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O'Gorman EJ, Zhao L, Kordas RL, Dudgeon S, Woodward G. Warming indirectly simplifies food webs through effects on apex predators. Nat Ecol Evol 2023; 7:1983-1992. [PMID: 37798434 PMCID: PMC10697836 DOI: 10.1038/s41559-023-02216-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 09/06/2023] [Indexed: 10/07/2023]
Abstract
Warming alters ecosystems through direct physiological effects on organisms and indirect effects via biotic interactions, but their relative impacts in the wild are unknown due to the difficulty in warming natural environments. Here we bridge this gap by embedding manipulative field experiments within a natural stream temperature gradient to test whether warming and apex fish predators have interactive effects on freshwater ecosystems. Fish exerted cascading effects on algal production and microbial decomposition via both green and brown pathways in the food web, but only under warming. Neither temperature nor the presence of fish altered food web structure alone, but connectance and mean trophic level declined as consumer species were lost when both drivers acted together. A mechanistic model indicates that this temperature-induced trophic cascade is determined primarily by altered interactions, which cautions against extrapolating the impacts of warming from reductionist approaches that do not consider the wider food web.
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Affiliation(s)
- Eoin J O'Gorman
- School of Life Sciences, University of Essex, Colchester, UK.
| | - Lei Zhao
- Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University, Beijing, China.
| | - Rebecca L Kordas
- Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Ascot, Berkshire, UK
| | - Steve Dudgeon
- Department of Biology, California State University, Northridge, CA, USA
| | - Guy Woodward
- Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Ascot, Berkshire, UK.
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2
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Shukla I, Gaynor KM, Worm B, Darimont CT. The diversity of animals identified as keystone species. Ecol Evol 2023; 13:e10561. [PMID: 37818247 PMCID: PMC10560868 DOI: 10.1002/ece3.10561] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 10/12/2023] Open
Abstract
Although the keystone species concept was conceived of over 50 years ago, contemporary efforts to synthesize related literature have been limited. Our objective was to create a list of keystone animal species identified in the literature and to examine the variation in the traits of species and the ecosystem influences they elicit. We documented 230 species considered keystones. A clustering analysis classified them into five archetypes based on combinations of their taxonomic class, body size, trophic level, and role (consumers, modifiers, or prey). Although conservation and public perception of keystones primarily focuses on large vertebrate consumers, our analysis reveals that researchers have defined a wide diversity of keystone species, with large variation in associated ecosystem processes. Future research may confront ambiguity in the definition of keystone status, as well as clarify the type, abundance, and quality of data required to assign the term. Identifying keystones with increased rigor would not only enrich the literature but also inform intervention to safeguard threatened keystones and their associated influences on ecosystems.
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Affiliation(s)
- Ishana Shukla
- Department of GeographyUniversity of VictoriaVictoriaBritish ColumbiaCanada
| | - Kaitlyn M. Gaynor
- Departments of Botany and ZoologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Boris Worm
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | - Chris T. Darimont
- Department of GeographyUniversity of VictoriaVictoriaBritish ColumbiaCanada
- Raincoast Conservation FoundationDenny IslandBritish ColumbiaCanada
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3
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Cereghetti E, Altermatt F. Spatiotemporal dynamics in freshwater amphipod assemblages are associated with surrounding terrestrial land use type. Ecosphere 2023. [DOI: 10.1002/ecs2.4469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Affiliation(s)
- Eva Cereghetti
- Department of Aquatic Ecology Eawag, Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Florian Altermatt
- Department of Aquatic Ecology Eawag, Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
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4
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Alther R, Krähenbühl A, Bucher P, Altermatt F. Optimizing laboratory cultures of Gammarus fossarum (Crustacea: Amphipoda) as a study organism in environmental sciences and ecotoxicology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 855:158730. [PMID: 36122725 DOI: 10.1016/j.scitotenv.2022.158730] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/26/2022] [Accepted: 09/09/2022] [Indexed: 06/15/2023]
Abstract
Amphipods are among the most abundant macroinvertebrates in freshwater ecosystems of the Palaearctic and crucial for ecosystem functioning. Furthermore, their high sensitivity to environmental change and pollutants makes them widely used model organisms in environmental sciences and ecotoxicology. In field studies and surveys across Eurasia, species of the genus Gammarus are commonly used, yet laboratory-based studies and ecotoxicological tests are often restricted to the in most parts of the world non-native Hyalella azteca, as Gammarus is much harder to breed and maintain under laboratory conditions. However, for direct comparisons and extrapolations of results of field- vs. laboratory-based studies, the use of the same species would be desirable. Here, we investigated different settings with respect to feeding, shelter and day length to successfully increase survival, juvenile production and their respective growth and survival, and ultimately multi-generation breeding of the amphipod Gammarus fossarum. Amphipod populations persisted and reproduced successfully under optimized husbandry conditions for 12 months and were partially maintained for another year in populations up to a few hundred individuals. Specifically, supplementing diet with protein-rich food sources as well as the provisioning of shelters improved survival rate of G. fossarum significantly. However, we found no significant effect of different day length treatments on the overall relative reproductive activity or on the total amphipod abundance maintained. We conclude that G. fossarum can be kept and reared under standardized conditions. Despite the longer generation times of G. fossarum and higher effort required for maintenance compared to H. azteca, direct ecological relevance and comparability of results to natural systems may justify its future use and development as a study organism for environmental sciences and ecotoxicology.
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Affiliation(s)
- Roman Alther
- Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlan dstrasse 133, CH-8600 Dübendorf, Switzerland; Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
| | - Andrin Krähenbühl
- Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlan dstrasse 133, CH-8600 Dübendorf, Switzerland.
| | - Pascal Bucher
- Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlan dstrasse 133, CH-8600 Dübendorf, Switzerland.
| | - Florian Altermatt
- Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlan dstrasse 133, CH-8600 Dübendorf, Switzerland; Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
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5
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Shadrin N, Yakovenko V, Anufriieva E. Feeding behavior of Gammarus aequicauda in the presence of two prey species of Artemia sp. and Baeotendipes noctivagus. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2022; 337:768-775. [PMID: 35713191 DOI: 10.1002/jez.2635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
Gammarus aequicauda is the most abundant amphipod species in the Crimean hypersaline lakes, and is predatory upon other invertebrate species, suppressing their populations. The authors studied a time balance during the feeding of G. aequicauda in the presence of two prey species. The different variants of prey composition were: (1) two Artemia sp., (2) two chironomid larvae, and (3) one Artemia sp. and one chironomid larva. The duration of the experiments differed and continued until both prey were consumed. The experiments were carried out in vessels with and without bottom sediments. The result showed that in vessels with and without sediments in the case of both species of prey, the time to the capture of the first prey did not depend on whether Artemia sp. or chironomid larva was the first prey; the time differences are statistically insignificant. The duration of eating prey in all experimental variants depended on the kind of prey, and those differences were highly significant. The average hourly consumption rate was dependent on prey composition and order of prey capture and eating. The maximum consumption for two prey was when both were brine shrimp. In vessels without sediments and containing both Artemia sp. and chironomid larva the consumption rate was higher if the first caught prey was Artemia sp. rather than сhironomid larva. The order of prey eating did not influence a ration size in vessels with bottom sediments. When both prey were chironomid larvae, the total diet did not practically differ in vessels with or without sediments.
