scholarly journals Watershed geomorphology modifies the sensitivity of aquatic ecosystem metabolism to temperature

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
K. J. Jankowski ◽  
D. E. Schindler
Keyword(s):  
Temperature Sensitivity ◽  
Aquatic Ecosystem ◽  
Aquatic Ecosystems ◽  
Ecosystem Respiration ◽  
Ecosystem Metabolism ◽  
Temperature Sensitive ◽  
Carbon Quality ◽  
Carbon Cycles ◽  
Boreal River

AbstractThe regulation of aquatic carbon cycles by temperature is a significant uncertainty in our understanding of how watersheds will respond to climate change. Aquatic ecosystems transport substantial quantities of carbon to the atmosphere and ocean, yet we have limited understanding of how temperature modifies aquatic ecosystem metabolic processes and contributions to carbon cycles at watershed to global scales. We propose that geomorphology controls the distribution and quality of organic material that forms the metabolic base of aquatic ecosystems, thereby controlling the response of aquatic ecosystem metabolism to temperature across landscapes. Across 23 streams and four years during summer baseflow, we estimated variation in the temperature sensitivity of ecosystem respiration (R) among streams draining watersheds with different geomorphic characteristics across a boreal river basin. We found that geomorphic features imposed strong controls on temperature sensitivity; R in streams draining flat watersheds was up to six times more temperature sensitive than streams draining steeper watersheds. Further, our results show that this association between watershed geomorphology and temperature sensitivity of R was linked to the carbon quality of substrates that changed systematically across the geomorphic gradient. This suggests that geomorphology will control how carbon is transported, stored, and incorporated into river food webs as the climate warms.

Natural vs. anthropogenic effects in the composition of dissolved inorganic carbon in a boreal river with a seasonal base flow component

2017 ◽  
Vol 48 (6) ◽  
pp. 1585-1593
Author(s):  
Paula I. A. Niinikoski ◽  
Juha A. Karhu
Keyword(s):  
Carbon Balance ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Surface Flow ◽  
Base Flow ◽  
Annual Cycles ◽  
Carbon Quality ◽  
Flow Component ◽  
Boreal River

Abstract Studying the carbon balance in surface waters gives information on the annual cycles of photosynthesis and respiration. It also provides insight on the water body's capability to serve as a source or sink for atmospheric CO2, which may be essential in evaluating the effects of climate change. The target of this study was the Vantaanjoki River known to have a significant base flow component, located in a densely populated area in southern Finland. The aims of this study were firstly to study if human induced changes are evident in the inorganic carbon quality of the river, and secondly to determine whether the river releases carbon to the atmosphere. These aims were achieved by studying the isotopic composition and contents of dissolved inorganic carbon (DIC) in relation to river discharge. It was evident from the results that the human activities only have mild local and temporal effects on the quality of the DIC in the river. The most important contributors to the changes in the carbon balance are the annual changes in the proportion of the base flow and surface flow components and the escape of CO2 to the atmosphere.

Sensitivity of peatland respiration to vegetation community and temperature metric during a hot drought

2020 ◽  
Author(s):  
Julia Kelly ◽  
Natascha Kljun ◽  
Lars Eklundh ◽  
Leif Klemedtsson ◽  
Bengt Liljebladh ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Vascular Plant ◽  
Carbon Sources ◽  
Temperature Sensitive ◽  
Vegetation Community ◽  
Vegetation Communities ◽  
Drought Conditions ◽  
The Impact

