scholarly journals Flexibility of Microcystis Overwintering Strategy in Response to Winter Temperatures

2021 ◽  
Vol 9 (11) ◽  
pp. 2278
Author(s):  
Pei Cai ◽  
Qijia Cai ◽  
Feng He ◽  
Yuhong Huang ◽  
Cuicui Tian ◽  
...  
Keyword(s):  
Water Column ◽  
Low Temperatures ◽  
Temporal Dynamics ◽  
Management Strategies ◽  
Freshwater Ecosystems ◽  
Long Duration ◽  
Winter Temperatures ◽  
Key Factor ◽  
Robust Prediction ◽  
Geographical Locations

Microcystis is one of the most common bloom-forming cyanobacteria in freshwater ecosystems throughout the world. However, the underlying life history mechanism and distinct temporal dynamics (inter- and intra-annual) of Microcystis populations in different geographical locations and lakes remain unclear but is critical information needed for the development of robust prediction, prevention, and management strategies. Perennial observations indicate that temperature may be the key factor driving differences in the overwintering strategy. This study quantitatively compared the overwintering abilities of Microcystis aeruginosa (Ma) in both the water column and sediments under a gradient of overwintering water temperatures (i.e., 4, 8, and 12 °C) using the death and proliferation rates of Ma. The results show that the dynamics of the Microcystis overwintering strategy were significantly affected by water temperatures. At 4 and 8 °C, Ma mainly overwintered in sediments and disappeared from the water column after exposure to low temperatures for a long duration, although some Microcystis cells can overwinter in the water column for short durations at low temperatures. At 12 °C, most Ma can overwinter in the water column. Rising temperatures promoted the proliferation of pelagic Ma but accelerated the death of benthic Ma. With warmer winter temperatures, pelagic Microcystis might become the primary inoculum sources in the spring. Our study highlights the overwintering strategy flexibility in explaining temporal dynamics differences of Microcystis among in geographical locations and should be considered in the context of global warming.

scholarly journals Meeting the challenge of interacting threats in freshwater ecosystems: A call to scientists and managers

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Laura S. Craig ◽  
Julian D. Olden ◽  
Angela H. Arthington ◽  
Sally Entrekin ◽  
Charles P. Hawkins ◽  
...  
Keyword(s):  
Decision Making ◽  
Temporal Dynamics ◽  
Management Strategies ◽  
Freshwater Ecosystems ◽  
Unintended Consequences ◽  
Multidisciplinary Teams ◽  
Economic Framework ◽  
Spatio Temporal ◽  
Testing Management ◽  
Management Approaches

Human activities create threats that have consequences for freshwater ecosystems and, in most watersheds, observed ecological responses are the result of complex interactions among multiple threats and their associated ecological alterations. Here we discuss the value of considering multiple threats in research and management, offer suggestions for filling knowledge gaps, and provide guidance for addressing the urgent management challenges posed by multiple threats in freshwater ecosystems. There is a growing literature assessing responses to multiple alterations, and we build off this background to identify three areas that require greater attention: linking observed alterations to threats, understanding when and where threats overlap, and choosing metrics that best quantify the effects of multiple threats. Advancing science in these areas will help us understand existing ecosystem conditions and predict future risk from multiple threats. Because addressing the complex issues and novel ecosystems that arise from the interaction of multiple threats in freshwater ecosystems represents a significant management challenge, and the risks of management failure include loss of biodiversity, ecological goods, and ecosystem services, we also identify actions that could improve decision-making and management outcomes. These actions include drawing insights from management of individual threats, using threat attributes (e.g., causes and spatio-temporal dynamics) to identify suitable management approaches, testing management strategies that are likely to be successful despite uncertainties about the nature of interactions among threats, avoiding unintended consequences, and maximizing conservation benefits. We also acknowledge the broadly applicable challenges of decision-making within a socio-political and economic framework, and suggest that multidisciplinary teams will be needed to innovate solutions to meet the current and future challenge of interacting threats in freshwater ecosystems.

