scholarly journals Regime shifts in exploited marine food webs: detecting mechanisms underlying alternative stable states using size-structured community dynamics theory

2015 ◽  
Vol 370 (1659) ◽  
pp. 20130262 ◽  
Author(s):  
Anna Gårdmark ◽  
Michele Casini ◽  
Magnus Huss ◽  
Anieke van Leeuwen ◽  
Joakim Hjelm ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Prey Availability ◽  
Alternative Stable States ◽  
Individual Performance ◽  
Regime Shifts ◽  
Trophic Levels ◽  
Stable States ◽  
Ecosystem Recovery ◽  
Piscivorous Fish ◽  
Combining Data

Many marine ecosystems have undergone ‘regime shifts’, i.e. abrupt reorganizations across trophic levels. Establishing whether these constitute shifts between alternative stable states is of key importance for the prospects of ecosystem recovery and for management. We show how mechanisms underlying alternative stable states caused by predator–prey interactions can be revealed in field data, using analyses guided by theory on size-structured community dynamics. This is done by combining data on individual performance (such as growth and fecundity) with information on population size and prey availability. We use Atlantic cod ( Gadus morhua ) and their prey in the Baltic Sea as an example to discuss and distinguish two types of mechanisms, ‘cultivation-depensation’ and ‘overcompensation’, that can cause alternative stable states preventing the recovery of overexploited piscivorous fish populations. Importantly, the type of mechanism can be inferred already from changes in the predators' body growth in different life stages. Our approach can thus be readily applied to monitored stocks of piscivorous fish species, for which this information often can be assembled. Using this tool can help resolve the causes of catastrophic collapses in marine predatory–prey systems and guide fisheries managers on how to successfully restore collapsed piscivorous fish stocks.

scholarly journals Geometric Analysis of Regime Shifts in Coral Reef Communities

2020 ◽  
Author(s):  
Edward W. Tekwa ◽  
Lisa C. McManus ◽  
Ariel Greiner ◽  
Madhavi A. Colton ◽  
Michael S. Webster ◽  
...  
Keyword(s):  
Spatial Clustering ◽  
Alternative Stable States ◽  
Geometric Analysis ◽  
Three Dimensional ◽  
Single Species ◽  
Regime Shifts ◽  
State Transitions ◽  
Stable States ◽  
Species Dominance ◽  
Community Grazing

AbstractCoral reefs are among the many communities believed to exhibit regime shifts between alternative stable states, single-species dominance, and coexistence. Proposed drivers of regime shifts include changes in grazing, spatial clustering, and ocean temperature. Here we distill the dynamic regimes of coral-macroalgal interaction into a three-dimensional geometry, akin to thermodynamic phase diagrams of state transitions, to facilitate analysis. Specific regime-shifting forces can be understood as bifurcation vectors through the cubic regime geometry. This geometric perspective allows us to understand multiple forces simultaneously in terms of the stability and persistence of interacting species. For example, in a coral-macroalgae community, grazing on macroalgae can lead to alternative stable states when there is no spatial clustering (e.g., high habitat connectivity). However, with spatial clustering, grazing can lead to coexistence because of elevated local intraspecific competition. The geometrical analysis of regime shifts is applicable to any two-species communities and can help conservation efforts navigate complexity and abrupt changes.

scholarly journals Gradual regime shifts in fairy circles

2015 ◽  
Vol 112 (40) ◽  
pp. 12327-12331 ◽  
Author(s):  
Yuval R. Zelnik ◽  
Ehud Meron ◽  
Golan Bel
Keyword(s):  
Mathematical Modeling ◽  
Alternative Stable States ◽  
Regime Shifts ◽  
Self Organization ◽  
Stable States ◽  
Birth And Death Processes ◽  
Spatially Extended ◽  
Pattern Forming ◽  
Water Vegetation

Large responses of ecosystems to small changes in the conditions—regime shifts—are of great interest and importance. In spatially extended ecosystems, these shifts may be local or global. Using empirical data and mathematical modeling, we investigated the dynamics of the Namibian fairy circle ecosystem as a case study of regime shifts in a pattern-forming ecosystem. Our results provide new support, based on the dynamics of the ecosystem, for the view of fairy circles as a self-organization phenomenon driven by water–vegetation interactions. The study further suggests that fairy circle birth and death processes correspond to spatially confined transitions between alternative stable states. Cascades of such transitions, possible in various pattern-forming systems, result in gradual rather than abrupt regime shifts.

