Arctic lakes emit methane (CH4) to the atmosphere. The magnitude of this flux could increase with permafrost thaw but might also be mitigated by microbial CH4 oxidation. Methane oxidation in oxic water has been extensively studied, while the contribution of anaerobic oxidation of methane (AOM) to CH4 mitigation is not fully understood. We have investigated four Northern Siberian stratified lakes in an area of discontinuous permafrost nearby Igarka, Russia. Analyses of CH4 concentrations in the water column demonstrated that 60 to 100% of upward diffusing CH4 was oxidized in the anoxic layers of the four lakes. A combination of pmoA and mcrA gene qPCR and 16S rRNA gene metabarcoding showed that the same taxa, all within Methylomonadaceae and including the predominant genus Methylobacter as well as Crenothrix, could be the major methane-oxidizing bacteria (MOB) in the anoxic water of the four lakes. Correlation between Methylomonadaceae and OTUs within Methylotenera, Geothrix and Geobacter genera indicated that AOM might occur in an interaction between MOB, denitrifiers and iron-cycling partners. We conclude that MOB within Methylomonadaceae could have a crucial impact on CH4 cycling in these Siberian Arctic lakes by mitigating the majority of produced CH4 before it leaves the anoxic zone. This finding emphasizes the importance of AOM by Methylomonadaceae and extends our knowledge about CH4 cycle in lakes, a crucial component of the global CH4 cycle.Aquatic plants are essential components in the regulation of microhabitat complexity and physico-chemical parameters in lake ecosystems. Increased eutrophication, land use change, modification of hydrological regimes, and expansion of invasive species are expected to impact aquatic plant community composition; however, historical pathways and response patterns are not well understood at the national scale. We analyzed temporal changes in aquatic plant communities in Japan from the early 1900s to the 2000s using field survey records from 248 lakes. Relationships of species associations with climate, land use, and lake characteristics were described using a joint species distribution model. The mean variation attributable to lake characteristics was 25.4%, followed by climate (14.0%), and land use (10.5%). Among the 13 functional traits used in our analysis, sexual and pollination traits showed marked responses to precipitation and land use. Hypohydrophily increased with precipitation, whereas monoecious aquatic plants increased in lakes surrounded by urbanized area. The relative ratio of floating to submerged plants has increased over time. Our results provide insight into long-term changes in aquatic plant communities and identify functional traits sensitive to environmental change.Compared with interdecadal, interannual, or seasonal scales, the variations of diurnal temperature range (DTR) at the intraseasonal scale and their driving forces are less understood. Using surface meteorological observations and multi-source satellite retrievals during 2013-2017, together with Random Forest modeling, this study examines the intraseasonal variation of summer DTR in the Yangtze River Delta (YRD) region, China, and determines its potential driving factors [i.e., daily maximum/minimum surface air temperature (SATmax/SATmin), sunshine duration (SSD), rainfall, altitude, land vegetation cover, and land surface thermal environment including daytime/nighttime land surface temperature (LSTD/LSTN) and anthropogenic heat flux (AHF)]. It is found that the intraseasonal variation of DTR at both 8-day and monthly scales in the YRD exhibits regional differences and is modulated by different primary factors across the region. The evident intraseasonal variation of DTR, with a peak in June, in the northern Yhat experience various external forcings.The commercial production of docosahexaenoic acid (DHA) from oleaginous microorganisms is getting more attention due to several advantages over fish oils. The processing cost became a major bottleneck for commercialization of DHA from microorganisms. The most of cost shares in the feedstock to cultivate the microorganisms and downstream processing. The cost of feedstock can be compensated with the utilization of substrate from waste stream whereas production of value-added chemicals boosts the economic viability of nutraceutical production. In the present study, the docosahexaenoic acid (DHA)-producing marine protist Aurantiochytrium sp. T66 was cultivated on post-consumption food waste hydrolysate for the mining of squalene. After 120 h of cultivation, cell dry weight was 14.7 g/L, of which 6.34 g/L (43.13%; w/w) were lipids. DHA accounted for 2.15 g/L (34.05%) of total extracted lipids or 0.15 g/gCDW. Maximum squalene concentration and yield were 1.05 g/L and 69.31 mg/gCDW, respectively. Hence, utilization of food waste represents an excellent low-cost strategy for cultivating marine oleaginous thraustochytrids and produce squalene as a byproduct of DHA.Improving risk assessment and remediation rests on better understanding of contaminant bioavailability. Despite their strong toxicological attributes, little is known about the partitioning behaviour and bioavailability of polar polycyclic aromatic hydrocarbons (PAHs) in aquatic environments. The present study provides an insight into the bioavailable fractions of polar PAHs and their parent analogues in the tissues of the Sydney rock oyster, Saccostrea glomerata, a model aquatic bio-indicator organism. The concentration and distribution patterns of parent and polar PAHs including oxygenated PAHs (oxyPAHs), nitrated PAHs (NPAHs) and heterocyclic PAHs (HPAHs) were determined in water, sediment and