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  1. Article ; Online: Toward eDNA‐based bioassessment of freshwater reservoirs with small volumes of water

    Rebecca K. Loh / Sujatha N. Kutty / Darren C. J. Yeo / Rudolf Meier

    Environmental DNA, Vol 5, Iss 2, Pp 264-

    Robust molecular protocols

    2023  Volume 281

    Abstract: Abstract Bioassessment of freshwater quality with eDNA is a powerful alternative to traditional methods involving collecting, sorting, and identifying metazoan taxa with morphology (e.g., macroinvertebrates). Particularly attractive for routine ... ...

    Abstract Abstract Bioassessment of freshwater quality with eDNA is a powerful alternative to traditional methods involving collecting, sorting, and identifying metazoan taxa with morphology (e.g., macroinvertebrates). Particularly attractive for routine monitoring would be an eDNA method that uses a remote‐controlled boat for collecting small volumes of water without filtration in order to simplify sampling. Such a method would not likely capture eDNA signals for all metazoan species, but may nevertheless allow for cost‐effective, and frequent monitoring of water quality, which is important for tropical waterbodies that require year‐round surveillance. We here optimize a molecular protocol for capturing metazoan signatures based on eDNA obtained from 15 ml of water. To test the robustness of the method, we used samples from two tropical reservoirs with known differences in water quality to optimize molecular procedures so that they yield repeatable results. Each reservoir was sampled at three sites (“biological replicates”) and each water sample was subsampled twice before extracting the eDNA using ethanol precipitation for both subsamples (“technical replicates”). We then tested how much DNA (0.1 ng to 15 ng) and how many PCR cycles (25 or 35) minimized the variance of the metazoan eDNA signal between biological and technical replicates. For this purpose, we amplified a 313 bp COI minibarcode using a universal metazoan primer pair. We found that regardless of template amounts or PCR cycle numbers, the eDNA signatures for both reservoirs were distinct because only 17 of 59 mOTUs (mainly planktonic crustaceans and rotifers) were shared. We also found that template amounts between 0.5 and 15 ng yielded overall similar results, but the use of 35 PCR cycles significantly depressed the number of detected species (p‐value < 0.05). Fortunately, the differences between the detected metazoan community of the reservoirs were so strong that all biological and technical replicates could be assigned unambiguously to their source ...
    Keywords Bioassessment ; DNA metabarcoding ; environmental DNA ; freshwater reservoir ; small water volumes ; universal metazoan COI primer ; Environmental sciences ; GE1-350 ; Microbial ecology ; QR100-130
    Subject code 500
    Language English
    Publishing date 2023-03-01T00:00:00Z
    Publisher Wiley
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Evaluation of a diatom eDNA-based technique for assessing water quality variations in tropical lakes and reservoirs

    Sujatha Narayanan Kutty / Rebecca K. Loh / Wayne Bannister / David Taylor

    Ecological Indicators, Vol 141, Iss , Pp 109108- (2022)

    2022  

    Abstract: Freshwater bodies, both lotic (canals, rivers) and lentic (lakes and reservoirs), in the tropics have only rarely been subjected to intense monitoring regimes owing to limited expertise and resources, despite tropical habitats being among the most ... ...

    Abstract Freshwater bodies, both lotic (canals, rivers) and lentic (lakes and reservoirs), in the tropics have only rarely been subjected to intense monitoring regimes owing to limited expertise and resources, despite tropical habitats being among the most dynamic and threatened globally. Diatoms are an important part of assessing aquatic environmental changes in parts of the world where monitoring is well-established because of their sensitivity to a range of indicators of water quality. In such cases, diatoms have traditionally been identified based on morphology. Morphological information on tropical diatom taxa and the expertise to assemble it are sparse. However, DNA-based assessment is less reliant on taxonomic expertise and has the potential to be more cost-efficient. The application of DNA-based technology could thus expedite the incorporation of diatoms into routine monitoring in the tropics. Here we evaluate an environmental DNA (eDNA) metabarcoding workflow for diatom identifications based on 109 water samples from six freshwater reservoirs in Singapore, a highly urbanised part of tropical Southeast Asia. The six reservoirs span a range of sizes and catchment settings. We generate baseline information for lentic systems by targeting planktonic assemblages and including two commonly used barcodes, rbcL and 18S, to assess detection differences. Congruence with morphological identifications is generally low and each technique reveals distinct species lists, but overall congruence between methods improves when comparisons are at the genus level. We discuss the probable methodological and analytical causes for this incongruence and conclude that both approaches be used concurrently for generating reference databases of relatively poorly-known diatom diversity in tropical freshwater habitats. More promisingly, we find that eDNA datasets were sufficient to reveal both spatial and temporal patterns in diatom assemblages across the six study sites. We also show that regardless of the detection method used, diatom ...
    Keywords Biological monitoring ; Diatom ; eDNA ; Environmental DNA ; Freshwater ; Metabarcoding ; Ecology ; QH540-549.5
    Subject code 333
    Language English
    Publishing date 2022-08-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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