An eDNA‐based assessment of Garra cambodgiensis (stonelapping minnow) distribution on a megadiverse river, the Mekong

• Published in: Ecology and evolution 2024-02, Vol.14 (2), p.e10898-n/a
• Main Authors: Osathanunkul, Maslin, Suwannapoom, Chatmongkon
• Format: Article
• Language: English
• Subjects: Biodiversity Ecology; Conservation; Conservation Ecology; Conservation Genetics; Dams; data‐poor area; Decision making; economically important fish; Environmental DNA; Environmental monitoring; Feasibility studies; Fish; Fisheries; Fisheries management; Fishing; Freshwater fish; Garra cambodgiensis; Genetic testing; Genetics; Geographical distribution; Methods; Monitoring; Population decline; River systems; Rivers; Species; species occurrence and distribution; species‐specific detection; Surveys; System effectiveness; the Mekong River; Water analysis; Water sampling
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.10898

Garra cambodgiensis (stonelapping minnow) has experienced significant population declines, prompting intensive research and management, although its distribution in river systems such as the Mekong remains obscure. Effective conservation and management necessitate accurate monitoring and survey data on the distribution of freshwater species. Traditional surveying techniques for fish may be challenging and generate insufficient data on species distribution. This study developed an eDNA‐based method for detecting G. cambodgiensis to address this void. Twenty‐one locations were surveyed. Water samples were collected in triplicate from the river's surface at each site and processed within 48 h in a dedicated laboratory. Primers and probes for G. cambodgiensis were meticulously designed and species‐specificity tested to ensure accurate detection without interference from co‐occurring species in the same geographic range. Each water sample was analysed by qPCR using six technical replicates. The results of qPCR were reported as positive with quantifiable eDNA concentration (copies/mL), below the limit of quantification, or non‐detectable. G. cambodgiensis eDNA was detected in water samples collected from 10 out of 21 sampling sites, with concentrations ranging from 8.5 to 2990.0 copies/mL. Importantly, G. cambodgiensis eDNA was consistently detected in all three replicate water samples at each site where the qPCR experiment yielded positive results. The findings of this study demonstrate the feasibility and effectiveness of incorporating eDNA‐based monitoring or surveys for G. cambodgiensis in the ecologically diverse Mekong River. Monitoring based on eDNA can aid in targeting and informing conservation and management of G. cambodgiensis in its natural habitat. Comprehensive and robust information on species distribution can be obtained via an eDNA‐based survey, which could contribute to more efficient and informed decision‐making processes in fisheries management and conservation efforts. This study developed an eDNA‐based method to accurately monitor the distribution of Garra cambodgiensis in the Mekong River, where population declines have raised conservation concerns. The eDNA technique successfully detected G. cambodgiensis in water samples from 10 out of 21 survey sites, demonstrating its feasibility and effectiveness in the ecologically diverse Mekong River. This innovative approach can enhance conservation and management efforts by providing comprehensiv