Use of environmental DNA (eDNA) to assess distributions of aquatic and semi-aquatic macroorganisms is promising, but sampling schemes may need to be tailored to specific objectives. Given the potentially high variance in aquatic eDNA among replicate grab samples, compositing smaller water volumes collected over a period of time may be more effective for some applications. In this study, we compared eDNA profiles from composite water samples aggregated over three hours with grab water samples. Both sampling patterns were performed with identical autosamplers paired at two different sites in a headwater stream environment, augmented with exogenous fish eDNA from an upstream rearing facility. Samples were filtered through 0.8 μm cellulose nitrate filters and DNA was extracted with a cetyl trimethylammonium bromide procedure. Eukaryotic and bacterial community profiles were derived by amplicon sequencing of 12S ribosomal, 16S ribosomal, and cytochrome oxidase I loci. Operational taxa were assigned to genus with a lowest common ancestor approach for eukaryotes and to family with the RDP Classifier software for prokaryotes. Eukaryotic community profiles were more consistent with composite sampling than grab sampling. Downstream, rarefaction curves suggested faster taxon accumulation for composite samples, and estimated richness was higher for composite samples as a set than for grab samples. Upstream, composite sampling produced lower estimated richness than grab samples, but with overlapping standard errors. Furthermore, a bimodal pattern of richness as a function of sequence counts suggested the impact of clumped particles on upstream samples. Bacterial profiles were insensitive to sample method, consistent with the more even dispersion expected for bacteria compared with eukaryotic eDNA. Overall, samples composited over 3 h performed equal to or better than triplicate grab sampling for quantitative community metrics, despite the higher total sequencing effort provided to grab replicates. On the other hand, taxon-specific detection rates did not differ appreciably and the two methods gave similar estimates of the ratio of the common fish genera and at each site. Unexpectedly, eDNA dropped out substantially faster than eDNA between the two sites regardless of sampling method, suggesting that differential settling affects the estimation of relative abundance. We identified bacterial patterns that were associated with eukaryotic diversity, suggesting potential roles as biomarkers of sample representativeness.
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http://dx.doi.org/10.7717/peerj.5871 | DOI Listing |
Arch Environ Contam Toxicol
January 2025
Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK, S7N 5B3, Canada.
Mining operations in Canada, including uranium mining and milling, generate by-products containing radionuclides, including radium-226 (Ra), a long-lived, bioaccumulative calcium (Ca) analog. Despite strict discharge regulations, there is limited evidence to suggest that current thresholds for Ra adequately protect aquatic organisms. Furthermore, Canada lacks a federal water quality guideline for Ra, underscoring the need for protective limits to safeguard aquatic ecosystems.
View Article and Find Full Text PDFEnviron Pollut
December 2024
Department of Exposure Science, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig Germany; Department Evolutionary Ecology & Environmental Toxicology, Institute of Ecology, Evolution and Diversity-Goethe University, Max-von-Laue-Straße 13, Frankfurt am Main, Germany. Electronic address:
Steroid hormones are significant contributors to endocrine disruption, affecting the hormonal functions of both humans and aquatic organisms. However, data on their occurrence and risks in fresh water systems particularly in low- and middle-income countries, is scarce. In this regard, a comprehensive investigation of 58 steroid hormones in rivers and wastewater treatment plants (WWTPs) was conducted in western Kenya.
View Article and Find Full Text PDFJ Hazard Mater
December 2024
Civil & Environmental Engineering, University of Nebraska Lincoln, Lincoln, NE 68588, USA.
Little is known about the potential impact of point source contamination from seed treatment pesticide residues and degradation products in waste products in treated seed. The presence of these pesticides and their degradation products in the environment has been associated with toxic effects on non-target organisms including bees, aquatic organisms and humans. In this study, we investigated the occurrence of twenty-two pesticide residues and their degradation products in two streams receiving runoff from land-applied wet cake, applied and spilled wastewater originating at a biofuels production facility using pesticide-treated seed as a feedstock.
View Article and Find Full Text PDFFront Public Health
December 2024
Environment & Health Research Unit, South African Medical Research Council (SAMRC), Cape Town, South Africa.
Background: Wastewater surveillance has become an important public health tool with numerous research studies indicating its potential for monitoring coronavirus disease 2019 (COVID-19) outbreaks. The aim of this study was to apply wastewater surveillance as an indicator for COVID-19 to monitor the impact of a mass sporting event in the City of Cape Town. The study compared the same event over 2 years (2022 and 2023).
View Article and Find Full Text PDFJ Dairy Sci
December 2024
Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, PO Box 5003, 1432 Ås, Norway. Electronic address:
The aim of this study was to examine how silages from different grassland species and harvesting frequencies affect feed intake, milk production, and methane (CH) emission in dairy cows. We hypothesized that cows consuming silages of more frequent harvest, grass species with greater organic matter digestibility and legumes with lower NDFom concentration would have greater silage dry matter intake and milk yield and thereby lower CH yield and intensity. Forty Norwegian Red cows were allocated to 5 treatments in a cyclic changeover design with 4 21-d periods (14 d of adaptation, 7 d of data collection).
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