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Wyatt KH, McCann KS, Rober AR, Turetsky MR. Letter: Trophic interactions regulate peatland carbon cycling. Ecol Lett 2021; 24:781-790. [PMID: 33554469 DOI: 10.1111/ele.13697] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 12/28/2020] [Accepted: 01/06/2021] [Indexed: 12/01/2022]
Abstract
Peatlands are the most efficient natural ecosystems for long-term storage of atmospheric carbon. Our understanding of peatland carbon cycling is based entirely on bottom-up controls regulated by low nutrient availability. Recent studies have shown that top-down controls through predator-prey dynamics can influence ecosystem function, yet this has not been evaluated in peatlands to date. Here, we used a combination of nutrient enrichment and trophic-level manipulation to test the hypothesis that interactions between nutrient availability (bottom-up) and predation (top-down) influence peatland carbon fluxes. Elevated nutrients stimulated bacterial biomass and organic matter decomposition. In the absence of top-down regulation, carbon dioxide (CO2 ) respiration driven by greater decomposition was offset by elevated algal productivity. Herbivores accelerated CO2 emissions by removing algal biomass, while predators indirectly reduced CO2 emissions by muting herbivory in a trophic cascade. This study demonstrates that trophic interactions can mitigate CO2 emissions associated with elevated nutrient levels in northern peatlands.
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Affiliation(s)
- Kevin H Wyatt
- Department of Biology, Ball State University, Muncie, IN, 47306, USA
| | - Kevin S McCann
- Department of Integrative Biology, University of Guelph, Guelph, ON, NIG2WI, Canada
| | - Allison R Rober
- Department of Biology, Ball State University, Muncie, IN, 47306, USA
| | - Merritt R Turetsky
- Institute of Arctic and Alpine Research and Ecology and Evolutionary Biology Department, University of Colorado Boulder, Boulder, CO, 80309, USA
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2
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Ni M, Li S, Santos I, Zhang J, Luo J. Linking riverine partial pressure of carbon dioxide to dissolved organic matter optical properties in a Dry-hot Valley Region. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 704:135353. [PMID: 31812378 DOI: 10.1016/j.scitotenv.2019.135353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/28/2019] [Accepted: 11/01/2019] [Indexed: 06/10/2023]
Abstract
The mineralization of dissolved organic matter (DOM) can partially explain riverine carbon dioxide (CO2) emissions to the atmosphere. However, little is known about how the DOM origin and composition drive CO2 partial pressures (pCO2). Here, we reveal links between aquatic pCO2, DOM optical parameters (a254, a350 and S275-295 and S350-400) and nutrients in a subtropical river in China's Dry-hot Valley Region. Biodegradation preferentially decomposed low molecular weight (LMW) DOMs, increasing high molecular weight (HMW) DOMs along the main stem. pCO2 was positively correlated with aromatic and lignin compounds, but negatively correlated with DOM molecular weight. Aquatic respiration of DOMs largely explained the pCO2 levels in the drought period, while terrestrial inputs were a pCO2 source in the initial-wet period. Our results illustrate how both DOM concentrations and speciation can explain pCO2 distribution and sources in rivers.
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Affiliation(s)
- Maofei Ni
- Key Laboratory of Reservoir Aquatic Environment, Research Center for Ecohydrology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Siyue Li
- Key Laboratory of Reservoir Aquatic Environment, Research Center for Ecohydrology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
| | - Isaac Santos
- National Marine Science Centre, Southern Cross University, PO Box 4321, Coffs Harbour, New South Wales 2450, Australia
| | - Jing Zhang
- Key Laboratory of Reservoir Aquatic Environment, Research Center for Ecohydrology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Jiachen Luo
- Key Laboratory of Reservoir Aquatic Environment, Research Center for Ecohydrology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
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Hammill E, Hawkins CP, Greig HS, Kratina P, Shurin JB, Atwood TB. Landscape heterogeneity strengthens the relationship between β-diversity and ecosystem function. Ecology 2018; 99:2467-2475. [PMID: 30289979 DOI: 10.1002/ecy.2492] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/16/2018] [Accepted: 07/23/2018] [Indexed: 11/08/2022]
Abstract
Consensus has emerged in the literature that increased biodiversity enhances the capacity of ecosystems to perform multiple functions. However, most biodiversity/ecosystem function studies focus on a single ecosystem, or on landscapes of homogenous ecosystems. Here, we investigate how increased landscape-level environmental dissimilarity may affect the relationship between different metrics of diversity (α, β, or γ) and ecosystem function. We produced a suite of simulated landscapes, each of which contained four experimental outdoor aquatic mesocosms. Differences in temperature and nutrient conditions of the mesocosms allowed us to simulate landscapes containing a range of within-landscape environmental heterogeneities. We found that the variation in ecosystem functions was primarily controlled by environmental conditions, with diversity metrics accounting for a smaller (but significant) amount of variation in function. When landscapes were more homogeneous, α, β, and γ diversity was not associated with differences in primary production, and only γ was associated with changes in decomposition. In these homogeneous landscapes, differences in these two ecosystem functions were most strongly related to nutrient and temperature conditions in the ecosystems. However, as landscape-level environmental dissimilarity increased, the relationship between α, β, or γ and ecosystem functions strengthened, with β being a greater predictor of variation in decomposition at the highest levels of environmental dissimilarity than α or γ. We propose that when all ecosystems in a landscape have similar environmental conditions, species sorting is likely to generate a single community composition that is well suited to those environmental conditions, β is low, and the efficiency of diversity-ecosystem function couplings is similar across communities. Under this low β, the effect of abiotic conditions on ecosystem function will be most apparent. However, when environmental conditions vary among ecosystems, species sorting pressures are different among ecosystems, producing different communities among locations in a landscape. These conditions lead to stronger relationships between β and the magnitude of ecosystem functions. Our results illustrate that abiotic conditions and the homogeneity of communities influence ecosystem function expressed at the landscape scale.
