scholarly journals Contrasting effects of ocean acidification on the microbial food web under different trophic conditions

2015 ◽  
Vol 73 (3) ◽  
pp. 670-679 ◽  
Author(s):  
M. M. Sala ◽  
F. L. Aparicio ◽  
V. Balagué ◽  
J. A. Boras ◽  
E. Borrull ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Microbial Communities ◽  
Heterotrophic Bacteria ◽  
Phytoplankton Bloom ◽  
Extracellular Enzyme ◽  
Nutrient Concentrations ◽  
Leucine Incorporation ◽  
Negative Effects ◽  
Trophic Conditions ◽  
Positive Effects

AbstractWe investigated the effects of an increase in dissolved CO2 on the microbial communities of the Mediterranean Sea during two mesocosm experiments in two contrasting seasons: winter, at the peak of the annual phytoplankton bloom, and summer, under low nutrient conditions. The experiments included treatments with acidification and nutrient addition, and combinations of the two. We followed the effects of ocean acidification (OA) on the abundance of the main groups of microorganisms (diatoms, dinoflagellates, nanoeukaryotes, picoeukaryotes, cyanobacteria, and heterotrophic bacteria) and on bacterial activity, leucine incorporation, and extracellular enzyme activity. Our results showed a clear stimulation effect of OA on the abundance of small phytoplankton (pico- and nanoeukaryotes), independently of the season and nutrient availability. A large number of the measured variables showed significant positive effects of acidification in summer compared with winter, when the effects were sometimes negative. Effects of OA were more conspicuous when nutrient concentrations were low. Our results therefore suggest that microbial communities in oligotrophic waters are considerably affected by OA, whereas microbes in more productive waters are less affected. The overall enhancing effect of acidification on eukaryotic pico- and nanophytoplankton, in comparison with the non-significant or even negative response to nutrient-rich conditions of larger groups and autotrophic prokaryotes, suggests a shift towards medium-sized producers in a future acidified ocean.

Microbial Communities on Leaf Material Protected from Macroinvertebrate Grazing in Acidic and Circumneutral Streams

1987 ◽  
Vol 44 (5) ◽  
pp. 1064-1070 ◽  
Author(s):  
Anthony V. Palumbo ◽  
Patrick J. Mulholland ◽  
Jerry W. Elwood
Keyword(s):  
Microbial Communities ◽  
Microbial Activity ◽  
Standing Stock ◽  
Low Ph ◽  
Negative Effects ◽  
High Ph ◽  
Leaf Material ◽  
Positive Effects ◽  
Leaf Surfaces ◽  
Flow Through

To determine how low pH and high aluminum concentrations directly affect microbial activity on decomposing leaves in streams, we examined microbial communities on leaf surfaces using in situ flow-through chambers which exclude macroinvertebrates. Bacterial production (thymidine incorporation) on leaf material was significantly higher at pH 6.4 than at 4.9 after 4 wk of incubation, and this difference persisted for the last 5 wk of the experiment. Microbial respiration was greater at the high pH site after 6 wk, and there were no significant differences in ATP standing stock. Concentrations of oxalate-extractable aluminum on the leaf material increased significantly within the first 4 wk of incubation and stabilized at significantly greater levels at low pH (4.66 mg∙g−1) than at high pH (1.70 mg∙g−1). Transferring leaf material from the high-pH to the low-pH stream had negative effects after only 1 wk of incubation. However, transferring from low pH to high pH did not result in significant positive effects until 4 wk after the transfers. The reduced microbial production and respiration in the low-pH stream imply that decomposition rates may be slower in acidified systems due, at least in part, to direct effects of acidification on microbial activity.

scholarly journals Effects of increased atmospheric CO<sub>2</sub> on small and intermediate sized osmotrophs during a nutrient induced phytoplankton bloom

2007 ◽  
Vol 4 (6) ◽  
pp. 4173-4195 ◽  
Author(s):  
A. I. Paulino ◽  
J. K. Egge ◽  
A. Larsen
Keyword(s):  
Microbial Communities ◽  
Population Dynamic ◽  
Temporal Dynamics ◽  
Heterotrophic Bacteria ◽  
Phytoplankton Bloom ◽  
Co2 Concentration ◽  
Transient Population ◽  
The Difference ◽  
High Concentrations ◽  
Co2 Treatment

