scholarly journals The role of methanotrophy in the microbial carbon metabolism of temperate lakes

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Paula C. J. Reis ◽  
Shoji D. Thottathil ◽  
Yves T. Prairie
Keyword(s):  
Water Column ◽  
Carbon Metabolism ◽  
Volume Fraction ◽  
Specific Activity ◽  
Freshwater Ecosystems ◽  
Carbon Consumption ◽  
Temperate Lakes ◽  
Relative Contribution ◽  
Methane Oxidizing Bacteria ◽  
Microbial Carbon

AbstractPrevious stable isotope and biomarker evidence has indicated that methanotrophy is an important pathway in the microbial loop of freshwater ecosystems, despite the low cell abundance of methane-oxidizing bacteria (MOB) and the low methane concentrations relative to the more abundant dissolved organic carbon (DOC). However, quantitative estimations of the relative contribution of methanotrophy to the microbial carbon metabolism of lakes are scarce, and the mechanism allowing methanotrophy to be of comparable importance to DOC-consuming heterotrophy remained elusive. Using incubation experiments, microscopy, and multiple water column profiles in six temperate lakes, we show that MOB play a much larger role than their abundances alone suggest because of their larger cell size and higher specific activity. MOB activity is tightly constrained by the local methane:oxygen ratio, with DOC-rich lakes with large hypolimnetic volume fraction showing a higher carbon consumption through methanotrophy than heterotrophy at the whole water column level. Our findings suggest that methanotrophy could be a critical microbial carbon consumption pathway in many temperate lakes, challenging the prevailing view of a DOC-centric microbial metabolism in these ecosystems.

scholarly journals Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

2018 ◽  
Vol 15 (20) ◽  
pp. 6127-6138 ◽  
Author(s):  
Qixing Ji ◽  
Claudia Frey ◽  
Xin Sun ◽  
Melanie Jackson ◽  
Yea-Shine Lee ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Chesapeake Bay ◽  
Water Column ◽  
N2o Emissions ◽  
N2o Production ◽  
Isotope Tracer ◽  
Relative Contribution ◽  
Environmental Controls ◽  
Long Run ◽  
Nitrate And Nitrite

Abstract. Nitrous oxide (N2O) is a greenhouse gas and an ozone depletion agent. Estuaries that are subject to seasonal anoxia are generally regarded as N2O sources. However, insufficient understanding of the environmental controls on N2O production results in large uncertainty about the estuarine contribution to the global N2O budget. Incubation experiments with nitrogen stable isotope tracer were used to investigate the geochemical factors controlling N2O production from denitrification in the Chesapeake Bay, the largest estuary in North America. The highest potential rates of water column N2O production via denitrification (7.5±1.2 nmol-N L−1 h−1) were detected during summer anoxia, during which oxidized nitrogen species (nitrate and nitrite) were absent from the water column. At the top of the anoxic layer, N2O production from denitrification was stimulated by addition of nitrate and nitrite. The relative contribution of nitrate and nitrite to N2O production was positively correlated with the ratio of nitrate to nitrite concentrations. Increased oxygen availability, up to 7 µmol L−1 oxygen, inhibited both N2O production and the reduction of nitrate to nitrite. In spring, high oxygen and low abundance of denitrifying microbes resulted in undetectable N2O production from denitrification. Thus, decreasing the nitrogen input into the Chesapeake Bay has two potential impacts on the N2O production: a lower availability of nitrogen substrates may mitigate short-term N2O emissions during summer anoxia; and, in the long-run (timescale of years), eutrophication will be alleviated and subsequent reoxygenation of the bay will further inhibit N2O production.

scholarly journals Simple quality control technique to identify dissolved oxygen diffusion issues with biochemical oxygen demand bottle incubations

2017 ◽  
Author(s):  
Johnathan Daniel Maxey ◽  
Neil David Hartstein ◽  
Dorathy Penjinus ◽  
Alan Kerroux
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Biochemical Oxygen Demand ◽  
Oxygen Demand ◽  
Freshwater Ecosystems ◽  
Control Technique ◽  
Community Respiration ◽  
Parallel Diffusion ◽  
Quality Control Technique

