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Rocher-Ros G, Stanley EH, Loken LC, Casson NJ, Raymond PA, Liu S, Amatulli G, Sponseller RA. Global methane emissions from rivers and streams. Nature 2023; 621:530-535. [PMID: 37587344 PMCID: PMC10511311 DOI: 10.1038/s41586-023-06344-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 06/20/2023] [Indexed: 08/18/2023]
Abstract
Methane (CH4) is a potent greenhouse gas and its concentrations have tripled in the atmosphere since the industrial revolution. There is evidence that global warming has increased CH4 emissions from freshwater ecosystems1,2, providing positive feedback to the global climate. Yet for rivers and streams, the controls and the magnitude of CH4 emissions remain highly uncertain3,4. Here we report a spatially explicit global estimate of CH4 emissions from running waters, accounting for 27.9 (16.7-39.7) Tg CH4 per year and roughly equal in magnitude to those of other freshwater systems5,6. Riverine CH4 emissions are not strongly temperature dependent, with low average activation energy (EM = 0.14 eV) compared with that of lakes and wetlands (EM = 0.96 eV)1. By contrast, global patterns of emissions are characterized by large fluxes in high- and low-latitude settings as well as in human-dominated environments. These patterns are explained by edaphic and climate features that are linked to anoxia in and near fluvial habitats, including a high supply of organic matter and water saturation in hydrologically connected soils. Our results highlight the importance of land-water connections in regulating CH4 supply to running waters, which is vulnerable not only to direct human modifications but also to several climate change responses on land.
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Affiliation(s)
- Gerard Rocher-Ros
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
- Integrative Freshwater Ecology Group, Centre for Advanced Studies of Blanes (CEAB-CSIC), Blanes, Spain.
| | - Emily H Stanley
- Center for Limnology, University of Wisconsin-Madison, Madison, WI, USA
| | - Luke C Loken
- Upper Midwest Water Science Center, United States Geological Survey, Madison, WI, USA
| | - Nora J Casson
- Department of Geography, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Peter A Raymond
- School of the Environment, Yale University, New Haven, CT, USA
| | - Shaoda Liu
- School of the Environment, Yale University, New Haven, CT, USA
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, China
| | | | - Ryan A Sponseller
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
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2
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Zhang Y, Huo Y, Zhang Z, Zhu S, Fan W, Wang X, Huo M. Deciphering the influence of multiple anthropogenic inputs on taxonomic and functional profiles of the microbial communities in Yitong River, Northeast China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:39973-39984. [PMID: 35112248 DOI: 10.1007/s11356-021-18386-2] [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: 07/21/2021] [Accepted: 12/24/2021] [Indexed: 06/14/2023]
Abstract
We conducted the analysis of physicochemical parameters, 16S rRNA amplicon sequencing and real-time quantitative polymerase chain reaction to explore the impact of human inputs on the bacterioplankton communities within a tributary of the largest river flowing through a megacity in northeast China. Agriculture largely accounted for the alteration of diversity and functions of the microbial communities. Furthermore, nitrate and total phosphorus declined at the reservoir outlet. The WWTP effluent discharge caused a decrease of the relative abundance of Actinobacteria and Cyanobacteria, while the impact on the variation of alpha diversity of river microbial community was slight. Carbon fixation and nitrogen cycle varied with the change of land use type. The rare taxa contributed with a predominant role in the response to environmental variables and NH3-N as well as NO3--N were the main environmental factors that drove the shift in the bacterial community. The occurrence of the human-specific fecal indicator was mostly derived from agriculture, and its increase in relative abundance was observed in the WWTP effluent. Thus, our study provides guidance for ecological assessment and management of rivers by revealing the response pattern of river bacterioplankton to multiple types of anthropogenic stressors.
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Affiliation(s)
- Ying Zhang
- School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Yang Huo
- Science and Technology Innovation Center for Municipal Wastewater Treatment and Water Quality Protection, Northeast Normal University, Changchun, 130117, China.
