Publications
140 results found
Aspin TWH, Khamis K, Matthews TJ, et al., 2019, Extreme drought pushes stream invertebrate communities over functional thresholds, Global Change Biology, Vol: 25, Pages: 230-244, ISSN: 1354-1013
Functional traits are increasingly being used to predict extinction risks and range shifts under long‐term climate change scenarios, but have rarely been used to study vulnerability to extreme climatic events, such as supraseasonal droughts. In streams, drought intensification can cross thresholds of habitat loss, where marginal changes in environmental conditions trigger disproportionate biotic responses. However, these thresholds have been studied only from a structural perspective, and the existence of functional nonlinearity remains unknown. We explored trends in invertebrate community functional traits along a gradient of drought intensity, simulated over 18 months, using mesocosms analogous to lowland headwater streams. We modelled the responses of 16 traits based on a priori predictions of trait filtering by drought, and also examined the responses of trait profile groups (TPGs) identified via hierarchical cluster analysis. As responses to drought intensification were both linear and nonlinear, generalized additive models (GAMs) were chosen to model response curves, with the slopes of fitted splines used to detect functional thresholds during drought. Drought triggered significant responses in 12 (75%) of the a priori‐selected traits. Behavioural traits describing movement (dispersal, locomotion) and diet were sensitive to moderate‐intensity drought, as channels fragmented into isolated pools. By comparison, morphological and physiological traits showed little response until surface water was lost, at which point we observed sudden shifts in body size, respiration mode and thermal tolerance. Responses varied widely among TPGs, ranging from population collapses of non‐aerial dispersers as channels fragmented to irruptions of small, eurythermic dietary generalists upon extreme dewatering. Our study demonstrates for the first time that relatively small changes in drought intensity can trigger disproportionately large functional shifts in stream communities, sugg
Perkins DM, Durance I, Edwards FK, et al., 2018, Bending the rules: exploitation of allochthonous resources by a top-predator modifies size-abundance scaling in stream food webs, Ecology Letters, Vol: 21, Pages: 1771-1780, ISSN: 1461-023X
Body mass–abundance (M‐N) allometries provide a key measure of community structure, and deviations from scaling predictions could reveal how cross‐ecosystem subsidies alter food webs. For 31 streams across the UK, we tested the hypothesis that linear log‐log M‐N scaling is shallower than that predicted by allometric scaling theory when top predators have access to allochthonous prey. These streams all contained a common and widespread top predator (brown trout) that regularly feeds on terrestrial prey and, as hypothesised, deviations from predicted scaling increased with its dominance of the fish assemblage. Our study identifies a key beneficiary of cross‐ecosystem subsidies at the top of stream food webs and elucidates how these inputs can reshape the size‐structure of these ‘open’ systems.
Isaac NJB, Brotherton PNM, Bullock JM, et al., 2018, Defining and delivering resilient ecological networks: Nature conservation in England, JOURNAL OF APPLIED ECOLOGY, Vol: 55, Pages: 2537-2543, ISSN: 0021-8901
Woodward G, 2018, Bending the rules: exploitation of allochthonous resources by atop-predator modifies size-abundance scaling in stream foodwebs, Ecology Letters, ISSN: 1461-023X
Thompson MSA, Brooks SJ, Sayer CD, et al., 2018, Large woody debris "rewilding" rapidly restores biodiversity in riverine food webs, JOURNAL OF APPLIED ECOLOGY, Vol: 55, Pages: 895-904, ISSN: 0021-8901
Palinkas Z, Zalai M, Szenasi A, et al., 2018, Arthropods dataset from different genetically modified maize events and associated controls, SCIENTIFIC DATA, Vol: 5
- Author Web Link
- Cite
- Citations: 2
Andujar C, Arribas P, Gray C, et al., 2017, Metabarcoding of freshwater invertebrates to detect the effects of a pesticide spill, Molecular Ecology, Vol: 27, Pages: 146-166, ISSN: 0962-1083
