Predictable feedbacks between warming, community structure and ecosystem functioning: a combined experimental and theoretical approach
Lead Research Organisation:
Queen Mary University of London
Department Name: Sch of Biological and Chemical Sciences
Abstract
Global warming is creating an extensively modified world. An ever increasing number of animals and plants are having to migrate to keep up with changes to their habitats, alterations in the timing of key seasonal events e.g., breeding season and local extinction. New evidence suggests that the underlying structure of marine and freshwater ecosystems is changing, and potentially most alarmingly, key global cycles which control climate have been altered. However, how the processes that sustain life in these ecosystems will respond to future global warming are unknown. An understanding of these processes is crucial if we are to be able to predict how ecosystems will respond to warming in the future and furthermore implement management strategies to protect the fundamentals of these ecosystems. This represents a significant challenge for scientists because ecosystems are inherently complex and their response to environmental change can often be idiosyncratic. We will adopt a powerful, multi-disciplined approach to this challenge. We will develop mathematical models that capture the structure of aquatic communities and the cycling of key elements and their relationships with temperature. At the same time we will continue a large scale experiment which has been running since 2006 which involves the warming of a series of replicated artificial ponds to simulate the effects of future global warming. The combination of these approaches will allow us to determine the biological mechanisms that will govern the response of aquatic ecosystems to the elevated temperatures predicted for the end of the century. The general mathematical models that will come from this research will provide scientists will crucial predictive tools for the study of global warming on ecosystems. While our experimental manipulation will allow us to test or model predictions and provide direct evidence of the effects of warming on whole aquatic ecosystems. Ecologists typically break ecosystems down into structural (animals and plants) and functional (photosynthesis, decomposition) components. The structural component generally focuses on the numbers, diversity and interactions between plants and animals. While the functional component typically analyses the cycling of key biological elements. The study of these components in isolation has hindered progress in understanding how ecosystems will respond to environmental change e.g. warming. Using the described experimental system we have already shown that warming changes the size structure of aquatic ecosystems, reduces their ability to absorb carbon dioxide, and increases the amount of methane they release. Furthermore, our results have hinted towards the possible interactions between structural and functional components. Determining the 'links' between the structure and function of aquatic ecosystems and how they will respond to warming will represent a significant advance in the science of ecology and understanding the effects of future global warming. We will combine two theories in ecology that are both well established but not yet fully integrated: the Metabolic Theory of Ecology (MTE), which looks at the changes in energy within an ecosystem; and the Ecological Stoichiometric Theory (EST), which looks at the balance or 'harmony' of nutrients within an ecosystem. Using these theories, we hypothesise that warming will alter the balance of essential elements in plants which will go onto to affect the structure of the reliant animal food web. Further, we predict imbalances in the nutrient cycles (nitrogen and phosphorous) which maintain the integrity of these ecosystems. We will test our ideas by making high resolution seasonal measurements of nutrients and the size distribution of plants and animals, along with rates of photosynthesis and decomposition in our experimental systems.
Publications
Barneche DR
(2021)
Warming impairs trophic transfer efficiency in a long-term field experiment.
in Nature
Dossena M
(2012)
Warming alters community size structure and ecosystem functioning.
in Proceedings. Biological sciences
Perkins D
(2012)
Consistent temperature dependence of respiration across ecosystems contrasting in thermal history
in Global Change Biology
Yvon-Durocher G
(2012)
Reconciling the temperature dependence of respiration across timescales and ecosystem types.
in Nature
Yvon-Durocher G
(2015)
Five Years of Experimental Warming Increases the Biodiversity and Productivity of Phytoplankton.
in PLoS biology
Yvon-Durocher G
(2017)
The Temperature Dependence of Phytoplankton Stoichiometry: Investigating the Roles of Species Sorting and Local Adaptation.