- School of Physics, Northeast Normal University, Changchun, 130024, China.
| | - Zhiruo Zhang
- Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun, 130118, China
| | - Suiyi Zhu
- School of Environment, Northeast Normal University, Changchun, 130117, China
- Science and Technology Innovation Center for Municipal Wastewater Treatment and Water Quality Protection, Northeast Normal University, Changchun, 130117, China
| | - Wei Fan
- School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Xianze Wang
- School of Environment, Northeast Normal University, Changchun, 130117, China
- Science and Technology Innovation Center for Municipal Wastewater Treatment and Water Quality Protection, Northeast Normal University, Changchun, 130117, China
| | - Mingxin Huo
- School of Environment, Northeast Normal University, Changchun, 130117, China.
- Science and Technology Innovation Center for Municipal Wastewater Treatment and Water Quality Protection, Northeast Normal University, Changchun, 130117, China.
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3
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Kreiling RM, Bartsch LA, Perner PM, Hlavacek EJ, Christensen VG. Riparian Forest Cover Modulates Phosphorus Storage and Nitrogen Cycling in Agricultural Stream Sediments. ENVIRONMENTAL MANAGEMENT 2021; 68:279-293. [PMID: 34105016 DOI: 10.1007/s00267-021-01484-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
Watershed land cover affects in-stream water quality and sediment nutrient dynamics. The presence of natural land cover in the riparian zone can reduce the negative effects of agricultural land use on water quality; however, literature evaluating the effects of natural riparian land cover on stream sediment nutrient dynamics is scarce. The objective of this study was to assess if stream sediment phosphorus retention and nitrogen removal varies with riparian forest cover in agricultural watersheds. Stream sediment nutrient dynamics from 28 sites with mixed land cover were sampled three times during the growing season. Phosphorus dynamics and nitrification rates did not change considerably throughout the study period. Sediment total phosphorus concentrations and nitrification rates decreased as riparian forest cover increased likely due to a decline in fine, organic material. Denitrification rates were strongly correlated to surface water nitrate concentrations. Denitrification rate and denitrification enzyme activity decreased with an increase in forest cover during the first sampling period only. The first sampling period coincided with the greatest connectivity between the watershed and in-stream processing, indicating that riparian forest cover indirectly decreased denitrification rates by reducing the concentrations of dissolved nutrients entering the stream. This reduction in load may allow the sediment to maintain greater nitrogen removal efficiency, because bacteria are not saturated with nitrogen. Riparian forest cover also appeared to lessen the effect of agriculture in the watershed by decreasing the amount of fine material in the stream, resulting in reduced phosphorus storage in the stream sediment.
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Affiliation(s)
- R M Kreiling
- U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI, USA.
| | - L A Bartsch
- U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI, USA
| | - P M Perner
- U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI, USA
| | - E J Hlavacek
- U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI, USA
| | - V G Christensen
- U.S. Geological Survey, Upper Midwest Water Science Center, Moundsview, MN, USA
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4
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Identifying the Mechanisms behind the Positive Feedback Loop between Nitrogen Cycling and Algal Blooms in a Shallow Eutrophic Lake. WATER 2021. [DOI: 10.3390/w13040524] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Algal blooms have increased in frequency, intensity, and duration in response to nitrogen (N) cycling in freshwater ecosystems. We conducted a high-resolution sedimentary study of N transformation and its associated microbial activity in Lake Taihu to assess the accumulation rates of the different N fractions in response to algal blooms, aiming to understand the mechanisms of N cycling in lacustrine environments. Downcore nitrification and denitrification processes were measured simultaneously in situ via diffusive gradients in thin-films technique, peeper, and microelectrode devices in a region of intensified algal blooms of shallow lake. The decomposition of different biomasses of algal blooms did not change the main controlling factor on different N fractions in profundal sediment. However, the decomposition of different algal biomasses led to significant differences in the nitrification and denitrification processes at the sediment–water interface (SWI). Low algal biomasses facilitated the classic process of N cycling, with the balanced interaction between nitrification and denitrification. However, the extreme hypoxia under high algal biomasses significantly limited nitrification at the SWI, which in turn, restricted denitrification due to the lack of available substrates. Our high-resolution results combined with estimates of apparent diffusion fluxes of the different N fractions inferred that the lack of substrates for denitrification was the main factor influencing the positive feedback loop between N and eutrophication in freshwater ecosystems. Moreover, this positive feedback can become irreversible without technological intervention.