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Affiliation(s)
- Nickolai Shadrin
- A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Sevastopol, Russia
| | - Vladimir Yakovenko
- A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Sevastopol, Russia
| | - Elena Anufriieva
- A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Sevastopol, Russia
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7
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McLeod AM, Leroux SJ. Incongruent drivers of network, species and interaction persistence in food webs. OIKOS 2021. [DOI: 10.1111/oik.08512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Anne M. McLeod
- Dept of Biology, Memorial Univ. of Newfoundland St John's NL Canada
| | - Shawn J. Leroux
- Dept of Biology, Memorial Univ. of Newfoundland St John's NL Canada
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Seer FK, Putze G, Pennings SC, Zimmer M. Drivers of litter mass loss and faunal composition of detritus patches change over time. Ecol Evol 2021; 11:9642-9651. [PMID: 34306650 PMCID: PMC8293728 DOI: 10.1002/ece3.7787] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 05/07/2021] [Accepted: 05/19/2021] [Indexed: 11/10/2022] Open
Abstract
Decomposition of vegetal detritus is one of the most fundamental ecosystem processes. In complex landscapes, the fate of litter of terrestrial plants may depend on whether it ends up decomposing in terrestrial or aquatic conditions. However, (1) to what extent decomposition rates are controlled by environmental conditions or by detritus type, and (2) how important the composition of the detritivorous fauna is in mediating decomposition in different habitats, remain as unanswered questions. We incubated two contrasting detritus types in three distinct habitat types in Coastal Georgia, USA, to test the hypotheses that (1) the litter fauna composition depends on the habitat and the litter type available, and (2) litter mass loss (as a proxy for decomposition) depends on environmental conditions (habitat) and the litter type. We found that the abundance of most taxa of the litter fauna depends primarily on habitat. Litter type became a stronger driver for some taxa over time, but the overall faunal composition was only weakly affected by litter type. Decomposition also depends strongly on habitat, with up to ca. 80% of the initial detrital mass lost over 25 months in the marsh and forest habitats, but less than 50% lost in the creek bank habitat. Mass loss rates of oak versus pine litter differed initially but converged within habitat types within 12 months. We conclude that, although the habitat type is the principle driver of the community composition of the litter fauna, litter type is a significant driver of litter mass loss in the early stages of the decomposition process. With time, however, litter types become more and more similar, and habitat becomes the dominating factor in determining decomposition of older litter. Thus, the major driver of litter mass loss changes over time from being the litter type in the early stages to the habitat (environmental conditions) in later stages.
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Affiliation(s)
| | - Gregor Putze
- Zoologisches InstitutChristian‐Albrechts‐Universität zu KielKielGermany
| | | | - Martin Zimmer
- Zoologisches InstitutChristian‐Albrechts‐Universität zu KielKielGermany
- Leibniz‐Centre for Tropical Marine ResearchBremenGermany
- Faculty 02 Biology/ChemistryUniversity BremenBremenGermany
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9
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Bayer MO, Lowe WH. Top-Down Effects of Salamanders on Macroinvertebrates in Fishless Headwater Streams. HERPETOLOGICA 2021. [DOI: 10.1655/herpetologica-d-20-00054.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Miriam O. Bayer
- Wildlife Biology Program, University of Montana, College of Forestry and Conservation, Missoula, MT 59812, USA
| | - Winsor H. Lowe
- Wildlife Biology Program, University of Montana, College of Forestry and Conservation, Missoula, MT 59812, USA
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10
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Zatkos L, Arismendi I, Johnson SL, Penaluna BE. Geophysical templates modulate the structure of stream food webs dominated by omnivory. Ecosphere 2021. [DOI: 10.1002/ecs2.3444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Lauren Zatkos
- Department of Fisheries and Wildlife Oregon State University 2820 SW Campus Way Corvallis Oregon97331USA
| | - Ivan Arismendi
- Department of Fisheries and Wildlife Oregon State University 2820 SW Campus Way Corvallis Oregon97331USA
| | - Sherri L. Johnson
- USDA Forest ServicePacific Northwest Research Station 3200 Southwest Jefferson Way Corvallis Oregon97331USA
| | - Brooke E. Penaluna
- USDA Forest ServicePacific Northwest Research Station 3200 Southwest Jefferson Way Corvallis Oregon97331USA
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11
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Pott CM, Dala-Corte RB, Becker FG. Body size responses to land use in stream fish: the importance of different metrics and functional groups. NEOTROPICAL ICHTHYOLOGY 2021. [DOI: 10.1590/1982-0224-2021-0004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract Body size influences the effect of individuals and assemblages on ecosystem functioning and defines how they respond to ecosystem changes. We evaluated how body size structure of fish assemblages and functional groups respond to human modifications at catchment, riparian and local scales in 40 streams of the Pampa grasslands, southern Brazil. To describe body size structure, we calculated the mean, coefficient of variation, skewness, and kurtosis, using individual biomass data for the entire fish assemblages and separately by functional group. The results suggested that body size response depends on body size metrics, functional group, and the spatial scale of land use. From 11 functional groups, only five showed a clear response to land use. In general, most functional groups had a higher concentration of small sizes (left-skewed) in response to increased land use measured at distinct spatial scales (local, riparian, and catchment), and a greater concentration of sizes in a narrow and central distribution (higher kurtosis). However, the responses were complex and varied between the functional groups. We conclude that considering ecomorphological and trophic features separately by functional group and assessing multiple body size metrics contributed greatly to detecting the influence of land use on fish body size.
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12
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Consolandi G, Ford AT, Bloor MC. Feeding Behavioural Studies with Freshwater Gammarus spp.: The Importance of a Standardised Methodology. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 253:1-41. [PMID: 31605212 DOI: 10.1007/398_2019_36] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Freshwater Gammarids are common leaf-shredding detritivores, and they usually feed on naturally conditioned organic material, in other words leaf litter that is characterised by an increased palatability, due to the action and presence of microorganisms (Chaumot et al. 2015; Cummins 1974: Maltby et al. 2002). Gammarus spp. are biologically omnivorous organisms, so they are involved in shredding leaf litter and are also prone to cannibalism, predation behaviour (Kelly et al. 2002) and coprophagy when juveniles (McCahon and Pascoe 1988). Gammarus spp. is a keystone species (Woodward et al. 2008), and it plays an important role in the decomposition of organic matter (Alonso et al. 2009; Bundschuh et al. 2013) and is also a noteworthy prey for fish and birds (Andrén and Eriksson Wiklund 2013; Blarer and Burkhardt-Holm 2016). Gammarids are considered to be fairly sensitive to different contaminants (Ashauer et al. 2010; Bloor et al. 2005; Felten et al. 2008a; Lahive et al. 2015; Kunz et al. 2010); in fact Amphipods have been reported to be one of the most sensitive orders to metals and organic compounds (Wogram and Liess 2001), which makes them representative test organisms for ecotoxicological studies and valid sentinel species for assessing water quality status (Garcia-Galan et al. 2017).