Abstract. We report the transient population dynamic response of the osmotrophic community initiated by a nutrient pulse in mesocosms exposed to different pCO2 levels as well as quantitative variations in phytoplankton and heterotrophic bacteria created by the difference in CO2 exposure. Coastal seawater was enclosed in floating mesocosms (27 m3) and nutrients were supplied initially in order to stimulate growth of microbial organisms, including the coccolitophorid Emiliania huxleyi. The mesocosms were modified to achieve 350 μatm (1×CO2), 700 μatm (2×CO2) and 1050 µatm (3×CO2) CO2 pressure. The temporal dynamics was related to the nutrient conditions in the enclosures. Numerically small osmotrophs (picoeukaryotes and Synechoccocus sp.) dominated initially and towards the end of the experiment, whereas intermediate sized osmotrophs bloomed as the initial bloom of small sized osmotrophs ceased. Maximum concentrations of E. huxleyi were approximately 4.6×103 cells ml−1 whereas other intermediate sized osmotrophs reached approximately twice as high concentrations. Osmotrophic succession pattern did not change, and we were not able to detect differences with regard to presence or absence of specific osmotrophic taxa as a consequence of altered atmospheric CO2 concentration. Quantitative effects on the microbial communities associated with the CO2 treatment were, however, observed towards the end of the experiment.

scholarly journals Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

2020 ◽  
Vol 17 (16) ◽  
pp. 4153-4171
Author(s):  
Stacy Deppeler ◽  
Kai G. Schulz ◽  
Alyce Hancock ◽  
Penelope Pascoe ◽  
John McKinlay ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Food Web ◽  
Microbial Communities ◽  
Heterotrophic Bacteria ◽  
Trophic Levels ◽  
Heterotrophic Nanoflagellates ◽  
Grazing Impact ◽  
Antarctic Marine ◽  
Morphological Differences ◽  
Organic Matter Recycling

Abstract. High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. At CO2 levels ≥634 µatm, HNF abundance was reduced, coinciding with increased abundance of picophytoplankton and prokaryotes. This increase in picophytoplankton and prokaryote abundance was likely due to a reduction in top-down control of grazing HNFs. Nanophytoplankton abundance was elevated in the 634 µatm treatment, suggesting that moderate increases in CO2 may stimulate growth. The taxonomic and morphological differences in CO2 tolerance we observed are likely to favour dominance of microbial communities by prokaryotes, nanophytoplankton, and picophytoplankton. Such changes in predator–prey interactions with ocean acidification could have a significant effect on the food web and biogeochemistry in the Southern Ocean, intensifying organic-matter recycling in surface waters; reducing vertical carbon flux; and reducing the quality, quantity, and availability of food for higher trophic levels.

scholarly journals Ocean acidification indirectly alters trophic interaction of heterotrophic bacteria at low nutrient conditions

2016 ◽  
Author(s):  
Thomas Hornick ◽  
Lennart T. Bach ◽  
Katharine J. Crawfurd ◽  
Kristian Spilling ◽  
Eric P. Achterberg ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Algal Blooms ◽  
Atmospheric Carbon Dioxide ◽  
Heterotrophic Bacteria ◽  
Bacterial Cells ◽  
Negative Effects ◽  
Food Web Interactions ◽  
Water Ph ◽  
The Baltic ◽  
Nutrient Conditions

Abstract. Annually, the oceans absorb about one fourth of the anthropogenically produced atmospheric carbon dioxide (CO2) resulting in a drop in surface water pH, a process termed ocean acidification (OA). Surprisingly little is known about how OA affects physiology as well as food web interactions of heterotrophic bacteria when essential nutrients are limited, since most previous experiments were carried out during productive phases or even after nutrient additions to stimulate algal blooms. Therefore, we conducted an in situ large-volume mesocosm (~55 m3) experiment in the Baltic Sea by simulating different fugacities of CO2 (fCO2) extending from present to future conditions. The study was carried out after the spring-bloom in July–August to maintain low-nutrient conditions throughout the experiment, which resulted in a small-sized phytoplankton community dominated by picophytoplankton. Several positive as well as negative effects on free-living (FL) and particle-associated (PA) bacterial protein production (BPP) and biovolume (BV) could be related to fCO2-induced differences in phytoplankton composition and subsequent the availability of phytoplankton-derived organic matter. However, dynamics of BV and cell-specific BPP (csBPP) of FL heterotrophic bacteria could not be explained exclusively by the availability of phytoplankton-derived organic carbon. The dynamics were also related to enhanced grazing on DNA rich (HDNA) bacterial cells at higher fCO2 as revealed by flow cytometry. Additionally, a decoupling of autotrophic production and heterotrophic consumption during the last third of the experiment resulted in low, but significantly higher accumulation of DOC at enhanced fCO2. Interestingly we could not detect any consistent and direct fCO2-induced effect on BPP, csBPP nor BV of either FL or PA heterotrophic bacteria. In contrast, our results reveal several indirect fCO2-induced effects on BPP and bacterial BV with potential consequences for oceanic carbon cycling, in particular in a low nutrient and high fCO2 future ocean.

