scholarly journals Decreased Snow Cover Stimulates Under-Ice Primary Producers but Impairs Methanotrophic Capacity

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Sarahi L. Garcia ◽  
Anna J. Szekely ◽  
Christoffer Bergvall ◽  
Martha Schattenhofer ◽  
Sari Peura
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Water Column ◽  
Relative Abundance ◽  
Heterotrophic Bacteria ◽  
Methane Emissions ◽  
Boreal Lakes ◽  
Climate Change Scenarios ◽  
Primary Producers ◽  
Microbial Composition

ABSTRACT Climate change scenarios anticipate decreased spring snow cover in boreal and subarctic regions. Forest lakes are abundant in these regions and substantial contributors of methane emissions. To investigate the effect of reduced snow cover, we experimentally removed snow from an anoxic frozen lake. We observed that the removal of snow increased light penetration through the ice, increasing water temperature and modifying microbial composition in the different depths. Chlorophyll a and b concentrations increased in the upper water column, suggesting activation of algal primary producers. At the same time, Chlorobiaceae, one of the key photosynthetic bacterial families in anoxic lakes, shifted to lower depths. Moreover, a decrease in the relative abundance of methanotrophs within the bacterial family Methylococcaceae was detected, concurrent with an increase in methane concentration in the water column. These results indicate that decreased snow cover impacts both primary production and methane production and/or consumption, which may ultimately lead to increased methane emissions after spring ice off. IMPORTANCE Small lakes are an important source of greenhouse gases in the boreal zone. These lakes are severely impacted by the winter season, when ice and snow cover obstruct gas exchange between the lake and the atmosphere and diminish light availability in the water column. Currently, climate change is resulting in reduced spring snow cover. A short-term removal of the snow from the ice stimulated algal primary producers and subsequently heterotrophic bacteria. Concurrently, the relative abundance of methanotrophic bacteria decreased and methane concentrations increased. Our results increase the general knowledge of microbial life under ice and, specifically, the understanding of the potential impact of climate change on boreal lakes.

scholarly journals Decreased snow cover stimulates under ice primary producers, but impairs methanotrophic capacity

2018 ◽  
Author(s):  
Sarahi L Garcia ◽  
Anna J. Szekely ◽  
Christoffer Bergvall ◽  
Martha Schattenhofer ◽  
Sari Peura
Keyword(s):  
Primary Production ◽  
Snow Cover ◽  
Water Column ◽  
Photosynthetic Bacteria ◽  
Methane Emissions ◽  
Climate Change Scenarios ◽  
Light Penetration ◽  
Microbial Composition ◽  
Forest Lakes ◽  
Chlorophyll A And B

AbstractClimate change scenarios anticipate decrease of spring snow cover in boreal and subarctic regions. Forest lakes are abundant in these regions and substantial contributors of methane emissions. We performed an experiment on an anoxic frozen lake and observed that the removal of snow increased light penetration through the ice into the water modifying the microbial composition across depths. A shift in photosynthetic primary production was reflected by the increase of chlorophyll a and b concentrations in the upper depths of the water column, while Chlorobia, one of the key photosynthetic bacteria in anoxic lakes, shifted to lower depths. Moreover, a decrease in abundance of methanotrophs, such as Methylococcaceae, was noted concurrently to an increase in methane concentration in the water column. These results indicate that decrease of snow cover impacts both primary production and methane production/consumption, ultimately leading to increased methane emissions after spring ice off.

scholarly journals Effects of temperature and organic pollution on nutrient cycling in marine sediments

2015 ◽  
Vol 12 (15) ◽  
pp. 4565-4575 ◽  
Author(s):  
C. Sanz-Lázaro ◽  
T. Valdemarsen ◽  
M. Holmer
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Nutrient Cycling ◽  
Water Column ◽  
Temperature Rise ◽  
Nutrient Release ◽  
Organic Pollution ◽  
Coastal Sediments ◽  
Effect Of Temperature ◽  
Climate Change Scenarios

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems. In these systems sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, increased linearly with temperature and were significantly higher under organic pollution than under nonpolluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and it was significantly higher in organic polluted compared to nonpolluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible for this behavior. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at a temperature rise > 6 °C could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.