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Affiliation(s)
- Giulia Consolandi
- School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, Hampshire, UK.
| | - Alex T Ford
- Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth, Portsmouth, Hampshire, UK
| | - Michelle C Bloor
- School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, Hampshire, UK
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13
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Abstract
Climate change represents a major threat to lotic freshwater ecosystems and their ability to support the provision of ecosystem services. England’s chalk streams are in a poor state of health, with significant concerns regarding their resilience, the ability to adapt, under a changing climate. This paper aims to quantify the effect of climate change on hydroecological response for the River Nar, south-east England. To this end, we apply a coupled hydrological and hydroecological modelling framework, with the UK probabilistic climate projections 2009 (UKCP09) weather generator serving as input (CMIP3 A1B high emissions scenario, 2021 to the end-of-century). The results indicate a minimal change in the long-term mean hydroecological response over this period. In terms of interannual variability, the median hydroecological response is subject to increased uncertainty, whilst lower probability extremes are virtually certain to become more homogeneous (assuming a high emissions scenario). A functional matrix, relating species-level macroinvertebrate functional flow preferences to functional food groups reveals that, on the baseline, under extreme conditions, key groups are underrepresented. To date, despite this limited range, the River Nar has been able to adapt to extreme events due to interannual variation. In the future, this variation is greatly reduced, raising real concerns over the resilience of the river ecosystem, and chalk ecosystems more generally, under climate change.
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Solagaistua L, de Guzmán I, Barrado M, Mijangos L, Etxebarria N, García-Baquero G, Larrañaga A, von Schiller D, Elosegi A. Testing wastewater treatment plant effluent effects on microbial and detritivore performance: A combined field and laboratory experiment. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 203:159-171. [PMID: 30138800 DOI: 10.1016/j.aquatox.2018.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/08/2018] [Accepted: 08/09/2018] [Indexed: 06/08/2023]
Abstract
The amount of pollutants and nutrients entering rivers via point sources is increasing along with human population and activity. Although wastewater treatment plants (WWTPs) greatly reduce pollutant loads into the environment, excess nutrient loading is a problem in many streams. Using a Community and Ecosystem Function (CEF) approach, we quantified the effects of WWTP effluent on the performance of microbes and detritivores associated to organic matter decomposition, a key ecosystem process. We measured organic matter breakdown rates, respiration rates and exo-enzymatic activities of aquatic microbes. We also measured food consumption and growth rates and RNA to body-mass ratios (RNA:BM) of a dominant amphipod Echinogammarus berilloni. We predicted responses to follow a subsidy-stress pattern and differences between treatments to increase over time. To examine temporal effects of effluent, we performed a laboratory microcosm experiment under a range of effluent concentrations (0, 20, 40, 60, 80 and 100%), taking samples over time (days 8, 15 and 30; 4 and 10 replicates to assess microbe and detritivore performance respectively, per treatment and day). This experiment was combined with a field in situ Before-After Control-Impact Paired (BACIP) experiment whereby we added WWTP effluent poured (10 L s-1 during 20-40 min every 2 h) into a stream and collected microbial and detritivore samples at days 8 and 15 (5 and 15 replicates to assess the microbe and detritivore performance respectively, per period, reach and sampling day). Responses were clearer in the laboratory experiment, where the effluent caused a general subsidy response. Field measures did not show any significant response, probably because of the high dilution of the effluent in stream water (average of 1.6%). None of the measured variables in any of the experiments followed the predicted subsidy-stress response. Microbial breakdown, respiration rates, exo-enzymatic activities and invertebrate RNA:BM increased with effluent concentrations. Differences in microbial respiration and exo-enzymatic activities among effluent treatments increased with incubation time, whereas microbial breakdown rates and RNA:BM were consistent over time. At the end of the laboratory experiment, microbial respiration rates increased 156% and RN:BM 115% at 100% effluent concentration. Detritivore consumption and growth rates increased asymptotically, and both responses increased with by incubation time. Our results indicate that WWTP effluent stimulates microbial activities and alters detritivore performance, and stream water dilution may mitigate these effects.
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Affiliation(s)
- Libe Solagaistua
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain.
| | - Ioar de Guzmán
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
| | - Miren Barrado
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
| | - Leire Mijangos
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
| | - Nestor Etxebarria
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain; Research Centre for Experimental Marine Biology and Biotechnology (PIE), University of the Basque Country (UPV/EHU), Areatza 48620 Plentzia, Spain
| | - Gonzalo García-Baquero
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
| | - Aitor Larrañaga
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
| | - Daniel von Schiller
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
| | - Arturo Elosegi
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain
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15
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Reczuga MK, Lamentowicz M, Mulot M, Mitchell EAD, Buttler A, Chojnicki B, Słowiński M, Binet P, Chiapusio G, Gilbert D, Słowińska S, Jassey VEJ. Predator-prey mass ratio drives microbial activity under dry conditions in Sphagnum peatlands. Ecol Evol 2018; 8:5752-5764. [PMID: 29938090 PMCID: PMC6010735 DOI: 10.1002/ece3.4114] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 02/13/2018] [Accepted: 03/29/2018] [Indexed: 01/17/2023] Open
Abstract
Mid- to high-latitude peatlands are a major terrestrial carbon stock but become carbon sources during droughts, which are increasingly frequent as a result of climate warming. A critical question within this context is the sensitivity to drought of peatland microbial food webs. Microbiota drive key ecological and biogeochemical processes, but their response to drought is likely to impact these processes. Peatland food webs have, however, been little studied, especially the response of microbial predators. We studied the response of microbial predators (testate amoebae, ciliates, rotifers, and nematodes) living in Sphagnum moss carpet to droughts, and their influence on lower trophic levels and on related microbial enzyme activity. We assessed the impact of reduced water availability on microbial predators in two peatlands using experimental (Linje mire, Poland) and natural (Forbonnet mire, France) water level gradients, reflecting a sudden change in moisture regime (Linje), and a typically drier environment (Forbonnet). The sensitivity of different microbial groups to drought was size dependent; large sized microbiota such as testate amoebae declined most under dry conditions (-41% in Forbonnet and -80% in Linje). These shifts caused a decrease in the predator-prey mass ratio (PPMR). We related microbial enzymatic activity to PPMR; we found that a decrease in PPMR can have divergent effects on microbial enzymatic activity. In a community adapted to drier conditions, decreasing PPMR stimulated microbial enzyme activity, while in extreme drought experiment, it reduced microbial activity. These results suggest that microbial enzymatic activity resulting from food web structure is optimal only within a certain range of PPMR, and that different trophic mechanisms are involved in the response of peatlands to droughts. Our findings confirm the importance of large microbial consumers living at the surface of peatlands on the functioning of peatlands, and illustrate their value as early warning indicators of change.