Extracellular enzymatic activities in the aquatic ecosystems of the Danube Delta. 2. Alkaline phosphatase activity

2021 ◽  
Vol 26 (1) ◽  
pp. 2269-2274
Author(s):  
IOAN PĂCEŞILĂ ◽  
EMILIA RADU
Keyword(s):  
Alkaline Phosphatase ◽  
Water Column ◽  
Aquatic Ecosystems ◽  
Temporal Dynamics ◽  
Extracellular Enzyme ◽  
Danube Delta ◽  
Phytoplankton Communities ◽  
Extracellular Enzymatic Activities ◽  
Adjacent Channels ◽  
Hydrolysis Of

Phosphorus is one of the most important inorganic nutrients in aquatic ecosystems, the development and functioning of the phytoplankton communities being often correlated with the degree of availability in assimilable forms of this element. Alkaline phosphatase (AP) is an extracellular enzyme with nonspecific activity that catalyses the hydrolysis of a large variety of organic phosphate esters and release orthophosphates. During 2011-2013, AP Activity (APA) was assessed in the water column and sediments of several aquatic ecosystems from Danube Delta: Roșu Lake, Mândra Lake and their adjacent channels – Roșu-Împuțita and Roșu-Puiu. The intensity of APA widely fluctuated, ranging between 230-2578 nmol p-nitrophenol L-1h-1 in the water column and 2104-15631 nmol p-nitrophenol g-1h-1 in sediment. Along the entire period of the study, APA was the most intense in Roșu-Împuțita channel, for both water and sediment samples. Temporal dynamics revealed its highest values in summer for the water column and in autumn for sediment. Statistical analysis showed significant seasonal diferences of the APA dynamics in spring vs. summer and autumn for the water column, and any relevant diferences for sediment.

scholarly journals Inhibitory Copulation Effect of Vibrational Rival Female Signals of Three Stink Bug Species as a Tool for Mating Disruption

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 177
Author(s):  
Aline Moreira Dias ◽  
Miguel Borges ◽  
Maria Carolina Blassioli Moraes ◽  
Matheus Lorran Figueira Coelho ◽  
Andrej Čokl ◽  
...  
Keyword(s):  
Pest Management ◽  
Mating Behavior ◽  
Mating Disruption ◽  
Management Strategies ◽  
Stink Bug ◽  
Stink Bugs ◽  
Vibratory Communication ◽  
Communication Signals ◽  
Long Duration ◽  
Bean Plants

Stink bugs are major pests in diverse crops around the world. Pest management strategies based on insect behavioral manipulation could help to develop biorational management strategies of stink bugs. Insect mating disruption using vibratory signals is an approach with high potential for pest management. The objective of this work was to investigate the effect of conspecific female rival signals on the mating behavior and copulation of three stink bug species to establish their potential for mating disruption. Previously recorded female rival signals were played back to bean plants where pairs of the Neotropical brown stink bug, Euschistus heros, and two green stink bugs, Chinavia ubica and Chinavia impicticornis were placed. Vibratory communication and mating behavior were recorded for each pair throughout the experimental time (20 min). Female rival signals show a disrupting effect on the reproductive behavior of three conspecific investigated stink bug species. This effect was more clearly expressed in E. heros and C. ubica than in C. impicticornis. The likelihood of copulating in pairs placed on control plants, without rival signals, increased 29.41 times in E. heros, 4.6 times in C. ubica and 1.71 times in C. impicticornis. However, in the last case, the effect of female rivalry signals in copulation was not significant. The effect of mating disruption of female rival signals of the three stink bug species may originate from the observed reduction in specific vibratory communication signals emitted, which influences the duet formation and further development of different phases of mating behavior. Our results suggest that female rival signals have potential for application in manipulation and disruption of mating behavior of stink bugs. Further work needs to focus on the effects of female rival signals used in long duration experiments and also their interactions with chemical communication of stink bugs.

scholarly journals Generalized receptor law governs phototaxis in the phytoplanktonEuglena gracilis

2015 ◽  
Vol 112 (22) ◽  
pp. 7045-7050 ◽  
Author(s):  
Andrea Giometto ◽  
Florian Altermatt ◽  
Amos Maritan ◽  
Roman Stocker ◽  
Andrea Rinaldo
Keyword(s):  
Algal Blooms ◽  
Nonlinear Response ◽  
Temporal Dynamics ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Light Fields ◽  
Light Sources ◽  
Mathematical Framework ◽  
Heterogeneous Environments ◽  
Light Conditions