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Gweon HS, Bowes MJ, Moorhouse HL, Oliver AE, Bailey MJ, Acreman MC, Read DS. Contrasting community assembly processes structure lotic bacteria metacommunities along the river continuum. Environ Microbiol 2021; 23:484-498. [PMID: 33258525 PMCID: PMC7898806 DOI: 10.1111/1462-2920.15337] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 11/03/2020] [Accepted: 11/24/2020] [Indexed: 01/26/2023]
Abstract
The heterogeneous nature of lotic habitats plays an important role in the complex ecological and evolutionary processes that structure the microbial communities within them. Due to such complexity, our understanding of lotic microbial ecology still lacks conceptual frameworks for the ecological processes that shape these communities. We explored how bacterial community composition and underlying ecological assembly processes differ between lotic habitats by examining community composition and inferring community assembly processes across four major habitat types (free-living, particle-associated, biofilm on benthic stones and rocks, and sediment). This was conducted at 12 river sites from headwater streams to the main river in the River Thames, UK. Our results indicate that there are distinct differences in the bacterial communities between four major habitat types, with contrasting ecological processes shaping their community assembly processes. While the mobile free-living and particle-associated communities were consistently less diverse than the fixed sediment and biofilm communities, the latter two communities displayed higher homogeneity across the sampling sites. This indicates that the relative influence of deterministic environmental filtering is elevated in sediment and biofilm communities compared with free-living and particle-associated communities, where stochastic processes play a larger role.
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Affiliation(s)
- Hyun S. Gweon
- UK Centre for Ecology & HydrologyWallingford, OxfordshireOX10 8BBUK
- School of Biological SciencesUniversity of ReadingReadingRG6 6EXUK
| | - Michael J. Bowes
- UK Centre for Ecology & HydrologyWallingford, OxfordshireOX10 8BBUK
| | - Heather L. Moorhouse
- UK Centre for Ecology & HydrologyWallingford, OxfordshireOX10 8BBUK
- Lancaster Environment CentreLancaster UniversityLibrary Avenue, LancasterLA1 4YQUK
| | - Anna E. Oliver
- UK Centre for Ecology & HydrologyWallingford, OxfordshireOX10 8BBUK
| | - Mark J. Bailey
- UK Centre for Ecology & HydrologyWallingford, OxfordshireOX10 8BBUK
| | | | - Daniel S. Read
- UK Centre for Ecology & HydrologyWallingford, OxfordshireOX10 8BBUK
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6
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Junker JR, Cross WF, Benstead JP, Huryn AD, Hood JM, Nelson D, Gíslason GM, Ólafsson JS. Flow is more Important than Temperature in Driving Patterns of Organic Matter Storage and Stoichiometry in Stream Ecosystems. Ecosystems 2020. [DOI: 10.1007/s10021-020-00585-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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Impact of Nutrient and Stoichiometry Gradients on Microbial Assemblages in Erhai Lake and Its Input Streams. WATER 2019. [DOI: 10.3390/w11081711] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Networks of lakes and streams are linked by downslope flows of material and energy within catchments. Understanding how bacterial assemblages are associated with nutrients and stoichiometric gradients in lakes and streams is essential for understanding biogeochemical cycling in freshwater ecosystems. In this study, we conducted field sampling of bacterial communities from lake water and stream biofilms in Erhai Lake watershed. We determined bacterial communities using high-throughput 16S rRNA gene sequencing and explored the relationship between bacterial composition and environmental factors using networking analysis, canonical correspondence analysis (CCA), and variation partitioning analysis (VPA). Physicochemical parameters, nutrients, and nutrient ratios gradients between the lake and the streams were strongly associated with the differences in community composition and the dominant taxa. Cyanobacteria dominated in Erhai Lake, while Proteobacteria dominated in streams. The stream bacterial network was more stable with multiple stressors, including physicochemical-factors and nutrient-factors, while the lake bacterial network was more fragile and susceptible to human activities with dominant nutrients (phosphorus). Negative correlations between bacterial communities and soluble reactive phosphorus (SRP) as well as positive correlations between bacterial communities and dissolved organic carbon (DOC) in the network indicated these factors had strong effect on bacterial succession. Erhai Lake is in a eutrophic state, and high relative abundances of Synechococcus (40.62%) and Microcystis (16.2%) were noted during the course of our study. CCA indicated that nutrients (phosphorus) were key parameters driving Cyanobacteria-dominated community structure. By classifying the environmental factors into five categories, VPA analyses identified that P-factor (total phosphorus (TP) and SRP) as well as the synergistic effect of C-factor (DOC), N-factor (NO3−), and P-factor (TP and SRP) played a central role in structuring the bacterial communities in Erhai Lake. Heterogeneous physicochemical conditions explained the variations in bacterial assemblages in streams. This study provides a picture of stream–lake linkages from the perspective of bacterial community structure as well as key factors driving bacterial assemblages within lakes and streams at the whole watershed scale. We further argue that better management of phosphorus on the watershed scale is needed for ameliorating eutrophication of Erhai Lake.
