| 1. |
- Yan, Dongna, et al.
(författare)
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Anthropogenic drivers accelerate the changes of lake microbial eukaryotic communities over the past 160 years
- 2024
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Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 327
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Tidskriftsartikel (refereegranskat)abstract
- Human impacts on Earth's atmosphere, hydrosphere, litosphere and biosphere are so significant as to naming a new geological epoch, the Anthropocene. Lakes and their biota are highly sensitive to environmental changes. Among aquatic organisms, microbial eukaryotes play fundamental roles associated with lake ecosystem functioning, food webs, nutrient cycling, and pollutant degradation. However, the response of lake microbial eukaryotic community during the Anthropocene to changes in environmental conditions remain poorly understood. Here, we applied a 18S metabarcoding approach to sedimentary DNA to reconstruct the temporal dynamics of microbial eukaryotic community over the past 160 years. We investigated the influence of environmental conditions and of biotic interactions on the microbial eukaryotes in Sihailongwan Maar Lake, one of the candidate sites of Global boundary Stratotype Section and Point (GSSP) for demarcation of the Anthropocene. Microbial eukaryotes were dominated by dinoflagellates, chlorophytes, ciliates, pirsoniales, rotifers, ochrophytes, apicomplexans and cercozoans that were divided into four functional groups that are photoautotrophs, mixotrophs, consumers and parasites. The predominance of phototrophs and their strong associations with organisms from other trophic levels, confirmed their crucial roles in nutrient cycling, energy flows and ecosystem services in freshwater ecosystems. Abrupt changes in the 1950s in microbial eukaryotic diversity and composition were consistent with changes observed in the pollutants emissions i.e., heavy metals, combustion indices (spheroidal carbonaceous particles, polycyclic aromatic hydrocarbon, Soot F14C), radioactivity indicators (239,240Pu, 129I/127I), nutrients (total organic carbon, total nitrogen, phosphorus), and temperature. Statistical analysis revealed that anthropogenic drivers controlled the temporal dynamic of microbial eukaryotic community. Our findings provide additional biostratigraphy evidence of the impact of environmental change on this lake biota, which further supports the value of this system to characterize the Anthropocene.
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| 2. |
- Yan, Dongna, et al.
(författare)
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Historical trajectories of antibiotics resistance genes assessed through sedimentary DNA analysis of a subtropical eutrophic lake
- 2024
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- Investigating the occurrence of antibiotic-resistance genes (ARGs) in sedimentary archives provides opportunities for reconstructing the distribution and dissemination of historical (i.e., non-anthropogenic origin) ARGs. Although ARGs in freshwater environments have attracted great attention, historical variations in the diversity and abundance of ARGs over centuries to millennia remain largely unknown. In this study, we investigated the vertical change patterns of bacterial communities, ARGs and mobile genetic elements (MGEs) found in sediments of Lake Chenghai spanning the past 600 years. Within resistome preserved in sediments, 177 ARGs subtypes were found with aminoglycosides and multidrug resistance being the most abundant. The ARG abundance in the upper sediment layers (equivalent to the post-antibiotic era since the 1940s) was lower than those during the pre-antibiotic era, whereas the ARG diversity was higher during the post-antibiotic era, possibly because human-induced lake eutrophication over the recent decades facilitated the spread and proliferation of drug-resistant bacteria. Statistical analysis suggested that MGEs abundance and the bacterial community structure were significantly correlated with the abundance and diversity of ARGs, suggesting that the occurrence and distribution of ARGs may be transferred between different bacteria by MGEs. Our results provide new perspectives on the natural history of ARGs in freshwater environments and are essential for understanding the temporal dynamics and dissemination of ARGs.
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| 3. |
- Yan, Dongna, et al.
(författare)
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Organic matter content and source is associated with the depth-dependent distribution of prokaryotes in lake sediments
- 2024
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Ingår i: Freshwater Biology. - : John Wiley & Sons. - 0046-5070 .- 1365-2427. ; 69, s. 496-508
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Tidskriftsartikel (refereegranskat)abstract
- Aquatic sediments harbour a diverse array of microorganisms that drive organic matter recycling, carbon sequestration and greenhouse gases (e.g., CO2, CH4, N2O) emissions. Although largely studied in water columns, vertical profiles of the diversity and composition of prokaryotic communities (i.e., Bacteria and Archaea) in aquatic sediments are still rare. More specifically, much remains to be learnt about their vertical distribution in lake sediments and how environmental conditions at the time of burial have impacted their diversity and composition.We investigated the vertical distribution of prokaryotic community with 16S rRNA gene quantitative (q)PCR and metabarcoding approaches applied to 93 sediment layers collected in a 2-m-long sediment core from the eutrophic alkaline Lake Chenghai in subtropical China. We aimed to study the diversity, composition and structure distribution of the prokaryotic community as well as environmental factors influencing it.Bacterial abundance was found to decrease with sediment depth although the richness of both bacterial and archaeal assemblages slightly increased with sediment depth. In terms of composition, a strongly stratified sediment–depth pattern was observed in which Proteobacteria, Desulfobacterota, Bacteroidota and Verrucomicrobiota dominated the inventories in the surface sediment layers, whereas Chloroflexi, Spirochaetota, Planctomycetota, Crenarchaeota were more abundant in the deep sediment layers. Organic matter contents and sources were identified as major factors shaping the structure of the prokaryotic community.Overall, our study provides new evidence about how lake sediment's prokaryotic community are linked to external sources of energy. This complement existing data from other lake systems towards a better understanding of sediment prokaryotic community's contribution to biogeochemical cycle in lakes.
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| 4. |
- Yan, Dongna, et al.
(författare)
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Sedimentary DNA reveals phytoplankton diversity loss in a deep maar lake during the Anthropocene
- 2024
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 69:6, s. 1299-1315
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic-driven environmental change, including current climate warming, has influenced lake ecosystems globally during the Anthropocene. Phytoplankton are important indicators of environmental changes in lakes and play a fundamental role in maintaining the functioning and stability of these ecosystems. However, the extent to which lake phytoplankton were affected by anthropogenic or climatic forces during the Anthropocene remains unclear. Here, we investigated the 160-yr-long dynamics of the phytoplankton community (cyanobacteria and eukaryotic microalgae) in response to anthropogenic forcing in Sihailongwan Maar Lake—a candidate for a Global boundary Stratotype Section and Point for demarcation of the Anthropocene—using DNA metabarcoding and traditional paleolimnological approaches. Our results show a significant decline in phytoplankton diversity and an abrupt shift in community composition around the 1950s, corresponding to the beginning of the “Great Acceleration” period. Specifically, phytoplankton taxa coexistence patterns, niche differentiation, and assembly mechanisms changed significantly after the 1950s. Overall, increases in air temperature and anthropogenic forcing appear to be the dominant controls for community reorganization and diversity decline of the phytoplankton from this deep maar lake. A neutral community model suggests that phytoplankton community composition was mainly controlled by stochastic processes before the 1950s; however, as time progressed, deterministic effects driven by anthropogenic global warming increased. The results of this study imply that anthropogenic perturbations have led to a loss of phytoplankton diversity and a further decline in ecological resilience in deep lakes, with likely knock-on effects on the productivity and function of lake ecosystems.
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