Conserving aquatic ecosystems requires efficient tools to accurately assess the biodiversity of aquatic species. However, existing knowledge is insufficient in terms of the reliability and the comparability of methods measuring fish diversity. Environmental DNA (eDNA), as a promising method, was used to detect fish taxa in this study. We optimized the eDNA method in the laboratory, and applied the optimal eDNA method to survey fish diversity in a natural aquatic life reserve. We simulated necessary steps of the eDNA method in the lab to increase the confidence of the field survey. Specifically, we compared different eDNA sampling, extraction, and sequencing strategies for accurately capturing fish species of the target area. We found that 1L water samples were sufficient for sampling eDNA information of the majority taxa. The filtration was more effective than the centrifugal precipitation for the eDNA extraction. The cloning sequencing was better than the high-throughput sequencing. The field survey showed that the Shannon–Wiener diversity index of fish taxa was the highest in Huairou Reservoir. The diversity index also showed seasonal changes. The accuracy rate of detecting fish taxa was positively correlated with the eDNA concentration. This study provides a scientific reference for an application of the eDNA method in terms of surveying and estimating the biodiversity of aquatic species.
Oral reference dose (RfD) is a key parameter for deriving the human health ambient water quality criteria (AWQC) for non-carcinogenic substances. In this study, a non-experimental approach was used to calculate the RfD values, which explore the potential correlation between toxicity and physicochemical characteristics and the chemical structure of pesticides. The molecular descriptors of contaminants were calculated using T.E.S.T software from EPA, and a prediction model was developed using a stepwise multiple linear regression (MLR) approaches. Approximately 95% and 85% of the data points differ by less than 10-fold and 5-fold between predicted values and true values, respectively, which improves the efficiency of RfD calculation. The model prediction values have certain reference values in the absence of experimental data, which is beneficial to the advancement of contaminant health risk assessment. In addition, using the prediction model constructed in this manuscript, the RfD values of two pesticide substances in the list of priority pollutants are calculated to derive human health water quality criteria. Furthermore, an initial assessment of the health risk was performed by the quotient value method based on the human health water quality criteria calculated by the prediction model.
The genetic diversities of 5 populations of Solidago canadensis were studied using intersimple sequence repeat markers method (ISSR). Genomic DNA was extracted by a modified NaOH method from samples collected in Zejiang province, China. Meanwhile, the generative organs (buds and rhizomes) of S. canadensis and plant species number in its grown site were investigated. Our results indicated that among 5 populations, the polymorphic percentages ranged from 78.08 to 91.03. Neis gene diversity index and Shannon diversity index were more than 0.25 and 0.38 respectively. The 5 populations displayed some genetic differentiations (Gst=0.3208), showing Jiaxing population and Zhoushan population in one group, while Hangzhou population, Wenzhou population and Quzhou population in another group. We found that the number of buds varied greatly among the 5 populations, genetic diversity of S. canadensis displayed significant negative correlation with the number of buds and significant positive correlation with plant species number in its grown site. S. canadensis population has higher genetic diversity index and less buds, when grown with more other species, than with less other species. The result implied that increased competition from other species of plant community could reduce fecundity of S. canadensis.
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