scholarly journals Evaluation of future hydrological cycle under climate change scenarios in a mesoscale Alpine watershed of Italy

2011 ◽  
Vol 11 (6) ◽  
pp. 1769-1785 ◽  
Author(s):  
B. Groppelli ◽  
A. Soncini ◽  
D. Bocchiola ◽  
R. Rosso
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
General Circulation ◽  
Hydrological Model ◽  
Hydrological Cycle ◽  
Precipitation Amount ◽  
Climate Change Scenarios ◽  
Precipitation Patterns ◽  
Alpine Watershed ◽  
Flow Variables

Abstract. We investigate future (2045–2054) hydrological cycle of the snow fed Oglio (≈1800 km2) Alpine watershed in Northern Italy. A Stochastic Space Random Cascade (SSRC) approach is used to downscale future precipitation from three general circulation models, GCMs (PCM, CCSM3, and HadCM3) available within the IPCC's data base and chosen for this purpose based upon previous studies. We then downscale temperature output from the GCMs to obtain temperature fields for the area. We also consider a projected scenario based upon trends locally observed in former studies, LOC scenario. Then, we feed the downscaled fields to a minimal hydrological model to build future hydrological scenarios. We provide projected flow duration curves and selected flow descriptors, giving indication of expected modified (against control run for 1990–1999) regime of low flows and droughts and flood hazard, and thus evaluate modified peak floods regime through indexed flood. We then assess the degree of uncertainty, or spread, of the projected water resources scenarios by feeding the hydrological model with ensembles projections consistent with our deterministic (GCMs + LOC) scenarios, and we evaluate the significance of the projected flow variables against those observed in the control run. The climate scenarios from the adopted GCMs differ greatly from one another with respect to projected precipitation amount and temperature regimes, and so do the projected hydrological scenarios. A relatively good agreement is found upon prospective shrinkage and shorter duration of the seasonal snow cover due to increased temperature patterns, and upon prospective increase of hydrological losses, i.e. evapotranspiration, for the same reason. However, precipitation patterns are less consistent, because HadCM3 and PCM models project noticeably increased precipitation for 2045–2054, whereas CCSM3 provides decreased precipitation patterns therein. The LOC scenario instead displays unchanged precipitation. The ensemble simulations indicate that several projected flow variables under the considered scenarios are significantly different from their control run counterparts, and also that snow cover seems to significantly decrease in duration and depth. The proposed hydrological scenarios eventually provide a what-if analysis, giving a broad view of the possible expected impacts of climate change within the Italian Alps, necessary to trigger the discussion about future adaptation strategies.

The Effect of Climate Change on River Flow and Snow Cover in the NOPEX Area Simulated by a Simple Water Balance Model

1997 ◽  
Vol 28 (4-5) ◽  
pp. 273-282 ◽  
Author(s):  
C-Y Xu ◽  
Sven Halldin
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Snow Cover ◽  
Annual Runoff ◽  
Snow Accumulation ◽  
Water Balance Model ◽  
Annual Precipitation ◽  
Balance Model ◽  
Climate Change Scenarios ◽  
Average Annual Runoff

Within the next few decades, changes in global temperature and precipitation patterns may appear, especially at high latitudes. A simple monthly water-balance model of the NOPEX basins was developed and used for the purposes of investigating the effects on water availability of changes in climate. Eleven case study catchments were used together with a number of climate change scenarios. The effects of climate change on average annual runoff depended on the ratio of average annual runoff to average annual precipitation, with the greatest sensitivity in the catchments with lowest runoff coefficients. A 20% increase in annual precipitation resulted in an increase in annual runoff ranging from 31% to 51%. The greatest changes in monthly runoff were in winter (from December to March) whereas the smallest changes were found in summer. The time of the highest spring flow changed from April to March. An increase in temperature by 4°C greatly shortened the time of snow cover and the snow accumulation period. The maximum amount of snow during these short winters diminished by 50% for the NOPEX area even with an assumed increase of total precipitation by 20%.

scholarly journals Effects of global climate change and organic pollution on nutrient cycling in marine sediments