Undesirable Effects of Goal Setting on Perceived Fairness, Commitment, and Unethical Behavior

2018 ◽  
Vol 62 (2) ◽  
pp. 97-107 ◽  
Author(s):  
Nina Keith
Keyword(s):  
Goal Setting ◽  
Unethical Behavior ◽  
The United States ◽  
Goal Commitment ◽  
Management Technique ◽  
Long Term Effects ◽  
Perceived Fairness ◽  
Negative Effects ◽  
Positive Effects ◽  
And Performance

Abstract. The positive effects of goal setting on motivation and performance are among the most established findings of industrial–organizational psychology. Accordingly, goal setting is a common management technique. Lately, however, potential negative effects of goal-setting, for example, on unethical behavior, are increasingly being discussed. This research replicates and extends a laboratory experiment conducted in the United States. In one of three goal conditions (do-your-best goals, consistently high goals, increasingly high goals), 101 participants worked on a search task in five rounds. Half of them (transparency yes/no) were informed at the outset about goal development. We did not find the expected effects on unethical behavior but medium-to-large effects on subjective variables: Perceived fairness of goals and goal commitment were least favorable in the increasing-goal condition, particularly in later goal rounds. Results indicate that when designing goal-setting interventions, organizations may consider potential undesirable long-term effects.

Mobilizing for Some

2016 ◽  
Vol 28 (3) ◽  
pp. 123-135 ◽  
Author(s):  
Raffael Heiss ◽  
Jörg Matthes
Keyword(s):  
High School ◽  
Social Media ◽  
High School Students ◽  
Experimental Design ◽  
Collective Efficacy ◽  
Political Efficacy ◽  
Negative Effects ◽  
School Students ◽  
Positive Effects ◽  
Specific Factors

Abstract. This study investigated the effects of politicians’ nonparticipatory and participatory Facebook posts on young people’s political efficacy – a key determinant of political participation. We employed an experimental design, using a sample of N = 125 high school students (15–20 years). Participants either saw a Facebook profile with no posts (control condition), nonparticipatory posts, or participatory posts. While nonparticipatory posts did not affect participants’ political efficacy, participatory posts exerted distinct effects. For those high in trait evaluations of the politician presented in the stimulus material or low in political cynicism, we found significant positive effects on external and collective efficacy. By contrast, for those low in trait evaluations or high in cynicism, we found significant negative effects on external and collective efficacy. We did not find any effects on internal efficacy. The importance of content-specific factors and individual predispositions in assessing the influence of social media use on participation is discussed.

On the diversity of the effects of the state support for agriculture

2019 ◽  
pp. 59-73 ◽  
Author(s):  
Nikolai M. Svetlov ◽  
Renata G. Yanbykh ◽  
Dariya A. Loginova
Keyword(s):  
Agricultural Production ◽  
The State ◽  
Russian Regions ◽  
Negative Effects ◽  
State Support ◽  
Soft Budget Constraints ◽  
Institutional Conditions ◽  
Positive Effects ◽  
Production Factors ◽  
Corporate Farms

In this paper, we assess the effects of agricultural state support of corporate farms on their revenues from agricultural production sales in 14 Russian regions that differ in technology, environment and institutional conditions. In addition to the direct effect of the state support, the indirect effects via labor and capital are revealed. For this purpose, we identify production functions and statistical models of production factors for each of these regions separately. We find out diverse effects of the state support on revenues among the regions. Positive effects prevail. Negative effects are mainly caused by labor reductions that follow subsidy inflows. Another cause of negative effects is the soft budget constraints phenomenon.