Biomonitoring underpins the environmental assessment of freshwater ecosystems and guides management and conservation. Current methodology for surveys of (macro)invertebrates uses coarse taxonomic identification where species‐level resolution is difficult to obtain. Next‐generation sequencing of entire assemblages (metabarcoding) provides a new approach for species detection, but requires further validation. We used metabarcoding of invertebrate assemblages with two fragments of the cox1 “barcode” and partial nuclear ribosomal (SSU) genes, to assess the effects of a pesticide spill in the River Kennet (southern England). Operational taxonomic unit (OTU) recovery was tested under 72 parameters (read denoising, filtering, pair merging and clustering). Similar taxonomic profiles were obtained under a broad range of parameters. The SSU marker recovered Platyhelminthes and Nematoda, missed by cox1, while Rotifera were only amplified with cox1. A reference set was created from all available barcode entries for Arthropoda in the BOLD database and clustered into OTUs. The River Kennet metabarcoding produced matches to 207 of these reference OTUs, five times the number of species recognized with morphological monitoring. The increase was due to the following: greater taxonomic resolution (e.g., splitting a single morphotaxon “Chironomidae” into 55 named OTUs); splitting of Linnaean binomials into multiple molecular OTUs; and the use of a filtration‐flotation protocol for extraction of minute specimens (meiofauna). Community analyses revealed strong differences between “impacted” vs. “control” samples, detectable with each gene marker, for each major taxonomic group, and for meio‐ and macrofaunal samples separately. Thus, highly resolved taxonomic data can be extracted at a fraction of the time and cost of traditional nonmolecular methods, opening new avenues for freshwater invertebrate biodiversity monitoring and molecular ecolo
O'Gorman EJ, Zhao L, Pichler DE, et al., 2017, Unexpected changes in community size structure in a natural warming experiment, NATURE CLIMATE CHANGE, Vol: 7, Pages: 659-+, ISSN: 1758-678X
Bohan D, Dumbrell A, Raybould A, et al., 2017, Next-generation global biomonitoring: large-scale, automated reconstruction of ecological networks, Trends in Ecology and Evolution, Vol: 32, Pages: 477-487, ISSN: 1872-8383
We foresee a new global-scale, ecological approach to biomonitoring emerging within the next decade that can detect ecosystem change accurately, cheaply, and generically. Next-generation sequencing of DNA sampled from the Earth’s environments would provide data for the relative abundance of operational taxonomic units or ecological functions. Machine-learning methods would then be used to reconstruct the ecological networks of interactions implicit in the raw NGS data. Ultimately, we envision the development of autonomous samplers that would sample nucleic acids and upload NGS sequence data to the cloud for network reconstruction. Large numbers of these samplers, in a global array, would allow sensitive automated biomonitoring of the Earth’s major ecosystems at high spatial and temporal resolution, revolutionising our understanding of ecosystem change.
Palinkas Z, Kiss J, Zalai M, et al., 2017, Effects of genetically modified maize events expressing Cry34Ab1, Cry35Ab1, Cry1F, and CP4 EPSPS proteins on arthropod complex food webs, Ecology and Evolution, Vol: 7, Pages: 2286-2293, ISSN: 2045-7758
Four genetically modified (GM) maize (Zea mays L.) hybrids (coleopteran resistant, coleopteran and lepidopteran resistant, lepidopteran resistant and herbicide tolerant, coleopteran and herbicide tolerant) and its non-GM control maize stands were tested to compare the functional diversity of arthropods and to determine whether genetic modifications alter the structure of arthropods food webs. A total number of 399,239 arthropod individuals were used for analyses. The trophic groups’ number and the links between them indicated that neither the higher magnitude of Bt toxins (included resistance against insect, and against both insects and glyphosate) nor the extra glyphosate treatment changed the structure of food webs. However, differences in the average trophic links/trophic groups were detected between GM and non-GM food webs for herbivore groups and plants. Also, differences in characteristic path lengths between GM and non-GM food webs for herbivores were observed. Food webs parameterized based on 2-year in-field assessments, and their properties can be considered a useful and simple tool to evaluate the effects of Bt toxins on non-target organisms.
