1
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Blubaugh CK. An omnivore vigour hypothesis? Nutrient availability strengthens herbivore suppression by omnivores across 48 field sites. J Anim Ecol 2023; 92:751-759. [PMID: 36695631 DOI: 10.1111/1365-2656.13890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 01/13/2023] [Indexed: 01/26/2023]
Abstract
Nutrients regulate herbivore growth from the 'bottom-up' via improved plant vigour and food quality. Nitrogen also affects 'top-down' control of herbivores by moderating attraction of predators and the rates at which they consume herbivorous prey. Tri-trophic consequences of nitrogen availability are more challenging to predict among omnivorous natural enemies who feed on both plants and herbivores, limiting our ability to predict net outcomes of nutrient availability in food webs. In a two-year field survey of insects on zucchini host plants at 48 sites, I predicted that both herbivores and foliar-feeding omnivores would increase with nutrient availability, while predators would not. My results revealed positive relationships between omnivores and foliar nitrogen concentrations, while predators had neutral responses to foliar N. Surprisingly, herbivores declined with increasing foliar N across the field sites. Greenhouse experiments re-enforced these patterns, as herbivore growth inversely correlated with soil N concentrations in communities that included foliar-feeding omnivores. Conversely, herbivore growth was uncorrelated with soil N on plants with predators, nor on predator-free plants. These results suggest that omnivores mount strong and consistent responses to nitrogen in plant tissues in a variety of ecological contexts. In environments where omnivorous arthropods can thrive, their recruitment to nitrogen-rich plants may increase predation and thereby counterbalance and stabilize 'bottom-up' increases in herbivore performance supported by enhanced foliar nutrition.
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Affiliation(s)
- C K Blubaugh
- Department of Entomology, University of Georgia, Athens, Georgia, USA
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2
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Sura SA, Gehris CG, Liang MY, Lim AN, Fong P. Press versus pulse nutrient supply and species interactions mediate growth of coral reef macroalgae. OIKOS 2023. [DOI: 10.1111/oik.09716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Shayna A. Sura
- Univ. of California Los Angeles, Dept of Ecology and Evolutionary Biology Los Angeles CA USA
- Dauphin Island Sea Lab Dauphin Island AL USA
| | - Connor G. Gehris
- Univ. of California Los Angeles, Dept of Ecology and Evolutionary Biology Los Angeles CA USA
| | - Michelle Y. Liang
- Univ. of California Los Angeles, Dept of Ecology and Evolutionary Biology Los Angeles CA USA
| | - Alexandra N. Lim
- Univ. of California Los Angeles, Dept of Ecology and Evolutionary Biology Los Angeles CA USA
| | - Peggy Fong
- Univ. of California Los Angeles, Dept of Ecology and Evolutionary Biology Los Angeles CA USA
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3
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Beck M, Billoir E, Floury M, Usseglio-Polatera P, Danger M. A 34-year survey under phosphorus decline and warming: Consequences on stoichiometry and functional trait composition of freshwater macroinvertebrate communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159786. [PMID: 36377090 DOI: 10.1016/j.scitotenv.2022.159786] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/24/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Worldwide, freshwater systems are subjected to increasing temperatures and nutrient changes. Under phosphorus and nitrogen enrichment consumer communities are often thought to shift towards fast-growing and P-rich taxa, supporting the well-known link between growth rate and body stoichiometry. While these traits are also favoured under warming, the temperature effect on stoichiometry is less clear. As recently shown, there is a general link between functional traits and body stoichiometry, which makes the integration of stoichiometric traits a promising tool to help understanding the mechanisms behind taxonomic and functional community responses to nutrient changes and/or warming. Yet, such approaches have been scarcely developed at community level and on a long-term perspective. In this study, we investigated long-term responses in stoichiometry and functional trait composition of macroinvertebrate communities to nutrient changes (decreasing water P; increasing water N:P) and warming over a 34-year period in the Middle Loire River (France), testing the potentially opposing responses to these drivers. Both drivers should cause shifts in species composition, which will alter the overall community stoichiometry and functional composition following assumptions from ecological stoichiometry theory. We found that the macroinvertebrate community shifted towards P-poor taxa, causing significant trends in overall community stoichiometry which indicates long-term changes in the nutrient pool provided by these consumers (i.e. decrease in %N and %P, increase in N:P). Further, while the former high-P conditions favoured traits associated to detritus feeding and fast development (i.e. small maximum body size, short life duration), recent conditions favoured predators and slow-developing taxa. These results suggest nutrients to be a more important driver than temperature over this period. By providing a pivotal link between environmental changes and functional trait composition of communities, approaches based on stoichiometric traits offer sound perspectives to investigate ecological relationships between multiple drivers operating at various scales and ecosystem functioning.
