Predictable feedbacks between warming, community structure and ecosystem functioning: a combined experimental and theoretical approach

Lead Research Organisation: Imperial College London
Department Name: Life Sciences

Abstract

This is a joint submission. Please see the main grant with PI Mark Trimmer of Queen Mary University of London.

Publications

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Adams G (2016) Community management indicators can conflate divergent phenomena: two challenges and a decomposition-based solution in Journal of Applied Ecology

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Adams GL (2013) Diatoms can be an important exception to temperature-size rules at species and community levels of organization. in Global change biology

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Barnes C (2010) Global patterns in predator-prey size relationships reveal size dependency of trophic transfer efficiency. in Ecology

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Defriez EJ (2016) Climate change-related regime shifts have altered spatial synchrony of plankton dynamics in the North Sea. in Global change biology

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Ewers RM (2013) Using landscape history to predict biodiversity patterns in fragmented landscapes. in Ecology letters

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García-Carreras B (2013) Are changes in the mean or variability of climate signals more important for long-term stochastic growth rate? in PloS one

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Hudson L (2012) Cheddar: analysis and visualisation of ecological communities in R in Methods in Ecology and Evolution

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Hudson LN (2013) A cure for the plague of parameters: constraining models of complex population dynamics with allometries. in Proceedings. Biological sciences

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Hudson LN (2013) The relationship between body mass and field metabolic rate among individual birds and mammals. in The Journal of animal ecology

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Reuman DC (2014) A metabolic perspective on competition and body size reductions with warming. in The Journal of animal ecology

 
Description One of the observations of the experimental system of this grant is that phytoplankton communities under the influence of warming consist of smaller cells. It has also been observed that warmer natural waters contain smaller phytoplankton cells. This is related to a field of prior research concerned with similar phenomena, and has been summarized under various ecological "laws", e.g., the temperature-size rule, James's Rule, and Bergmann's Rule. In short, warming benefits the small. Most prior explanations of this phenomenon have focused on physiological explanations, but our work shows for the first time that competition can also be an important factor: smaller phytoplankton cells are expected, based on our work, to have an accentuated competitive advantage for nutrient uptake and rapid growth in warmer waters. The same may be true of other ectotherms.

We also published a paper with this abstract:
1. Community indicators are used to assess the state of ecological communities and to guide management. They are usually calculated from monitoring data, often collected annually. Since any given community indicator provides a univariate summary of complex multivariate phenomena, different changes in the community may lead to the same response in the indicator. Sampling variation can also mask ecologically important trends.
2. This study addresses these challenges for community indicators, with a focus on the large fish indicator (LFI), internationally used to report status of marine fish communities. The LFI expresses 'large' fish biomass as a proportion of total fish biomass and is calculated from species-size-abundance data collected on trawl surveys. We develop new methods to decompose the contributions of species, sampling locations and season to trends over time in the LFI, and highlight consequences for assessment and management.
3. Our results showed that both species and locations made divergent contributions to overall trends in the LFI indicator, with contributions differing by several orders of magnitude and in sign. Only small proportions of species and locations drove overall LFI trends, and their contributions changed with season (spring and autumn surveys). To assess significance of component trends, a resampling method was developed. Our method can be generalised and applied to many other community indicators based on survey data.
4. Synthesis and applications. Our new method for decomposing community indicators and generating confidence intervals makes it possible to extract much more information on what drives a 'headline' indicator, providing a solution to challenges arising from multiple possible interpretations of changes in the indicator, and from sampling variation. Analysis of the effects of indicator components on headline indicator values is recommended, because the results allow assessors and managers to identify and interpret how divergent factors (e.g. species, sampling locations and seasons) contribute to the headline indicator value.


Many further results related to marine fisheries are underway, to be published within the next year or so.
Exploitation Route Understanding the mechanisms by which organisms become smaller in warmed ecosystems may help is predict when this will occur, and thereby understand effects on the food chains that depend on the species. The work is basic science - it illuminates one of the key impacts of climate change on biota. See also above-copied abstract of a paper published in Journal of Applied Ecology, an applied journal.
Sectors Communities and Social Services/Policy,Environment
URL http://onlinelibrary.wiley.com/doi/10.1111/gcb.12285/full
 
Title "cheddar" software package for the R programming language 
Description A package of software tools for manipulating certain kinds of food web data, now on the Comprehensive R Archive Network 
Type Of Material Improvements to research infrastructure 
Year Produced 2013 
Provided To Others? Yes  
Impact At least five papers in prep or in press so far have used the package for their analysis 
URL http://cran.r-project.org/web/packages/cheddar/index.html
 
Title The relationship between body mass and field metabolic rate among individual birds and mammals 
Description The online supplement to this paper contains the complete dataset used, which is the biggest ever dataset assembled on metabolic rates and body sizes of individual birds and mammals. 
Type Of Material Database/Collection of data 
Year Produced 2013 
Provided To Others? Yes  
Impact The data are available to be used in future research. 
URL http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12086/suppinfo
 
Title diatom data 
Description Body sizes of diatoms in icelandic streams across a temperature gradient 
Type Of Material Database/Collection of data 
Year Produced 2013 
Provided To Others? Yes  
Impact The database is available to other researchers 
URL http://onlinelibrary.wiley.com/doi/10.1111/gcb.12285/suppinfo
 
Title Cheddar: Analysis and visualization of ecological communities in R 
Description A package in the R programming language. Released on the Comprehensive R Archive Network, and described in a publication that is also listed as an outcome of the grant. 
Type Of Technology Software 
Impact Publication date is an estimate of completion or near completion, as the software was available open source throughout a large part of its developments.