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Effect of River Ecological Restoration on Biofilm Microbial Community Composition. WATER 2019. [DOI: 10.3390/w11061244] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Across the world, there have been increasing attempts to restore good ecological condition to degraded rivers through habitat restoration. Microbial communities developing as biofilms play an important role in river ecosystem functioning by driving organic matter decomposition and ecosystem respiration. However, little is known about the structure and function of microbial communities in riverine systems and how these change when habitat restoration is implemented. Here, we compared the biofilm bacterial community composition using 16S rRNA genes targeted high-throughput Illumina Miseq sequencing in three river types, degraded urban rivers, urban rivers undergoing habitat restoration and forested rivers (our reference conditions). We aimed to determine: (i) the biofilm bacterial community composition affected by habitat restoration (ii) the difference in bacterial diversity in restored rivers, and (iii) correlations between environmental variables and bacterial community composition. The results showed that both water quality and biofilm bacterial community structure were changed by habitat restoration. In rivers where habitat had been restored, there was an increase in dissolved oxygen, a reduction in organic pollutants, a reduction in bacterial diversity and a related developing pattern of microbial communities, which is moving towards that of the reference conditions (forested rivers). River habitat management stimulated the processing of organic pollutants through the variation in microbial community composition, however, a big difference in bacterial structure still existed between the restored rivers and the reference forest rivers. Thus, habitat restoration is an efficient way of modifying the biofilm microbial community composition for sustainable freshwater management. It will, however, take a much longer time for degraded rivers to attain a similar ecosystem quality as the “pristine” forest sites than the seven years of restoration studied here.
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9
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Huryn AD, Benstead JP. Seasonal changes in light availability modify the temperature dependence of secondary production in an Arctic stream. Ecology 2019; 100:e02690. [PMID: 30854634 DOI: 10.1002/ecy.2690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/12/2019] [Accepted: 02/21/2019] [Indexed: 11/05/2022]
Abstract
Light and temperature are key drivers of ecosystem productivity, but synchrony of their annual cycles typically obscures their relative influence. The coupling of annual light-temperature regimes also drives complementary seasonal cycles of energy supply (primary production) and demand (metabolism), perhaps promoting temporal stability in carbon (C) storage and food web production that may be difficult to discern in most ecosystems. Spring-fed streams in the Arctic are subject to extreme annual fluctuations in light availability but have relatively stable water temperatures, which allows assessment of the independent effects of light and temperature. We used the unusual annual light and temperature regimes of Ivishak Spring, Alaska, USA (latitude 69° N, annual water temperature range ~4-7°C) to test predictions about the effect of light availability on consumer productivity with minimally confounding effects of temperature. We predicted that (1) annual patterns of secondary production would follow patterns of primary production, rather than temperature, due to organic C limitation during winter darkness when photosynthesis is effectively halted, (2) C limitation would propagate from primary producers upward through several trophic levels, (3) the lack of temperature dependence during winter darkness would be expressed as anomalous Arrhenius plots of growth rates indicating decoupled production-temperature relationships, and (4) consumer diets would reflect C limitation during winter. As predicted, we found (1) lowest production by macroinvertebrates and Salvelinus malma (Dolly Varden char) at the lowest light levels rather than the lowest temperatures, (2) apparent winter C limitation propagated upward through three trophic levels, (3) anomalous Arrhenius plots indicating lack of temperature dependence of consumer growth rates during winter, and (4) lowest consumption of diatoms (by macroinvertebrates) and invertebrate prey (by S. malma) during winter. Together, these results indicate that light drives annual patterns of animal production in Ivishak Spring, with stable annual temperatures likely exacerbating C limitation of ectotherm metabolism during winter. The timing and severity of winter C limitation in this unusual Arctic-spring food web highlight a fundamental role for light-temperature synchrony in matching energy supply with demand in most other ecosystem types, thereby conferring a measure of stability in the metabolism of their food webs over annual time scales.
