimentation in the wetland. Parts of the marsh have already been converted into aquaculture ponds and agricultural land. Proposed development projects in the water catchment area include the construction of dams and reservoirs for hydroelectric power, flood control and irrigation purposes. Other pressures on this IBA include the collection of forest products, mercury pollution from small-scale mining, and the hunting of birds. The crocodiles are also heavily persecuted.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Biological resource use | Logging & wood harvesting | Unintentional effects: large scale (species being assessed is not the target) [harvest] | Ongoing |
| Pollution | Industrial & military effluents | Seepage from mining | Ongoing |
| Agriculture & aquaculture | Marine & freshwater aquaculture | Subsistence/artisinal aquaculture | Ongoing |
| Agriculture & aquaculture | Annual & perennial non-timber crops | Small-holder farming | Ongoing |
| Natural system modifications | Dams & water management/use | Large dams | Only in the future |
| Biological resource use | Gathering terrestrial plants | Unintentional effects (species being assessed is not the target) | Ongoing |
| Biological resource use | Hunting & collecting terrestrial animals | Intentional use (species being assessed is the target) | Ongoing |
Additional information
References: Davies et al. (1990); Scott (1989).