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Affiliation(s)
- Monika K. Reczuga
- Laboratory of Wetland Ecology and MonitoringFaculty of Geographical and Geological SciencesAdam Mickiewicz UniversityPoznańPoland
- Department of Biogeography and PalaeoecologyFaculty of Geographical and Geological SciencesAdam Mickiewicz UniversityPoznańPoland
- Faculty of BiologyAdam Mickiewicz UniversityPoznańPoland
| | - Mariusz Lamentowicz
- Laboratory of Wetland Ecology and MonitoringFaculty of Geographical and Geological SciencesAdam Mickiewicz UniversityPoznańPoland
- Department of Biogeography and PalaeoecologyFaculty of Geographical and Geological SciencesAdam Mickiewicz UniversityPoznańPoland
| | - Matthieu Mulot
- Laboratory of Soil BiodiversityUniversity of NeuchatelNeuchatelSwitzerland
| | - Edward A. D. Mitchell
- Laboratory of Soil BiodiversityUniversity of NeuchatelNeuchatelSwitzerland
- Jardin Botanique de NeuchâtelNeuchatelSwitzerland
| | - Alexandre Buttler
- Laboratory of Wetland Ecology and MonitoringFaculty of Geographical and Geological SciencesAdam Mickiewicz UniversityPoznańPoland
- Swiss Federal Research InstituteWSL Site LausanneLausanneSwitzerland
- Laboratoire des Systèmes ÉcologiquesSchool of Architecture, Civil and Environmental EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
- Laboratoire de Chrono‐EnvironnementUMR CNRS 6249UFR des Sciences et TechniquesUniversité de Franche‐ComtéBesançonFrance
| | - Bogdan Chojnicki
- Department of MeteorologyFaculty of Environmental Engineering and Spatial ManagementPoznan University of Life Sciences60‐649 PoznańPoland
| | - Michał Słowiński
- Department of Environmental Resources and GeohazardPolish Academy of SciencesInstitute of Geography and Spatial OrganizationWarszawaPoland
| | - Philippe Binet
- Laboratoire de Chrono‐EnvironnementUMR CNRS 6249UFR des Sciences et TechniquesUniversité de Franche‐ComtéBesançonFrance
| | - Geneviève Chiapusio
- Laboratoire de Chrono‐EnvironnementUMR CNRS 6249UFR des Sciences et TechniquesUniversité de Franche‐ComtéBesançonFrance
- UMR CARRTEL INRA 042 University of Savoie Mont‐BlancFR‐ 73376 Le Bourget du lacFrance
| | - Daniel Gilbert
- Laboratoire de Chrono‐EnvironnementUMR CNRS 6249UFR des Sciences et TechniquesUniversité de Franche‐ComtéBesançonFrance
| | - Sandra Słowińska
- Department of Geoecology and ClimatologyPolish Academy of SciencesInstitute of Geography and Spatial OrganizationWarsawPoland
| | - Vincent E. J. Jassey
- Swiss Federal Research InstituteWSL Site LausanneLausanneSwitzerland
- Laboratoire des Systèmes ÉcologiquesSchool of Architecture, Civil and Environmental EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
- Laboratoire d'Ecologie Fonctionnelle et Environnement (Ecolab)INPT, UPS, CNRSUniversité de ToulouseToulouse CedexFrance
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16
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Copilaş-Ciocianu D, Zimţa AA, Grabowski M, Petrusek A. Survival in northern microrefugia in an endemic Carpathian gammarid (Crustacea: Amphipoda). ZOOL SCR 2018. [DOI: 10.1111/zsc.12285] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Denis Copilaş-Ciocianu
- Department of Ecology; Faculty of Science; Charles University; Prague Czech Republic
- Laboratory of Evolutionary Ecology of Hydrobionts; Nature Research Centre; Vilnius Lithuania
| | - Alina-Andreea Zimţa
- Department of Ecology; Faculty of Science; Charles University; Prague Czech Republic
- Department of Biology-Chemistry; Faculty of Chemistry, Biology, Geography; West University of Timişoara; Timişoara Romania
| | - Michał Grabowski
- Department of Invertebrate Zoology and Hydrobiology; Faculty of Biology and Environmental Protection; University of Lodz; Łódź Poland
| | - Adam Petrusek
- Department of Ecology; Faculty of Science; Charles University; Prague Czech Republic
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17
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Little CJ, Altermatt F. Species turnover and invasion of dominant freshwater invertebrates alter biodiversity-ecosystem-function relationship. ECOL MONOGR 2018. [DOI: 10.1002/ecm.1299] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Chelsea J. Little
- Department of Aquatic Ecology; Eawag: Swiss Federal Institute of Aquatic Science and Technology; Überlandstrasse 133 8600 Dübendorf Switzerland
- Department of Evolutionary Biology and Environmental Studies; University of Zürich; Winterthurerstrasse 190 8057 Zürich Switzerland
| | - Florian Altermatt
- Department of Aquatic Ecology; Eawag: Swiss Federal Institute of Aquatic Science and Technology; Überlandstrasse 133 8600 Dübendorf Switzerland
- Department of Evolutionary Biology and Environmental Studies; University of Zürich; Winterthurerstrasse 190 8057 Zürich Switzerland
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18
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Benke AC. River food webs: an integrative approach to bottom-up flow webs, top-down impact webs, and trophic position. Ecology 2018; 99:1370-1381. [PMID: 29604060 DOI: 10.1002/ecy.2228] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 01/30/2018] [Accepted: 03/02/2018] [Indexed: 11/11/2022]
Abstract
The majority of food web studies are based on connectivity, top-down impacts, bottom-up flows, or trophic position (TP), and ecologists have argued for decades which is best. Rarely have any two been considered simultaneously. The present study uses a procedure that integrates the last three approaches based on taxon-specific secondary production and gut analyses. Ingestion flows are quantified to create a flow web and the same data are used to quantify TP for all taxa. An individual predator's impacts also are estimated using the ratio of its ingestion (I) of each prey to prey production (P) to create an I/P web. This procedure was applied to 41 invertebrate taxa inhabiting submerged woody habitat in a southeastern U.S. river. A complex flow web starting with five basal food resources had 462 flows >1 mg·m-2 ·yr-1 , providing far more information than a connectivity web. Total flows from basal resources to primary consumers/omnivores were dominated by allochthonous amorphous detritus and ranged from 1 to >50,000 mg·m-2 ·yr-1 . Most predator-prey flows were much lower (<50 mg·m-2 ·yr-1 ), but some were >1,000 mg·m-2 ·yr-1 . The I/P web showed that 83% of individual predator impacts were weak (<10%), whereas total predator impacts were often strong (e.g., 35% of prey sustained an impact >90%). Quantitative estimates of TP ranged from 2 to 3.7, contrasting sharply with seven integer-based trophic levels based on longest feeding chain. Traditional omnivores (TP = 2.4-2.9) played an important role by consuming more prey and exerting higher impacts on primary consumers than strict predators (TP ≥ 3). This study illustrates how simultaneous quantification of flow pathways, predator impacts, and TP together provide an integrated characterization of natural food webs.
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Affiliation(s)
- Arthur C Benke
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, 35487, USA
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19
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Defining Seasonal Functional Traits of a Freshwater Zooplankton Community Using δ13C and δ15N Stable Isotope Analysis. WATER 2018. [DOI: 10.3390/w10020108] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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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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21
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22
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Rossiter W, King G, Johnson B. Revisiting the Energetic Efficiency Hypothesis: Body Mass, Metabolism, and Food Chain Length. AMERICAN MIDLAND NATURALIST 2017. [DOI: 10.1674/0003-0031-177.1.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Zhao L, Zhang H, O'Gorman EJ, Tian W, Ma A, Moore JC, Borrett SR, Woodward G. Weighting and indirect effects identify keystone species in food webs. Ecol Lett 2016; 19:1032-40. [PMID: 27346328 PMCID: PMC5008267 DOI: 10.1111/ele.12638] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/13/2016] [Accepted: 05/20/2016] [Indexed: 11/27/2022]
Abstract
Species extinctions are accelerating globally, yet the mechanisms that maintain local biodiversity remain poorly understood. The extinction of species that feed on or are fed on by many others (i.e. 'hubs') has traditionally been thought to cause the greatest threat of further biodiversity loss. Very little attention has been paid to the strength of those feeding links (i.e. link weight) and the prevalence of indirect interactions. Here, we used a dynamical model based on empirical energy budget data to assess changes in ecosystem stability after simulating the loss of species according to various extinction scenarios. Link weight and/or indirect effects had stronger effects on food-web stability than the simple removal of 'hubs', demonstrating that both quantitative fluxes and species dissipating their effects across many links should be of great concern in biodiversity conservation, and the potential for 'hubs' to act as keystone species may have been exaggerated to date.