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Affiliation(s)
- Alexander D Huryn
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, 35487-0344, USA
| | - Jonathan P Benstead
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, 35487-0344, USA
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10
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Abstract
Pollution abatement through phosphorus and nitrogen retention is a key ecosystem service provided by streams. Human activities have been changing in-stream nutrient concentrations, thereby altering lotic ecosystem functioning, especially in developing countries. We estimated nutrient uptake metrics (ambient uptake length, areal uptake rate, and uptake velocity) for nitrate (NO3–N), ammonium (NH4–N), and soluble reactive phosphorus (SRP) in four tropical Cerrado headwater streams during 2017, through whole-stream nutrient addition experiments. According to multiple regression models, ambient SRP concentration was an important explanatory variable of nutrient uptake. Further, best models included ambient NO3–N and water velocity (for NO3–N uptake metrics), dissolved oxygen (DO) and canopy cover (for NH4–N); and DO, discharge, water velocity, and temperature (for SRP). The best kinetic models describing nutrient uptake were efficiency-loss (R2 from 0.47–0.88) and first-order models (R2 from 0.60–0.85). NO3–N, NH4–N, and SRP uptake in these streams seemed coupled as a result of complex interactions of biotic P limitation, abiotic P cycling processes, and the preferential uptake of NH4–N among N-forms. Global change effects on these tropical streams, such as temperature increase and nutrient enrichment due to urban and agricultural expansion, may have adverse and partially unpredictable impacts on whole-stream nutrient processing.
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11
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Hood JM, Benstead JP, Cross WF, Huryn AD, Johnson PW, Gíslason GM, Junker JR, Nelson D, Ólafsson JS, Tran C. Increased resource use efficiency amplifies positive response of aquatic primary production to experimental warming. GLOBAL CHANGE BIOLOGY 2018; 24:1069-1084. [PMID: 28922515 DOI: 10.1111/gcb.13912] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 08/21/2017] [Accepted: 09/03/2017] [Indexed: 06/07/2023]
Abstract
Climate warming is affecting the structure and function of river ecosystems, including their role in transforming and transporting carbon (C), nitrogen (N), and phosphorus (P). Predicting how river ecosystems respond to warming has been hindered by a dearth of information about how otherwise well-studied physiological responses to temperature scale from organismal to ecosystem levels. We conducted an ecosystem-level temperature manipulation to quantify how coupling of stream ecosystem metabolism and nutrient uptake responded to a realistic warming scenario. A ~3.3°C increase in mean water temperature altered coupling of C, N, and P fluxes in ways inconsistent with single-species laboratory experiments. Net primary production tripled during the year of experimental warming, while whole-stream N and P uptake rates did not change, resulting in 289% and 281% increases in autotrophic dissolved inorganic N and P use efficiency (UE), respectively. Increased ecosystem production was a product of unexpectedly large increases in mass-specific net primary production and autotroph biomass, supported by (i) combined increases in resource availability (via N mineralization and N2 fixation) and (ii) elevated resource use efficiency, the latter associated with changes in community structure. These large changes in C and nutrient cycling could not have been predicted from the physiological effects of temperature alone. Our experiment provides clear ecosystem-level evidence that warming can shift the balance between C and nutrient cycling in rivers, demonstrating that warming will alter the important role of in-stream processes in C, N, and P transformations. Moreover, our results reveal a key role for nutrient supply and use efficiency in mediating responses of primary producers to climate warming.
