Jujing Wang,Haimei Lin,Jinsheng Xiao,Guiyu Tan,Luobin Yan,Jiabo Chen,Jun Zhao,Junjie Wang
The wild resources ofSpinibarbus caldwelli, once an important economic fish in southern China, have been drastically reduced in recent years due to environmental changes and human activities. The Liuxi RiverS. caldwelliNational Aquatic Germplasm Reserve was established in Conghua District, Guangzhou city, and the release ofS. caldwelliwas carried out. However, traditional fishery resource survey methods yield less accurate results when the abundance of the surveyed species is low or when they are difficult to catch. As a non-destructive and non-invasive approach, environmental DNA (eDNA) is widely employed in aquatic species monitoring, though its detection efficiency may be affected by environmental conditions. Therefore, this study explored the eDNA monitoring methods ofS. caldwelliin Liuxi River from the following four aspects: (1) the relationship between eDNA release and biomass/abundance; (2) the concentration and diffusion range of eDNA over time in a lentic ecosystem; (3) the diffusion range of eDNA in a lotic ecosystem; and (4) the effects of eDNA application in field monitoring. Our results showed a correlation between eDNA concentration and abundance/biomass ofS. caldwelli. eDNA ofS. caldwellican diffuse up to 18 m in lentic ecosystems within 2 h and decreases with distance. eDNA ofS. caldwellireleased by 10 individuals in Liuxi River could be detected 900 m downstream. Field studies in Liuxi River showed that the eDNA method has high sensitivity in detecting the presence or absence of species and is highly consistent with the results of traditional methods. This study explored the application of environmental DNA technology in species monitoring in Liuxi River. Our aim was to evaluate the applicability and potential of eDNA in ecological monitoring of stream fishes.
Zongwu Wei,Xuzhe Zhang,Yingzhan Chen,Hongjie Liu,Shaopeng Wang,Man Zhang,Honglin Ma,Kefu Yu,Liwei Wang
Population outbreaks of the crown-of-thorns starfish (COTS) seriously threaten the sustainability of coral reef ecosystems. However, traditional ecological monitoring techniques cannot provide early warning before the outbreaks, thus preventing timely intervention. Therefore, there is an urgent need for a more accurate and faster technology to predict the outbreaks of COTS. In this work, we developed an electrochemical biosensor based on a programmed catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) cyclic amplification strategy for sensitive and selective detection of COTS environmental DNA (eDNA) in water bodies. This biosensor exhibited excellent electrochemical characteristics, including a low limit of detection (LOD = 18.4 fM), low limit of quantification (LOQ = 41.1 fM), and wide linear range (50 fM – 10 nM). The biosensing technology successfully allowed the detection of COTS eDNA in the aquarium environment, and the results also demonstrated a significant correlation between eDNA concentration and COTS number ( r = 0.990; P < 0.001). The reliability and accuracy of the biosensor results have been further validated through comparison with digital droplet PCR (ddPCR). Moreover, the applicability and accuracy of the biosensor were reconfirmed in field tests at the COTS outbreak site in the South China Sea, which has shown potential application in dynamically monitoring the larvae before the COTS outbreak. Therefore, this efficient electrochemical biosensing technology offers a new solution for on-site monitoring and early warning of the COTS outbreak.
Wastewater discharge is considered to be one of the anthropogenic factors affecting the water quality of urban rivers. The source and composition of wastewater are complex and diverse, and it is difficult to evaluate its effect on water quality and ecological health of receiving waters. Environmental DNA method can determine all species living in waters by examining DNA sequences, reflecting the impact of water quality changes on aquatic systems. In this study, water samples from two urban rivers were collected in dry and wet seasons, and the composition of pollutants was investigated by nontarget screening. Based on the pollutant composition, compound toxicity prediction and concentration addition model were used to predict the toxicity changes of pollutants in the urban rivers. More than 1500 suspect organic pollutants were nontarget screened, and silafluofen was found to be a major toxicity contributor. Environmental DNA analysis was combined with water quality measure and pollutant toxicity prediction to reveal the effects of pollutants from different sources on aquatic ecosystems . Fish diversity was negatively correlated with the mixed toxicity of organic pollutants, suggesting potential ecological risk in these two urban rivers. Our study developed a water quality assessment method based on pollutant composition and toxicity, and the potential risk of nonpoint source pollutants on aquatic ecosystems should not be neglected.
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