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Affiliation(s)
- Lei Zhao
- Research Center for Engineering Ecology and Nonlinear Science, North China Electric Power University, Beijing, 102206, China.,Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK
| | - Huayong Zhang
- Research Center for Engineering Ecology and Nonlinear Science, North China Electric Power University, Beijing, 102206, China
| | - Eoin J O'Gorman
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK
| | - Wang Tian
- Research Center for Engineering Ecology and Nonlinear Science, North China Electric Power University, Beijing, 102206, China
| | - Athen Ma
- School of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - John C Moore
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO, 80523, USA.,Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523, USA
| | - Stuart R Borrett
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, 28403, USA.,Duke Network Analysis Center, Duke University, Durham, NC, 27708, USA
| | - Guy Woodward
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK
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24
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Sitvarin MI, Rypstra AL, Harwood JD. Linking the green and brown worlds through nonconsumptive predator effects. OIKOS 2016. [DOI: 10.1111/oik.03190] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Osorio V, Larrañaga A, Aceña J, Pérez S, Barceló D. Concentration and risk of pharmaceuticals in freshwater systems are related to the population density and the livestock units in Iberian Rivers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 540:267-77. [PMID: 26170112 DOI: 10.1016/j.scitotenv.2015.06.143] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/29/2015] [Accepted: 06/29/2015] [Indexed: 05/25/2023]
Abstract
Considerable amounts of pharmaceuticals are used in human and veterinary medicine, which are not efficiently removed during wastewater and slurries treatment and subsequently entering continuously into freshwater systems. The intrinsic biological activity of these non-regulated pollutants turns their presence in the aquatic environment into an ecological matter of concern. We present the first quantitative study relating the presence of pharmaceuticals and their predicted ecotoxicological effects with human population and livestock units. Four representative Iberian River basins (Spain) were studied: Llobregat, Ebro, Júcar and Guadalquivir. The levels of pharmaceuticals were determined in surface water and sediment samples collected from 77 locations along their stream networks. Predicted total toxic units to algae, Daphnia and fish were estimated for pharmaceuticals detected in surface waters. The use of chemometrics enabled the study of pharmaceuticals for: their spatial distribution along the rivers in two consecutive years; their potential ecotoxicological risk to aquatic organisms; and the relationships among their occurrence and predicted ecotoxicity with human population and animal farming pressure. The Llobregat and the Ebro River basins were characterized as the most polluted and at highest ecotoxicological risk, followed by Júcar and Guadalquivir. No significant acute risks of pharmaceuticals to aquatic organisms were observed. However potential chronic ecotoxicological effects on algae could be expected at two hot spots of pharmaceuticals pollution identified in the Llobregat and Ebro basins. Analgesics/antiinflammatories, antibiotics and diuretics were the most relevant therapeutic groups across the four river basins. Among them, hydrochlorothiazide and gemfibrozil, as well as azithromycin and ibuprofen were widely spread and concentrated pharmaceuticals in surface waters and sediments, respectively. Regarding their predicted ecotoxicity, sertraline, gemfibrozil and loratidine were identified as the more concerning compounds. Significantly positive relationships were found among levels of pharmaceuticals and toxic units and population density and livestock units in both surface water and sediment matrices.
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Affiliation(s)
- Victoria Osorio
- Water and Soil Quality Research Group, IDAEA-CSIC, c/ JordiGirona, 18-26, 08034 Barcelona, Spain
| | - Aitor Larrañaga
- Laboratory of Stream Ecology, Dept. of Plant Biology and Ecology, University of the Basque Country, UPV/EHU, PO Box 644, 48080 Bilbao, Spain
| | - Jaume Aceña
- Water and Soil Quality Research Group, IDAEA-CSIC, c/ JordiGirona, 18-26, 08034 Barcelona, Spain
| | - Sandra Pérez
- Water and Soil Quality Research Group, IDAEA-CSIC, c/ JordiGirona, 18-26, 08034 Barcelona, Spain.
| | - Damià Barceló
- Water and Soil Quality Research Group, IDAEA-CSIC, c/ JordiGirona, 18-26, 08034 Barcelona, Spain; Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Spain
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26
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Litter Decomposition as an Indicator of Stream Ecosystem Functioning at Local-to-Continental Scales. ADV ECOL RES 2016. [DOI: 10.1016/bs.aecr.2016.08.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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27
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Peckarsky BL, McIntosh AR, Àlvarez M, Moslemi JM. Disturbance legacies and nutrient limitation influence interactions between grazers and algae in high elevation streams. Ecosphere 2015. [DOI: 10.1890/es15-00236.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Rodríguez-Lozano P, Verkaik I, Rieradevall M, Prat N. Small but powerful: top predator local extinction affects ecosystem structure and function in an intermittent stream. PLoS One 2015; 10:e0117630. [PMID: 25714337 PMCID: PMC4340793 DOI: 10.1371/journal.pone.0117630] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 12/29/2014] [Indexed: 12/03/2022] Open
Abstract
Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore ecosystem structure and function.
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Affiliation(s)
- Pablo Rodríguez-Lozano
- Freshwater Ecology and Management (F.E.M.) Research Group, Departament d’Ecologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Iraima Verkaik
- Freshwater Ecology and Management (F.E.M.) Research Group, Departament d’Ecologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Maria Rieradevall
- Freshwater Ecology and Management (F.E.M.) Research Group, Departament d’Ecologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Narcís Prat
- Freshwater Ecology and Management (F.E.M.) Research Group, Departament d’Ecologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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29
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Mancinelli G, Mulder C. Detrital Dynamics and Cascading Effects on Supporting Ecosystem Services. ADV ECOL RES 2015. [DOI: 10.1016/bs.aecr.2015.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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30
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Perkins DM, Bailey RA, Dossena M, Gamfeldt L, Reiss J, Trimmer M, Woodward G. Higher biodiversity is required to sustain multiple ecosystem processes across temperature regimes. GLOBAL CHANGE BIOLOGY 2015; 21:396-406. [PMID: 25131335 PMCID: PMC4310294 DOI: 10.1111/gcb.12688] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/12/2014] [Indexed: 05/27/2023]
Abstract
Biodiversity loss is occurring rapidly worldwide, yet it is uncertain whether few or many species are required to sustain ecosystem functioning in the face of environmental change. The importance of biodiversity might be enhanced when multiple ecosystem processes (termed multifunctionality) and environmental contexts are considered, yet no studies have quantified this explicitly to date. We measured five key processes and their combined multifunctionality at three temperatures (5, 10 and 15 °C) in freshwater aquaria containing different animal assemblages (1-4 benthic macroinvertebrate species). For single processes, biodiversity effects were weak and were best predicted by additive-based models, i.e. polyculture performances represented the sum of their monoculture parts. There were, however, significant effects of biodiversity on multifunctionality at the low and the high (but not the intermediate) temperature. Variation in the contribution of species to processes across temperatures meant that greater biodiversity was required to sustain multifunctionality across different temperatures than was the case for single processes. This suggests that previous studies might have underestimated the importance of biodiversity in sustaining ecosystem functioning in a changing environment.