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Affiliation(s)
- Edd Hammill
- Department of Watershed Sciences and the Ecology Center, Utah State University, 5210 Old Main Hill, Logan, Utah, 84322, USA
| | - Charles P Hawkins
- Department of Watershed Sciences and the Ecology Center, Utah State University, 5210 Old Main Hill, Logan, Utah, 84322, USA
| | - Hamish S Greig
- School of Biology and Ecology, 5751 Murray Hall, Orono, Maine, 04469, USA
| | - Pavel Kratina
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Jonathan B Shurin
- Division of Biological Sciences, University of California, 9500 Gilman Dr., La Jolla, California, 92093, USA
| | - Trisha B Atwood
- Department of Watershed Sciences and the Ecology Center, Utah State University, 5210 Old Main Hill, Logan, Utah, 84322, USA
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Atwood TB, Madin EMP, Harborne AR, Hammill E, Luiz OJ, Ollivier QR, Roelfsema CM, Macreadie PI, Lovelock CE. Predators Shape Sedimentary Organic Carbon Storage in a Coral Reef Ecosystem. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00110] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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5
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Pearson CE, Symondson WOC, Clare EL, Ormerod SJ, Iparraguirre Bolaños E, Vaughan IP. The effects of pastoral intensification on the feeding interactions of generalist predators in streams. Mol Ecol 2017; 27:590-602. [PMID: 29219224 PMCID: PMC5887918 DOI: 10.1111/mec.14459] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 10/10/2017] [Accepted: 11/08/2017] [Indexed: 12/29/2022]
Abstract
Land‐use change can alter trophic interactions with wide‐ranging functional consequences, yet the consequences for aquatic food webs have been little studied. In part, this may reflect the challenges of resolving the diets of aquatic organisms using classical gut contents analysis, especially for soft‐bodied prey. We used next‐generation sequencing to resolve prey use in nearly 400 individuals of two predatory invertebrates (the Caddisfly, Rhyacophila dorsalis, and the Stonefly Dinocras cephalotes) in streams draining land with increasingly intensive livestock farming. Rhyacophila dorsalis occurred in all streams, whereas D. cephalotes was restricted to low intensities, allowing us to test whether: (i) apparent sensitivity to agriculture in the latter species reflects a more specialized diet and (ii) diet in R. dorsalis varied between sites with and without D. cephalotes. DNA was extracted from dissected gut contents, amplified without blocking probes and sequenced using Ion Torrent technology. Both predators were generalists, consuming 30 prey taxa with a preference for taxa that were abundant in all streams or that increased with intensification. Where both predators were present, their diets were nearly identical, and R. dorsalis's diet was virtually unchanged in the absence of D. cephalotes. The loss of D. cephalotes from more intensive sites was probably due to physicochemical stressors, such as sedimentation, rather than to dietary specialization, although wider biotic factors (e.g., competition with other predatory taxa) could not be excluded. This study provides a uniquely detailed description of predator diets along a land‐use intensity gradient, offering new insights into how anthropogenic stressors affect stream communities.
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Affiliation(s)
- C E Pearson
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - W O C Symondson
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - E L Clare
- School of Biological and Chemical Sciences, Queen Mary University, London, UK
| | - S J Ormerod
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - E Iparraguirre Bolaños
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK.,Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain
| | - I P Vaughan
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK
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Atwood TB, Hammill E, Kratina P, Greig HS, Shurin JB, Richardson JS. Warming alters food web-driven changes in the CO2 flux of experimental pond ecosystems. Biol Lett 2017; 11:20150785. [PMID: 26631247 DOI: 10.1098/rsbl.2015.0785] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Evidence shows the important role biota play in the carbon cycle, and strategic management of plant and animal populations could enhance CO2 uptake in aquatic ecosystems. However, it is currently unknown how management-driven changes to community structure may interact with climate warming and other anthropogenic perturbations to alter CO2 fluxes. Here we showed that under ambient water temperatures, predators (three-spined stickleback) and nutrient enrichment synergistically increased primary producer biomass, resulting in increased CO2 uptake by mesocosms in early dawn. However, a 3°C increase in water temperatures counteracted positive effects of predators and nutrients, leading to reduced primary producer biomass and a switch from CO2 influx to efflux. This confounding effect of temperature demonstrates that climate scenarios must be accounted for when undertaking ecosystem management actions to increase biosequestration.
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Affiliation(s)
- T B Atwood
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT 84322, USA
| | - E Hammill
- Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT 84322, USA
| | - P Kratina
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - H S Greig
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | - J B Shurin
- Section of Ecology, Behavior and Evolution, University of California-San Diego, La Jolla, CA 92093, USA
| | - J S Richardson
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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