Stratified estuaries are home to expanding aquaculture activities whose ecological footprints can be observed through trends in microbial community respiration in the water column. Bottle incubations are widely used to measure water column community respiration in marine and freshwater ecosystems by measuring the flux of dissolved oxygen occurring in the bottle over a period of time. When in situ dissolved oxygen (DO) concentrations are markedly different than DO concentration of the incubation medium the potential for diffusion of oxygen across the bottle opening is great and may be especially pronounced in strongly stratified systems with relatively low rates of pelagic oxygen consumption. We incubated 60 Biochemical Oxygen Demand (BOD) bottles filled with sterilized water with DO concentrations ranging from 2.51 mg O2 L-1 to 10.03 mg O2 L-1 for 24 hours in a temperature controlled water bath. There was a significant relationship when DO flux was set as a function of initial DO (DO Flux = -0.0017x + 0.0085, r2 = 0.72, p < 2.2 e-16). DO fluxes ranged from -0.012 mg O2 L-1 hour-1 to 0.005 mg O2 L-1 hour-1 for bottles incubated with initial DO ranging from 10.03 mg O2 L-1 to 3.31 mg O2 L-1, respectively. These results suggest that diffusion across the ground glass seal of BOD bottles is possible and that extra precaution through parallel diffusion controls should be considered when measuring pelagic respiration using BOD bottle incubations in systems with relatively low or relatively high in situ DO concentrations.

scholarly journals Long-term cover cropping seasonally affects soil microbial carbon metabolism in an apple orchard

Bioengineered ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 207-217 ◽  
Author(s):  
Jianfeng Yang ◽  
Tairan Zhang ◽  
Rongqin Zhang ◽  
Qianqian Huang ◽  
Huike Li
Keyword(s):  
Carbon Metabolism ◽  
Apple Orchard ◽  
Soil Microbial ◽  
Cover Cropping ◽  
Microbial Carbon

Dynamics of Selenium in Mercury-Contaminated Experimental Freshwater Ecosystems

1980 ◽  
Vol 37 (5) ◽  
pp. 848-857 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner ◽  
Bruce E. Townsend ◽  
Alison Swick ◽  
Akira Furutani
Keyword(s):  
Water Column ◽  
Aquatic Organisms ◽  
Selenium Concentration ◽  
Freshwater Ecosystems ◽  
Aquatic Herbicides ◽  
Mercury Bioaccumulation ◽  
Simultaneous Movement ◽  
Experimental Treatments ◽  
Aquatic Herbicide ◽  
Rate Of Movement

The simultaneous movement of radiolabeled selenium and mercury was followed in experimental aquatic ecosystems ([Formula: see text] tube enclosures) set into a mercury-contaminated lake. The experimental treatments consisted of increasing stable selenium or sulfate water concentrations, addition of an aquatic herbicide, and isolation of a portion of the water column from contact with sediments. Selenium and mercury did not move together through the ecosystems either geochemically or biologically. Selenium bioaccumulation was rapid by fish, crayfish, and haptobenthos and was enhanced by increased sulfate concentration and in the absence of exposure to bottom sediments. It was reduced in the presence of aquatic herbicides. A selenium concentration of 0.1 mg/L did not affect the rate of movement of mercury out of the water column but it did stabilize the movement of mercury among various compartments in the water column. Elevated selenium appeared to retard the rate of mercury bioaccumulation by fish, crayfish, and haptobenthos. Preliminary observations of selenium toxicity to several aquatic organisms were carried out. The possibility of using selenium as an ameliorating agent for heavy metal polluted freshwater systems is discussed.Key words: selenium, mercury, methylmercury, fish, crayfish

scholarly journals Influence of environmental disturbances on the bacteriological quality of Pagbanganan river in Baybay City, Leyte, Philippines

2019 ◽  
pp. 81-91 ◽  
Keyword(s):  
Water Quality ◽  
Water Column ◽  
Heterotrophic Bacteria ◽  
Freshwater Ecosystems ◽  
Most Probable Number ◽  
Public Water Supply ◽  
Environmental Disturbances ◽  
Probable Number ◽  
Fermentation Test