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Affiliation(s)
- James M Hood
- Aquatic Ecology Laboratory, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH, USA
- Department of Ecology, Montana State University, Bozeman, MT, USA
| | - Jonathan P Benstead
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Wyatt F Cross
- Department of Ecology, Montana State University, Bozeman, MT, USA
| | - Alexander D Huryn
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Philip W Johnson
- Department of Civil, Construction, and Environmental Engineering, University of Alabama, Tuscaloosa, AL, USA
| | - Gísli M Gíslason
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | - James R Junker
- Department of Ecology, Montana State University, Bozeman, MT, USA
| | - Daniel Nelson
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Jón S Ólafsson
- Marine and Freshwater Research Institute, Reykjavík, Iceland
| | - Chau Tran
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
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12
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Tank JL, Martí E, Riis T, Schiller D, Reisinger AJ, Dodds WK, Whiles MR, Ashkenas LR, Bowden WB, Collins SM, Crenshaw CL, Crowl TA, Griffiths NA, Grimm NB, Hamilton SK, Johnson SL, McDowell WH, Norman BM, Rosi EJ, Simon KS, Thomas SA, Webster JR. Partitioning assimilatory nitrogen uptake in streams: an analysis of stable isotope tracer additions across continents. ECOL MONOGR 2017. [DOI: 10.1002/ecm.1280] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- J. L. Tank
- Department of Biological Sciences University of Notre Dame Notre Dame Indiana 46656 USA
| | - E. Martí
- Integrative Freshwater Ecology Group Centre d'Estudis Avançats de Blanes (CEAB‐CSIC) 17300 Blanes Catalonia Spain
| | - T. Riis
- Department of Bioscience Aarhus University Ole Worms Alle 1 8000 Aarhus C Denmark
| | - D. Schiller
- Faculty of Science and Technology University of the Basque Country 48080 Bilbao Spain
| | - A. J. Reisinger
- Cary Institute of Ecosystem Studies Millbrook New York 12545 USA
| | - W. K. Dodds
- Division of Biology Kansas State University 106 Ackert Hall Manhattan Kansas 66506 USA
| | - M. R. Whiles
- Department of Zoology and Center for Ecology Southern Illinois University Carbondale Illinois 62901 USA
| | - L. R. Ashkenas
- Department of Fisheries & Wildlife Oregon State University Corvallis Oregon 97331 USA
| | - W. B. Bowden
- Rubenstein School of Environment and Natural Resources University of Vermont 303D Aiken Center Burlington Vermont 05405 USA
| | - S. M. Collins
- Center for Limnology University of Wisconsin Madison Wisconsin 53706 USA
| | - C. L. Crenshaw
- Department of Biology University of New Mexico Albuquerque New Mexico 87131 USA
| | - T. A. Crowl
- Department of Biology Southeast Environmental Research Center Florida International University Miami Florida 33199 USA
| | - N. A. Griffiths
- Climate Change Science Institute and Environmental Sciences Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
| | - N. B. Grimm
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
| | - S. K. Hamilton
- W. K. Kellogg Biological Station Michigan State University Hickory Corners Michigan 49060 USA
| | - S. L. Johnson
- Pacific Northwest Research Station USDA Forest Service 3200 SW Jefferson Way Corvallis Oregon 97331 USA
| | - W. H. McDowell
- Natural Resources and the Environment University of New Hampshire Durham New Hampshire 03824 USA
| | - B. M. Norman
- Department of Microbiology and Molecular Genetics Michigan State University East Lansing Michigan 48824 USA
| | - E. J. Rosi
- Cary Institute of Ecosystem Studies Millbrook New York 12545 USA
| | - K. S. Simon
- School of Environment University of Auckland P.O. Box 92019 Auckland 1142 New Zealand
| | - S. A. Thomas
- School of Natural Resources University of Nebraska 403 Hardin Hall Lincoln Nebraska 68583 USA
| | - J. R. Webster
- Department of Biological Sciences Virginia Tech 1405 Perry Street Blacksburg Virginia 24601 USA
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Ren Z, Wang F, Qu X, Elser JJ, Liu Y, Chu L. Taxonomic and Functional Differences between Microbial Communities in Qinghai Lake and Its Input Streams. Front Microbiol 2017; 8:2319. [PMID: 29213266 PMCID: PMC5702853 DOI: 10.3389/fmicb.2017.02319] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/10/2017] [Indexed: 12/22/2022] Open
Abstract