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Affiliation(s)
| | | | - Mathieu Floury
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F- 69622, Villeurbanne, France
| | | | - Michael Danger
- LIEC, Université de Lorraine, France; Institut Universitaire de France, Paris, France
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4
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Gaiser EE, Kominoski JS, McKnight DM, Bahlai CA, Cheng C, Record S, Wollheim WM, Christianson KR, Downs MR, Hawman PA, Holbrook SJ, Kumar A, Mishra DR, Molotch NP, Primack RB, Rassweiler A, Schmitt RJ, Sutter LA. Long-term ecological research and the COVID-19 anthropause: A window to understanding social-ecological disturbance. Ecosphere 2022; 13:e4019. [PMID: 35573027 PMCID: PMC9087370 DOI: 10.1002/ecs2.4019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/16/2021] [Accepted: 12/07/2021] [Indexed: 11/07/2022] Open
Abstract
The period of disrupted human activity caused by the COVID-19 pandemic, coined the "anthropause," altered the nature of interactions between humans and ecosystems. It is uncertain how the anthropause has changed ecosystem states, functions, and feedback to human systems through shifts in ecosystem services. Here, we used an existing disturbance framework to propose new investigation pathways for coordinated studies of distributed, long-term social-ecological research to capture effects of the anthropause. Although it is still too early to comprehensively evaluate effects due to pandemic-related delays in data availability and ecological response lags, we detail three case studies that show how long-term data can be used to document and interpret changes in air and water quality and wildlife populations and behavior coinciding with the anthropause. These early findings may guide interpretations of effects of the anthropause as it interacts with other ongoing environmental changes in the future, particularly highlighting the importance of long-term data in separating disturbance impacts from natural variation and long-term trends. Effects of this global disturbance have local to global effects on ecosystems with feedback to social systems that may be detectable at spatial scales captured by nationally to globally distributed research networks.
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Affiliation(s)
- Evelyn E. Gaiser
- Institute of Environment and Department of Biological SciencesFlorida International UniversityMiamiFloridaUSA
| | - John S. Kominoski
- Institute of Environment and Department of Biological SciencesFlorida International UniversityMiamiFloridaUSA
| | - Diane M. McKnight
- Institute of Arctic and Alpine Research and Environmental Studies ProgramUniversity of ColoradoBoulderColoradoUSA
| | | | - Chingwen Cheng
- The Design SchoolArizona State UniversityTempeArizonaUSA
| | - Sydne Record
- Department of BiologyBryn Mawr CollegeBryn MawrPennsylvaniaUSA
| | - Wilfred M. Wollheim
- Department of Natural Resources and the EnvironmentUniversity of New HampshireDurhamNew HampshireUSA
| | | | - Martha R. Downs
- National Center for Ecological Analysis and SynthesisUniversity of California Santa BarbaraSanta BarbaraCaliforniaUSA
| | - Peter A. Hawman
- Department of GeographyUniversity of GeorgiaAthensGeorgiaUSA
| | - Sally J. Holbrook
- Department of Ecology, Evolution and Marine BiologyUniversity of California Santa BarbaraSanta BarbaraCaliforniaUSA
| | - Abhishek Kumar
- Department of Environmental ConservationUniversity of Massachusetts AmherstAmherstMassachusettsUSA
| | | | - Noah P. Molotch
- Institute of Arctic and Alpine ResearchUniversity of ColoradoBoulderColoradoUSA
| | | | - Andrew Rassweiler
- Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Russell J. Schmitt
- Department of Ecology, Evolution and Marine BiologyUniversity of California Santa BarbaraSanta BarbaraCaliforniaUSA
| | - Lori A. Sutter
- Warnell School of Forestry and Natural ResourcesUniversity of GeorgiaAthensGeorgiaUSA
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5
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Murphy SM, Vyas DK, Sher AA, Grenis K. Light pollution affects invasive and native plant traits important to plant competition and herbivorous insects. Biol Invasions 2021. [DOI: 10.1007/s10530-021-02670-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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6
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Rippel TM, Tomasula J, Murphy SM, Wimp GM. Global change in marine coastal habitats impacts insect populations and communities. CURRENT OPINION IN INSECT SCIENCE 2021; 47:1-6. [PMID: 33610775 DOI: 10.1016/j.cois.2021.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 02/07/2021] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Salt marsh and mangrove coastal ecosystems provide critical ecosystem services, but are being lost at an alarming rate. Insect communities in these ecosystems are threatened by human impacts, including sea level rise, habitat loss, external inputs including nutrients, metals, and hydrocarbons, as well as weather events, such as hurricanes. While some disturbances are felt throughout the food web (e.g. hurricanes), others are mediated by impacts on the dominant plants (e.g. nutrient subsidies). The impacts of these disturbances on insects/spiders and their rate of recovery is dependent on trophic level, life history, and diet breadth. While we understand impacts of single disturbances relatively well, we have very little understanding of how multiple disturbances interact to affect insect communities.