Microorganisms like bacteria are frequently used as indicators of water quality in freshwater ecosystems. Thus, this study was conducted to evaluate the total coliforms (TC) and total aerobic heterotrophic bacteria (TAHB) present in the upstream (Kantagnos), midstream (lgang), and downstream (Kan-ipa) of Pagbanganan River. The most probable number (MPN/100 mL) of TC was determined through multiple tube fermentation test while counts of TAHB present in both water and sediments were enumerated by serial dilution and plating methods. MPN of TC revealed that the river water should not be used as a source of public water supply and as a venue for contact recreational activities like bathing and swimming. Furthermore, TAHB in the sediments of the river did not differ significantly across sites although their values showed a decreasing trend. Conversely, TAHB in the water column of the river significantly increased from upstream to downstream. These results are most probably influenced by the quarrying activities present in the area. In the upstream where there is no quarrying activity, TAHB was higher in sediment than in the water, while in the downstream where quarrying activities are present, it is otherwise. Because of these significant differences, it is believed that the ratios of TAHB present in the water column and sediments are potential indicators of sediment disturbance in the aquatic environment. The results of this study imply that proper management of Pagbanganan River by all sectors of the community is needed to keep it sustainable for safe use.

scholarly journals Trophic transfer of microplastics enhances tissue accumulation of chemical additives in fish

2021 ◽  
Author(s):  
Takaaki Hasegawa ◽  
Kaoruko Mizukawa ◽  
Yeo Bee Geok ◽  
Tomonori Sekioka ◽  
Hideshige Takada ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Water Column ◽  
Flame Retardants ◽  
Direct Evidence ◽  
Trophic Transfer ◽  
Chemical Additives ◽  
Exposed Fish ◽  
Tissue Accumulation ◽  
Relative Contribution ◽  
Significant Difference

AbstractA variety of chemical additives are incorporated into plastics during their production process to give desirable properties. Although studies have suggested that microplastic ingestion can lead to accumulation of these chemicals in marine organisms, none provided the direct evidence in fish species. Here, we demonstrated the tissue accumulation of chemical additives in fish following microplastic ingestion. We exposed fish (Myoxocephalus brandti) to polyethylene microplastics compounded with brominated flame retardants (BFRs; BDE209, DBDPE) and ultraviolet stabilizers (UVs; UV-234, UV-327, BP-12) suspended in the water column, or to mysids (Neomysis spp.) pre-exposed to the same microplastics. Our results showed a maximum of 345-fold higher concentrations of additives in fish exposed to microplastics than the ambient sample. Also, fish fed plastic-exposed mysids accumulated significantly greater concentrations of BFRs in muscle than fish exposed to microplastics suspended in the water column (p < 0.001). This indicates that trophic transfer of microplastics has greater contribution to tissue accumulation of BFRs in fish than the waterborne ingestion. In contrast, no significant difference in the accumulation of UVs was found between the treatments, except for UV-327 in liver. These results suggests that the relative contribution between direct ingestion of microplastics from the water column and indirect ingestion via trophic transfer on tissue accumulation of additives in fish varies among compounds. Compounds with high molecular weight and high hydrophobicity like BDE209 and DBDPE were considered difficult to leach out from plastics, however, our study showed that trophic transfer of microplastics can facilitate the accumulation of such compounds from plastics to fish.

scholarly journals Tissue translocation, multigenerational and population effects of microplastics in Daphnia magna

2021 ◽  
Author(s):  
◽  
Schür Christoph
Keyword(s):  
Water Column ◽  
Daphnia Magna ◽  
Food Limitation ◽  
Freshwater Ecosystems ◽  
Plastic Waste ◽  
Lipid Storage ◽  
Fluorescence Signal ◽  
Naturally Occurring ◽  
Plastic Materials ◽  
Population Effects