oysters from an ecologically and economically important estuary of New South Wales, Australia. Total concentrations of PAHs, oxyPAHs, NPAHs and HPAHs were higher in sediments compared to oyster tissue and water. For most polar PAHs, total concentrations for water, sediment and oyster samples were 1). BSAF individual computation showed that bioaccumulation of nine investigated HPAHs in oyster tissues were relatively low and only 2-EAQ (oxyPAH) and 1N-NAP (NPAH) showed high levels of accumulation in oyster tissues, similar to parent PAHs. To the best of our knowledge, this is the first known study on the bioavailability of polar and non-polar PAHs in an Australian aquatic environment. The outcome of this study might be a useful indicator of the potential risks of polar PAHs to humans and other living organisms.Today’s benthic offshore biological monitoring of oil & gas (O&G) activities relies on macrofauna taxa enumeration. For the future, analysis of DNA isolated directly from sediments holds great potential for multi-trophic biodiversity surveys and the monitoring of a larger spectrum of benthic taxa, including micro-fauna. Here, we evaluate more specifically the potential of microfauna-specific gene quantification in relation to both petroleum-related discharge compounds and other seafloor environmental properties. We carried out this evaluation using sediment samples collected at drilling Region III on the Norwegian continental shelf where DNA metabarcoding of eukaryotic diversity was already performed. Generally, the quantification of microfauna indicator taxa related well to the gradient of contamination on the seafloor. Contrary to eukaryotic Euplotida, metabarcoding data and qPCR numbers for indicative prokaryotic taxa showed the same relationship to offshore contaminants (both showed positive relationship). We found absolute numbers of SSU rRNA gene copies of (1) Dinophyceae, Bacillariophyceae and Alcanivorax were correlated with the level of petroleum-related compounds but not with other environmental variables, (2) bacteria closely related to Shewanella were correlated with the concentration of Ba, PAH, as well to percent of gravel, (3) Desulfobacteriales correlated with petroleum-related contaminants, but as well with percent of gravel and grain size. Findings from our study suggest that biomonitoring surveys of O&G activities on benthos could benefit from quantification of specific micro-fauna indicators that is simpler and faster than the methods currently used for impact assessment of benthos.Microplastics are ubiquitous to most marine environments worldwide, and their management has become one of the major challenges facing stakeholders. Here we monitored monthly, between March 2018 and March 2019, the abundance of microplastics (0.3-18.2 mm) at the sea surface within the Kiel Fjord, southwest Baltic Sea. Microplastics were sampled at eight locations, inside and outside the fjord, near potential source of microplastics, such as the outlets of storm drains or the Kiel-Bülk wastewater treatment plant, the Schwentine River mouth and the entrance of the Kiel Canal. Weather (wind, precipitations) and seawater (salinity, temperature) parameters were compared to the spatiotemporal distribution of the microplastics. We found an overall stable, and low (0.04 particles/m3), microplastic load within the Kiel Fjord compared to other urban areas worldwide with comparable population densities. No relationship was found between the microplastic abundance and the environmental factors, but the few samples that yielded unusually high amount of microplastics were all preceded by rainfall and snow/ice melt. During such events, vast amounts of water, potentially contaminated with microplastics, were released into the fjord via the storm drainage system. The microplastic abundances at the wastewater plant outflow were among the lowest of our survey, likely thanks to an efficient filtering system. The results of this study highlight the importance to repeat microplastic samplings over time and space to determine with confidence baseline microplastic abundance and to detect unusual acute contamination, especially during snow and ice melting. Overall, the microplastic abundance within the Kiel Fjord was low, probably thanks to efficient waste management on land. However, improvements are still needed to filter millimetre-sized particles within the storm drainage system, which is likely a major source of microplastics into the marine environment.Reagents that can selectively recognize specific toxic tau variants associated with onset and progression of Alzheimer’s disease (AD) and other tauopathies can be effective diagnostic and therapeutic tools. We utilized a novel atomic force microscopy-based biopanning protocol to isolate antibody fragments (single chain variable fragments, scFvs) that selectively bind tau variants present in human AD but not cognitively normal age-matched brain tissue. We identified 6 scFvs [Alzheimer’s disease tau (ADT)-1 through 6] that readily distinguished between AD and control tissue and sera samples. We utilized 3 of the scFvs (ADT-2, ADT-4, and ADT-6) to analyze longitudinal plasma samples from 50 human patients, 25 patients which converted to AD during the study and 25 that remained cognitively normal. All 3 scFvs could distinguish the AD from control samples with higher tau levels in apolipoprotein E3/3 AD cases compared to apolipoprotein E3/4. Immunohistochemical analyses of human AD brain slices indicated several but not all tau variants overlapping with phosphorylated tau staining. Several reagents also showed therapeutic potential, protecting neuronal cells against AD tau-induced toxicity.