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Affiliation(s)
- Tyler M Rippel
- Department of Biology, Georgetown University, 3700 O Street NW, Washington, D.C., USA.
| | - Jewel Tomasula
- Department of Biology, Georgetown University, 3700 O Street NW, Washington, D.C., USA
| | - Shannon M Murphy
- Department of Biology, University of Denver, 2190 E. Iliff Ave, Denver, CO, USA
| | - Gina M Wimp
- Department of Biology, Georgetown University, 3700 O Street NW, Washington, D.C., USA
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Murphy SM, Vyas DK, Hoffman JL, Jenck CS, Washburn BA, Hunnicutt KE, Davidson A, Andersen JM, Bennet RK, Gifford A, Herrera M, Lawler B, Lorman S, Peacock V, Walker L, Watkins E, Wilkinson L, Williams Z, Tinghitella RM. Streetlights positively affect the presence of an invasive grass species. Ecol Evol 2021; 11:10320-10326. [PMID: 34367577 PMCID: PMC8328438 DOI: 10.1002/ece3.7835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 05/27/2021] [Accepted: 06/04/2021] [Indexed: 11/09/2022] Open
Abstract
Anthropogenic disturbances associated with urban ecosystems can create favorable conditions for populations of some invasive plant species. Light pollution is one of these disturbances, but how it affects the growth and establishment of invasive plant populations is unknown. Cheatgrass (Bromus tectorum) is a problematic invasive species where it has displaced native grassland communities in the United States, but to our knowledge, there have been no studies of the ecological factors that affect cheatgrass presence in urban ecosystems. We conducted field surveys in urban alleys in Denver, Colorado, to compare the presence of cheatgrass at sites with and without artificial light at night (hereafter artificial light) from streetlights. These streetlights are mounted on utility poles, which cause ground disturbance when installed in alleys; we were able to test the independent effect of poles on cheatgrass establishment because not all poles have streetlights on them. We found that cheatgrass was positively associated with the presence of streetlights and to a lesser extent poles. In addition to cheatgrass, we also found that other plants were positively associated with the presence of both poles and streetlights. Our results suggest that artificial light may benefit the occurrence of cheatgrass and other plant species in urban settings. While invasive populations of cheatgrass in wild habitats attract the most attention from managers, we suggest more consideration for this grass in urban environments where its growth and establishment benefit from anthropogenic changes.
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Affiliation(s)
| | - Dhaval K. Vyas
- Department of Biological SciencesUniversity of DenverDenverCOUSA
| | | | - Clara S. Jenck
- Department of Biological SciencesUniversity of DenverDenverCOUSA
| | | | | | - Angie Davidson
- Department of Physics and AstronomyUniversity of DenverDenverCOUSA
| | | | - Rachel K. Bennet
- Department of Physics and AstronomyUniversity of DenverDenverCOUSA
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8
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Wimp GM, Murphy SM. Disentangling the effects of primary productivity and host plant traits on arthropod communities. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gina M. Wimp
- Department of Biology Georgetown University Washington DC USA
| | - Shannon M. Murphy
- Department of Biological Sciences University of Denver Denver CO USA
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9
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Bell K, Driscoll DA, Patykowski J, Doherty TS. Abundance, Condition and Size of a Foundation Species Vary with Altered Soil Conditions, Remnant Type and Potential Competitors. Ecosystems 2021. [DOI: 10.1007/s10021-020-00598-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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10
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Wimp GM, Lewis D, Murphy SM. Prey identity but not prey quality affects spider performance. CURRENT RESEARCH IN INSECT SCIENCE 2021; 1:100013. [PMID: 36003602 PMCID: PMC9387502 DOI: 10.1016/j.cris.2021.100013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 12/01/2022]
Abstract
Prey identity affected the survival and body mass of a generalist spider predator. Trophic level of the prey did not affect spider survival and body mass. Prey identity and cordgrass quality had an interactive effect on spider body mass. Greater spider body mass led to greater egg production. In a literature review, female spider fitness increased with greater body size.
Increasing host plant quality affects higher trophic level predators, but whether such changes are simply a result of prey density or are also affected by changes in prey quality remain uncertain. Moreover, whether changes in prey quality affect measures of predator performance is understudied. Using a combination of field and greenhouse mesocosm experiments, we demonstrate that the survival and body size of a hunting spider (Pardosa littoralis Araneae: Lycosidae) is affected more by prey species identity than the trophic level of the prey. Furthermore, increasing host plant quality does not necessarily propagate through the food web by altering prey quality. While changes in plant quality affected spider body mass, they did so in opposite ways for spiders feeding on Prokelisia (Hemiptera: Delphacodes) herbivores relative to Tytthus (Hemiptera: Miridae) egg predators, and had no impact on spider body mass for two additional species of intraguild prey. These changes in body mass were important because greater body mass increased spider egg production. To examine the generality of this pattern, we reviewed the literature and found a consistent positive relationship between female body size and egg production for Pardosa species, indicating that body size is a reliable proxy for fitness. While many studies emphasize the importance of nitrogen to arthropod diets, this focus may be driven largely by our understanding of herbivore diets rather than predator diets. Thus, the positive impact of host plant quality on higher trophic level predators appears to be driven more by altering prey composition, density, and availability rather than simply providing predators with more nutritious prey.