Phototaxis, the process through which motile organisms direct their swimming toward or away from light, is implicated in key ecological phenomena (including algal blooms and diel vertical migration) that shape the distribution, diversity, and productivity of phytoplankton and thus energy transfer to higher trophic levels in aquatic ecosystems. Phototaxis also finds important applications in biofuel reactors and microbiopropellers and is argued to serve as a benchmark for the study of biological invasions in heterogeneous environments owing to the ease of generating stochastic light fields. Despite its ecological and technological relevance, an experimentally tested, general theoretical model of phototaxis seems unavailable to date. Here, we present accurate measurements of the behavior of the algaEuglena graciliswhen exposed to controlled light fields. Analysis ofE. gracilis’ phototactic accumulation dynamics over a broad range of light intensities proves that the classic Keller–Segel mathematical framework for taxis provides an accurate description of both positive and negative phototaxis only when phototactic sensitivity is modeled by a generalized “receptor law,” a specific nonlinear response function to light intensity that drives algae toward beneficial light conditions and away from harmful ones. The proposed phototactic model captures the temporal dynamics of both cells’ accumulation toward light sources and their dispersion upon light cessation. The model could thus be of use in integrating models of vertical phytoplankton migrations in marine and freshwater ecosystems, and in the design of bioreactors.

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 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 Angiogenesis as a Therapeutic Target in Endometriosis

2014 ◽  
Vol 27 (4) ◽  
pp. 489 ◽  
Author(s):  
Dusan Djokovic ◽  
Carlos Calhaz-Jorge
Keyword(s):  
Drug Resistance ◽  
Literature Search ◽  
Molecular Mechanisms ◽  
Management Strategies ◽  
Angiogenesis Inhibitors ◽  
Resistance Development ◽  
Key Factor ◽  
Successful Establishment ◽  
Multimodal Management ◽  
Gynecological Disorder

<p><strong>Introduction:</strong> Angiogenesis is a key factor for the successful establishment and growth of endometriotic lesions.<br /><strong>Material and Methods:</strong> We performed a literature search in PubMed and reviewed the most pertinent studies published until January 2014 and focused on the endometriosis-associated angiogenesis and/or anti-angiogenic strategies for the treatment of this gynecological disorder.<br /><strong>Results:</strong> The present review provides a concise summary of the known molecular mechanisms that promote vascularization of endometriotic lesions and may serve as potential therapeutic targets. We also present a systematic overview of the inclusive and exclusive anti-angiogenic agents that have been already studied in cell cultures, animal models and/or endometriosis patients.<br /><strong>Discussion and Conclusion:</strong> The integration of anti-angiogenic approaches in the multimodal management strategies for endometriosis patients will be conditioned by the outcomes of future assessments regarding the effectiveness of such treatments, the risk of drug resistance development and the incidence of unacceptable side effects.<br /><strong>Keywords:</strong> Angiogenesis Inhibitors/therapeutic use; Endometriosis/drug therapy.</p>

Suspended sediment and discharge dynamics across multiple spatial and temporal scales in a glaciated alpine environment: the case of the upper Ötztal, Austria

2021 ◽  
Author(s):  
Lena Katharina Schmidt ◽  
Till Francke ◽  
Theresa Blume ◽  
Johannes Schöber ◽  
Daniel Pfurtscheller ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Temporal Dynamics ◽  
Management Strategies ◽  
Transient State ◽  
Data Availability ◽  
Spatial And Temporal Scales ◽  
Sediment Yields ◽  
Catchment Areas ◽  
Suspended Sediment Concentrations ◽  
Alpine Catchments

&lt;p&gt;High alpine areas are affected disproportionately by global warming and are thus found to be in a transient state. This causes accelerating glacial retreat, which can have severe impacts on discharge and potentially sediment dynamics. Possible effects include changes in water quantities and hydrograph timing as well as changing sediment source areas and the associated magnitude and timing of transport capacities. In turn, the resulting changes in water and sediment supplies and timing have the potential to severely impact downstream ecosystems and infrastructure.&lt;/p&gt;&lt;p&gt;An essential step towards estimating the effects of future changes and developing sustainable management strategies is to quantify the behavior in the past and present. We therefore used the excellent data availability of discharge and suspended sediment concentrations in our study area in the upper &amp;#214;tztal in Tyrol, Austria, to make such an assessment. We study discharge and suspended sediment concentrations, which have been monitored at three gauges and for a minimum of seven years in the case of the youngest gauge. The resulting nested catchment setup, with catchment sizes ranging between 98 km&amp;#178; and 785 km&amp;#178;, allows us to learn about discharge and sediment fluxes and their spatial distribution, thus allowing us to quantify the relative importance of the glaciated areas as compared to the lower-lying catchment areas. It also allows us to study the temporal dynamics, such as the seasonal timing of the peaks and their interannual differences. In turn, the nested catchments allows us to investigate the spatial variability of these temporal dynamics. &amp;#160;&lt;/p&gt;&lt;p&gt;The results confirm the high specific sediment yields for alpine catchments in the order of 10&amp;#179; t/km&amp;#178; per year and higher yields in areas with higher glacier cover as well as a very pronounced seasonality.&lt;/p&gt;