Understanding microbial communities in terms of taxon and function is essential to decipher the biogeochemical cycling in aquatic ecosystems. Lakes and their input streams are highly linked. However, the differences between microbial assemblages in streams and lakes are still unclear. In this study, we conducted an intensive field sampling of microbial communities from lake water and stream biofilms in the Qinghai Lake watershed, the largest lake in China. We determined bacterial communities using high-throughput 16S rRNA gene sequencing and predicted functional profiles using PICRUSt to determine the taxonomic and functional differences between microbial communities in stream biofilms and lake water. The results showed that stream biofilms and lake water harbored distinct microbial communities. The microbial communities were different taxonomically and functionally between stream and lake. Moreover, streams biofilms had a microbial network with higher connectivity and modularity than lake water. Functional beta diversity was strongly correlated with taxonomic beta diversity in both the stream and lake microbial communities. Lake microbial assemblages displayed greater predicted metabolic potentials of many metabolism pathways while the microbial assemblages in stream biofilms were more abundant in xenobiotic biodegradation and metabolism and lipid metabolism. Furthermore, lake microbial assemblages had stronger predicted metabolic potentials in amino acid metabolism, carbon fixation, and photosynthesis while stream microbial assemblages were higher in carbohydrate metabolism, oxidative phosphorylation, and nitrogen metabolism. This study adds to our knowledge of stream-lake linkages from the functional and taxonomic composition of microbial assemblages.
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Affiliation(s)
- Ze Ren
- Flathead Lake Biological Station, University of Montana, Polson, MT, United States
| | - Fang Wang
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China
- Department of Water Resources, China Institute of Water Resources and Hydropower Research, Beijing, China
| | - Xiaodong Qu
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China
- Department of Water Environment, China Institute of Water Resources and Hydropower Research, Beijing, China
| | - James J. Elser
- Flathead Lake Biological Station, University of Montana, Polson, MT, United States
| | - Yang Liu
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China
- Department of Water Resources, China Institute of Water Resources and Hydropower Research, Beijing, China
| | - Limin Chu
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China
- Department of Water Resources, China Institute of Water Resources and Hydropower Research, Beijing, China
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Welti N, Striebel M, Ulseth AJ, Cross WF, DeVilbiss S, Glibert PM, Guo L, Hirst AG, Hood J, Kominoski JS, MacNeill KL, Mehring AS, Welter JR, Hillebrand H. Bridging Food Webs, Ecosystem Metabolism, and Biogeochemistry Using Ecological Stoichiometry Theory. Front Microbiol 2017; 8:1298. [PMID: 28747904 PMCID: PMC5507128 DOI: 10.3389/fmicb.2017.01298] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 06/27/2017] [Indexed: 11/26/2022] Open
Abstract
Although aquatic ecologists and biogeochemists are well aware of the crucial importance of ecosystem functions, i.e., how biota drive biogeochemical processes and vice-versa, linking these fields in conceptual models is still uncommon. Attempts to explain the variability in elemental cycling consequently miss an important biological component and thereby impede a comprehensive understanding of the underlying processes governing energy and matter flow and transformation. The fate of multiple chemical elements in ecosystems is strongly linked by biotic demand and uptake; thus, considering elemental stoichiometry is important for both biogeochemical and ecological research. Nonetheless, assessments of ecological stoichiometry (ES) often focus on the elemental content of biota rather than taking a more holistic view by examining both elemental pools and fluxes (e.g., organismal stoichiometry and ecosystem process rates). ES theory holds the promise to be a unifying concept to link across hierarchical scales of patterns and processes in ecology, but this has not been fully achieved. Therefore, we propose connecting the expertise of aquatic ecologists and biogeochemists with ES theory as a common currency to connect food webs, ecosystem metabolism, and biogeochemistry, as they are inherently concatenated by the transfer of carbon, nitrogen, and phosphorous through biotic and abiotic nutrient transformation and fluxes. Several new studies exist that demonstrate the connections between food web ecology, biogeochemistry, and ecosystem metabolism. In addition to a general introduction into the topic, this paper presents examples of how these fields can be combined with a focus on ES. In this review, a series of concepts have guided the discussion: (1) changing biogeochemistry affects trophic interactions and ecosystem processes by altering the elemental ratios of key species and assemblages; (2) changing trophic dynamics influences the transformation and fluxes of matter across environmental boundaries; (3) changing ecosystem metabolism will alter the chemical diversity of the non-living environment. Finally, we propose that using ES to link nutrient cycling, trophic dynamics, and ecosystem metabolism would allow for a more holistic understanding of ecosystem functions in a changing environment.