The last century saw the widespread adoption of plastic materials throughout nearly every aspect of our lives. Plastics are synthetic polymers that are made up of monomer chains. The properties of the monomer in conjunction with chemical additives allow plastics to have a sheer endless variety of features and use cases. They are cheap, lightweight, and extremely durable. Plastic materials are often engineered for single-use and in conjunction with high production volumes and insufficient waste management and recycling across the globe, this leads to a large number of plastics entering the environment. Marine ecosystems are considered sinks. However, freshwater ecosystems as entry pathways are highly affected by plastic waste as well. Throughout the past decade, the impact of plastic waste on human and environmental health has received a lot of attention from the ecotoxicological community as well as the public. Small plastic fragments (< 1 mm called microplastics) are a large part of this emerging field of research. Within this, the water flea Daphnia magna is probably the most common organism that is used to assess microplastics toxicity. As a filter-feeding organism, it indiscriminately ingests particles from the water column and is thus highly susceptible to microplastics. For this thesis, we identified some gaps in the available data on the ecotoxicity of microplastics to daphnids. To illuminate some of those gaps the present thesis was aimed at five main aspects: (1) Tissue translocation of spherical microplastics in Daphnia magna (2) Investigation of the toxicity of irregularly shaped microplastics (3) Multigenerational and population effects of microplastics (4) Comparison of the toxicity of microplastics and natural particles (5) Effects of particle-aging on microplastics toxicity The thesis is comprised of three peer-reviewed articles and one so-far unpublished study as “additional results”. The first study was aimed at understanding tissue translocation of spherical microplastics to lipid storage droplets of daphnids. The crossing of biological membranes is discussed as a prerequisite to eliciting tissue damage and an inflammatory response. Previously, researchers reported the translocation of fluorescently labeled spherical microplastics to lipid storage droplets of daphnids, even though no plausible biological mechanism to explain this occurrence. Therefore, in order to learn more about this process and potentially illuminate the mechanism we replicated the study. We were able to observe a fluorescence signal inside the lipid droplets only after increasing the exposure concentrations. Nonetheless, it appeared to be independent of particles. This led to the hypothesis, that the lipophilic fluorescent dye uncoupled from the particles and subsequently accumulated in lipid storage droplets. The hypothesis was further confirmed through an additional experiment with a silicone-based passive sampling device showing that the fluorescence occurred both independent of particles and digestive processes. Accordingly, we concluded that the reported findings were a microscopic artifact caused by the uncoupling of the dye from the particles. Therefore, a fluorescence signal alone is not a sufficient proxy to assume that particles have translocated. It needs to be coupled with additional methods to ensure that the observation is indeed caused by the translocation of particles. It is still unclear whether the toxicity profile of microplastics is different from that of naturally occurring particles or if they are “just another particle”, as there are innumerable amounts in the natural environment surrounding an organism. The goal of the second study was to compare the toxicity of irregularly shaped polystyrene microplastics to that of the natural particle kaolin. The environment is full of natural non-food particles that daphnids ingest more or less indiscriminately and therefore are well adapted to deal with. Daphnids have a short generation time and usually experience food limitation in nature. Therefore, short-term studies only looking at acute toxicity with ad libitum food availability are not representative of the exposure scenario in nature. For a more realistic scenario, we, therefore, used a four-generation multigenerational design under food limitation to investigate how effects translate from one generation to the next. We observed concentration-dependent effects of microplastics but not of natural particles on mortality, reproduction, and growth. Some of the effects increased from generation to generation, leading to the extinction of two treatment groups. Here, microplastics were more toxic than natural particles. At least part of this difference can be explained by physical properties leading to the quick sedimentation of the kaolin, while microplastics remained in the water column. Nonetheless, buoyancy and sedimentation would also affect exposure in the environment and are likely different for most microplastics than for most naturally occurring particle types. ...

scholarly journals Vertical and horizontal composition of fecal pollution indicator bacteria in lotic and lentic ecosystems at Turkish Thrace

2017 ◽  
Vol 118 (4) ◽  
Author(s):  
Pinar Altinoluk-Mimiroglu ◽  
Belgin Camur-Elipek
Keyword(s):  
Water Column ◽  
Heterotrophic Bacteria ◽  
Similarity Index ◽  
Freshwater Ecosystems ◽  
Indicator Bacteria ◽  
Coliform Bacteria ◽  
Freshwater Ecosystem ◽  
Bacterial Populations ◽  
Running Water ◽  
Pollution Indicator

Background and Purpose:Although freshwater ecosystems have natural bacterial populations, their distributions are negatively affected by agricultural activities, domestic and industrial discharges. Bacterial composition at different depths can limit the usage of the water column for drinking, irrigation or other intentions. This study was designed to give similar indications concerning the nature of distribution of indicator bacteria in two different freshwater ecosystem types (lotic and lentic biotopes), and also to identify the factors that might be responsible in shaping them.Materials and Methods:For this aim, stagnant and running water resources located in Meric-Ergene River Basin at Turkish Thrace were sampled at three water depths (surface, middle, bottom) and two sediment depths (shore and bottom) between the dates October 2014 and September 2015 at seasonal intervals. While the heterotrophic bacteria, total and fecal coliform bacteria, and Escherichia coli were recorded by the CFU and MPN techniques, some features (temperature, dissolved oxygen, pH, conductivity, salinity, nutrients, ions, and elements) were also measured by classical chemical, chromatographic or spectrometric methods.Results and Conslusions:According to the data, the bacterial distribution in each ecosystem was found as similar for the bottom and the surface water columns. Results were also supported statistically by Bray-Curtis similarity index and correspondence analyse. The relationships between the bacterial distribution and environmental features were evaluated by Spearman correlation index. Consequently, it was observed that the bacterial distribution can differ in both water column/sediment depths and lotic/lentic ecosystems. And, it was suggested that the middle water column in each ecosystem is the most proper column for human usage.