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Affiliation(s)
- Gina M. Wimp
- Department of Biology, Georgetown University, Washington, DC, USA
- Corresponding author.
| | - Danny Lewis
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Shannon M. Murphy
- Department of Biological Sciences, University of Denver, Denver, CO, USA
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11
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Bowen JL, Giblin AE, Murphy AE, Bulseco AN, Deegan LA, Johnson DS, Nelson JA, Mozdzer TJ, Sullivan HL. Not All Nitrogen Is Created Equal: Differential Effects of Nitrate and Ammonium Enrichment in Coastal Wetlands. Bioscience 2020; 70:1108-1119. [PMID: 33376455 PMCID: PMC7750101 DOI: 10.1093/biosci/biaa140] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Excess reactive nitrogen (N) flows from agricultural, suburban, and urban systems to coasts, where it causes eutrophication. Coastal wetlands take up some of this N, thereby ameliorating the impacts on nearshore waters. Although the consequences of N on coastal wetlands have been extensively studied, the effect of the specific form of N is not often considered. Both oxidized N forms (nitrate, NO3-) and reduced forms (ammonium, NH4+) can relieve nutrient limitation and increase primary production. However, unlike NH4+, NO3- can also be used as an electron acceptor for microbial respiration. We present results demonstrating that, in salt marshes, microbes use NO3- to support organic matter decomposition and primary production is less stimulated than when enriched with reduced N. Understanding how different forms of N mediate the balance between primary production and decomposition is essential for managing coastal wetlands as N enrichment and sea level rise continue to assail our coasts.
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Affiliation(s)
- Jennifer L Bowen
- Northeastern University's Marine Science Center, Nahant, Massachusetts, and a senior scientist at INSPIRE Environmental, Newport, Rhode Island
| | - Anne E Giblin
- Marine Biological Laboratory, Woods Hole, Massachusetts, and is now an assistant professor of Marine Science at Eckerd College, St. Petersburg, Florida
| | - Anna E Murphy
- Northeastern University's Marine Science Center, Nahant, Massachusetts, and a senior scientist at INSPIRE Environmental, Newport, Rhode Island
| | - Ashley N Bulseco
- Marine Biological Laboratory, Woods Hole, Massachusetts, and is now an assistant professor of Marine Science at Eckerd College, St. Petersburg, Florida
| | - Linda A Deegan
- Woodwell Climate Research Center (formerly, the Woods Hole Research Center), in Falmouth, Massachusetts. Deegan leads the TIDE project, the long-term nutrient enrichment experiment from which much of these results derive
| | - David S Johnson
- Virginia Institute of Marine Science, William and Mary, Gloucester Point, Virginia
| | | | | | - Hillary L Sullivan
- Woodwell Climate Research Center (formerly, the Woods Hole Research Center), in Falmouth, Massachusetts. Deegan leads the TIDE project, the long-term nutrient enrichment experiment from which much of these results derive
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12
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Fong CR, Gaynus CJ, Carpenter RC. Complex interactions among stressors evolve over time to drive shifts from short turfs to macroalgae on tropical reefs. Ecosphere 2020. [DOI: 10.1002/ecs2.3130] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Caitlin R. Fong
- Department of Biology California State University Northridge Northridge California USA
| | - Camille J. Gaynus
- Department of Ecology and Evolutionary Biology University of California Los Angeles Los Angeles California USA
| | - Robert C. Carpenter
- Department of Ecology and Evolutionary Biology University of California Los Angeles Los Angeles California USA
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13
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Karasawa S. Sphaerillo boninensis Nunomura, 1990 (Crustacea, Isopoda, Oniscidea) is a junior synonym of a pantropical species, Venezillo parvus (Budde-Lund, 1885). Zookeys 2020; 923:1-14. [PMID: 32292267 PMCID: PMC7142170 DOI: 10.3897/zookeys.923.26018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 02/14/2020] [Indexed: 11/12/2022] Open
Abstract
Re-examination of the holotype and paratype of Sphaerillo boninensis Nunomura, 1990 from Chichijima Island of the Ogasawara archipelago, which is registered as a UNESCO World Heritage Site, indicates that this species is a junior synonym of a pantropical species, Venezillo parvus (Budde-Lund, 1885).