MORPHOLOGICAL AND BIOCHEMICAL RESPOSES OF COW PEA (CV. PUSA BARSATI) GROWN ON FLY ASH AMENDED SOIL IN PRESENCE AND ABSENCE OF MELOIDOGYNE JAVANICA AND RHIZOBIUM LEGUMINOSARUM

1970 ◽  
Vol 17 ◽  
pp. 17-22 ◽  
Author(s):  
Kamal Singh ◽  
A. A. Khan ◽  
Iram Khan ◽  
Rose Rizvi ◽  
M. Saquib
Keyword(s):  
Fly Ash ◽  
Plant Growth ◽  
Rhizobium Leguminosarum ◽  
Growth Yield ◽  
Maximum Growth ◽  
Meloidogyne Javanica ◽  
Growth And Yield ◽  
Negative Effects ◽  
Positive Effects ◽  
Insignificant Difference

Plant growth, yield, pigment and protein content of cow-pea were increased significantly at lower levels (20 and 40%) of fly ash but reverse was true at higher levels (80 and 100%). Soil amended by 60% fly ash could cause suppression in growth and yield in respect to 40% fly ash treated cow-pea plants but former was found at par with control (fly ash untreated plants). Maximum growth occurred in plants grown in soil amended with 40% fly ash. Nitrogen content of cow-pea was suppressed progressively in increasing levels of fly ash. Moreover,  Rhizobium leguminosarum  influenced the growth and yield positively but Meloidogyne javanica caused opposite effects particularly at 20 and 40% fly ash levels. The positive effects of R. leguminosarum were marked by M. javanica at initial levels. However, at 80 and 100% fly ash levels, the positive and negative effects of R. leguminosarum and/or M. javanica did not appear as insignificant difference persist among such treatments.Key words:  Meloidogyne javanica; Rhizobium leguminosarum; Fly ash; Growth; YieldDOI: 10.3126/eco.v17i0.4098Ecoprint An International Journal of Ecology Vol. 17, 2010 Page: 17-22 Uploaded date: 28 December, 2010  

Nutrient Input and Trophic Status of the “Neue Donau”, a High-Water Control System along the River Danube in Vienna, Austria

1990 ◽  
Vol 22 (5) ◽  
pp. 137-144 ◽  
Author(s):  
M. T. Dokulil ◽  
G. A. Janauer
Keyword(s):  
Water Quality ◽  
Control System ◽  
Trophic Status ◽  
High Water ◽  
Nutrient Concentrations ◽  
Nutrient Input ◽  
Water Control ◽  
Trophic Conditions ◽  
River Danube ◽  
High Nutrient

The system “Neue Donau” functions as a control system for high waters of the river Danube and is an important recreational area for many people. Water quality and trophic status of the water body is thereforeof prime importance. The high nutrient concentrations of the river Danube (P-tot 238±41µg/l, N-tot 2.53±0.78 mg/l) reach the system via groundwater seepage. Present conditions in the basin of Neue Donau are,as a result of this nutrient in-flux,eutrophic to hypertrophic. Average values during the summer period have declined from 366 µg/l total phosphorus to 78 µg/l, and from 86 µg/l chlorophyll-a tol7µg/l between the years 1985 and 1988. However, a dam which is planned in the river at Vienna will permanently raise the water level of the river thus increasing the the groundwater flow in the direction to the Neue Donau and therefore the nutrient input which will enhance trophic conditions in the impoundment. Since macrophytes play an important role in one part of the system macrophyte management together with measures along the river are some of the suggested strategies to keep the system Neue Donau at acceptable trophic conditions and good water quality.

Remedies in BRICS Countries

2018 ◽  
Author(s):  
Svetlana Avdasheva ◽  
Tatiana Radchenko
Keyword(s):  
South Africa ◽  
Division Of Labor ◽  
Market Performance ◽  
International Division ◽  
Negative Effects ◽  
Positive Effects ◽  
Managerial Decisions ◽  
Brics Countries ◽  
Target Company ◽  
Specific Position

Within the group of BRICS, China, Russia, and South Africa use conduct remedies more often than developed jurisdictions. Remedies are applied under merger approval or as an outcome of investigation of anticompetitive conducts. Effects of conduct remedies on companies’ decisions and market performance still need explanation. This chapter explains the use of conduct remedies, with special emphasis on Russia, by the specific position of BRICS in international division of labor, which allows the large companies, and first of all domestic ones, to discriminate customers in BRICS home markets, vis-à-vis international customers. Together with positive effects on domestic customers, competition economics predicts the possibility of negative effects of remedies on the managerial decisions within the target company. Under some circumstances, remedies may even weaken competition in the global product markets.

Sign in / Sign up

Export Citation Format

Share Document