Microplastics from the Sources to Sinks: Assessment of Microplastics in the River Freshwater Environments and Wastewater Treatment Plants

2021 ◽  
Author(s):  
A H M Enamul Kabir ◽  
Masahiko Sekine ◽  
Tsuyoshi Imai ◽  
Koichi Yamamoto ◽  
Ariyo Kanno ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Point Source ◽  
Pollution Control ◽  
Wastewater Treatment Plants ◽  
Management Strategies ◽  
Freshwater Ecosystems ◽  
Point Sources ◽  
Source To Sink ◽  
Comprehensive Knowledge ◽  
Marine Realm

&lt;p&gt;Freshwater microplastics pollution has been a recent focus. River freshwater microplastics pollution are vital towards freshwater ecosystems as well as have been the prominent source-to-sink conduits to export MPs into the marine realm. Wastewater treatment plants (WWTPs) have been identified as one of the major point-sources. To date, sources-to-sinks comprehensive knowledge are highly limited. This study explored sources-to-sinks microplastics pollution i.e., WWTPs-to-river-to-marine comprehensively. The two rivers i.e., Koya River (KR) and Nishiki River (NR) which are flowing to the Seto Inland Sea (SIS) and the WWTPs effluent samples were collected from selected (n=37) stations in the Yamaguchi prefecture, Japan. Filtration, wet peroxidation, and density separation methods were employed to extract microplastics particles. Polymers were identified via attenuated total reflectance-Fourier transform infrared spectroscopy. The average microplastics abundances were found KR&amp;#8212;82.25&amp;#177;67.84 n/L and NR&amp;#8212;38.73&amp;#177;24.13 n/L for the river water, and KRWWTPs&amp;#8212;79.5&amp;#177;3.5 n/L and NRWWTPs&amp;#8212;72.25&amp;#177;23.64 n/L for WWTPs effluents, respectively. The KR were found to be more polluted than the NR. WWTPs effluents were found posing higher abundances than rivers. Significantly higher microplastics concentration were found in the WWTPs downstream stations than other river stations. Characterization revealed that small MPs (&lt;1000 &amp;#181;m) in size, fibers in shape, polymers&amp;#8212; polyethylene, polypropylene, polyethylene terephthalate, vinylon were major in both of the WWTPs effluents and rivers. WWTPs influenced river environments by means both of the abundances and microplastics characteristics (shapes-size-polymers). The estimated source-to-sink emission demonstrated a substantial number of MPs discharge into the rivers by the WWTPs (0.007&amp;#8212;0.086 billion/day) and rivers-to-SIS marine environments (1.15&amp;#8212;7.951 billion/day). The emission represented that the WWTPs were the prominent point-source to cause river microplastics pollution. Rivers were the initial sinks of the Japan land-sourced microplastics and prominent pathways to emit microplastics to the ultimate marine sink i.e., SIS. Large amounts of MPs are being generated on land sources before the plastics wastes degrade into MPs secondarily. The pollution characteristics (shapes-sizes-polymers) indicated ecotoxicological threats to these rivers and the downstream environments. Overall, this study provided an insight of sources-to-sinks pollution, fulfilled the preliminary knowledge gaps of pollution occurring land-sources, fate and loadings. We recommended microplastics pollution control at source. This study will aid in developing microplastics pollution control and management strategies for environmental protection and sustainability in the regional Japan as well as global context upon &amp;#8220;thinking globally and acting locally&amp;#8221;.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;Abundance, Point-source, Source-to-sink, Riverine microplastics pollution, Wastewater treatment plants&lt;/p&gt;

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