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Affiliation(s)
- Shigenori Karasawa
- Department of Life and Environmental Agricultural Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-machi Minami, Tottori 680-8553, Japan Tottori University Tottori Japan
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14
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Predator population size structure alters consumption of prey from epigeic and grazing food webs. Oecologia 2020; 192:791-799. [PMID: 32086561 DOI: 10.1007/s00442-020-04619-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 02/07/2020] [Indexed: 10/24/2022]
Abstract
Numerous studies have found that predators can suppress prey densities and thereby impact important ecosystem processes such as plant productivity and decomposition. However, prey suppression by spiders can be highly variable. Unlike predators that feed on prey within a single energy channel, spiders often consume prey from asynchronous energy channels, such as grazing (live plant) and epigeic (soil surface) channels. Spiders undergo few life cycle changes and thus appear to be ideally suited to link energy channels, but ontogenetic diet shifts in spiders have received little attention. For example, spider use of different food channels may be highly specialized in different life stages and thus a species may be a multichannel omnivore only when we consider all life stages. Using stable isotopes, we investigated whether wolf spider (Pardosa littoralis, henceforth Pardosa) prey consumption is driven by changes in spider size. Small spiders obtained > 80% of their prey from the epigeic channel, whereas larger spiders used grazing and epigeic prey almost equally. Changes in prey consumption were not driven by changes in prey density, but by changes in prey use by different spider size classes. Thus, because the population size structure of Pardosa changes dramatically over the growing season, changes in spider size may have important implications for the strength of trophic cascades. Our research demonstrates that life history can be an important component of predator diet, which may in turn affect community- and ecosystem-level processes.
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15
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Wimp GM, Lewis D, Murphy SM. Impacts of Nutrient Subsidies on Salt Marsh Arthropod Food Webs: A Latitudinal Survey. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00350] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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16
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Wimp GM, Ries L, Lewis D, Murphy SM. Habitat edge responses of generalist predators are predicted by prey and structural resources. Ecology 2019; 100:e02662. [PMID: 31013545 DOI: 10.1002/ecy.2662] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 11/30/2018] [Accepted: 01/02/2019] [Indexed: 11/09/2022]
Abstract
Generalist predators are thought to be less vulnerable to habitat fragmentation because they use diverse resources across larger spatial scales than specialist predators. Thus, it has been suggested that generalist predators may respond positively to habitat edges or demonstrate no edge response, because they can potentially use prey resources equally well on both sides of the habitat edge. However, most predictions about generalist predator responses to the habitat edge are based solely on prey resources, without consideration of other potential drivers. For instance, structural resources are essential for some species to build webs to capture prey or to avoid intraguild predation and cannibalism. In this study, we used both prey and structural resources to predict the response of four predator functional groups (hunting spiders, web-building spiders, aerial predators, and epigeic predators that feed on the detrital/algal food web) to a habitat edge between two salt-marsh grasses (Spartina alterniflora and Spartina patens). We found that generalist predators largely demonstrated negative responses to the habitat edge and had distinct habitat associations. Positive edge responses were only observed in one functional group (hunting spiders), and this pattern was driven by the two most abundant species. Negative responses to the habitat edge were more common among taxa and were better explained by structural resources rather than prey resources in the two habitats. Although it is generally acknowledged that specialists decline in fragmented habitats, generalists are thought to be more resilient. However, our research demonstrates that even generalists have habitat structural or food resource requirements that may limit their resilience to habitat loss and fragmentation.
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Affiliation(s)
- Gina M Wimp
- Biology Department, Georgetown University, Washington, D.C., 20057, USA
| | - Leslie Ries
- Biology Department, Georgetown University, Washington, D.C., 20057, USA
| | - Danny Lewis
- Biology Department, Georgetown University, Washington, D.C., 20057, USA
| | - Shannon M Murphy
- Department of Biological Sciences, University of Denver, Denver, Colorado, 80208, USA
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17
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Koltz AM, Burkle LA, Pressler Y, Dell JE, Vidal MC, Richards LA, Murphy SM. Global change and the importance of fire for the ecology and evolution of insects. CURRENT OPINION IN INSECT SCIENCE 2018; 29:110-116. [PMID: 30551816 DOI: 10.1016/j.cois.2018.07.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 07/24/2018] [Accepted: 07/26/2018] [Indexed: 06/09/2023]
Abstract
Climate change is drastically altering global fire regimes, which may affect the structure and function of insect communities. Insect responses to fire are strongly tied to fire history, plant responses, and changes in species interactions. Many insects already possess adaptive traits to survive fire or benefit from post-fire resources, which may result in community composition shifting toward habitat and dietary generalists as well as species with high dispersal abilities. However, predicting community-level resilience of insects is inherently challenging due to the high degree of spatiotemporal and historical heterogeneity of fires, diversity of insect life histories, and potential interactions with other global change drivers. Future work should incorporate experimental approaches that specifically consider spatiotemporal variability and regional fire history in order to integrate eco-evolutionary processes in understanding insect responses to fire.
