Ratha Sor

• PhD in Ecology and Environmental Modelling
• Director at National University of Cheasim Kamchaymear

The Lower Mekong Basin has had extensive hydropower dam development, which changes its hydrologic conditions and threatens the exceptional aquatic biodiversity. This study quantifies the degree of hydrologic change between pre-impact (1965–1968) and post-impact (2018–2021) peak hydropower development in two major tributaries of the Lower Mekong Bas...

Fish from Cambodia's Tonle Sap Lake are economically, culturally, and nutritionally significant for people in the Lower Mekong Basin, providing income, livelihoods, and protein. Fish in this system generally migrate toward upstream Mekong River in dry season and return in early wet season. However, drivers of fish migration from Tonle Sap Lake to t...

The gekkonid lizard Cyrtodactylus intermedius was formerly considered to be a single widespread species in hilly areas across eastern Thailand through southern Vietnam but has recently been partitioned into a complex of 12 nominal species across its range. A population belonging to the C. intermedius group was recently found in an isolated limeston...

The Lower Mekong Basin has had extensive hydropower dam development, which changes hydrologic conditions and threatens the exceptional aquatic biodiver-sity. This study quantifies the degree of hydrologic change between pre-impact (1965-1968) and post-impact (2018-2021) peak hydropower development in two major tributaries of the Lower Mekong Basin,...

Migratory fishes of the Mekong Basin are facing challenges from human-induced stressors. Quantifying the patterns of fish’s early life stages provides important information on spawning seasons, spawning and nursery habitats, reproductive strategies, migration and dispersal patterns, and stock status. However, the ecology of the Mekong larval fishes...

The Tonle Sap Lake and River basin cover almost half of Cambodia's land surface, contain one of the world's largest inland fi sheries and are rich in biodiversity. While the Tonle Sap Lake and its relationship to the Mekong River is well studied, until now the freshwater health of the basin has been overlooked. We used a freshwater health index to...

Predictive models are widely used to investigate relationships between the distribution of fish diversity, abundance, and the environmental conditions in which they inhabit, and can guide management actions and conservation policies. Generally, the framework to model such relationships is established; however, which models perform best in predictin...

Hydropower dams are a source of renewable energy, but dam development and hydropower generation negatively affect freshwater ecosystems, biodiversity, and food security. We assess the effects of hydropower dam development on spatial–temporal changes in fish biodiversity from 2007 to 2014 in the Sekong, Sesan, and Srepok Basins—major tributaries to...

Drought is a natural hazard that stresses ecosystems, agricultural production, food security, and local economies. Given ongoing hydropower dam development in the Sesan and Srepok Basins, the two most dammed tributaries in the Lower Mekong Basin, characterizing baseline drought events and understanding how dams modify downstream flow is needed to m...

Cambodia has experienced political and economic changes in recent decades and the same is true of agricultural land use in the country. We assessed past (1980-1989), present (2010-2019) and potential future trends in agricultural land-use, economic efficiency and management practices around the Tonle Sap Lake (TSL) and upper and lower sections of t...

The Mekong River is one of the world’s largest rivers, unparalleled in terms of its biodiversity and ecosystem services. As in other regions, sufficient water quality is required to support diverse organisms, habitats, and ecosystems, but in the Mekong region, water quality has not been well studied. Based on biological and physical-chemical data c...

Oceanic islands harbor unique yet fragile marine ecosystems that require evidence-based environmental management. Among these islands, the Galapagos archipelago is well known for its fish diversity, but the factors that structure communities within and between its islands remain poorly understood. In this study, water quality, physical habitats and...

Mayflies (Ephemeroptera) are an aquatic order of insects whose larval stages are generally associated with different habitat types in freshwater ecosystems. We investigated the species diversity, abundance and habitat associations of mayflies along a previously unstudied freshwater stream in the Chambok area of Kampong Speu Province, southwest Camb...

In Mekong riparian countries, hydropower development provides energy, but also threatens biodiversity, ecosystems, food security, and an unparalleled freshwater fishery. The Sekong, Sesan, and Srepok Rivers (3S Basin) are major tributaries to the Lower Mekong River (LMB), making up 10% of the Mekong watershed but supporting nearly 40% of the fish s...

The Lower Mekong Basin (LMB) is a key biodiversity hotspot. To facilitate conservation and management, we examine mollusc biodiversity patterns and distribution along LMB's longitudinal gradients, identify environmental drivers, and discuss the importance of these drivers to management. Cluster analysis, redundancy analysis (RDA), and variation par...

Bats provide economically significant ecosystem services in insect pest suppression. As little is known regarding the diets of insectivorous bats in Cambodia, we sampled these in the Chambok area of Kampong Speu Province in August 2018 so as to describe and compare their specific diet preferences. Our field survey yielded 294 faecal pellets produce...

