Prior to this study, few collections and records were made of the land snails in Cambodia and the historical taxa had never been reviewed. Herein a report on the land snail diversity based on specimens collected recently from karstic and non-karstic areas in southern Cambodia is provided. This checklist presents 36 species of land snails (two Neritimorpha, six Caenogastropoda, and 28 Heterobranchia). Illustrations and brief taxonomic notes/remarks are provided for every species. We also describedGeorrisa carinataSutcharit & Jirapatrasilp,sp. nov.based on some distinct shell morphological characters. Since the first descriptions during the colonial period in the nineteenth century, some land snail species (e.g.,Trichochloritis norodomiana,Durgella russeola,Anceyoconcha siamensis obesulacomb. nov.,Anceyoconcha chaudoensiscomb. nov., andSuccinea tenuis) have not been reported subsequently. This probably reflects a lack of knowledge concerning land snail biodiversity in this country. To our knowledge, this is the first comprehensive survey of land snails in southern Cambodia. A need for more field research and systematic revision of the land snails in this interesting region is also highlighted and demonstrated.

Optimizing flow in dammed rivers: Hydropower dams radically alter river flow regimes, often with consequences for the functioning and productivity of the waters downstream. Where fisheries in large tropical river systems are affected, there can be knock-on effects on food security. For the Mekong River, Sabo et al. used a data-based time series modeling approach to estimate the features of the flow regime that optimize the fishery that is crucial to food security in Cambodia (see the Perspective by Poff and Olden). Fish futures can be maximized within a managed hydrologic system with careful prescription of flows. Such data-driven approaches can be used to link hydrology to ecology and food production and specify design principles that could help to deliver food security in other river systems. Science , this issue p. eaao1053 ; see also p. 1252

While human impacts like fishing have altered marine food web composition and body size, the status of the world’s important tropical inland fisheries remains largely unknown. Here, we look for signatures of human impacts on the indiscriminately fished Tonle Sap fish community that supports one of the world’s largest freshwater fisheries. By analyzing a 15-year time-series (2000–2015) of fish catches for 116 species obtained from an industrial-scale ‘Dai’ fishery, we find: (i) 78% of the species exhibited decreasing catches through time; (ii) downward trends in catches occurred primarily in medium to large-bodied species that tend to occupy high trophic levels; (iii) a relatively stable or increasing trend in catches of small-sized species, and; (iv) a decrease in the individual fish weights and lengths for several common species. Because total biomass of the catch has remained remarkably resilient over the last 15 years, the increase in catch of smaller species has compensated for declines in larger species. Our finding of sustained production but altered community composition is consistent with predictions from recent indiscriminate theory, and gives a warning signal to fisheries managers and conservationists that the species-rich Tonle Sap is being affected by heavy indiscriminate fishing pressure.

Taxonomic work on the land snail genus Sarika Godwin-Austen, 1907 in Cambodia is scarce. A total of three species were recognized from Cambodia prior to this study. However, their taxonomic descriptions were based mainly on shell morphology, with limited genital data. To address this knowledge gap, we opportunistically surveyed for land snails in Cambodia. Our inventory yielded four species of Sarika – one recognized species, Sarika bocourti (Morelet, 1875), from Battambang Province and three new species, Sarika khmeriana Pholyotha & Panha sp. nov., Sarika lactoconcha Pholyotha & Panha sp. nov. and Sarika nana Pholyotha & Panha sp. nov. from Kampot and Takeo Provinces in southern Cambodia. Our discovery involves the first species of Sarika to be described from Cambodia in more than a century highlights the extent to which the diversity of Cambodian land snails remains to be discovered. The status of two species, Sarika benoiti (Crosse & Fischer, 1863) and Sarika resplendens (Philippi, 1846), is at present ambiguous because no material identifiable as these species was found in recent extensive surveys. Although S. bocourti was recently collected from Cambodia, its taxonomic position remained unclear due to a lack of living specimens. Detailed descriptions and illustrations of living animals, shell morphology and reproductive anatomy are provided, and a map showing their distributions is given.