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Affiliation(s)
- Amanda M Koltz
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA.
| | - Laura A Burkle
- Department of Ecology, Montana State University, 310 Lewis Hall, Bozeman, MT 59717, USA
| | - Yamina Pressler
- Natural Resource Ecology Laboratory, Colorado State University, 1499 Campus Delivery, Fort Collins, CO 80523, USA
| | - Jane E Dell
- Department of Biology, University of Nevada, 1664 N. Virginia St., Reno, NV 89557, USA
| | - Mayra C Vidal
- Department of Biological Sciences, University of Denver, 2050 E Iliff Ave, Boettcher West, Denver, CO 80210, USA
| | - Lora A Richards
- Department of Biology, University of Nevada, 1664 N. Virginia St., Reno, NV 89557, USA
| | - Shannon M Murphy
- Department of Biological Sciences, University of Denver, 2050 E Iliff Ave, Boettcher West, Denver, CO 80210, USA.
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18
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Lin ZH, Wu CH, Ho CK. Warming neutralizes host-specific competitive advantages between a native and invasive herbivore. Sci Rep 2018; 8:11130. [PMID: 30042428 PMCID: PMC6057923 DOI: 10.1038/s41598-018-29517-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 07/14/2018] [Indexed: 11/09/2022] Open
Abstract
Although native-invasive species interactions have become a common mechanism shaping ecosystems, whether these interactions shift under warming remains unclear. To investigate how warming may affect native and invasive species separately and together (intraspecific and interspecific competition, respectively) and whether any warming impact is resource dependent, we examined the performance of two competing herbivores (native Pieris canidia and invasive P. rapae) on two common host plants under three temperature settings (control, 3 °C, and 6 °C warming using environmental chambers). The results revealed that warming benefited the development and growth of both Pieris under intraspecific competition, but the benefits were host-plant dependent. Notably, the native or invasive Pieris gained an advantage from interspecific competition (host-plant dependent), but warming neutralized the competitive advantages of either Pieris species. These findings raise the possibility that warming-induced shifts in competitive status may become a crucial mechanism shaping ecosystems worldwide, because most ecosystems are challenged by species invasion and warming. Moreover, this study revealed a discrepancy in species thermal performance between intra- and interspecific competition. Therefore, to predict native-invasive species competition under warming, current thermal performance applications should use species performance curves derived from interspecific rather than intraspecific competition studies (although the latter is more readily available).
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Affiliation(s)
- Zheng-Hong Lin
- Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan
| | - Chung-Huey Wu
- Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan.,Australian Research Council Centre of Excellence for Environmental Decisions, University of Melbourne, Melbourne, Australia
| | - Chuan-Kai Ho
- Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan. .,Department of Life Science, National Taiwan University, Taipei, Taiwan.
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Molecular level responses to chronic versus pulse nutrient loading in the seagrass Posidonia oceanica undergoing herbivore pressure. Oecologia 2018; 188:23-39. [PMID: 29845353 DOI: 10.1007/s00442-018-4172-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/20/2018] [Indexed: 12/31/2022]
Abstract
Seagrasses are key marine foundation species, currently declining due to the compounded action of global and regional anthropogenic stressors. Eutrophication has been associated with seagrass decline, while grazing has been traditionally considered to be a natural disturbance with a relatively low impact on seagrasses. In the recent years, this assumption has been revisited. Here, by means of a 16-month field-experiment, we investigated the molecular mechanisms driving the long-term response of Posidonia oceanica to the combination of nutrient enrichment, either as a chronic (press) or pulse disturbance, and herbivory. Changes in expression levels of 19 target genes involved in key steps of photosynthesis, nutrient assimilation, chlorophyll metabolism, oxidative-stress response and plant defense were evaluated through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). High herbivore pressure affected the molecular response of P. oceanica more dramatically than did enhanced nutrient levels, altering the expression of genes involved in plant tolerance and resistance traits, such as photosynthesis and defense mechanisms. Genes involved in carbon fixation and N assimilation modulated the response of plants to high nutrient levels. Availability of resources seems to modify P. oceanica response to herbivory, where the upregulation of a nitrate transporter gene was accompanied by the decline in the expression of nitrate reductase in the leaves, suggesting a change in plant-nutrient allocation strategy. Finally, press and pulse fertilizations altered nitrate uptake and reduction-related genes in opposite ways, suggesting that taking into account the temporal regime of nutrient loading is important to assess the physiological response of seagrasses to eutrophication.