2015 ◽  
Vol 12 (1) ◽  
pp. 21-49
Author(s):  
C. Sanz-Lázaro ◽  
T. Valdemarsen ◽  
M. Holmer
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Nutrient Cycling ◽  
Water Column ◽  
Temperature Rise ◽  
Nutrient Release ◽  
Organic Pollution ◽  
Coastal Sediments ◽  
Effect Of Temperature ◽  
Climate Change Scenarios

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems, where sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios especially when the interactions among drivers may not be just additive. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, and increased linearly with temperature and were significantly higher under organic pollution than under non-polluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and was significantly higher in organic polluted compared to non-polluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible of this behaviour. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at temperature rise >6 ° could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.

scholarly journals VOLUME AND HEAT TRANSPORTS ANALYSIS IN THE SOUTH ATLANTIC BASIN RELATED TO CLIMATE CHANGE SCENARIOS

2015 ◽  
Vol 33 (2) ◽  
Author(s):  
Lívia Maria Barbosa Sancho ◽  
Luiz Paulo De Freitas Assad ◽  
Luiz Landau
Keyword(s):  
Climate Change ◽  
Fluid Dynamics ◽  
Water Column ◽  
Heat Transport ◽  
South Atlantic ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Climate Change Scenarios ◽  
Geophysical Fluid Dynamics ◽  
Zonal Section ◽  
Advective Heat Transport

ABSTRACT. This study evaluates how climate change might affect advective heat and volume transports in the South Atlantic Basin based on Intergovernmental Panel on Climate Change (IPCC) A1FI and B1 climate change scenarios projections. Using the Climatic Model 2.1 (CM2.1) results that were developed by the Geophysical Fluid Dynamics Laboratory (GFDL), integrated on the water column, analyses were conducted through two meridional sections and one zonal section of the study area (between 25◦S-70◦S and 70◦W-20◦E). The annual mean time series were analyzed using historical 100-year climate change scenarios. The analyses of the climate change experiment parameters were compared with those of the H2 climate scenario. The volume transport (VT) through the water column weakened of about 5% in average and the advective heat transport (HT) increased of about 22% at the Drake and Africa-Antarctic (AF-AA) passages at the end of the experiments. For the zonal section at 25◦S, direction oscillations were observed in the integrated VT through the water column due to velocity intensity variations of the water masses and a decrease of about 22% in the HT was observed. Thus, it was observed a decrease in the water and heat supplies at 25◦S due to the Drake and AF-AA VT behavior, which may alter deep circulation patterns.Keywords: water column analysis, advective heat transport, flow direction, Drake Passage, Africa-Antarctic passage.RESUMO. Baseado nas projeções dos cenários de mudanças climáticas A1FI e B1 do Painel Intergovernamental de Mudanc¸as Climáticas (IPCC), esse estudo avalia como as mudanças climáticas podem impactar os transportes advectivos de calor e volume na bacia do Atlântico Sul. Através de resultados gerados pelo Modelo Climático 2.1 (CM2.1) desenvolvido pelo Geophysical Fluid Dynamics Laboratory (GFDL), foram feitas análises através de duas seções meridionais e uma seção zonal na área de estudo (entre 25◦S-70◦S e 70◦W-20◦E) integradas na coluna d’água. Foram analisados campos prognósticos médios anuais referentes a experimentos com 100 anos de duração. As análises dos parâmetros dos experimentos de mudanças climáticas foram realizadas em comparação com o experimento clima (H2). O transporte de volume (TV) integrado na coluna d’água enfraqueceu aproximadamente 5%, enquanto o transporte advectivo de calor (TC) aumentou em torno de 22% no Drake e na Passagem África-Antártida (AF-AA) ao final dos experimentos. Para a seção em 25◦S, foram observadas oscilações de direção do fluxo devido a variações na intensidade das velocidades das massas d’água com um enfraquecimento médio de 22% para o TC. Adicionalmente, foi observada uma diminuição no suprimento de água em 25◦S devido ao comportamento do TV das demais seções, o que pode alterar os padrões de circulação profunda.Palavras-chave: análise na coluna d’água, transporte advectivo de calor, direção do fluxo, Passagem de Drake, passagem África-Antártida.

