Stability trophic cascades in food chains

While previous studies have evaluated the change in stability for the addition or removal of individual species from trophic food chains and food webs, we know of no study that presents a general theory for how stability changes with the addition or removal of trophic levels. In this study, we present a simple model of a linear food chain and systematically evaluate how stability—measured as invariability—changes with the addition or removal of trophic levels. We identify the presence of trophic cascades in the stability of species. Owing to top-down control by predation and bottom-up regulation by prey, we find that stability of a species is highest when it is at the top of the food chain and lowest when it is just under the top of the food chain. Thus, stability shows patterns identical to those of mean biomass with the addition or removal of trophic levels in food chains. Our results provide a baseline towards a general theory of the effect of adding or removing trophic levels on stability, which can be used to inform empirical studies.

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Can biomass distribution across trophic levels predict trophic cascades?

10.1101/2020.04.04.025460 ◽

2020 ◽

Cited By ~ 1

Author(s):

Núria Galiana ◽

Jean-François Arnoldi ◽

Matthieu Barbier ◽

Amandine Acloque ◽

Claire de Mazancourt ◽

...

Keyword(s):

Direct Relationship ◽

Trophic Cascades ◽

Trophic Levels ◽

Food Chains ◽

Biomass Distribution ◽

Top Down ◽

Road Map ◽

Vast Literature ◽

Mesocosm Experiments ◽

Dynamical Properties

AbstractThe biomass distribution across trophic levels (biomass pyramid), and cascading responses to perturbations (trophic cascades), are archetypal representatives of the interconnected set of static and dynamical properties of food chains. A vast literature has explored their respective ecological drivers, sometimes generating correlations between them. Here we instead reveal a fundamental connection: both pyramids and cascades reflect the dynamical sensitivity of the food chain to changes in species intrinsic rates. We deduce a direct relationship between cascades and pyramids, modulated by what we call trophic dissipation – a synthetic concept that encodes the contribution of top-down propagation of consumer losses in the biomass pyramid. Predictable across-ecosystem patterns emerge when systems are in similar regimes of trophic dissipation. Data from 31 aquatic mesocosm experiments demonstrate how our approach can reveal the causal mechanisms linking trophic cascades and biomass distributions, thus providing a road map to deduce reliable predictions from empirical patterns.

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THE EFFECT OF SELENIUM ON MERCURY TRANSPORT ALONG THE FOOD CHAIN

AGROFOR ◽

10.7251/agreng1603119z ◽

2016 ◽

Vol 1 (3) ◽

Cited By ~ 1

Author(s):

Primož ZIDAR ◽

Špela KRŽIŠNIK ◽

Marta DEBELJAK ◽

Suzana ŽIŽEK ◽

Katarina VOGEL MIKUŠ

Keyword(s):

Food Chain ◽

Contaminated Soil ◽

Local Population ◽

Trophic Levels ◽

Food Chains ◽

Chemical Transformations ◽

Soil Concentration ◽

Preliminary Results ◽

Mercury Transport ◽

Hg Accumulation

More than 500 years of mercury (Hg) production in Idrija (Slovenia) resulted in aconsiderable pollution of Idrija region with Hg. Although the mine is closed formore than 20 years, the total soil concentration of Hg may still reach up to severalhundred mgkg-1dry weightin local gardens and more that thousand inother urbanregions. Hg in soil undergoesdifferent chemical transformations and in someformsit may enterplants and higher trophic levelsin food chains, also withbiomagnification pattern.The local population is, besides air and dust, thus exposedto mercury also via consumption of locally produced food.Several studies showedthat the increased level of selenium in soil may reduce the uptake of mercury inplants but very few include other trophic levels in a food chain as well.In our pilotstudy we followed an impact of Seon Hg transport from soil to plants(Lactucasativa) and further to soil dwelling animals (Porcellioscaber). Lettuce wasplanted in a contaminated soil from Idrija and in soil with added HgCl2. The leavesof half of the plants weresprayed with Sesolution (5μg L-1)threeand five weeksafter planting.After six weeks plants were analyzed for Hg and Se and offered asfood to terrestrial isopods for two weeks. Our preliminary results revealed thatfoliar treatment of plants with Se may affect Hg accumulation in plants andtherefore further transport of Hg across the food chain.