<p>The majority of the world’s peatlands are located in northern regions where climate change is occurring most rapidly. Therefore, there is an urgent need to understand whether, and under what conditions, peatlands will remain carbon sinks or become carbon sources. The uncertainties in our predictions stem from a variety of sources, including uncertainty about the competing effects of rising air temperature on ecosystem respiration (R<sub>e</sub>) and gross primary production. Furthermore, peatlands contain a mixture of plant communities that respond differently to changes in temperature and precipitation. Such heterogeneity complicates attempts to upscale peatland carbon fluxes and predict the future peatland carbon balance.</p><p> </p><p>We focus on understanding the sensitivity of peatland R<sub>e</sub> to temperature and how it relates to vegetation community and the choice of temperature metric. We assess how these relationships changed during and after the severe heatwave and drought (‘hot drought’) in 2018. We conducted manual dark chamber CO<sub>2</sub> efflux measurements in Mycklemossen, an oligotrophic mire in southern Sweden in 2018 and in 2019, when weather conditions were closer to the long-term mean. The measurements covered the two main vegetation communities at the site: hummocks (vascular-plant dominated) and hollows (<em>Sphagnum</em>-dominated). We statistically compared the fluxes for both years and vegetation communities, then modelled them using three temperature metrics (air, surface, soil).</p><p> </p><p>We found that R<sub>e</sub> decreased during the hot drought for both vegetation communities, with maximum fluxes of 0.18 and 0.34 mgCO<sub>2</sub> m<sup>-2</sup> s<sup>-1</sup> in 2018 and 2019, respectively. However, the change in R<sub>e</sub> during the hot drought was dependent on vegetation community: hummock R<sub>e</sub> decreased substantially more than hollow R<sub>e</sub> (mean decrease: 48% and 15%, respectively). As a result, hollow R<sub>e</sub> was highest during drought whereas hummock R<sub>e</sub> was highest during non-drought conditions. Despite significant differences in R<sub>e</sub> between the vegetation communities, we found no significant differences in temperature between hummock and hollow vegetation, apart from in July and August 2018, at the peak of the hot drought. Nevertheless, hollow R<sub>e</sub> was more temperature-sensitive than hummock R<sub>e</sub> both during and after the hot drought. Furthermore, the temperature sensitivity of modelled R<sub>e</sub> depended on the choice of driving temperature, such that the surface temperature driven model produced the lowest whilst the soil temperature driven model produced the highest temperature sensitivity. Differences in temperature sensitivity of R<sub>e</sub> between the drought and non-drought conditions were similarly dependent on the temperature metric used to drive the R<sub>e</sub> model.</p><p> </p><p>We found that peatland R<sub>e</sub> almost halved during a hot drought. Our results show that predictions of peatland response to warming must account for the proportion of different vegetation communities present, and how this may change, due to their differing responses to warming. The choice of driving temperature in peatland R<sub>e</sub> models does not impact model accuracy but it does influence the temperature-sensitivity, and thus the impact of temperature variations on the modelled flux. Modellers should therefore base parameter choices on vegetation community and driving temperature. Furthermore, comparisons of R<sub>e</sub> sensitivity to warming between studies using different driving temperatures may be misleading.  </p>

Metabolic changes and the resistance and resilience of a subtropical heterotrophic lake to typhoon disturbance

2011 ◽  
Vol 68 (5) ◽  
pp. 768-780 ◽  
Author(s):  
Jeng-Wei Tsai ◽  
Timothy K. Kratz ◽  
Paul C. Hanson ◽  
Nobuaki Kimura ◽  
Wen-Cheng Liu ◽  
...  
Keyword(s):  
High Frequency ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Ecosystem Metabolism ◽  
Lake Metabolism ◽  
Typhoon Disturbance ◽  
Ecosystem Production ◽  
Rate Of Recovery ◽  
Induced Changes

We studied how typhoon strength affects the daily dynamics of ecosystem metabolism of a subtropical alpine lake in Taiwan. We identified proximal agents of typhoon disturbance and assessed the resistance (the extent of change induced by a disturbance) and resilience (the rate of recovery after a disturbance) of lake metabolism to them. Gross primary production (GPP), ecosystem respiration (ER), and net ecosystem production were estimated from high-frequency dissolved oxygen data provided by an instrumented buoy. Typhoons resulted in significantly lower GPP (3%–81% decrease), and higher ER (7%–828% increase) compared with immediately before the events, and thus the lake became more heterotrophic (28%–852% increase in heterotrophy). The resistance and resilience of lake metabolism depended on the intensity of the typhoon. Smaller typhoons (with average daily accumulated precipitation (ADAP) < 200 mm·day–1) had greater effects on lake metabolism than medium (ADAP = 200–350 mm·day–1) and large (ADAP > 350 mm·day–1) typhoons. However, metabolism also recovered more quickly after smaller typhoons than after medium or larger typhoons. Typhoon effects on ecosystem metabolism is likely mediated by the magnitude and duration of typhoon-induced changes in lake mixing, the quantity and quality of dissolved organic carbon, and the biomass of primary producers.