Yvon-Durocher G, Hulatt CJ, Woodward G, et al., 2017, Long-term warming amplifies shifts in the carbon cycle of experimental ponds, Nature Climate Change, Vol: 7, Pages: 209-213, ISSN: 1758-678X
Lakes and ponds cover only about 4% of the Earth’s non-glaciated surface1, yet they represent disproportionately large sources of methane and carbon dioxide2, 3, 4. Indeed, very small ponds (for example, <0.001 km2) may account for approximately 40% of all CH4 emissions from inland waters5. Understanding how greenhouse gas emissions from aquatic ecosystems will respond to global warming is therefore vital for forecasting biosphere–carbon cycle feedbacks. Here, we present findings on the long-term effects of warming on the fluxes of GHGs and rates of ecosystem metabolism in experimental ponds. We show that shifts in CH4 and CO2 fluxes, and rates of gross primary production and ecosystem respiration, observed in the first year became amplified over seven years of warming. The capacity to absorb CO2 was nearly halved after seven years of warmer conditions. The phenology of greenhouse gas fluxes was also altered, with CO2 drawdown and CH4 emissions peaking one month earlier in the warmed treatments. These findings show that warming can fundamentally alter the carbon balance of small ponds over a number of years, reducing their capacity to sequester CO2 and increasing emissions of CH4; such positive feedbacks could ultimately accelerate climate change.
Jackson M, Weyl O, Altermatt F, et al., 2016, Chapter twelve - recommendations for the next generation of global freshwater biological monitoring tools, Advances in Ecological Research, Vol: 55, Pages: 615-636, ISSN: 0065-2504
Biological monitoring has a long history in freshwaters, where much of the pioneering work in this field was developed over a hundred years ago – but few of the traditional monitoring tools provide the global perspective on biodiversity loss and its consequences for ecosystem functioning that are now needed. Rather than forcing existing monitoring paradigms to respond to questions they were never originally designed to address, we need to take a step back and assess the prospects for novel approaches that could be developed and adopted in the future. To resolve some of the issues with indicators currently used to inform policymakers, we highlight new biological monitoring tools that are being used, or could be developed in the near future, which (1) consider less-studied taxonomic groups; (2) are standardised across regions to allow global comparisons, and (3) measure change over multiple time points. The new tools we suggest make use of some of the key technological and logistical advances seen in recent years – including remote sensing, molecular tools, and local-to-global citizen science networks. We recommend that these new indicators should be considered in future assessments of freshwater ecosystem health and contribute to the evidence base for global to regional (and national) assessments of biodiversity and ecosystem services: for example, within the emerging framework of the Intergovernmental Platform on Biodiversity and Ecosystem Services.
Zhao L, Moore J, O'Gorman EJ, et al., 2016, Weighting and indirect effects identify keystone species in food webs, Ecology Letters, Vol: 19, Pages: 1032-1040, ISSN: 1461-0248
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.
Lu X, Gray C, Brown LE, et al., 2016, Drought rewires the cores of food webs, Nature Climate Change, Vol: 6, Pages: 875-878, ISSN: 1758-678X
Droughts are intensifying across the globe with potentially devastating implications for freshwater ecosystems. We used new network science approaches to investigate drought impacts on stream food webs and explored potential consequences for web robustness to future perturbations. The substructure of the webs was characterized by a core of richly connected species surrounded by poorly connected peripheral species. Although drought caused the partial collapse of the food webs, the loss of the most extinction-prone peripheral species triggered a substantial rewiring of interactions within the networks’ cores. These shifts in species interactions in the core conserved the underlying core/periphery substructure and stability of the drought-impacted webs. When we subsequently perturbed the webs by simulating species loss in silico, the rewired drought webs were as robust as the larger, undisturbed webs. Our research unearths previously unknown compensatory dynamics arising from within the core that could underpin food web stability in the face of environmental perturbations.
Woodward G, Bonada N, Brown LE, et al., 2016, The effects of climatic fluctuations and extreme events on running water ecosystems, Philisophical Transactions of the Royal Society B, Vol: 371, ISSN: 0962-8436
Most research on the effects of environmental change in freshwaters hasfocused on incremental changes in average conditions, rather than fluctuationsor extreme events such as heatwaves, cold snaps, droughts, floodsor wildfires, which may have even more profound consequences. Suchevents are commonly predicted to increase in frequency, intensity and durationwith global climate change, with many systems being exposed toconditions with no recent historical precedent. We propose a mechanisticframework for predicting potential impacts of environmental fluctuationson running-water ecosystems by scaling up effects of fluctuations from individualsto entire ecosystems. This framework requires integration of four keycomponents: effects of the environment on individual metabolism, metabolicand biomechanical constraints on fluctuating species interactions,assembly dynamics of local food webs, and mapping the dynamics of themeta-community onto ecosystem function. We illustrate the framework bydeveloping a mathematical model of environmental fluctuations on dynamicallyassembling food webs. We highlight (currently limited) empiricalevidence for emerging insights and theoretical predictions. For example,widely supported predictions about the effects of environmental fluctuationsare: high vulnerability of species with high per capita metabolic demandssuch as large-bodied ones at the top of food webs; simplification of foodweb network structure and impaired energetic transfer efficiency; andreduced resilience and top-down relative to bottom-up regulation of foodweb and ecosystem processes. We conclude by identifying key questionsand challenges that need to be addressed to develop more accurate and predictivebio-assessments of the effects of fluctuations, and implications offluctuations for management practices in an increasingly uncertain world.
