scholarly journals Ecosystem functioning from a geomicrobiological perspective – a conceptual framework for biogeochemical iron cycling

2010 ◽  
Vol 7 (5) ◽  
pp. 399 ◽  
Author(s):  
Caroline Schmidt ◽  
Sebastian Behrens ◽  
Andreas Kappler
Keyword(s):  
Conceptual Framework ◽  
Environmental Conditions ◽  
Spatial Location ◽  
Iron Cycling ◽  
Dynamic Interactions ◽  
Natural Systems ◽  
Microbial Ecosystems ◽  
Key Variables ◽  
Flow Directions ◽  
Iron Redox

Environmental context.Microbial ecosystems are characterised by the interplay of various microorganisms with their biotic and abiotic environment. Biogeochemical niches host adapted microbial communities that are in constant competition for substrates and nutrients. Their natural distribution, interactions and responses to fluctuating environmental conditions are often impossible to simulate in laboratory studies. Using biogeochemical iron redox cycling as an example, we suggest the application of a conceptual framework to improve our understanding of the principal functioning of (geo)microbial ecosystems. Abstract.Our knowledge on how microbial ecosystems function profits from the support of biogeochemical concepts which describe the cycling of elements through various geochemical gradients. Using the example of the iron cycle in freshwater sediments, we propose a theoretical framework that describes the dynamic interactions between chemical and microbial FeII oxidation and FeIII reduction, their spatial location and how they are affected by changing environmental conditions. This contribution emphasises the complexity ecological research faces when dealing with heterogeneous and dynamic natural systems. Our concept aims to provide further insights into how flows of energy and matter are controlled during microbial and chemical Fe redox transformations and how various key variables, such as substrate availability and competition as well as thermodynamic and kinetic parameters, affect flow directions.

Chromium(iii) oxidation by biogenic manganese oxides with varying structural ripening

2014 ◽  
Vol 16 (9) ◽  
pp. 2127-2136 ◽  
Author(s):  
Yuanzhi Tang ◽  
Samuel M. Webb ◽  
Emily R. Estes ◽  
Colleen M. Hansel
Keyword(s):  
Environmental Conditions ◽  
Manganese Oxides ◽  
Natural Systems ◽  
Mn Oxides

Manganese (Mn) oxides, which are generally considered biogenic in origin within natural systems, are the only oxidants of Cr(iii) under typical environmental conditions.

scholarly journals Facilitation costs and benefits function simultaneously on stress gradients for animals

2018 ◽  
Vol 285 (1885) ◽  
pp. 20180983 ◽  
Author(s):  
Olivier Dangles ◽  
Mario Herrera ◽  
Carlos Carpio ◽  
Christopher J. Lortie
Keyword(s):  
Conceptual Framework ◽  
Environmental Conditions ◽  
Species Interactions ◽  
Stress Gradient ◽  
Species Interaction ◽  
Positive Interactions ◽  
Costs And Benefits ◽  
Strong Basis ◽  
Stress Gradients ◽  
High Resource

Understanding the variation in species interactions along environmental stress gradients is crucial for making robust ecological predictions about community responses to changing environmental conditions. The facilitation–competition framework has provided a strong basis for predictions (e.g. the stress-gradient hypothesis, SGH), yet the mechanisms behind patterns in animal interactions on stress gradients are poorly explored in particular for mobile animals. Here, we proposed a conceptual framework modelling changes in facilitation costs and benefits along stress gradients and experimentally tested this framework by measuring fitness outcomes of benefactor–beneficiary interactions across resource quality levels. Three arthropod consumer models from a broad array of environmental conditions were used including aquatic detritivores, potato moths and rainforest carrion beetles. We detected a shift to more positive interactions at increasing levels of stress thereby supporting the application of the SGH to mobile animals. While most benefactors paid no significant cost of facilitation, an increase in potato moth beneficiary's growth at high resource stress triggered costs for benefactors. This study is the first to experimentally show that both costs and benefits function simultaneously on stress gradients for animals. The proposed conceptual framework could guide future studies examining species interaction outcomes for both animals and plants in an increasingly stressed world.

scholarly journals Horizontal-vertical movement relationships: Adélie penguins forage continuously throughout provisioning trips

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Javed Riaz ◽  
Sophie Bestley ◽  
Simon Wotherspoon ◽  
Louise Emmerson
Keyword(s):  
Environmental Conditions ◽  
Optimal Foraging ◽  
Three Dimensional ◽  
Spatial Location ◽  
Vertical Movement ◽  
Foraging Activity ◽  
Directed Movement ◽  
Vertical Movements ◽  
Movement Trajectories ◽  
Adélie Penguins