Evaluation of Landfill Effects on Aquatic Ecosystems Using Benthic Macro-Invertebrates

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2365-2367
Author(s):  
L. Cingolani ◽  
A. Morosi
Keyword(s):  
Aquatic Ecosystem ◽  
Aquatic Ecosystems ◽  
Drainage Area ◽  
Taxonomic Level ◽  
Significant Difference ◽  
Downstream Communities

The aim of this work was to verify the effectiveness of benthic macro-invertebrate observation in providing information about the effects of a landfill on an aquatic ecosystem. A significant difference between upstream and downstream communities from landfill drainage area was found. The adopted taxonomic level was sufficient to reach our object.

scholarly journals A Single Point Mutation, Asn16→Lys, Dictates the Temperature-Sensitivity of the Reovirus tsG453 Mutant

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 289
Author(s):  
Kathleen K. M. Glover ◽  
Danica M. Sutherland ◽  
Terence S. Dermody ◽  
Kevin M. Coombs
Keyword(s):  
Amino Acid ◽  
Temperature Sensitivity ◽  
Reverse Genetics ◽  
Core Protein ◽  
Single Point ◽  
Single Amino Acid ◽  
Single Point Mutation ◽  
Temperature Sensitive ◽  
Amino Acid Substitutions ◽  
Gene Encoding

Studies of conditionally lethal mutants can help delineate the structure-function relationships of biomolecules. Temperature-sensitive (ts) mammalian reovirus (MRV) mutants were isolated and characterized many years ago. Two of the most well-defined MRV ts mutants are tsC447, which contains mutations in the S2 gene encoding viral core protein σ2, and tsG453, which contains mutations in the S4 gene encoding major outer-capsid protein σ3. Because many MRV ts mutants, including both tsC447 and tsG453, encode multiple amino acid substitutions, the specific amino acid substitutions responsible for the ts phenotype are unknown. We used reverse genetics to recover recombinant reoviruses containing the single amino acid polymorphisms present in ts mutants tsC447 and tsG453 and assessed the recombinant viruses for temperature-sensitivity by efficiency-of-plating assays. Of the three amino acid substitutions in the tsG453 S4 gene, Asn16-Lys was solely responsible for the tsG453ts phenotype. Additionally, the mutant tsC447 Ala188-Val mutation did not induce a temperature-sensitive phenotype. This study is the first to employ reverse genetics to identify the dominant amino acid substitutions responsible for the tsC447 and tsG453 mutations and relate these substitutions to respective phenotypes. Further studies of other MRV ts mutants are warranted to define the sequence polymorphisms responsible for temperature sensitivity.

scholarly journals Omnivorous Carp (Carassius gibelio) Increase Eutrophication in Part by Preventing Development of Large-Bodied Zooplankton and Submerged Macrophytes

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1497
Author(s):  
Vladimir Razlutskij ◽  
Xueying Mei ◽  
Natallia Maisak ◽  
Elena Sysova ◽  
Dzmitry Lukashanets ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Submerged Macrophytes ◽  
Benthic Algae ◽  
Plankton Community ◽  
Prussian Carp ◽  
Omnivorous Fish ◽  
Outdoor Experiment ◽  
Nitrogen Concentrations ◽  
Lower Biomass

Fish, being an important consumer in aquatic ecosystems, plays a significant role by affecting the key processes of aquatic ecosystems. Omnivorous fish consume a variety of food both from pelagic and benthic habitats and may directly or indirectly affect the plankton community as well as the lake trophic state. We conducted a 72-day outdoor experiment in mesocosms with and without Prussian carp (Carassius auratus) to evaluate the effect of this often-stocked omnivorous fish on the plankton community and water quality. We found that the presence of fish increased the biomass of planktonic algae, total and inorganic suspended solids, leading to decreased light intensity in the water and a lower biomass of benthic algae. Fish also prevented development of submerged macrophytes and the establishment of large-bodied zooplankton. However, the fish did not increase nitrogen concentrations and even was lowered total phosphorus levels, in part due to nutrient storage in the fish. We conclude that stocking of Prussian carp should be avoided, or removed where stocked and abundant, to obtain good ecological quality of shallow lakes, characterized by clear water and high abundance of macrophytes.