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Affiliation(s)
- Daniel M Perkins
- Department of Life Sciences, Imperial College LondonSilwood Park Campus, Berkshire, SL5 7PY, UK
| | - R A Bailey
- School of Mathematical Sciences, Queen Mary University of LondonLondon, E1 4NS, UK
- School of Mathematics and Statistics, University of St AndrewsSt Andrews, Fife, KY16 9SS, UK
| | - Matteo Dossena
- School of Biological and Chemical Sciences, Queen Mary University of LondonLondon, E1 4NS, UK
| | - Lars Gamfeldt
- Department of Biological and Environmental Sciences, University of GothenburgBOX 461, Gothenburg, SE-40530, Sweden
| | - Julia Reiss
- Department of Life Sciences, Whitelands College, University of RoehamptonLondon, SW15 4JD, UK
| | - Mark Trimmer
- School of Biological and Chemical Sciences, Queen Mary University of LondonLondon, E1 4NS, UK
| | - Guy Woodward
- Department of Life Sciences, Imperial College LondonSilwood Park Campus, Berkshire, SL5 7PY, UK
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Atwood TB, Hammill E, Richardson JS. Trophic-level dependent effects on CO2 emissions from experimental stream ecosystems. GLOBAL CHANGE BIOLOGY 2014; 20:3386-3396. [PMID: 24753392 DOI: 10.1111/gcb.12516] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 11/30/2013] [Accepted: 12/16/2013] [Indexed: 06/03/2023]
Abstract
Concern over accelerating rates of species invasions and losses have initiated investigations into how local and global changes to predator abundance mediate trophic cascades that influence CO2 fluxes of aquatic ecosystems. However, to date, no studies have investigated how species additions or losses at other consumer trophic levels influence the CO2 flux of aquatic ecosystems. In this study, we added a large predatory stonefly, detritivorous stonefly, or grazer tadpole to experimental stream food webs and over a 70-day period quantified their effects on community composition, leaf litter decomposition, chlorophyll-a concentrations, and stream CO2 emissions. In general, streams where the large grazer or large detritivore were added showed no change in total invertebrate biomass, leaf litter loss, chlorophyll-a concentrations, or stream CO2 emissions compared with controls; although we did observe a spike in CO2 emissions in the large grazer treatment following a substantial reduction in chlorophyll-a concentrations on day 28. However, the large grazer and large detritivore altered the community composition of streams by reducing the densities of other grazer and detritivore taxa, respectively, compared with controls. Conversely, the addition of the large predator created trophic cascades that reduced total invertebrate biomass and increased primary producer biomass. The cascading effects of the predator additions on the food web ultimately led to decreased CO2 emissions from stream channels by up to 95%. Our results suggest that stream ecosystem processes were more influenced by changes in large predator abundance than large grazer or detritivore abundance, because of a lack of functionally similar large predators. Our study demonstrates that the presence/absence of species with unique functional roles may have consequences for the exchange of CO2 between the ecosystem and the atmosphere.
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Affiliation(s)
- Trisha B Atwood
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; Global Change Institute, University of Queensland, Brisbane, QLD, 4072, Australia
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Campos D, Alves A, Lemos MFL, Correia A, Soares AMVM, Pestana JLT. Effects of cadmium and resource quality on freshwater detritus processing chains: a microcosm approach with two insect species. ECOTOXICOLOGY (LONDON, ENGLAND) 2014; 23:830-839. [PMID: 24648031 DOI: 10.1007/s10646-014-1223-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/06/2014] [Indexed: 06/03/2023]
Abstract
Detritus processing is vital for freshwater ecosystems that depend on the leaf litter from riparian vegetation and is mediated by microorganisms and aquatic invertebrates. Shredder invertebrates transform coarse particulate organic matter into fine particulate organic matter used as food by collector species. Direct and indirect effects of contaminants can impair detritus processing and thus affect the functioning of these ecosystems. Here, we assessed the combined effects of a toxic metal (cadmium) and resource quality (leaf species) on detritus processing and shredder-collector interactions. We considered two types of leaves, alder and eucalyptus that were microbially conditioned under different Cd concentrations in the laboratory. The microbial communities present on leaves were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE), and we also measured microbial respiration rates. Sericostoma vittatum (a caddisfly shredder) and Chironomus riparius (a midge collector) were also exposed to Cd and allowed to consume the corresponding alder or eucalyptus leaves. We evaluated C. riparius growth and leaf mass loss in multispecies microcosms. Cadmium exposure affected leaf conditioning and fungal diversity on both leaf species, as assessed by DGGE. Cadmium exposure also affected the mass loss of alder leaves by reductions in detritivore feeding, and impaired C. riparius growth. Chironomus riparius consumed alder leaf discs in the absence of shredders, but S. vittatum appear to promote C. riparius growth in treatments containing eucalyptus. These results show that indirect effects of contaminants along detritus-processing chains can occur through effects on shredder-collector interactions such as facilitation but they also depend on the nutritional quality of detritus and on sensitivity and feeding plasticity of detritivore species.
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Affiliation(s)
- Diana Campos
- Departamento de Biologia and CESAM, Universidade de Aveiro, Campus Santiago, 3810-193, Aveiro, Portugal
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Jabiol J, Cornut J, Danger M, Jouffroy M, Elger A, Chauvet E. Litter identity mediates predator impacts on the functioning of an aquatic detritus-based food web. Oecologia 2014; 176:225-35. [PMID: 24938833 DOI: 10.1007/s00442-014-2990-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 05/30/2014] [Indexed: 12/01/2022]
Abstract
During past decades, several mechanisms such as resource quality and habitat complexity have been proposed to explain variations in the strength of trophic cascades across ecosystems. In detritus-based headwater streams, litter accumulations constitute both a habitat and a resource for detritivorous macroinvertebrates. Because litter edibility (which promotes trophic cascades) is usually inversely correlated with its structural complexity (which weakens trophic cascades), there is a great scope for stronger trophic cascades in litter accumulations that are dominated by easily degradable litter species. However, it remains unclear how mixing contrasting litter species (conferring both habitat complexity and high quality resource) may influence top-down controls on communities and processes. In enclosures exposed in a second-order stream, we manipulated litter species composition by using two contrasting litter (alder and oak), and the presence-absence of a macroinvertebrate predator (Cordulegaster boltonii larvae), enabling it to effectively exert predation pressure, or not, on detritivores (consumptive versus non-consumptive predation effects). Leaf mass loss, detritivore biomass and community structure were mostly controlled independently by litter identity and mixing and by predator consumption. However, the strength of predator control was mediated by litter quality (stronger on alder), and to a lesser extent by litter mixing (weaker on mixed litter). Refractory litter such as oak leaves may contribute to the structural complexity of the habitat for stream macroinvertebrates, allowing the maintenance of detritivore communities even when strong predation pressure occurs. We suggest that considering the interaction between top-down and bottom-up factors is important when investigating their influence on natural communities and ecosystem processes in detritus-based ecosystems.