scholarly journals Soil Microbial Community Responses to Multiple Experimental Climate Change Drivers

2009 ◽  
Vol 76 (4) ◽  
pp. 999-1007 ◽  
Author(s):  
Hector F. Castro ◽  
Aimée T. Classen ◽  
Emily E. Austin ◽  
Richard J. Norby ◽  
Christopher W. Schadt
Keyword(s):  
Climate Change ◽  
Community Composition ◽  
Relative Abundance ◽  
Rrna Genes ◽  
Climate Change Scenarios ◽  
Old Field ◽  
Fungal Abundance ◽  
Group I ◽  
Field Ecosystem ◽  
Climate Change Drivers

ABSTRACT Researchers agree that climate change factors such as rising atmospheric [CO2] and warming will likely interact to modify ecosystem properties and processes. However, the response of the microbial communities that regulate ecosystem processes is less predictable. We measured the direct and interactive effects of climatic change on soil fungal and bacterial communities (abundance and composition) in a multifactor climate change experiment that exposed a constructed old-field ecosystem to different atmospheric CO2 concentration (ambient, +300 ppm), temperature (ambient, +3°C), and precipitation (wet and dry) might interact to alter soil bacterial and fungal abundance and community structure in an old-field ecosystem. We found that (i) fungal abundance increased in warmed treatments; (ii) bacterial abundance increased in warmed plots with elevated atmospheric [CO2] but decreased in warmed plots under ambient atmospheric [CO2]; (iii) the phylogenetic distribution of bacterial and fungal clones and their relative abundance varied among treatments, as indicated by changes in 16S rRNA and 28S rRNA genes; (iv) changes in precipitation altered the relative abundance of Proteobacteria and Acidobacteria, where Acidobacteria decreased with a concomitant increase in the Proteobacteria in wet relative to dry treatments; and (v) changes in precipitation altered fungal community composition, primarily through lineage specific changes within a recently discovered group known as soil clone group I. Taken together, our results indicate that climate change drivers and their interactions may cause changes in bacterial and fungal overall abundance; however, changes in precipitation tended to have a much greater effect on the community composition. These results illustrate the potential for complex community changes in terrestrial ecosystems under climate change scenarios that alter multiple factors simultaneously.

scholarly journals Climate Change Scenarios and Effects on Snow-Melt Runoff

2020 ◽  
Vol 6 (9) ◽  
pp. 1715-1725 ◽  
Author(s):  
Safieh Javadinejad ◽  
Rebwar Dara ◽  
Forough Jafary
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Annual Runoff ◽  
Hydrologic Model ◽  
Climate Change Scenarios ◽  
Snow Melt ◽  
Snowmelt Runoff ◽  
Rcp Scenarios ◽  
Temperature And Precipitation ◽  
Spring Runoff

Climate change is an important environmental issue, as progression of melting glaciers and snow cover is sensitive to climate alteration. The aim of this research was to model climate alterations forecasts, and to assess potential changes in snow cover and snow-melt runoff under the different climate change scenarios in the case study of the Zayandeh-rud River Basin. Three cluster models for climate change (NorESM1-M, IPSL-CM5A-LR and CSIRO-MK3.6.0) were applied under RCP 8.5, 4.5 and 2.6 scenarios, to examine climate influences on precipitation and temperature in the basin. Temperature and precipitation were determined for all three scenarios for four periods of 2021-2030, 2031-2040, 2041-2050 and 2051-2060. MODIS (MOD10A1) was also applied to examine snow cover using temperature and precipitation data. The relationship between snow-covered area, temperature and precipitation was used to forecast future snow cover. For modeling future snow melt runoff, a hydrologic model of SRM was used including input data of precipitation, temperature and snow cover. The results indicated that all three RCP scenarios lead to an increase in temperature, and reduction in precipitation and snow cover. Investigation in snowmelt runoff throughout the observation period (November 1970 to May 2006) showed that most of annual runoff is derived from snow melting. Maximum snowmelt runoff is generated in winter. The share of melt water in the autumn and spring runoff is estimated at 35 and 53%, respectively. The results of this study can assist water manager in making better decisions for future water supply.

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