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Large mammals generate both top-down effects and extended trophic cascades on floral-visitor assemblages

Journal of Tropical Ecology ◽

10.1017/s0266467419000142 ◽

2019 ◽

Vol 35 (4) ◽

pp. 185-198 ◽

Cited By ~ 1

Author(s):

Allison Louthan ◽

Emily Valencia ◽

Dino J. Martins ◽

Travis Guy ◽

Jacob Goheen ◽

...

Keyword(s):

Trophic Cascade ◽

Structural Equation ◽

Trophic Cascades ◽

Trophic Levels ◽

Large Mammals ◽

Top Down ◽

Cascading Effects ◽

Floral Visitor ◽

Show Evidence ◽

Floral Visitors

AbstractCascading effects of high trophic levels onto lower trophic levels have been documented in many ecosystems. Some studies also show evidence of extended trophic cascades, in which guilds dependent on lower trophic levels, but uninvolved in the trophic cascade themselves, are affected by the trophic cascade due to their dependence on lower trophic levels. Top-down effects of large mammals on plants could lead to a variety of extended trophic cascades on the many guilds dependent on plants, such as pollinators. In this study, floral-visitor and floral abundances and assemblages were quantified within a series of 1-ha manipulations of large-mammalian herbivore density in an African savanna. Top-down effects of large mammals on the composition of flowers available for floral visitors are first shown, using regressions of herbivore activity on metrics of floral and floral-visitor assemblages. An extended trophic cascade is also shown: the floral assemblage further altered the assemblage of floral visitors, according to a variety of approaches, including a structural equation modelling approach (model with an extended trophic cascade was supported over a model without, AICc weight = 0.984). Our study provides support for extended trophic cascades affecting floral visitors, suggesting that trophic cascades can have impacts throughout entire communities.

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Loss of top-down biotic interactions changes the relative benefits for obligate mutualists

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.2501 ◽

2019 ◽

Vol 286 (1897) ◽

pp. 20182501 ◽

Cited By ~ 7

Author(s):

Rong Wang ◽

Xiao-Yong Chen ◽

Yan Chen ◽

Gang Wang ◽

Derek W. Dunn ◽

...

Keyword(s):

Biotic Interactions ◽

Trophic Levels ◽

Fig Wasp ◽

Negative Effects ◽

Top Down ◽

Top Predators ◽

Natural Range ◽

Obligate Mutualism ◽

The Stability ◽

Food Web Complexity

The collapse of mutualisms owing to anthropogenic changes is contributing to losses of biodiversity. Top predators can regulate biotic interactions between species at lower trophic levels and may contribute to the stability of such mutualisms, but they are particularly likely to be lost after disturbance of communities. We focused on the mutualism between the fig tree Ficus microcarpa and its host-specific pollinator fig wasp and compared the benefits accrued by the mutualists in natural and translocated areas of distribution. Parasitoids of the pollinator were rare or absent outside the natural range of the mutualists, where the relative benefits the mutualists gained from their interaction were changed significantly away from the plant's natural range owing to reduced seed production rather than increased numbers of pollinator offspring. Furthermore, in the absence of the negative effects of its parasitoids, we detected an oviposition range expansion by the pollinator, with the use of a wider range of ovules that could otherwise have generated seeds. Loss of top-down control has therefore resulted in a change in the balance of reciprocal benefits that underpins this obligate mutualism, emphasizing the value of maintaining food web complexity in the Anthropocene.