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Affiliation(s)
- Jérémy Jabiol
- Université de Toulouse, UPS, INPT, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, 31062, Toulouse, France,
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Flores L, Banjac Z, Farré M, Larrañaga A, Mas-Martí E, Muñoz I, Barceló D, Elosegi A. Effects of a fungicide (imazalil) and an insecticide (diazinon) on stream fungi and invertebrates associated with litter breakdown. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 476-477:532-41. [PMID: 24496026 DOI: 10.1016/j.scitotenv.2014.01.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/31/2013] [Accepted: 01/16/2014] [Indexed: 05/15/2023]
Abstract
The intensification of agriculture has promoted the use of pesticides such as fungicides and insecticides. Many pesticides readily leach into natural water bodies and affect both organisms and ecosystem processes such as leaf breakdown, a crucial process in headwater streams. As leaf breakdown in streams involves sequential steps by different groups of organisms (first microbial conditioning, then invertebrate shredding), pesticides targeting different organisms are likely to affect one or the other step, and a mixture of contaminants might have interactive effects. Our objective was to evaluate the effect of a fungicide (imazalil) and an insecticide (diazinon) on stream fungal and invertebrate activities, and their effects on leaf consumption. After an initial assay to define 'effective concentration' of both pesticides in a laboratory experiment, we manipulated pesticide presence/absence during the conditioning and shredding phases. Both pesticides affected fungal community and reduced the performance of the shredding amphipod Echinogammarus berilloni, and leaf consumption. The impact of pesticides on fungal sporulation depended on the length of the exposure period. In addition, pesticides seemed to cause an energetic imbalance in the amphipod, affecting body condition and mortality. The combined effect of both pesticides was similar to those of the fungicide. Overall, our results show that the effects of pesticide mixtures on leaf breakdown are hard to predict from those observed in either fungi or macroinvertebrate performance.
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Affiliation(s)
- L Flores
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain..
| | - Z Banjac
- Institute of Environmental Assessment and Water Research (IDAEA-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain
| | - M Farré
- Institute of Environmental Assessment and Water Research (IDAEA-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain
| | - A Larrañaga
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain
| | - E Mas-Martí
- Department of Ecology, University of Barcelona (UB), Av. Diagonal, 643, 08028 Barcelona, Spain
| | - I Muñoz
- Department of Ecology, University of Barcelona (UB), Av. Diagonal, 643, 08028 Barcelona, Spain
| | - D Barceló
- Institute of Environmental Assessment and Water Research (IDAEA-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain
| | - A Elosegi
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain
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Majdi N, Boiché A, Traunspurger W, Lecerf A. Predator effects on a detritus-based food web are primarily mediated by non-trophic interactions. J Anim Ecol 2014; 83:953-62. [DOI: 10.1111/1365-2656.12189] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 11/24/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Nabil Majdi
- EcoLab; Université de Toulouse; UPS; INPT; Toulouse France
- EcoLab; CNRS; Toulouse France
| | - Anatole Boiché
- EcoLab; Université de Toulouse; UPS; INPT; Toulouse France
- EcoLab; CNRS; Toulouse France
| | | | - Antoine Lecerf
- EcoLab; Université de Toulouse; UPS; INPT; Toulouse France
- EcoLab; CNRS; Toulouse France
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Weber S, Weber S, Traunspurger W. Consumption and prey size selection of the nematode Caenorhabditis elegans by different juvenile stages of freshwater fish. NEMATOLOGY 2014. [DOI: 10.1163/15685411-00002793] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Meiofauna, and nematodes in particular, play an essential role in the diet of certain juvenile freshwater fish. However, the specific consumption and prey size selection of fishes on nematodes is largely unrecognised. In this study, the effects of different juvenile stages of widely distributed common European freshwater fish, gudgeon (Gobio gobio), roach (Rutilus rutilus), ninespine stickleback (Pungitius pungitius), and two strains of common carp (Cyprinus carpio (scaled) and C. carpio (mirror)), on abundances of the nematode Caenorhabditis elegans were investigated in controlled laboratory experiments with a known number of prey. Gudgeon, carp (scaled), and carp (mirror) consumed significant amounts of nematodes, whereas the roach and ninespine stickleback did not. Both strains of common carp reduced nematode abundance dependent on the size of the fish, with smaller fish causing a greater reduction than medium-size or large fish, although fish of all sizes fed significantly on nematodes of all size classes (<0.5, 0.5-1.0 and >1.0 mm). While the gudgeon also reduced nematode abundance dependent on the size of the fish, with increasing body length there was a dietary shift towards larger nematode size classes (0.5-1.0 and >1.0 mm). Morphometric analysis of the branchial basket indicated that the mesh width of gudgeon and both strains of common carp, but not of roach and ninespine stickleback, is suitable for feeding on specific size classes of nematodes. Together, the results showed that nematodes are used as a food source for different juvenile stages of certain species of freshwater fish.
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Affiliation(s)
- Sebastian Weber
- Animal Ecology, Bielefeld University, Morgenbreede 45, 33615 Bielefeld, Germany
| | - Sebastian Weber
- Animal Ecology, Bielefeld University, Morgenbreede 45, 33615 Bielefeld, Germany
| | - Walter Traunspurger
- Animal Ecology, Bielefeld University, Morgenbreede 45, 33615 Bielefeld, Germany
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Travis J, Reznick D, Bassar RD, López-Sepulcre A, Ferriere R, Coulson T. Do Eco-Evo Feedbacks Help Us Understand Nature? Answers From Studies of the Trinidadian Guppy. ADV ECOL RES 2014. [DOI: 10.1016/b978-0-12-801374-8.00001-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Miranda M, Parrini F, Dalerum F. A categorization of recent network approaches to analyse trophic interactions. Methods Ecol Evol 2013. [DOI: 10.1111/2041-210x.12092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- María Miranda
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Private Bag 3, Wits 2050; Johannesburg; South Africa
| | - Francesca Parrini
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Private Bag 3, Wits 2050; Johannesburg; South Africa
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Lurgi M, López BC, Montoya JM. Climate change impacts on body size and food web structure on mountain ecosystems. Philos Trans R Soc Lond B Biol Sci 2013; 367:3050-7. [PMID: 23007094 DOI: 10.1098/rstb.2012.0239] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The current distribution of climatic conditions will be rearranged on the globe. To survive, species will have to keep pace with climates as they move. Mountains are among the most affected regions owing to both climate and land-use change. Here, we explore the effects of climate change in the vertebrate food web of the Pyrenees. We investigate elevation range expansions between two time-periods illustrative of warming conditions, to assess: (i) the taxonomic composition of range expanders; (ii) changes in food web properties such as the distribution of links per species and community size-structure; and (iii) what are the specific traits of range expanders that set them apart from the other species in the community-in particular, body mass, diet generalism, vulnerability and trophic position within the food web. We found an upward expansion of species at all elevations, which was not even for all taxonomic groups and trophic positions. At low and intermediate elevations, predator : prey mass ratios were significantly reduced. Expanders were larger, had fewer predators and were, in general, more specialists. Our study shows that elevation range expansions as climate warms have important and predictable impacts on the structure and size distribution of food webs across space.
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Affiliation(s)
- Miguel Lurgi
- CREAF, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalunya, Spain
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Torres-Alruiz MD, Rodríguez DJ. A topo-dynamical perspective to evaluate indirect interactions in trophic webs: New indexes. Ecol Modell 2013. [DOI: 10.1016/j.ecolmodel.2012.11.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Grazing and detritivory in 20 stream food webs across a broad pH gradient. Oecologia 2012; 171:459-71. [PMID: 22996363 PMCID: PMC3548098 DOI: 10.1007/s00442-012-2421-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 07/17/2012] [Indexed: 12/03/2022]
Abstract
Acidity is a major driving variable in the ecology of fresh waters, and we sought to quantify macroecological patterns in stream food webs across a wide pH gradient. We postulated that a few generalist herbivore-detritivores would dominate the invertebrate assemblage at low pH, with more specialists grazers at high pH. We also expected a switch towards algae in the diet of all primary consumers as the pH increased. For 20 stream food webs across the British Isles, spanning pH 5.0–8.4 (the acid sites being at least partially culturally acidified), we characterised basal resources and primary consumers, using both gut contents analysis and stable isotopes to study resource use by the latter. We found considerable species turnover across the pH gradient, with generalist herbivore-detritivores dominating the primary consumer assemblage at low pH and maintaining grazing. These were joined or replaced at higher pH by a suite of specialist grazers, while many taxa that persisted across the pH gradient broadened the range of algae consumed as acidity declined and increased their ingestion of biofilm, whose nutritional quality was higher than that of coarse detritus. There was thus an increased overall reliance on algae at higher pH, both by generalist herbivore-detritivores and due to the presence of specialist grazers, although detritus was important even in non-acidic streams. Both the ability of acid-tolerant, herbivore-detritivores to exploit both autochthonous and allochthonous food and the low nutritional value of basal resources might render chemically recovering systems resistant to invasion by the specialist grazers and help explain the sluggish ecological recovery of fresh waters whose water chemistry has ameliorated.