Abstract Background Diving marine predators forage in a three-dimensional environment, adjusting their horizontal and vertical movement behaviour in response to environmental conditions and the spatial distribution of prey. Expectations regarding horizontal-vertical movements are derived from optimal foraging theories, however, inconsistent empirical findings across a range of taxa suggests these behavioural assumptions are not universally applicable. Methods Here, we examined how changes in horizontal movement trajectories corresponded with diving behaviour and marine environmental conditions for a ubiquitous Southern Ocean predator, the Adélie penguin. Integrating extensive telemetry-based movement and environmental datasets for chick-rearing Adélie penguins at Béchervaise Island, we tested the relationships between horizontal move persistence (continuous scale indicating low [‘resident’] to high [‘directed’] movement autocorrelation), vertical dive effort and environmental variables. Results Penguins dived continuously over the course of their foraging trips and lower horizontal move persistence corresponded with less intense foraging activity, likely indicative of resting behaviour. This challenges the traditional interpretation of horizontal-vertical movement relationships based on optimal foraging models, which assumes increased residency within an area translates to increased foraging activity. Movement was also influenced by different environmental conditions during the two stages of chick-rearing: guard and crèche. These differences highlight the strong seasonality of foraging habitat for chick-rearing Adélie penguins at Béchervaise Island. Conclusions Our findings advance our understanding of the foraging behaviour for this marine predator and demonstrates the importance of integrating spatial location and behavioural data before inferring habitat use.

scholarly journals The effects of population synchrony, life history, and access constraints on benefits from fishing portfolios

2020 ◽  
Author(s):  
Kiva L. Oken ◽  
André E Punt ◽  
Daniel S. Holland
Keyword(s):  
Environmental Conditions ◽  
Life Histories ◽  
Oncorhynchus Tshawytscha ◽  
Environmental Drivers ◽  
Management Options ◽  
Population Synchrony ◽  
Natural Systems ◽  
Advantages And Disadvantages ◽  
Interannual Fluctuations ◽  
Short Time

Natural resources often exhibit large interannual fluctuations in productivity driven by shifting environmental conditions, and this translates to high variability in the revenue resource users can earn. However, users can dampen this variability by harvesting a portfolio of resources. In the context of fisheries, this means targeting multiple populations, though the ability to actually build diverse fishing portfolios is often constrained by the costs and availability of fishing permits. These constraints are generally intended to prevent overcapitalization of the fleet and ensure populations are fished sustainably. As linked human-natural systems, both ecological and fishing dynamics influence the specific advantages and disadvantages of increasing the diversity of fishing portfolios. Specifically, a portfolio of synchronous populations with similar responses to environmental drivers should reduce revenue variability less than a portfolio of asynchronous populations with opposite responses. We built a bioeconomic model characterized by the Dungeness crab (Metacarcinus magister), Chinook salmon (Oncorhynchus tshawytscha), and groundfish fisheries in the California Current, and used it to explore the influence of population synchrony and permit access on revenue patterns. As expected, synchronous populations reduced revenue variability less than asynchronous populations, but only for portfolios including crab and salmon. Synchrony with longer-lived groundfish populations was not important because environmentally-driven changes in groundfish early life survival were mediated by growth and natural mortality over the full population age structure, and overall biomass was relatively stable across years. Thus, building a portfolio of diverse life histories can buffer against the impacts of extremely poor environmental conditions over short time scales, though not for long-term declines. Increasing access to all permits generally led to increased revenue stability and decreased inequality of the fleet, but also resulted in less revenue earned by an individual from a given portfolio because more vessels shared the available biomass. This means managers are faced with a tradeoff between the average revenue individuals earn and the risk those individuals accept. These results illustrate the importance of considering connections between social and ecological dynamics when evaluating management options that constrain or facilitate fishers’ ability to diversify their fishing.

scholarly journals Why economics matters for understanding the effects of climate change on fisheries

2012 ◽  
Vol 69 (7) ◽  
pp. 1160-1167 ◽  
Author(s):  
Alan C. Haynie ◽  
Lisa Pfeiffer
Keyword(s):  
Climate Change ◽  
Conceptual Framework ◽  
Environmental Conditions ◽  
Economic Factors ◽  
Marine Science ◽  
Biological Factors ◽  
Climate Effects ◽  
Economic Mechanisms

Abstract Haynie, A. C., and Pfeiffer, L. 2012. Why economics matters for understanding the effects of climate change on fisheries. – ICES Journal of Marine Science, 69: . Research attempting to predict the effect of climate change on fisheries often neglects to consider how harvesters respond to changing economic, institutional, and environmental conditions, which leads to the overly simplistic prediction of “fisheries follow fish”. However, climate effects on fisheries can be complex because they arise through physical, biological, and economic mechanisms that interact or may not be well understood. Although most researchers find it obvious to include physical and biological factors in predicting the effects of climate change on fisheries, the behaviour of fish harvesters also matters for these predictions. A general but succinct conceptual framework for investigating the effects of climate change on fisheries that incorporates the biological and economic factors that determine how fisheries operate is presented. The use of this framework will result in more complete, reliable, and relevant investigations of the effects of climate change on fisheries. The uncertainty surrounding long-term projections, however, is inherent in the complexity of the system.

