Modelling future changes of habitat and fauna in the Tonle Sap wetland of the Mekong

Abstract

SUMMARYThe Tonle Sap is the largest wetland in Southeast Asia and the heart of the largest inland fishery in the world. Its unique flood pulse system and annual flow reversal is a hotspot for biodiversity and productivity, as well as an essential habitat for many endangered fishes and birds. Despite predicted changes to the wetland's hydrology due to climate change and hydropower development in the Mekong, the consequent impacts on the fauna of the lake are poorly understood. A spatial modelling framework was developed to simulate the impact of potential scenarios of change using relationships between fauna and biophysical characteristics. Potential impacts on 61 animal species with documented nutritional, conservation or ecological value were examined. A large number of species rely on gallery forest to provide important habitats for their life history, yet this area is likely to be highly impacted by permanent inundation. There is a strong synchronicity between life histories and the flood pulse; consequently continued hydrological disruptions will have a significant impact on ecosystem dynamics, imposing further challenges to conservation. Protecting areas that may become suitable for gallery forests and shrublands under a modified flood regime will be crucial to management planning and the maintenance of a diverse and healthy ecosystem.

Can river management improve the piping plover’s long-term survival on the Missouri River?

“…Many wild species use riverine and floodplain habitats for one or more life history stages. For many species, even the immediate, direct effects of river management decisions are still poorly understood (Arias et al, 2013;Cheek et al, 2014;Strayer and Dudgeon, 2010), but our results suggest that subtle, long-term effects also may occur. Given expected increases in the intensity of management of rivers and other freshwater systems (Strayer and Dudgeon, 2010;Vorosmarty et al, 2010), a deeper understanding of the multiple effects of river management actions is needed.…”

Spatio-temporal variation of fish taxonomic composition in a South-East Asian flood-pulse system

“…The TSL is the largest inland fisheries in South-east Asia and supports the livelihood of 2.5 million people around the lake [8]. Its flood-pulse dynamic combined to the flow reversal of the TSR make it a unique system worldwide supporting high biodiversity by providing a large diversity of food and habitats for many birds and fishes.…”

“…Its flood-pulse dynamic combined to the flow reversal of the TSR make it a unique system worldwide supporting high biodiversity by providing a large diversity of food and habitats for many birds and fishes. However, the growing demand for water for agricultural purposes and the construction of hydro-power dams along the Mekong river [8] combined to the effect of climate change is strongly threatening this system by altering and reducing flood intensity from 7% to 16% during the rainy season [35]. Such changes in the water regime are likely to have strong impacts on fish community composition by modifying several phenological events [36] such as the timing of migration or spawning and also by reducing the amount of submerged habitats upon which fish depends for growing and spawning.…”

“…it was designated as a UNESCO Biosphere Reserve in 1997), providing essential habitats for many endangered fishes and birds [8,9]. The TSL is a typical seasonal flood-pulse system and is a key element for the annual Mekong’s flood.…”

Modelling inundation patterns and sediment dynamics in the extensive floodplain along the Tonle Sap River

“…Average annual precipitation ranges from 1,300 to 1,500 mm. Flooding is an annual event, occurring as a flood pulse along the TSR and TSL and bringing in 65% of the total annual precipitation to the MR basin (Arias, Cochrane, & Elliott, ). The characteristics of the flood pulse vary year to year depending on the volume and water level of the TSR (Lamberts, ).…”