Relative importance of top-down and bottom-up forces in food webs of Sarracenia pitcher communities at a northern and a southern site

Oecologia ◽  
2010 ◽  
Vol 165 (4) ◽  
pp. 1073-1082 ◽  
Author(s):  
David Hoekman
Keyword(s):  
Food Webs ◽  
Relative Importance ◽  
Top Down ◽  
Bottom Up ◽  
Southern Site

scholarly journals Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes

2013 ◽  
Vol 71 (2) ◽  
pp. 406-416 ◽  
Author(s):  
T. O. M. Reilly ◽  
H. M. Fraser ◽  
R. J. Fryer ◽  
J. Clarke ◽  
S. P. R. Greenstreet
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Levels ◽  
Top Down ◽  
Bottom Up ◽  
Control Processes ◽  
Top Predators ◽  
Environmental Status ◽  
Fish Predators ◽  
Firth Of Forth

Abstract Reilly, T. O. M., Fraser, H. M., Fryer, R. J., Clarke, J., and Greenstreet, S. P. R. 2014. Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes. – ICES Journal of Marine Science, 71: 406–416. Proposed indicators for the Marine Strategy Framework Directive (MSFD) food webs Descriptor focus on structural elements of food webs, and in particular on the abundance and productivity of top predators. However, the inferences that can be drawn from such indicators depend on whether or not the predators are “bottom-up limited” by the availability of their prey. Many seabird populations appear to be “bottom-up limited” so that variation in their reproductive success and/or abundance reflects changes in lower trophic levels. Here we find that gadoid fish predators off the Firth of Forth, southeast Scotland, do not appear to be “bottom-up limited” by the biomass of their main prey, 0-group sandeels; gadoid biomass and feeding performance was independent of sandeel biomass. Variability in food web indicators based on these gadoid predators seems to impart little insight into underlying processes occurring at lower trophic levels in the local food web. The implications of this in terms of how the currently proposed MSFD food web indicators should be used and interpreted are considered, and the ramifications in terms of setting targets representing good environmental status for both fish and seabird communities are discussed.

scholarly journals Warming shifts top-down and bottom-up control of pond food web structure and function

2012 ◽  
Vol 367 (1605) ◽  
pp. 3008-3017 ◽  
Author(s):  
Jonathan B. Shurin ◽  
Jessica L. Clasen ◽  
Hamish S. Greig ◽  
Pavel Kratina ◽  
Patrick L. Thompson
Keyword(s):  
Food Webs ◽  
Environmental Changes ◽  
Lytic Cycle ◽  
Top Down ◽  
Food Web Structure ◽  
Bottom Up ◽  
Positive Effects ◽  
Freshwater Pond ◽  
Aquatic Food ◽  
The Impact

The effects of global and local environmental changes are transmitted through networks of interacting organisms to shape the structure of communities and the dynamics of ecosystems. We tested the impact of elevated temperature on the top-down and bottom-up forces structuring experimental freshwater pond food webs in western Canada over 16 months. Experimental warming was crossed with treatments manipulating the presence of planktivorous fish and eutrophication through enhanced nutrient supply. We found that higher temperatures produced top-heavy food webs with lower biomass of benthic and pelagic producers, equivalent biomass of zooplankton, zoobenthos and pelagic bacteria, and more pelagic viruses. Eutrophication increased the biomass of all organisms studied, while fish had cascading positive effects on periphyton, phytoplankton and bacteria, and reduced biomass of invertebrates. Surprisingly, virus biomass was reduced in the presence of fish, suggesting the possibility for complex mechanisms of top-down control of the lytic cycle. Warming reduced the effects of eutrophication on periphyton, and magnified the already strong effects of fish on phytoplankton and bacteria. Warming, fish and nutrients all increased whole-system rates of net production despite their distinct impacts on the distribution of biomass between producers and consumers, plankton and benthos, and microbes and macrobes. Our results indicate that warming exerts a host of indirect effects on aquatic food webs mediated through shifts in the magnitudes of top-down and bottom-up forcing.

scholarly journals The meaning of functional trait composition of food webs for ecosystem functioning

2016 ◽  
Vol 371 (1694) ◽  
pp. 20150268 ◽  
Author(s):  
Dominique Gravel ◽  
Camille Albouy ◽  
Wilfried Thuiller
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Ecosystem Functioning ◽  
Functional Trait ◽  
Plant Ecology ◽  
Functional Composition ◽  
Top Down ◽  
Bottom Up ◽  
Functional Trait Diversity

There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the ever-increasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and top-down control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with well-defined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists.

Top-down and bottom-up diversity cascades in detrital vs. living food webs

2002 ◽  
Vol 6 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Lee A. Dyer ◽  
Deborah Letourneau
Keyword(s):  
Food Webs ◽  
Top Down ◽  
Bottom Up

scholarly journals Ecosystem engineering strengthens bottom-up and weakens top-down effects via trait-mediated indirect interactions

2017 ◽  
Vol 284 (1863) ◽  
pp. 20170894 ◽  
Author(s):  
Zhiwei Zhong ◽  
Xiaofei Li ◽  
Dean Pearson ◽  
Deli Wang ◽  
Dirk Sanders ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Large Scale ◽  
Field Experiments ◽  
Ecosystem Engineering ◽  
Relative Importance ◽  
Top Down ◽  
Bottom Up ◽  
Spatial And Temporal Scales ◽  
Natural Systems ◽  
Ecological Scale

Trophic interactions and ecosystem engineering are ubiquitous and powerful forces structuring ecosystems, yet how these processes interact to shape natural systems is poorly understood. Moreover, trophic effects can be driven by both density- and trait-mediated interactions. Microcosm studies demonstrate that trait-mediated interactions may be as strong as density-mediated interactions, but the relative importance of these pathways at natural spatial and temporal scales is underexplored. Here, we integrate large-scale field experiments and microcosms to examine the effects of ecosystem engineering on trophic interactions while also exploring how ecological scale influences density- and trait-mediated interaction pathways. We demonstrate that (i) ecosystem engineering can shift the balance between top-down and bottom-up interactions, (ii) such effects can be driven by cryptic trait-mediated interactions, and (iii) the relative importance of density- versus trait-mediated interaction pathways can be scale dependent. Our findings reveal the complex interplay between ecosystem engineering, trophic interactions, and ecological scale in structuring natural systems.

scholarly journals Relative importance of top‐down vs. bottom‐up control of lake phytoplankton vertical distributions varies among fluorescence‐based spectral groups

2020 ◽  
Vol 65 (10) ◽  
pp. 2485-2501
Author(s):  
Mary E. Lofton ◽  
Taylor H. Leach ◽  
Beatrix E. Beisner ◽  
Cayelan C. Carey
Keyword(s):  
Relative Importance ◽  
Top Down ◽  
Bottom Up ◽  
Vertical Distributions
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