How Individualized Niches Arise: Mechanisms of Niche Construction, Niche Choice, and Niche Conformance

2021 ◽  
Author(s):  
Rose Trappes ◽  
Behzad Nematipour ◽  
Marie I. Kaiser ◽  
Ulrich Krohs ◽  
Koen J. van Benthem ◽  
...  
Keyword(s):  
Individual Differences ◽  
Conceptual Framework ◽  
Environmental Conditions ◽  
Niche Construction ◽  
Modern Synthesis ◽  
Evolutionary Synthesis ◽  
Narrow Sense ◽  
Extended Evolutionary Synthesis ◽  
Individual Level

The debate between the extended evolutionary synthesis (EES) and the modern synthesis (MS) partly relies on different interpretations of niche construction. We dissect the umbrella term of niche construction into three separate mechanisms: niche construction (taken in a narrow sense), in which individuals make changes to the environment; niche choice, in which individuals select an environment; and niche conformance, in which individuals change their phenotypes. Each of these individual-level mechanisms affects an individual’s phenotype-environment match, its fitness, and its individualized niche, defined in terms of the environmental conditions under which an individual can survive and reproduce. Our conceptual framework distinguishes several ways in which individuals alter the selective regimes that they and other organisms experience. It also places clear emphasis on individual differences and construes niche construction and other processes as evolved mechanisms. We therefore argue that our framework helps to resolve the tensions between EES and MS.

A case for low atmospheric oxygen levels during Earth's middle history

2018 ◽  
Vol 2 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Noah J. Planavsky ◽  
Devon B. Cole ◽  
Terry T. Isson ◽  
Christopher T. Reinhard ◽  
Peter W. Crockford ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Conceptual Framework ◽  
Environmental Conditions ◽  
Atmospheric Oxygen ◽  
Critical Factor ◽  
Planetary Surface ◽  
Surface Oxygen ◽  
Oxygen Levels ◽  
Early Diversification ◽  
Atmospheric Level

The oxygenation of the atmosphere — one of the most fundamental transformations in Earth's history — dramatically altered the chemical composition of the oceans and provides a compelling example of how life can reshape planetary surface environments. Furthermore, it is commonly proposed that surface oxygen levels played a key role in controlling the timing and tempo of the origin and early diversification of animals. Although oxygen levels were likely more dynamic than previously imagined, we make a case here that emerging records provide evidence for low atmospheric oxygen levels for the majority of Earth's history. Specifically, we review records and present a conceptual framework that suggest that background oxygen levels were below 1% of the present atmospheric level during the billon years leading up to the diversification of early animals. Evidence for low background oxygen levels through much of the Proterozoic bolsters the case that environmental conditions were a critical factor in controlling the structure of ecosystems through Earth's history.

scholarly journals A prototype framework for models of socio-hydrology: identification of key feedback loops and parameterisation approach

2014 ◽  
Vol 18 (6) ◽  
pp. 2141-2166 ◽  
Author(s):  
Y. Elshafei ◽  
M. Sivapalan ◽  
M. Tonts ◽  
M. R. Hipsey
Keyword(s):  
Conceptual Framework ◽  
Case Studies ◽  
Coupled System ◽  
Feedback Mechanism ◽  
Feedback Loops ◽  
Natural Systems ◽  
Agricultural Catchments ◽  
Building Models ◽  
Macro Scale ◽  
Study Sites

