Geometric Analysis of Regime Shifts in Coral Reef Communities

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.

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Small-scale switch in cover–perimeter relationships of patches indicates shift of dominant species during grassland degradation

Journal of Plant Ecology ◽

10.1093/jpe/rtaa057 ◽

2020 ◽

Vol 13 (6) ◽

pp. 704-712

Author(s):

Ming-Hua Song ◽

Johannes H C Cornelissen ◽

Yi-Kang Li ◽

Xing-Liang Xu ◽

Hua-Kun Zhou ◽

...

Keyword(s):

Climate Changes ◽

Alternative Stable States ◽

Species Abundance ◽

Black Soil ◽

Intersection Point ◽

State Transitions ◽

Small Scale ◽

Stable States ◽

Large Spatial Scale ◽

Vegetation Surveys

Abstract Aims Grasslands are globally threatened by climate changes and unsustainable land-use, which often cause transitions among alternative stable states, and even catastrophic transition to desertification. Spatial vegetation patch configurations have been shown to signify such transitions at large spatial scale. Here, we demonstrate how small-scale patch configurations can also indicate state transitions. Methods The whole spatial series of degradation successions were chosen in alpine grasslands characterized as seven typical communities. Patch numbers, and perimeter and cover of each patch were recorded using adjacent quadrats along transects in each type of the communities. Species abundance within each patch was measured. Important Findings Across seven grazing-induced degradation stages in the world’s largest expanse of grassland, from dense ungrazed turf to bare black-soil crust, patch numbers and perimeters first increased as patch cover decreased. Numbers and perimeters then decreased rapidly beyond an intersection point at 68% of initial continuous vegetation cover. Around this point, the vegetation fluctuated back and forth between the sedge-dominated grassland breaking-up phase and the forb-dominated phase, suggesting impending shift of grassland state. This study thus demonstrates how ground-based small-scale vegetation surveys can provide a quantitative, easy-to-use signals for vegetation degradation, with promise for detecting the catastrophic transition to desertification.

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Gradual regime shifts in fairy circles

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1504289112 ◽

2015 ◽

Vol 112 (40) ◽

pp. 12327-12331 ◽

Cited By ~ 46

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.

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

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2013.0262 ◽

2015 ◽

Vol 370 (1659) ◽

pp. 20130262 ◽

Cited By ~ 44

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.

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III.17 Alternative Stable States and Regime Shifts in Ecosystems

The Princeton Guide to Ecology ◽

10.1515/9781400833023.395 ◽

2009 ◽

pp. 395-406 ◽

Cited By ~ 8

Keyword(s):

Alternative Stable States ◽

Regime Shifts ◽

Stable States

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Regime shifts and alternative stable states in intertidal rocky habitats: State of the art and new trends of research

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2018.09.013 ◽

2018 ◽

Vol 214 ◽

pp. 57-63 ◽

Cited By ~ 3

Author(s):

Silvia Chemello ◽

Salvatrice Vizzini ◽

Antonio Mazzola

Keyword(s):

State Of The Art ◽

Alternative Stable States ◽

Regime Shifts ◽

Stable States ◽

Rocky Habitats

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

10.5194/egusphere-egu21-13294 ◽

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

<p>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&#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&#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 &#8211; the dynamics before the long-term dynamics are reached. &#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.</p><p>&#160;</p>

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Going Beyond 3-D Imaging: Automated 3-D Montaged image Analysis of Cytological Specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163873 ◽

1996 ◽

Vol 54 ◽

pp. 282-283

Author(s):

Badrinath Roysam ◽

Hakan Ancin ◽

Douglas E. Becker ◽

Robert W. Mackin ◽

Matthew M. Chestnut ◽

...

Keyword(s):

Image Analysis ◽

Structural Changes ◽

Sampling Methods ◽

Spatial Clustering ◽

Three Dimensional ◽

Field Of View ◽

Cell Counting ◽

Depth Of Field ◽

Tissue Cell ◽

Tissue Organization

This paper summarizes recent advances made by this group in the automated three-dimensional (3-D) image analysis of cytological specimens that are much thicker than the depth of field, and much wider than the field of view of the microscope. The imaging of thick samples is motivated by the need to sample large volumes of tissue rapidly, make more accurate measurements than possible with 2-D sampling, and also to perform analysis in a manner that preserves the relative locations and 3-D structures of the cells. The motivation to study specimens much wider than the field of view arises when measurements and insights at the tissue, rather than the cell level are needed.The term “analysis” indicates a activities ranging from cell counting, neuron tracing, cell morphometry, measurement of tracers, through characterization of large populations of cells with regard to higher-level tissue organization by detecting patterns such as 3-D spatial clustering, the presence of subpopulations, and their relationships to each other. Of even more interest are changes in these parameters as a function of development, and as a reaction to external stimuli. There is a widespread need to measure structural changes in tissue caused by toxins, physiologic states, biochemicals, aging, development, and electrochemical or physical stimuli. These agents could affect the number of cells per unit volume of tissue, cell volume and shape, and cause structural changes in individual cells, inter-connections, or subtle changes in higher-level tissue architecture. It is important to process large intact volumes of tissue to achieve adequate sampling and sensitivity to subtle changes. It is desirable to perform such studies rapidly, with utmost automation, and at minimal cost. Automated 3-D image analysis methods offer unique advantages and opportunities, without making simplifying assumptions of tissue uniformity, unlike random sampling methods such as stereology.12 Although stereological methods are known to be statistically unbiased, they may not be statistically efficient. Another disadvantage of sampling methods is the lack of full visual confirmation - an attractive feature of image analysis based methods.

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Macroorganisation and flexibility of thylakoid membranes

Biochemical Journal ◽

10.1042/bcj20190080 ◽

2019 ◽

Vol 476 (20) ◽

pp. 2981-3018 ◽

Cited By ~ 8

Author(s):

Petar H. Lambrev ◽

Parveen Akhtar

Keyword(s):

Light Harvesting ◽

Current Knowledge ◽

Three Dimensional ◽

Photosynthetic Apparatus ◽

Dynamic Responses ◽

State Transitions ◽

Photochemical Quenching ◽

Light Harvesting Complex ◽

Complex Ii ◽

Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

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