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Mercury Accumulation in Terrestrial Food Chains of the Liaohe Estuary Wetlands

10.21203/rs.3.rs-866142/v1 ◽

2021 ◽

Author(s):

yuqi wang ◽

Zheng Dongmei ◽

Ma Huanchi ◽

Li Huiying ◽

Wang Bing

Keyword(s):

Food Chain ◽

Rice Field ◽

Nitrogen Isotopes ◽

Mercury Content ◽

Trophic Levels ◽

Food Chains ◽

Mercury Accumulation ◽

Stable Carbon ◽

Carbon And Nitrogen ◽

Global Pollutant

Abstract Mercury is a global pollutant that can accumulate in organisms and endanger human health. This paper studied the soil, plants and animals in the light beach, Suaeda wing wetland, reed wetland and rice field in the Liaohe Estuary in 2018 and 2019, and determined the stable carbon and nitrogen isotopes of animals and plants to construct the food chain. The results show that from 2018 to 2019, the accumulation of mercury in the soil of the light beach, Suaeda winged wetland and reed wetland of the Liaohe Estuary continued to increase, but the accumulation of mercury in paddy soil showed a decreasing trend; the mercury content in plant samples also showed a certain degree There is a positive correlation between the accumulation of mercury in the food chain and the construction of trophic levels in the food chain. Mercury can carry out efficient biomagnification and bioaccumulation through the food chain.

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How trophic cascades and photic zone nutrient content interact to generate basin-scale differences in the microbial food web

ICES Journal of Marine Science ◽

10.1093/icesjms/fsaa028 ◽

2020 ◽

Vol 77 (5) ◽

pp. 1639-1647 ◽

Cited By ~ 1

Author(s):

T Frede Thingstad

Keyword(s):

Food Web ◽

Food Webs ◽

Trophic Cascades ◽

Trophic Levels ◽

Seasonal Migration ◽

The Arctic ◽

Microbial Food Web ◽

Food Chains ◽

Basin Scale ◽

The Mediterranean

Abstract In linear food chains, resource and predator control produce positive and negative correlations, respectively, between biomass at adjacent trophic levels. These simple relationships become more complex in food webs that contain alternative food chains of unequal lengths. We have used a “minimum” model for the microbial part of the pelagic food web that has three such food chains connecting free mineral nutrients to copepods: via diatoms, autotrophic flagellates, and heterotrophic bacteria. Trophic cascades from copepods strongly modulates the balance between the three pathways and, therefore, the functionality of the microbial food web in services such as food production for higher trophic levels, DOM degradation, and ocean carbon sequestration. The result is a theoretical framework able to explain, not only apparent conflicts in Arctic mesocosm experiments, but also biogeochemical features of the Mediterranean. Here, the fundamental difference between Arctic and Mediterranean microbial food webs is the way they are predator driven by seasonal migration of large copepods in the Arctic, but resource driven due to the anti-estuarine circulation in the Mediterranean. In this framework, global change effects on microbial ecosystem functions are more like to come indirectly through changes in these drivers than through direct temperature effects on the microbes.

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Predator complementarity dampens variability of phytoplankton biomass in a diversity-stability trophic cascade

10.1101/851642 ◽

2019 ◽

Author(s):

Chase J. Rakowski ◽

Caroline E. Farrior ◽

Schonna R. Manning ◽

Mathew A. Leibold

Keyword(s):