O'Gorman EJ, Ólafsson Ó, Demars BOL, et al., 2016, Temperature effects on fish production across a natural thermal gradient, Global Change Biology, Vol: 22, Pages: 3206-3220, ISSN: 1365-2486
Global warming is widely predicted to reduce the biomass production of top predators, or even result in species loss. Several exceptions to this expectation have been identified, however, and it is vital that we understand the underlying mechanisms if we are to improve our ability to predict future trends. Here, we used a natural warming experiment in Iceland and quantitative theoretical predictions to investigate the success of brown trout as top predators across a stream temperature gradient (4–25 °C). Brown trout are at the northern limit of their geographic distribution in this system, with ambient stream temperatures below their optimum for maximal growth, and above it in the warmest streams. A five-month mark-recapture study revealed that population abundance, biomass, growth rate, and production of trout all increased with stream temperature. We identified two mechanisms that contributed to these responses: (1) trout became more selective in their diet as stream temperature increased, feeding higher in the food web and increasing in trophic position; and (2) trophic transfer through the food web was more efficient in the warmer streams. We found little evidence to support a third potential mechanism: that external subsidies would play a more important role in the diet of trout with increasing stream temperature. Resource availability was also amplified through the trophic levels with warming, as predicted by metabolic theory in nutrient-replete systems. These results highlight circumstances in which top predators can thrive in warmer environments and contribute to our knowledge of warming impacts on natural communities and ecosystem functioning.
Huddart JEA, Thompson MSA, Woodward G, et al., 2016, Citizen science: from detecting pollution to evaluating ecological restoration, Wiley Interdisciplinary Reviews: Water, Vol: 3, Pages: 287-300, ISSN: 2049-1948
Gill RJ, Baldock KCR, Brown MJF, et al., 2016, Protecting an Ecosystem Service: Approaches to Understanding and Mitigating Threats to Wild Insect Pollinators, Advances in Ecological Research, Vol: 54, Pages: 135-206, ISSN: 0065-2504
Insect pollination constitutes an ecosystem service of global importance, providing significant economic and aesthetic benefits as well as cultural value to human society, alongside vital ecological processes in terrestrial ecosystems. It is therefore important to understand how insect pollinator populations and communities respond to rapidly changing environments if we are to maintain healthy and effective pollinator services. This chapter considers the importance of conserving pollinator diversity to maintain a suite of functional traits and provide a diverse set of pollinator services. We explore how we can better understand and mitigate the factors that threaten insect pollinator richness, placing our discussion within the context of populations in predominantly agricultural landscapes in addition to urban environments. We highlight a selection of important evidence gaps, with a number of complementary research steps that can be taken to better understand: (i) the stability of pollinator communities in different landscapes in order to provide diverse pollinator services; (ii) how we can study the drivers of population change to mitigate the effects and support stable sources of pollinator services and (iii) how we can manage habitats in complex landscapes to support insect pollinators and provide sustainable pollinator services for the future. We advocate a collaborative effort to gain higher quality abundance data to understand the stability of pollinator populations and predict future trends. In addition, for effective mitigation strategies to be adopted, researchers need to conduct rigorous field testing of outcomes under different landscape settings, acknowledge the needs of end-users when developing research proposals and consider effective methods of knowledge transfer to ensure effective uptake of actions.
Gill RJ, Woodward G, 2016, Networking our way to better ecosystem service provision, Trends in Ecology & Evolution, Vol: 31, Pages: 105-115, ISSN: 0169-5347
The ecosystem services (EcoS) concept is being used increasingly to attach values to natural systems and the multiple benefits they provide to human societies. Ecosystem processes or functions only become EcoS if they are shown to have social and/or economic value. This should assure an explicit connection between the natural and social sciences, but EcoS approaches have been criticized for retaining little natural science. Preserving the natural, ecological science context within EcoS research is challenging because the multiple disciplines involved have very different traditions and vocabularies (common-language challenge) and span many organizational levels and temporal and spatial scales (scale challenge) that define the relevant interacting entities (interaction challenge). We propose a network-based approach to transcend these discipline challenges and place the natural science context at the heart of EcoS research.