Use of stable isotopes in the evaluation of fish trophic guilds from a tropical hypersaline lagoon

2020 ◽  
Vol 100 (6) ◽  
pp. 979-988
Author(s):  
Marcos A. L. Franco ◽  
Alejandra F. G. N. Santos ◽  
Abílio S. Gomes ◽  
Marcelo G. de Almeida ◽  
Carlos E. de Rezende
Keyword(s):  
Stable Isotopes ◽  
Fish Species ◽  
Prey Availability ◽  
Niche Overlap ◽  
Abundant Species ◽  
Mean Value ◽  
Trophic Levels ◽  
Isotopic Niche ◽  
Trophic Guilds ◽  
Piscivorous Fish

AbstractEnvironmental factors, size-related isotopic changes of the most abundant species and isotopic niche overlap were investigated using stable isotopes in order to evaluate spatial changes of fish trophic guilds in the Araruama Lagoon. Based on 440 muscle samples, 17 fish species were grouped into five trophic guilds. Mean salinity was above 40 at both sites sampled and a significant spatial difference was observed. The highest δ13C mean value was observed for an omnivorous species, whereas the lowest carbon signatures were found for the three fish species belonging to the planktivorous guild. Analysis of the carbon signature of fish species in lower trophic levels showed influence of salinity variation, whilst size appeared to play a role for others. A narrow δ15N difference was observed, but the piscivorous fish species showed the highest δ15N values. The Standard Ellipses Analysis (SEA) detected spatial differences and varying degrees of isotopic niche overlap among trophic guilds, but the percentages of most overlaps (<60%) suggest that, to some extent, the guilds had a unique isotopic niche space. These results are in agreement with data previously reported for the Araruama Lagoon, that found the same prey items with varying relative importance among the most abundant species. Further studies are necessary to understand how the interaction between salinity and other factors, such as migration patterns, changes in prey availability, changes in contribution of primary sources and changes in baseline isotopic signatures could affect the stable isotope signatures shown here.

scholarly journals Quantifying the impact of ecological memory on the dynamics of interacting communities

2021 ◽  
Author(s):  
Moein Khalighi ◽  
Didier Gonze ◽  
Karoline Faust ◽  
Guilhem Sommeria-Klein ◽  
Leo Lahti
Keyword(s):  
Community Dynamics ◽  
Initial Conditions ◽  
Alternative Stable States ◽  
Interaction Model ◽  
Ecological Communities ◽  
Stable States ◽  
Ecological Memory ◽  
Recovery Times ◽  
Key Aspects ◽  
The Impact

Ecological memory refers to the influence of past events on the response of an ecosystem to exogenous or endogenous changes. Memory has been widely recognized as a key contributor to the dynamics of ecosystems and other complex systems, yet quantitative community models often ignore memory and its implications. Recent studies have shown how interactions between community members can lead to the emergence of resilience and multistability under environmental perturbations. We demonstrate how memory can complement such models. We use the framework of fractional calculus to study how the outcomes of a well-characterized interaction model are affected by gradual increases in ecological memory under varying initial conditions, perturbations, and stochasticity. Our results highlight the implications of memory on several key aspects of community dynamics. In general, memory slows down the overall dynamics and recovery times after perturbation, thus reducing the system's resilience. However, it simultaneously mitigates hysteresis and enhances the system's capacity to resist state shifts. Memory promotes long transient dynamics, such as long-standing oscillations and delayed regime shifts, and contributes to the emergence and persistence of alternative stable states. Collectively, these results highlight the fundamental role of memory on ecological communities and provide new quantitative tools to analyse its impact under varying conditions.

scholarly journals A macroecological description of alternative stable states reproduces intra- and inter-host variability of gut microbiome

2021 ◽  
Author(s):  
Silvia Zaoli ◽  
Jacopo Grilli
Keyword(s):  
Gut Microbiome ◽  
Community Dynamics ◽  
Temporal Dynamics ◽  
Alternative Stable States ◽  
Individual Variability ◽  
Statistical Properties ◽  
Stable States ◽  
Environmental Fluctuations ◽  
The Rich ◽  
Community Variability

The most fundamental questions in microbial ecology concern the diversity and variability of communities. Their composition varies widely across space and time, as it is determined by a non-trivial combination of stochastic and deterministic processes. The interplay between non-linear community dynamics and environmental fluctuations determines the rich statistical structure of community variability, with both rapid temporal dynamics fluctuations and non-trivial correlations across habitats. Here we analyze long time-series of gut microbiome and compare intra- and inter-community dissimilarity. Under a macroecological framework we characterize their statistical properties. We show that most taxa have large but stationary fluctuations over time, while a minority is characterized by quick changes of average abundance which cluster in time, suggesting the presence of alternative stable states. We disentangle inter-individual variability in a major stochastic component and a deterministic one, the latter recapitulated by differences in the carrying capacities of taxa. Finally, we develop a model which includes environmental fluctuations and alternative stable states. This model quantitatively predicts the statistical properties of both intra- and inter-individual community variability, therefore summarizing variation in a unique macroecological framework.