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Klemmer AJ, Wissinger SA, Greig HS, Ostrofsky ML. Nonlinear effects of consumer density on multiple ecosystem processes. J Anim Ecol 2012; 81:770-80. [PMID: 22339437 DOI: 10.1111/j.1365-2656.2012.01966.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. In the face of human-induced declines in the abundance of common species, ecologists have become interested in quantifying how changes in density affect rates of biophysical processes, hence ecosystem function. We manipulated the density of a dominant detritivore (the cased caddisfly, Limnephilus externus) in subalpine ponds to measure effects on the release of detritus-bound nutrients and energy. 2. Detritus decay rates (k, mass loss) increased threefold, and the loss of nitrogen (N) and phosphorus (P) from detrital substrates doubled across a range of historically observed caddisfly densities. Ammonium and total soluble phosphorus concentrations in the water column also increased with caddisfly density on some dates. Decay rates, nutrient release and the change in total detritivore biomass all exhibited threshold or declining responses at the highest densities. 3. We attributed these threshold responses in biophysical processes to intraspecific competition for limiting resources manifested at the population level, as density-dependent per-capita consumption, growth, development and case : body size in caddisflies was observed. Moreover, caddisflies increasingly grazed on algae at high densities, presumably in response to limiting detrital resources. 4. These results provide evidence that changes in population size of a common species will have nonlinear, threshold effects on the rates of biophysical processes at the ecosystem level. Given the ubiquity of negative density dependence in nature, nonlinear consumer density-ecosystem function relationships should be common across species and ecosystems.
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Affiliation(s)
- Amanda J Klemmer
- Biology Department, Allegheny College, Meadville, PA 16225, USA.
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44
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Hagen M, Kissling WD, Rasmussen C, De Aguiar MA, Brown LE, Carstensen DW, Alves-Dos-Santos I, Dupont YL, Edwards FK, Genini J, Guimarães PR, Jenkins GB, Jordano P, Kaiser-Bunbury CN, Ledger ME, Maia KP, Marquitti FMD, Mclaughlin Ó, Morellato LPC, O'Gorman EJ, Trøjelsgaard K, Tylianakis JM, Vidal MM, Woodward G, Olesen JM. Biodiversity, Species Interactions and Ecological Networks in a Fragmented World. ADV ECOL RES 2012. [DOI: 10.1016/b978-0-12-396992-7.00002-2] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Twomey M, Jacob U, Emmerson MC. Perturbing a Marine Food Web: Consequences for Food Web Structure and Trivariate Patterns. ADV ECOL RES 2012. [DOI: 10.1016/b978-0-12-398315-2.00005-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Brenneis VEF, Sih A, de Rivera CE. Integration of an invasive consumer into an estuarine food web: direct and indirect effects of the New Zealand mud snail. Oecologia 2011; 167:169-79. [PMID: 21448733 PMCID: PMC3155678 DOI: 10.1007/s00442-011-1962-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 02/16/2011] [Indexed: 11/30/2022]
Abstract
Introduced species interact both directly and indirectly with native species. We examine interactions between the introduced New Zealand mud snail (Potamopyrgus antipodarum) and native estuarine invertebrates and predators through experiments and field studies. A widely held management concern is that when P. antipodarum, which has low nutritional value, becomes abundant, it replaces nutritious prey in fish diets. We tested two key components of this view: (1) that fish consume, but get little direct nutritional value from P. antipodarum; and (2) that P. antipodarum has an indirect negative effect on fish by reducing the energy derived from native prey. We also examined predation by the native signal crayfish, Pacifastacus leniusculus. Laboratory feeding trials showed that both crayfish and fish consume P. antipodarum, a direct effect. Crayfish consumed and successfully digested higher numbers of snails than did fish [Pacific staghorn sculpin (Leptocottus armatus), three spine stickleback (Gasterosteus aculeatus), and juvenile starry flounder (Platicthys stellatus)]. P. antipodarum occurred at low frequencies in the stomachs of wild-caught fish. More interesting were the indirect effects of this invader, which ran counter to predictions. P. antipodarum presence was associated with no change or an increase in the amount of energy derived from native prey by predators. The presence of P. antipodarum also led to increased consumption of and preference for the native amphipod Americorophium salmonis over the native isopod Gnorimosphaeroma insulare. This is an example of short-term, asymmetric, apparent competition, in which the presence of one prey species (snails) increases predation on another prey species (the amphipod).
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Affiliation(s)
- Valance E F Brenneis
- Department of Environmental Science and Policy, University of California Davis, Davis, CA 95616, USA.
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48
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Liess A, Lange K. The snail Potamopyrgus antipodarum grows faster and is more active in the shade, independent of food quality. Oecologia 2011; 167:85-96. [DOI: 10.1007/s00442-011-1963-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 02/28/2011] [Indexed: 11/30/2022]
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Brown LE, Edwards FK, Milner AM, Woodward G, Ledger ME. Food web complexity and allometric scaling relationships in stream mesocosms: implications for experimentation. J Anim Ecol 2011; 80:884-95. [PMID: 21418207 DOI: 10.1111/j.1365-2656.2011.01814.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1. Mesocosms are used extensively by ecologists to gain a mechanistic understanding of ecosystems based on the often untested assumption that these systems can replicate the key attributes of natural assemblages. 2. Previous investigations of stream mesocosm utility have explored community composition, but here for the first time, we extend the approach to consider the replicability and realism of food webs in four outdoor channels (4 m(2)). 3. The four food webs were similarly complex, consisting of diverse assemblages (61-71 taxa) with dense feeding interactions (directed connectance 0.09-0.11). Mesocosm food web structural attributes were within the range reported for 82 well-characterized food webs from natural streams and rivers. When compared with 112 additional food webs from standing freshwater, marine, estuarine and terrestrial environments, stream food webs (including mesocosms) had similar characteristic path lengths, but typically lower mean food chain length and exponents for the species-link relationship. 4. Body size (M) abundance (N) allometric scaling coefficients for trivariate taxonomic mesocosm food webs (-0.53 to -0.49) and individual size distributions (-0.60 to -0.58) were consistent and similar to those from natural systems, suggesting that patterns of energy flux between mesocosm consumers and resources were realistic approximations. 5. These results suggest that stream mesocosms of this scale can support replicate food webs with a degree of biocomplexity that is comparable to 'natural' streams. The findings highlight the potential value of mesocosms as model systems for performing experimental manipulations to test ecological theories, at spatiotemporal scales of relevance to natural ecosystems.
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Affiliation(s)
- Lee E Brown
- School of Geography, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
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