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Asmus A, Koltz A, McLaren J, Shaver GR, Gough L. Long-term nutrient addition alters arthropod community composition but does not increase total biomass or abundance. OIKOS 2017. [DOI: 10.1111/oik.04398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Ashley Asmus
- Dept of Ecology; Evolution and Behavior, Univ. of Minnesota; St. Paul MN 55108 USA
| | - Amanda Koltz
- Dept of Biology; Washington Univ. in Saint Louis; St. Louis MO USA
| | - Jennie McLaren
- Dept of Biological Sciences; Univ. of Texas at El Paso; El Paso TX USA
| | - Gaius R. Shaver
- The Ecosystems Center, Marine Biological Laboratory; Woods Hole MA USA
| | - Laura Gough
- Dept of Ecology; Evolution and Behavior, Univ. of Minnesota; St. Paul MN 55108 USA
- Dept of Biological Sciences; Towson Univ.; Towson MD USA
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Effect of Chronic Versus Pulse Perturbations on a Marine Ecosystem: Integration of Functional Responses Across Organization Levels. Ecosystems 2015. [DOI: 10.1007/s10021-015-9911-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Thakur MP, Herrmann M, Steinauer K, Rennoch S, Cesarz S, Eisenhauer N. Cascading effects of belowground predators on plant communities are density-dependent. Ecol Evol 2015; 5:4300-14. [PMID: 26664680 PMCID: PMC4667818 DOI: 10.1002/ece3.1597] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/10/2015] [Accepted: 06/14/2015] [Indexed: 11/17/2022] Open
Abstract
Soil food webs comprise a multitude of trophic interactions that can affect the composition and productivity of plant communities. Belowground predators feeding on microbial grazers like Collembola could decelerate nutrient mineralization by reducing microbial turnover in the soil, which in turn could negatively influence plant growth. However, empirical evidences for the ecological significance of belowground predators on nutrient cycling and plant communities are scarce. Here, we manipulated predator density (Hypoaspis aculeifer: predatory mite) with equal densities of three Collembola species as a prey in four functionally dissimilar plant communities in experimental microcosms: grass monoculture (Poa pratensis), herb monoculture (Rumex acetosa), legume monoculture (Trifolium pratense), and all three species as a mixed plant community. Density manipulation of predators allowed us to test for density‐mediated effects of belowground predators on Collembola and lower trophic groups. We hypothesized that predator density will reduce Collembola population causing a decrease in nutrient mineralization and hence detrimentally affect plant growth. First, we found a density‐dependent population change in predators, that is, an increase in low‐density treatments, but a decrease in high‐density treatments. Second, prey suppression was lower at high predator density, which caused a shift in the soil microbial community by increasing the fungal: bacterial biomass ratio, and an increase of nitrification rates, particularly in legume monocultures. Despite the increase in nutrient mineralization, legume monocultures performed worse at high predator density. Further, individual grass shoot biomass decreased in monocultures, while it increased in mixed plant communities with increasing predator density, which coincided with elevated soil N uptake by grasses. As a consequence, high predator density significantly increased plant complementarity effects indicating a decrease in interspecific plant competition. These results highlight that belowground predators can relax interspecific plant competition by increasing nutrient mineralization through their density‐dependent cascading effects on detritivore and soil microbial communities.
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Affiliation(s)
- Madhav Prakash Thakur
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e 04103 Leipzig Germany ; Institute of Biology University of Leipzig Johannisallee 21 04103 Leipzig Germany
| | - Martina Herrmann
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e 04103 Leipzig Germany ; Institute of Ecology Friedrich Schiller Jena University Dornburger Str. 159 07743 Jena Germany
| | - Katja Steinauer
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e 04103 Leipzig Germany ; Institute of Biology University of Leipzig Johannisallee 21 04103 Leipzig Germany
| | - Saskia Rennoch
- Institute of Ecology Friedrich Schiller Jena University Dornburger Str. 159 07743 Jena Germany
| | - Simone Cesarz
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e 04103 Leipzig Germany ; Institute of Biology University of Leipzig Johannisallee 21 04103 Leipzig Germany
| | - Nico Eisenhauer
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e 04103 Leipzig Germany ; Institute of Biology University of Leipzig Johannisallee 21 04103 Leipzig Germany
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The interactive effects of pulsed grazing disturbance and patch size vary among wetland arthropod guilds. PLoS One 2013; 8:e76672. [PMID: 24116133 PMCID: PMC3792878 DOI: 10.1371/journal.pone.0076672] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 08/27/2013] [Indexed: 12/04/2022] Open
Abstract
Pulse disturbances and habitat patch size can determine community composition independently or in concert, and may be particularly influential on small spatial scales for organisms with low mobility. In a field experiment, we investigated whether the effects of a pulsed disturbance that simulated a grazing event varied with habitat patch size. We focused on the short-term responses of multiple co-occurring emergent salt marsh arthropods with differing levels of mobility and dispersal potential. As part of a marsh restoration project, two types of emergent marsh structures were created: small circular mounds (0.5 m diameter) separated by several meters of aquatic habitat, and larger, elongated terraces (>50 m long). Study plots (0.25 m2) were established on both structures; in a subset of plots, we simulated a pulsed grazing disturbance event by clipping the aboveground tissue of emergent plants, primarily Spartina alterniflora. At the end of the two-month recovery period, Ischnodemus (Hemiptera: Blissidae) density was over 50% lower in disturbed treatments within both large (terrace) and small (mound) patches. Predatory spider treatment responses were similar to Ischnodemus responses, suggesting a trophic relationship between those two arthropod groups. Alternatively, spiders may have been directly affected by the loss of shelter in the disturbed plots. Prokelisia (Homoptera: Delphacidae), which are generally more mobile than Ischnodemus, were not affected by disturbance treatment or by patch size, suggesting the potential for rapid recolonization following disturbance. Larval stem borers decreased by an order of magnitude in disturbed plots, but only in the large patches. In general, the disturbance effects of vegetation removal on arthropod density and community composition were stronger than patch size effects, and there were few interactions between pulsed disturbance and patch size. Rather, emergent marsh arthropod responses to disturbance and habitat area treatments were linked to the dispersal potential and mobility of each individual taxon.