Evolutionary rescue can prevent rate-induced tipping in predator-prey systems

2021 ◽  
Author(s):  
Ulrike Feudel ◽  
Anna Vanselow ◽  
Lukas Halekotte
Keyword(s):  
Environmental Change ◽  
Time Scale ◽  
Alternative Stable States ◽  
Rapid Evolution ◽  
Regime Shifts ◽  
Rate Of Change ◽  
Stable States ◽  
Critical Rate ◽  
Predator Prey ◽  
Evolutionary Rescue

&lt;p&gt;Nowadays, populations are faced with unprecedented rates of global climate change, habitat fragmentation and destruction causing an accelerating conversion of their living conditions. Critical transitions in ecosystems, often called regime shifts, lead to sudden shifts in the dominance of species or even to species&amp;#8217; extinction and decline of biodiversity. Many regime shifts are explained as transitions between alternative stable states caused by (i) certain bifurcations when certain parameters or external forcing cross critical thresholds, (ii) fluctuations or (iii) extreme events. We address a fourth mechanism which does not require alternative states but instead, the system performs a large excursion away from its usual behaviour when environmental&amp;#160; conditions change too fast. During this excursion, the system can embrace dangerously, unexpected states. We demonstrate that predator-prey systems can exhibit a population collapse if the rate of environmental change crosses a certain critical rate. In reference to this critical rate of change which has to be surpassed, this transition is called rate-induced tipping (R-tipping). A further difference to the other three tipping mechanisms is that R-tipping mainly manifests during the transient dynamics &amp;#8211; the dynamics before the long-term dynamics are reached. &amp;#160;Whether a system will track its usual state or will tip with the consequence of a possible extinction of a species depends crucially on the time scale relations between the ecological timescale and the time scale of environmental change as well as the initial condition. However, populations have the ability to respond to environmental change due to rapid evolution. Employing an eco-evolutionary model we show how such kind of adaptation can prevent rate-induced tipping in predator-prey systems. The corresponding mechanism, called evolutionary rescue, introduces a third timescale which needs to be taken into account. Only a large genetic variation within a population reflecting rapid evolution would be able to successfully counteract an overcritically fast environmental change.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Resources, mortality, and disease ecology: importance of positive feedbacks between host growth rate and pathogen dynamics

2015 ◽  
Vol 61 (1) ◽  
pp. 37-49 ◽  
Author(s):  
Val H. Smith ◽  
Robert D. Holt ◽  
Marilyn S. Smith ◽  
Yafen Niu ◽  
Michael Barfield
Keyword(s):  
Growth Rate ◽  
Disease Ecology ◽  
Community Dynamics ◽  
Physiological State ◽  
Alternative Stable States ◽  
Stable States ◽  
Metabolic Scaling ◽  
Pathogen Dynamics ◽  
Host Growth ◽  
Resource Effects

Resource theory and metabolic scaling theory suggest that the dynamics of a pathogen within a host should strongly depend upon the rate of host cell metabolism. Once an infection occurs, key ecological interactions occur on or within the host organism that determine whether the pathogen dies out, persists as a chronic infection, or grows to densities that lead to host death. We hypothesize that, in general, conditions favoring rapid host growth rates should amplify the replication and proliferation of both fungal and viral pathogens. If a host population experiences an increase in mortality, to persist it must have a higher growth rate, per host, often reflecting greater resource availability per capita. We hypothesize that this could indirectly foster the pathogen, which also benefits from increased within-host resource turnover. We first bring together in a short review a number of key prior studies which illustrate resource effects on viral and fungal pathogen dynamics. We then report new results from a semi-continuous cell culture experiment with SHIV, demonstrating that higher mortality rates indeed can promote viral proliferation. We develop a simple model that illustrates dynamical consequences of these resource effects, including interesting effects such as alternative stable states and oscillatory dynamics. Our paper contributes to a growing body of literature at the interface of ecology and infectious disease epidemiology, emphasizing that host abundances alone do not drive community dynamics: the physiological state and resource content of infected hosts also strongly influence host–pathogen interactions.

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