Abstract. It is increasingly acknowledged that, in order to sustainably manage global freshwater resources, it is critical that we better understand the nature of human–hydrology interactions at the broader catchment system scale. Yet to date, a generic conceptual framework for building models of catchment systems that include adequate representation of socioeconomic systems – and the dynamic feedbacks between human and natural systems – has remained elusive. In an attempt to work towards such a model, this paper outlines a generic framework for models of socio-hydrology applicable to agricultural catchments, made up of six key components that combine to form the coupled system dynamics: namely, catchment hydrology, population, economics, environment, socioeconomic sensitivity and collective response. The conceptual framework posits two novel constructs: (i) a composite socioeconomic driving variable, termed the Community Sensitivity state variable, which seeks to capture the perceived level of threat to a community's quality of life, and acts as a key link tying together one of the fundamental feedback loops of the coupled system, and (ii) a Behavioural Response variable as the observable feedback mechanism, which reflects land and water management decisions relevant to the hydrological context. The framework makes a further contribution through the introduction of three macro-scale parameters that enable it to normalise for differences in climate, socioeconomic and political gradients across study sites. In this way, the framework provides for both macro-scale contextual parameters, which allow for comparative studies to be undertaken, and catchment-specific conditions, by way of tailored "closure relationships", in order to ensure that site-specific and application-specific contexts of socio-hydrologic problems can be accommodated. To demonstrate how such a framework would be applied, two socio-hydrological case studies, taken from the Australian experience, are presented and the parameterisation approach that would be taken in each case is discussed. Preliminary findings in the case studies lend support to the conceptual theories outlined in the framework. It is envisioned that the application of this framework across study sites and gradients will aid in developing our understanding of the fundamental interactions and feedbacks in such complex human–hydrology systems, and allow hydrologists to improve social–ecological systems modelling through better representation of human feedbacks on hydrological processes.

Experimental Fretting-Wear Studies of Steam Generator Materials

1995 ◽  
Vol 117 (4) ◽  
pp. 312-320 ◽  
Author(s):  
N. J. Fisher ◽  
A. B. Chow ◽  
M. K. Weckwerth
Keyword(s):  
Steam Generator ◽  
Contact Force ◽  
Environmental Conditions ◽  
Analytical Techniques ◽  
Work Rate ◽  
Fretting Wear ◽  
Flow Induced Vibration ◽  
Dynamic Interactions ◽  
Support Materials ◽  
Wear Damage

Flow-induced vibration of steam generator tubes results in fretting-wear damage due to impacting and rubbing of the tubes against their supports. This damage can be predicted by computing tube response to flow-induced excitation forces using analytical techniques, and then relating this response to resultant wear damage using experimentally derived wear coefficients. Fretting-wear of steam generator materials has been studied experimentally at Chalk River Laboratories for two decades. Tests are conducted in machines that simulate steam generator environmental conditions and tube-to-support dynamic interactions. Different tube and support materials, tube-to-support clearances, and tube support geometries have been studied. The effect of environmental conditions, such as temperature, oxygen content, pH and chemistry control additive, have been investigated as well. Early studies showed that damage was related to contact force as long as other parameters, such as geometry and motion, were held constant. Later studies have shown that damage is related to a parameter called work-rate, which combines both contact force and sliding distance. Results of short and long-term fretting-wear tests for CANDU steam generator materials at realistic environmental conditions are presented. These results demonstrate that work-rate is an appropriate correlating parameter for impact-sliding interaction.

Metazoan endoparasites diversity of Pseudoplatystoma corruscans (Siluriformes: Pimelodidae) as an indicator of environmental alterations on a tropical aquatic system

2014 ◽  
Vol 59 (3) ◽  
Author(s):  
Thamy Ribeiro ◽  
Maria Lizama ◽  
Ricardo Takemoto
Keyword(s):  
Environmental Conditions ◽  
Parasite Species ◽  
Parasite Fauna ◽  
Local Extinction ◽  
Aquatic System ◽  
Dominance Index ◽  
Host Switch ◽  
River Floodplain ◽  
Natural Systems ◽  
Paraná River Floodplain

AbstractThe aim of the present study was to detect the alterations of Pseudoplatystoma corruscans parasite infracommunity structure, after the construction of the Porto Primavera dam on the high Paraná River floodplain. The execution of this research was based on 119 host specimens collected between March 2011 and September 2012, and the results were compared to studies performed on periods before the reservoir’s construction, when 110 fishes were collected between March 1992 and February 1993. Five parasite species still remain on the environment, despite the environmental modifications: Choanoscolex abscissus, Spasskyelina spinulifera, Nomimoscolex pertierrae, Harriscolex kaparari and Contracaecum sp 2. The Berger-Parker dominance index, calculated to the parasite fauna of 1992, did not show the dominance of any species, while, on the present days, this same index accused the dominance of Nomimoscolex pertierrae (49%) and Choanoscolex abscissus (50%). The present study reports the disappearance of Megathylacus travassosi, Contracaecum sp. 1, Contracaecum sp. 3, Procamallanus (Spirocamallanus) sp. and Cucullanus pseudoplatystomae, suggesting the possibility of a local extinction or a host switch of these species. It has also been registered an Acanthocephala specimen, a genus not observed on this host yet. The results here presented show that the antropic influences on natural systems alter the environmental conditions, what is reflected on the richness and diversity parasite levels.

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