Recent warming of Tonle Sap Lake, Cambodia: Implications for one of the world’s most productive inland fisheries

Abstract

Tonle Sap Lake in Cambodia is arguably the world's most productive freshwater ecosystems, as well as the dominant source of animal protein for the country. The rapid rise of hydropower schemes, deforestation, land development and climate change impacts in the Mekong River Basin, however, now represent serious concerns in regard to Tonle Sap Lake's ecological health and its role in future food security. To this end,

Annotated checklist of freshwater molluscs from the largest freshwater lake in Southeast Asia

“…Combined with other anthropogenic effects in the Tonle Sap basin such as floodplain infrastructure development ( Arias et al 2019 ), overfishing ( Ngor et al 2018c ; McCann et al 2016 ), invasive species (e.g., Pomacea spp. ), land cover change (e.g., habitat degradation) and climate change ( Arias et al 2014 ; Ngor et al 2018b ; Daly 2019 ), the future of these resources is in a precarious condition.…”

“…The presence of globally-invasive species like Pomacea maculata , and the prevalence of pest species like Limnoperna fortunei , which have the potential to replace and negatively impact the ecosystem and native species of the Tonle Sap basin is another major concern. In order to combat the combined pressures of invasive species, land cover change, climate change, dams along the main stem and tributaries of the Mekong River, among many other anthropogenic threats ( Ngor et al 2018b ; Uk et al 2018 ; Daly 2019 ), a multi-pronged approach is urgently required to study the biodiversity, ecology, ecosystem functioning of freshwater molluscs and other aquatic fauna in the Tonle Sap basin.…”

Temporal Dynamics of Fish Assemblages as a Reflection of Policy Shift from Fishing Concession to Co-Management in One of the World’s Largest Tropical Flood Pulse Fisheries

“…A similar situation has been described for many inland lakes around the world, leading to what has been termed "the tragedy of the inland lakes" [69]. Moreover, the declines are in part explained by the floodplain habitat alteration because substantial changes in land cover were observed recently during the ALA period, (e.g., decrease in scrubland, grassland, and flooded forest cover but increase in agricultural land), and flooded forest areas were shifted to woody savannah, grassland, and permanent wetland [31,[70][71][72]. By contrast, land cover did not change significantly during the BLA period [71], suggesting that fishing lot removal was likely a major factor influencing land cover change in the TSE.…”

“…Our results indeed strengthen the findings of many qualitative studies assessing the impacts of the two fisheries post-reform policies, consistently indicating that, while the reforms provided more access rights to small-scale fishers, the positive impacts of reforms on fish stocks in the TSL remain elusive. Fishing pressure, clearance of flooded forests, and industrial crop farming practices are indeed intensifying particularly in the TSL, threatening the TSL fish diversity and productivity [17,22,23,29,31,72,78]. These challenges were mainly attributed to the lack of effective legal and institutional instruments to implement the new fisheries policy and poor governance, e.g., lack of inter-sectoral coordination and cooperation among the government line agencies and other stakeholders at multiple levels, lack of knowledge on co-management regimes, and other basic means including funds to implement the policy, limited decentralization of roles and responsibilities from national to sub-national and community levels, overlapping stakeholders' roles and responsibilities among the government agencies to manage the TSL natural resources, pervasive illegal fishing activities, and strong livelihoods dependency of the local communities on fisheries, etc.…”

Spatial and Long-Term Temporal Changes in Water Quality Dynamics of the Tonle Sap Ecosystem

“…The flooded forest in the TSE has a constant annual loss rate of 1.2% for the last 25 years (from 1993 to 2017) [26]. Watershed characteristics of the TSE such as forest cover, climate, and agriculture influence lake characteristics (e.g., lake temperature) in the southern part of TSL [27]. The northern part of TSL receives higher nutrient concentrations due to human activities and development [2].…”