in Frontiers in microbiology
YVON-DUROCHER G
(2011)
Warming alters the size spectrum and shifts the distribution of biomass in freshwater ecosystems WARMING ALTERS COMMUNITY SIZE STRUCTURE
in Global Change Biology
YVON-DUROCHER G
(2011)
Warming increases the proportion of primary production emitted as methane from freshwater mesocosms
in Global Change Biology
Yvon-Durocher G
(2012)
Linking community size structure and ecosystem functioning using metabolic theory.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Yvon-Durocher G
(2017)
Long-term warming amplifies shifts in the carbon cycle of experimental ponds
in Nature Climate Change
Description | Ecosystem respiration is the biotic conversion of organic carbon to carbon dioxide by all of the organisms in an ecosystem, including both consumers and primary producers. Respiration exhibits an exponential temperature dependence at the subcellular and individual levels, but at the ecosystem level respiration can be modified by many variables including community abundance and biomass, which vary substantially among ecosystems. Despite its importance for predicting the responses of the biosphere to climate change, it is as yet unknown whether the temperature dependence of ecosystem respiration varies systematically between aquatic and terrestrial environments. Here we have used the largest database of respiratory measurements yet compiled to show that the sensitivity of ecosystem respiration to seasonal changes in temperature is remarkably similar for diverse environments encompassing lakes, rivers, estuaries, the open ocean and forested and non-forested terrestrial ecosystems, with an average activation energy similar to that of the respiratory complex (approximately 0.65 electronvolts (eV)). By contrast, annual ecosystem respiration shows a substantially greater temperature dependence across aquatic (approximately 0.65 eV) versus terrestrial ecosystems (approximately 0.32 eV) that span broad geographic gradients in temperature. Using a model derived from metabolic theory, these findings can be reconciled by similarities in the biochemical kinetics of metabolism at the subcellular level, and fundamental differences in the importance of other variables besides temperature-such as primary productivity and allochthonous carbon inputs-on the structure of aquatic and terrestrial biota at the community level. In addition, at the global scale, phytoplankton take up about as much carbon dioxide (CO2) as the tropical rainforests. However, in spite of their importance in global carbon cycles, we understand very little about how phytoplankton communities and the critical functions they mediate, including CO2 sequestration, are likely to change as the climate warms in the coming decades. In this study, we report the results of a five-year warming study in experimental outdoor ponds, known as mesocosms. Warmed (+4°C) communities had 67% more species and higher rates of gross primary productivity (CO2 fixation). Our results show that warming resulted in higher productivity by increasing the biodiversity and biomass of the phytoplankton. Warming also changed the species composition of the phytoplankton communities by favouring larger organisms that were more resistant to grazing from zooplankton. Our work demonstrates that future global warming is likely to have major impacts on the composition, biodiversity, and functioning of planktonic ecosystems by affecting metabolic rates and species interactions. The increases in the biodiversity and productivity of the phytoplankton seen in this study also highlights that the effects of a warming environment might not always be adverse for all ecosystems. |
Exploitation Route | Taken together, our results emphasize the fundamental role temperature plays in constraining patterns of species coexistence and dominance in local communities. They also suggest that warming can alter ecosystem functioning indirectly, by shifting community structure and biodiversity, in addition to its well-known direct effects mediated by metabolism. The findings we report are significant because they show that temperature can enhance the diversity of local communities through ecological mechanisms. Moreover, they mirror biodiversity patterns reported for aquatic and terrestrial taxa along broadscale gradients of temperature and latitude. Latitudinal biodiversity gradients are typically attributed to long-term macroevolutionary and/or historical mechanisms; however, our findings, which isolate the effects of temperature while controlling for other variables that may be confounded along latitudinal gradients (e.g., nutrients, productivity, disturbance regime), suggest that temperature may in part influence local biodiversity through its effects on ecological mechanisms of species coexistence. Through such mechanisms, future global warming could, in some cases, actually enhance species richness and primary productivity in phytoplankton communities and will be of value to climate model predictions on the effects of warming over the next century. |
Sectors | Environment |
Description | Understanding and management strategies for mitigating the risks associated with climate change |
Amount | £90,000 (GBP) |
Organisation | AXA |
Department | AXA Research Fund |
Sector | Private |
Country | France |
Start | 10/2011 |
End | 09/2014 |
Title | Five Years of Experimental Warming Increases the Biodiversity and Productivity of Phytoplankton |
Description | Underlying data used in all analyses and figures for the online paper http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002324 |
Type Of Material | Database/Collection of data |
Year Produced | 2015 |
Provided To Others? | Yes |
Impact | NA |
URL | http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002324 |
Description | Science Uncovered - Natural History Museum (September 2013) |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | |
Results and Impact | Science Uncovered is a widely-advertised and well-attended public outreach event hosted at the Natural History Museum in London, where scientist engage with the public face-to-face basis to discuss their research and its implications in an informal setting. I represented Imperial College London, accompanied by two PhD students, and discussed my group's work, which included the current grant, under the general theme of ecological responses and alterations to energy flux in food webs due to environmental stressors. At our stall we spoke to several hundred visitors throughout the day. See above. |
Year(s) Of Engagement Activity | 2013 |