Aquatic insects are commonly used as bioindicators of water quality in semi-natural and natural aquatic systems. However, such studies are still limited in urban environments in Cambodia. We investigated aquatic insect life and its relationship to water quality in fi ve ponds located on the grounds of the Royal University of Phnom Penh in Cambodia....

Aquatic insects are commonly used as bioindicators of water quality in semi-natural and natural aquatic systems. However, such studies are still limited in urban environments in Cambodia. We investigated aquatic insect life and its relationship to water quality in fi ve ponds located on the grounds of the Royal University of Phnom Penh in Cambodia....

Executive Summary Currently, the underground and aboveground water in Siem Reap city, which is mainly sourced in Phnom Kulen National Park (PKNP), was substantially extracted (approximately 6.8 million m3) and sold in an estimated value of US$ 1.9 million. In the same year for Preah Sihanouk Ville, approximately 10.7 million m3 is exploited and sol...

The main challenges for ecological studies are the complexity and non-stationarity of data that are difficult to handle using traditional modelling methods. Thus, to address these problems, modern modelling techniques have been developed and introduced for applications. In time-series data, the cross-wavelet transform (CWT) and cross-correlation fu...

Supplementary Information for: Ngor PB, Sor R, Prak LH, So N, Hogan ZS, Lek S. 2018. Mollusc fisheries and length–weight relationship in Tonle Sap flood pulse system, Cambodia. Ann. Limnol. - Int. J. Lim. 54: 34

Molluscs are important for ecological function, livelihoods and fisheries, but are often forgotten in research and management. Here, we investigated intra-annual variation in the landing and growth patterns of three mollusc species, i.e., Corbicula moreletiana, Pila virescens and Pila ampullacea, using one-year daily data on landing catches and val...

Species co-occurrence and site-specific characteristics have a great influence on biotic community composition at local scales and thus contribute to large variations at broad spatial scales. In this paper, we studied invertebrate communities in 63 river sites of the Lower Mekong Basin (LMB) sampled over 609 thousand km 2. We identified important m...

The number of macroinvertebrate species (299) identified in the present study is the largest ever reported from the Lower Mekong Basin. Each component (i.e. annelids, crustaceans, mollusks and insects) comprised a higher number of taxa than previous reports of field studies.

Freshwater tropical and temperate river systems are known to support different biotic communities. In this study, I investigated benthic macroinvertebrate community composition and diversity and its spatial and temporal variation both in tropical Asian and temperate European regions. I also examined the influences of physical-chemical water quality...

Predictive models are useful to support decision making, management and conservation planning. However, the performance of models varies across techniques and is affected by several factors including species prevalence (i.e. the occurrence rate of each species in the total samples). Here, we analysed and compared the performance of four common mode...

The invasion of alien species can have serious economic and ecological impacts. Ecologically, invasions often lead to an increased rate of native species replacement and decreased biodiversity. A critical step in the dominance of alien species is their successful co-occurrence with native species. In this study, we assessed the occurrence of alien...

In this study, we investigated patterns of spatial variation in macroinvertebrate assemblages in the Lower Mekong Basin (LMB) and examined their relationship with environmental factors. Cluster analysis was used to group macroinvertebrate samples and Linear Discriminant Analysis was performed to discriminate the major factors associated with the ma...

Rotifer samples were seasonally collected in 2010 from ponds, lakes, reservoirs and rivers in the upper part of the Cambodian Mekong River in Kratie, Stung Treng and Ratanakiri Provinces. A 30 μm mesh plankton net was used to collect samples. The water quality parameters: temperature, pH, electrical conductivity, turbidity and dissolved oxygen were...

The incidence and abundance of Monogononta rotifer species were recorded from lakes and reservoirs in the upper part of the Cambodian Mekong River basin in April and November 2010. One hundred and seven species are reported, 25 of which are new records to Cambodia and 8 taxa were unidentifiable to species level. Species richness at the regional and...

Despite the importance of rotifers in freshwater ecosystems and their dominance in zooplankton lake communities, the group is little studied in Southeast Asia. As rotifers have potential as bio-indicators, for example in assessing the impact of reservoir creation, such as in large dam creation projects, increased knowledge could be beneficial for w...

Despite the importance of rotifers in freshwater ecosystems and their dominance in zooplankton lake communities, the group is little studied in Southeast Asia. As rotifers have potential as bio-indicators, for example in assessing the impact of reservoir creation, such as in large dam creation projects, increased knowledge could be beneficial for w...

Despite the importance of rotifers in freshwater ecosystems and their dominance in zooplankton lake communities, the group is little studied in Southeast Asia. As rotifers have potential as bio-indicators, for example in assessing the impact of reservoir creation, such as in large dam creation projects, increased knowledge could be beneficial for w...