Durance I, Bruford MW, Chalmers R, et al., 2016, The Challenges of Linking Ecosystem Services to Biodiversity: Lessons from a Large-Scale Freshwater Study, Advances in Ecological Research, Vol: 54, Pages: 87-134, ISSN: 0065-2504
There is a growing consensus that inappropriate valuation of the world's ecosystem services has historically led to widespread errors in environmental management, with associated negative social consequences. Freshwater ecosystems are prime examples: when managed appropriately, they provide major services, such as fish production, water supply, nutrient transport, health benefits and recreational value. However, these services are often compromised because they are seldom recognised explicitly in catchment use and planning. Moreover, pressures on river ecosystem services will grow as land use intensifies, water demands increase, and climate change accelerates over the coming decades.Maintaining and protecting river ecosystem services will depend increasingly on understanding the processes that underpin and degrade them, and especially in terms of characterising the roles played by the biota. While the integrity and stability of ecosystem processes tend to increase with biodiversity, how services and biodiversity are related is largely unknown, due to a range of unresolved practical and philosophical issues.We explore some of the key challenges and opportunities that lie in assessing the role of freshwater biodiversity in sustaining ecosystem services, using the recent large interdisciplinary NERC-DURESS project (www.nerc-DURESS.org) as an exemplar case study of wider issues. The conceptual and methodological challenges raised are identified, explored and a range of methods are proposed to quantify how freshwater ecoservices, such as fish production or water quality regulation, depend on river organisms, and how we might identify biodiversity thresholds under which a service is likely to be compromised. We conclude that interdisciplinary, large scale, in situ approaches like these are needed to (i) fully understand how river biodiversity sustains ecosystem services; (ii) help evaluate if, where, and how the ecosystem approach can benefit long-term resource management
Dumbrell AJ, Kordas RL, Woodward G, 2016, ADVANCES IN ECOLOGICAL RESEARCH Large-Scale Ecology: Model Systems to Global Perspectives PREFACE, Publisher: ELSEVIER ACADEMIC PRESS INC, ISBN: 978-0-08-100935-2
- Author Web Link
- Cite
- Citations: 1
Chauvet E, Ferreira V, Giller PS, et al., 2016, Litter Decomposition as an Indicator of Stream Ecosystem Functioning at Local-to-ontinental Scales: Insights from the European <i>RivFunction</i> Project, ADVANCES IN ECOLOGICAL RESEARCH, VOL 55: LARGE-SCALE ECOLOGY: MODEL SYSTEMS TO GLOBAL PERSPECTIVES, Editors: Dumbrell, Kordas, Woodward, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 99-182, ISBN: 978-0-08-100935-2
- Author Web Link
- Cite
- Citations: 58
Gray C, Hildrew AG, Lu X, et al., 2016, Recovery and Nonrecovery of Freshwater Food Webs from the Effects of Acidification, ADVANCES IN ECOLOGICAL RESEARCH, VOL 55: LARGE-SCALE ECOLOGY: MODEL SYSTEMS TO GLOBAL PERSPECTIVES, Editors: Dumbrell, Kordas, Woodward, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 475-534, ISBN: 978-0-08-100935-2
- Author Web Link
- Cite
- Citations: 17
Bohan DA, Pocock MJO, Woodward G, 2016, Ecosystem Services: From Biodiversity to Society, Part 2 PREFACE, Publisher: ELSEVIER ACADEMIC PRESS INC, ISBN: 978-0-08-100978-9
Yvon-Durocher G, Allen AP, Cellamare M, et al., 2015, Five years of experimental warming increases the biodiversity and productivity of phytoplankton, PLOS Biology, Vol: 13, ISSN: 1545-7885
Phytoplankton are key components of aquatic ecosystems, fixing CO2 from the atmosphere through photosynthesis and supporting secondary production, yet relatively little is known about how future global warming might alter their biodiversity and associated ecosystem functioning. Here, we explore how the structure, function, and biodiversity of a planktonic metacommunity was altered after five years of experimental warming. Our outdoor mesocosm experiment was open to natural dispersal from the regional species pool, allowing us to explore the effects of experimental warming in the context of metacommunity dynamics. Warming of 4°C led to a 67% increase in the species richness of the phytoplankton, more evenly-distributed abundance, and higher rates of gross primary productivity. Warming elevated productivity indirectly, by increasing the biodiversity and biomass of the local phytoplankton communities. Warming also systematically shifted the taxonomic and functional trait composition of the phytoplankton, favoring large, colonial, inedible phytoplankton taxa, suggesting stronger top-down control, mediated by zooplankton grazing played an important role. Overall, our findings suggest that temperature can modulate species coexistence, and through such mechanisms, global warming could, in some cases, increase the species richness and productivity of phytoplankton communities.