Trophic Cascade ◽

Phytoplankton Biomass ◽

Trophic Cascades ◽

Trophic Levels ◽

Cascading Effects ◽

Predator Diversity ◽

Laboratory Microcosm ◽

Average Biomass ◽

Basal Resources ◽

The Stability

AbstractTrophic cascades – indirect effects of predators that propagate down through food webs – have been extensively documented, especially in aquatic ecosystems. It has also been shown that predator diversity can mediate these trophic cascades, and, separately, that herbivore biomass can impact the stability of primary producers. However, whether predator diversity can cause cascading effects on the stability of lower trophic levels has not yet been studied. We conducted a laboratory microcosm experiment and a field mesocosm experiment manipulating the presence and coexistence of two heteropteran predators and measuring their effects on zooplankton herbivores and phytoplankton basal resources. We predicted that, if the predators partitioned their herbivore prey, for example by size, then co-presence of the predators would lead to 1) increased average values and 2) decreased temporal variability of phytoplankton basal resources. We present evidence that the predators partitioned their herbivore prey and found that their simultaneous suppression of herbivore groups reduced the variability of edible (smaller) phytoplankton biomass, without affecting mean phytoplankton biomass. We also found that phytoplankton that were more resistant to herbivory were not affected by our manipulations, indicating that the zooplankton herbivores played an important role in mediating this cascading diversity-stability effect. Our results demonstrate that predator diversity may indirectly stabilize basal resource biomass via a “diversity-stability trophic cascade,” seemingly dependent on predator complementarity and the vulnerability of taxa to consumption, but independent of a classic trophic cascade in which average biomass is altered. Predator diversity, especially if correlated with diversity of prey use, may be important for regulating ecosystem stability, and this relationship suggests biological control methods for improving the reliability of microalgal yields.

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Faculty Opinions recommendation of Light, nutrients, and food-chain length constrain planktonic energy transfer efficiency across multiple trophic levels.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1131968.589080 ◽

2008 ◽

Author(s):

Robert Sterner

Keyword(s):

Energy Transfer ◽

Chain Length ◽

Food Chain ◽

Energy Transfer Efficiency ◽

Trophic Levels ◽

Transfer Efficiency ◽

Food Chain Length

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Environmental and Social Risks to Biodiversity and Ecosystem Health—A Bottom-Up, Resource-Focused Assessment Framework

Earth ◽

10.3390/earth2030026 ◽

2021 ◽

Vol 2 (3) ◽

pp. 440-456

Author(s):

Roger A. Pielke ◽

Jimmy Adegoke ◽

Faisal Hossain ◽

Dev Niyogi

Keyword(s):

Ecosystem Function ◽

Ecosystem Health ◽

Interactive System ◽

Integrative Approach ◽

Individual Species ◽

Assessment Framework ◽

Top Down ◽

Bottom Up ◽

Social Risks ◽

Biodiversity And Ecosystem Function

Risks from human intervention in the climate system are raising concerns with respect to individual species and ecosystem health and resiliency. A dominant approach uses global climate models to predict changes in climate in the coming decades and then to downscale this information to assess impacts to plant communities, animal habitats, agricultural and urban ecosystems, and other parts of the Earth’s life system. To achieve robust assessments of the threats to these systems in this top-down, outcome vulnerability approach, however, requires skillful prediction, and representation of changes in regional and local climate processes, which has not yet been satisfactorily achieved. Moreover, threats to biodiversity and ecosystem function, such as from invasive species, are in general, not adequately included in the assessments. We discuss a complementary assessment framework that builds on a bottom-up vulnerability concept that requires the determination of the major human and natural forcings on the environment including extreme events, and the interactions between these forcings. After these forcings and interactions are identified, then the relative risks of each issue can be compared with other risks or forcings in order to adopt optimal mitigation/adaptation strategies. This framework is a more inclusive way of assessing risks, including climate variability and longer-term natural and anthropogenic-driven change, than the outcome vulnerability approach which is mainly based on multi-decadal global and regional climate model predictions. We therefore conclude that the top-down approach alone is outmoded as it is inadequate for robustly assessing risks to biodiversity and ecosystem function. In contrast the bottom-up, integrative approach is feasible and much more in line with the needs of the assessment and conservation community. A key message of our paper is to emphasize the need to consider coupled feedbacks since the Earth is a dynamically interactive system. This should be done not just in the model structure, but also in its application and subsequent analyses. We recognize that the community is moving toward that goal and we urge an accelerated pace.

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