On methodological approaches to the improvement of surface water bodies and target indicators of the natural waters’ quality

2021 ◽  
Vol 27 (1) ◽  
pp. 6-14
Author(s):  
V. Zaslonovsky ◽  
◽  
N. Sharapov ◽  
M. Bosov ◽  
◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
Natural Water ◽  
Aquatic Ecosystems ◽  
Natural Waters ◽  
Water Bodies ◽  
Surface Water Bodies ◽  
Methodological Approaches ◽  
Natural Water Bodies

The paper is devoted to the development of proposals concerning the improvement of surface water bodies and the appointment of target indicators of the natural waters’ quality. The paper considers a variety of problems of preserving, restoring and improving the quality of natural surface waters: from regional features of the formation of natural water composition, to differences in the requirements for the quality of water consumed. The object of the study is the qualitative indicators of the waters of natural water bodies, and the subject of the study is the methodological approaches to the normalization of these indicators. The purpose of the work is to identify the main shortcomings in the domestic system of rationing the quality of natural waters, and to form appropriate proposals. For this purpose, the following tasks were set and solved: to review the methodological approaches to assessing and rationing the quality of natural waters used in some foreign countries and in the Russian Federation, to identify the main causes and shortcomings; to make proposals for improving the current system of water quality rationing. The result of this work is the conclusions about the lack of impact of the strategy operating in Russia in the development of schemes of complex use and protection of water objects, standards of permissible impact on water bodies, the appointment of permissible discharge limits in terms of maintaining and improving the water quality of natural water bodies. The reasons that led to this are indicated. The necessity of taking into account, in addition to the physical and chemical composition, also hydrobiological parameters is shown. It is concluded that instead of fisheries management standards, environmental standards should serve as the basis for target indicators of water quality of natural water bodies, which determine the well-being of humans and the stable functioning of aquatic ecosystems, taking into account regional factors. Proposals were made to adjust the methodological approaches to the implementation of this strategy. According to the authors, these proposals will speed up the solution of the main objectives of the strategy – the ecological improvement of water bodies, the preservation of unique aquatic ecosystems and the environmentally safe development of territories that previously experienced relatively small anthropogenic impacts (Eastern Siberia and the Far East)

The Neurospora crassa cyt-20 gene encodes cytosolic and mitochondrial valyl-tRNA synthetases and may have a second function in addition to protein synthesis

1991 ◽  
Vol 11 (8) ◽  
pp. 4022-4035
Author(s):  
A R Kubelik ◽  
B Turcq ◽  
A M Lambowitz
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Neurospora Crassa ◽  
Temperature Sensitivity ◽  
Temperature Sensitive ◽  
Cellular Transport ◽  
Missense Mutations ◽  
Reading Frame ◽  
Trna Synthetases ◽  
Cytosolic Protein

The cyt-20-1 mutant of Neurospora crassa is a temperature-sensitive, cytochrome b- and aa3-deficient strain that is severely deficient in both mitochondrial and cytosolic protein synthesis (R.A. Collins, H. Bertrand, R.J. LaPolla, and A.M. Lambowitz, Mol. Gen. Genet. 177:73-84, 1979). We cloned the cyt-20+ gene by complementation of the cyt-20-1 mutation and found that it contains a 1,093-amino-acid open reading frame (ORF) that encodes both the cytosolic and mitochondrial valyl-tRNA synthetases (vaIRSs). A second mutation, un-3, which is allelic with cyt-20-1, also results in temperature-sensitive growth, but not in gross deficiencies in cytochromes b and aa3 or protein synthesis. The un-3 mutant had also been reported to have pleiotropic defects in cellular transport process, resulting in resistance to amino acid analogs (M.S. Kappy and R.L. Metzenberg, J. Bacteriol. 94:1629-1637, 1967), but this resistance phenotype is separable from the temperature sensitivity in crosses and may result from a mutation in a different gene. The 1,093-amino-acid ORF encoding vaIRSs is the site of missense mutations resulting in temperature sensitivity in both cyt-20-1 and un-3 and is required for the transformation of both mutants. The opposite strand of the cyt-20 gene encodes an overlapping ORF of 532 amino acids, which may also be functional but is not required for transformation of either mutant. The cyt-20-1 mutation in the vaIRS ORF results in severe deficiencies of both mitochondrial and cytosolic vaIRS activities, whereas the un-3 mutation does not appear to result in a deficiency of these activities or of mitochondrial or cytosolic protein synthesis sufficient to account for its temperature-sensitive growth. The phenotype of the un-3 mutant raises the possibility that the vaIRS ORF has a second function in addition to protein synthesis.

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