Woodward G, Bonada N, Feeley HB, et al., 2015, Resilience of a stream community to extreme climatic events and long-term recovery from a catastrophic flood, FRESHWATER BIOLOGY, Vol: 60, Pages: 2497-2510, ISSN: 0046-5070
- Author Web Link
- Cite
- Citations: 55
Woodward G, 2015, 10 Years Later: Revisiting Priorities for Science and Society a Decade After the Millennium Ecosystem Assessment, Advances in Ecological Research
Gray CE, Figueroa D, Hudson LN, et al., 2015, Joining the dots: an automated method for constructing food webs from compendia of published interactions, Food Webs, Vol: 5, Pages: 11-20, ISSN: 2352-2496
Food webs are important tools for understanding how complex natural communities are structured and how they respond to environmental change. However their full potential has yet to be realised because of the huge amount of resources required to construct them de novo. Consequently, the current catalogue of networks that are suitable for rigorous and comparative analyses and theoretical development still suffers from a lack of standardisation and replication.Here, we present a novel R function, WebBuilder, which automates the construction of food webs from taxonomic lists, and a dataset of trophic interactions. This function works by matching species against those within a dataset of trophic interactions, and ‘filling in’ missing trophic interactions based on these matches. We also present a dataset of over 20,000 freshwater trophic interactions, and use this and four well-characterised freshwater food webs to test the method.The WebBuilder function facilitates the generation of food webs of comparable quality to the most detailed published food webs, but at a fraction of the research effort or cost. Furthermore, it matched and often outperformed a selection of predictive models, which are currently among the best, in terms of capturing key properties of empirical food webs. The method is simple to use, systematic and, perhaps most importantly, reproducible, which will facilitate (re-) analysis and data sharing. Although developed and tested on a sample of freshwater food webs, this method could easily be extended to cover other types of ecological interactions (such as mutualistic interactions).
Gray CE, Thompson M, Bankier C, et al., 2015, Gene-to-ecosystem impacts of a catastrophic pesticide spill: testing a multilevel bioassessment approach in a river ecosystem, Freshwater Biology, Vol: 61, Pages: 2037-2050, ISSN: 1365-2427
1.Pesticides can have strong deleterious impacts in fresh waters, but understanding how these effects cascade through natural ecosystems, from microbes to apex predators, is limited because research that spans multiple levels of biological organisation is rare.2.We report how an accidental insecticide spill altered the structure and functioning of a river across levels ranging from genes to ecosystems. We quantified the impacts on assemblages of microbes, diatoms, macroinvertebrates and fish and measured leaf-litter decomposition rates and microbial functional potential at upstream control and downstream impacted sites 2 months after the spill.3.Both direct and indirect impacts were evident across multiple levels of organisation and taxa, from the base of the food web to higher trophic levels. At the molecular level, differences in functional gene abundance within the impacted sites reflected a combination of direct and indirect effects of the pesticide, via elevated abundances of microbial populations capable of using chlorpyrifos as a resource (i.e. direct effect) and oxidising ammonia released by decaying macroinvertebrate carcasses (i.e. indirect effect).4.At the base of the food chains, diatom taxa found only in the impacted sites were an order-of-magnitude larger in cell size than the largest comparable taxa in control communities, following the near extirpation of their consumers. Population biomass of the key detritivore Gammarus pulex was markedly lower, as was the rate of litter decomposition in the impacted sites. This was partially compensated for, however, by elevated microbial breakdown, suggesting another indirect food-web effect of the toxic spill.5.Although many species exhibited population crashes or local extirpation, total macroinvertebrate biomass and abundance were largely unaffected due to a compensatory elevation in small tolerant taxa such as oligochaetes, and/or taxa which were in their adult aerial life stage at the time of the spill (e.g.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.