Riverine transport of microplastics from the Dutch border to the North sea

2020 ◽  
Author(s):  
Frans Buschman ◽  
Annelotte van der Linden ◽  
Arjen Markus
Keyword(s):  
The Netherlands ◽  
Water Column ◽  
Monitoring Program ◽  
Freshwater Ecosystems ◽  
Point Sources ◽  
Spatial And Temporal Variation ◽  
Final Report ◽  
Wear Particles ◽  
Critical Flow Velocity ◽  
Different Types

&lt;p&gt;Microplastics may affect marine and freshwater ecosystems and human health negatively. Important point sources of microplastics in rivers are locations where microplastics are released into the river, such as waste water treatment plants. Diffuse sources include the fragmentation of macroplastic items and tire and road wear particles that are flushed into the river (Unice et al., 2019). Once in the river, the different types and sizes of microplastics are transported with the flow. How this transport depends on environmental conditions is largely unknown. Due to the effort needed to monitor the microplastic concentration and composition, usually observations are carried out at one location in the water column only and are only repeated a few times. With a model, the spatial and temporal variation of the microplastics concentration can be predicted.&lt;/p&gt;&lt;p&gt;We modeled the transport and fate of microplastics (here defined as particles within 0.05 and 5 mm) in Dutch rivers and streams. We used a depth and width averaged flow model for the Netherlands. At the main upstream boundaries of the model (Lobith in the Rhine and Eijsden in the Meuse) microplastics were released. The concentration of different types of microplastics was based on observations by Urgert (2015). The model included the processes advection, deposition and hetero-aggregation of microplastics with sediment to determine the transport and fate. Overall, the model results suggest that the deposition is small: about 66-90 percent of the released microplastics are transported out of the model towards the sea, meaning that 10-34 percent are either deposited to the river bed or are stored in the water column. Resuspension of deposited microplastics was not included in the model. A sensitivity study for which resuspension was included suggests that it is not an important process in the current 1D simulation, since the flow velocities at accumulation areas rarely exceed the critical flow velocity for resuspension.&amp;#160; The simulated annual transport of microplastics is higher than estimates based on observations (van der Wal et al., 2015; Mani et al., 2015), although sources within the Netherlands are not yet included in the model. This needs to be re-evaluated in the future, after sources of microplastics from within The Netherlands have been introduced in the model.&lt;/p&gt;&lt;ul&gt;&lt;li&gt;Mani T., A. Hauk, U. Walter and P. Burkhardt-Holm (2015) Microplastics profile along the Rhine River. Nature Scientific Reports.&lt;/li&gt; &lt;li&gt;Unice, K.M., M.P. Weeber, M.M. Abramson, R.C.D. Reid, J.A.G. van Gils, A.A. Markus, A.D. Vethaak and J.M. Panko (2019) Characterizing export of land-based microplastics to the estuary &amp;#8211; Part I: Application of integrated geospatial microplastic transport models to assess tire and road wear particles in the Seine watershed. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2018.07.368&lt;/li&gt; &lt;li&gt;Urgert, W. (2015) Microplastics in the rivers Meuse and Rhine-Developing guidance for a possible future monitoring program (MSc Thesis)&lt;/li&gt; &lt;li&gt;Van der Wal, M., M. van der Meulen, G. Tweehuijsen, M. Peterlin, A. Palatinus, K. Virsek, L. Coscia and A. Krzan (2015) Identification and Assessment of Riverine Input of (Marine) Litter. Final Report for the European Commission DG Environment under Framework Contract No ENV.D.2/FRA/2012/0025.&lt;/li&gt; &lt;/ul&gt;

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