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Plant production and alternate prey channels impact the abundance of top predators. Oecologia 2013; 173:331-41. [PMID: 23604861 DOI: 10.1007/s00442-013-2618-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 02/05/2013] [Indexed: 10/26/2022]
Abstract
While numerous studies have examined the effects of increased primary production on higher trophic levels, most studies have focused primarily on the grazing food web and have not considered the importance of alternate prey channels. This has happened despite the fact that fertilization not only increases grazing herbivore abundance, but other types of consumers such as detritivores that serve as alternate prey for generalist predators. Alternate prey channels can sustain generalist predators at times when prey abundance in the grazing food web is low, thus increasing predator densities and the potential for trophic cascades. Using arthropod data from a fertilization experiment, we constructed a hierarchical Bayesian model to examine the direct and indirect effects of plant production and alternate prey channels on predators in a salt marsh. We found that increased plant production positively affected the density of top predators via effects on lower trophic level herbivores and mesopredators. Additionally, while the abundance of algivores and detritivores positively affected mesopredators and top predators, respectively, the effects of alternate prey were relatively weak. Because previous studies in the same system have found that mesopredators and top predators rely on alternate prey such as algivores and detritivores, future studies should examine whether fertilization shifts patterns of prey use by predators from alternate channels to the grazing channel. Finally, the hierarchical Bayesian model used in this study provided a useful method for exploring trophic relationships in the salt marsh food web, especially where causal relationships among trophic groups were unknown.
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Murphy SM, Wimp GM, Lewis D, Denno RF. Nutrient presses and pulses differentially impact plants, herbivores, detritivores and their natural enemies. PLoS One 2012; 7:e43929. [PMID: 22952814 PMCID: PMC3429447 DOI: 10.1371/journal.pone.0043929] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 07/27/2012] [Indexed: 11/18/2022] Open
Abstract
Anthropogenic nutrient inputs into native ecosystems cause fluctuations in resources that normally limit plant growth, which has important consequences for associated food webs. Such inputs from agricultural and urban habitats into nearby natural systems are increasing globally and can be highly variable, spanning the range from sporadic to continuous. Despite the global increase in anthropogenically-derived nutrient inputs into native ecosystems, the consequences of variation in subsidy duration on native plants and their associated food webs are poorly known. Specifically, while some studies have examined the effects of nutrient subsidies on native ecosystems for a single year (a nutrient pulse), repeated introductions of nutrients across multiple years (a nutrient press) better reflect the persistent nature of anthropogenic nutrient enrichment. We therefore contrasted the effects of a one-year nutrient pulse with a four-year nutrient press on arthropod consumers in two salt marshes. Salt marshes represent an ideal system to address the differential impacts of nutrient pulses and presses on ecosystem and community dynamics because human development and other anthropogenic activities lead to recurrent introductions of nutrients into these natural systems. We found that plant biomass and %N as well as arthropod density fell after the nutrient pulse ended but remained elevated throughout the nutrient press. Notably, higher trophic levels responded more strongly than lower trophic levels to fertilization, and the predator/prey ratio increased each year of the nutrient press, demonstrating that food web responses to anthropogenic nutrient enrichment can take years to fully manifest themselves. Vegetation at the two marshes also exhibited an apparent tradeoff between increasing %N and biomass in response to fertilization. Our research emphasizes the need for long-term, spatially diverse studies of nutrient enrichment in order to understand how variation in the duration of anthropogenic nutrient subsidies affects native ecosystems.
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Affiliation(s)
- Shannon M Murphy
- Department of Biological Sciences, University of Denver, Denver, Colorado, United States of America.
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