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Affiliation(s)
- Nina Welti
- Department of Environmental and Biological Sciences, University of Eastern FinlandKuopio, Finland
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, AdelaideSA, Australia
| | - Maren Striebel
- Institute for Chemistry and Biology of the Marine Environment, University of OldenburgOldenburg, Germany
| | - Amber J. Ulseth
- Stream Biofilm and Ecosystem Research, Ecole Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Wyatt F. Cross
- Department of Ecology, Montana State University, BozemanMT, United States
| | - Stephen DeVilbiss
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, MilwaukeeWI, United States
| | - Patricia M. Glibert
- University of Maryland Center for Environmental Science, CambridgeMD, United States
| | - Laodong Guo
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, MilwaukeeWI, United States
| | - Andrew G. Hirst
- The Hirst Lab, Organismal Biology, School of Biological and Chemical Sciences, Queen Mary University of LondonLondon, United Kingdom
- Centre for Ocean Life, National Institute for Aquatic Resources, Technical University of DenmarkCopenhagen, Denmark
| | - Jim Hood
- Department of Evolution, Ecology, and Organismal Biology, Aquatic Ecology Laboratory, The Ohio State University, ColumbusOH, United States
| | - John S. Kominoski
- The Kominoski Lab, Department of Biological Sciences, Florida International University, MiamiFL, United States
| | - Keeley L. MacNeill
- Department of Ecology and Evolutionary Biology, Cornell University, IthacaNY, United States
| | - Andrew S. Mehring
- Scripps Institution of Oceanography, University of California, San Diego, La JollaCA, United States
| | - Jill R. Welter
- Department of Biology, St. Catherine University, MinneapolisMN, United States
| | - Helmut Hillebrand
- Institute for Chemistry and Biology of the Marine Environment, University of OldenburgOldenburg, Germany
- Helmholtz-Institute for Functional Marine BiodiversityOldenburg, Germany
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Rode M, Halbedel Née Angelstein S, Anis MR, Borchardt D, Weitere M. Continuous In-Stream Assimilatory Nitrate Uptake from High-Frequency Sensor Measurements. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:5685-5694. [PMID: 27174385 DOI: 10.1021/acs.est.6b00943] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recently developed in situ NO3– sensors provide new opportunities to measure changes in stream concentration at high temporal frequencies that historically have not been feasible. In this study, we used multiparameter sensor measurements to relate assimilatory NO3– uptake to metabolic rates and calculate continuous uptake rates for two stream reaches and a whole stream network. Two years of continuous 15 min data from a forest and agricultural reach of the Selke river (456 km2) revealed a strong correlation between assimilatory NO3– uptake and growth primary production (GPP) for the forest (r2 = 0.72) and agricultural (r2 = 0.56) stream reach. The slopes of these regressions were in agreement with predicted assimilatory N-uptake based on additional metabolic data. Mean yearly assimilatory NO3– uptake rates (Ua) were 7.4 times higher in the agricultural stream reach (mean 78.3 mg N m–2 d–1, max 270 mg N m–2 d–1) than in the forest stream reach (mean 10.7 mg N m–2 d–1, max 97.5 mg N m–2 d–1). Nitrate uptake velocities (Vf,a) tended to decrease with increasing nitrate concentrations for periods with high light availability. Percentage daily assimilatory NO3– uptake peaked at 47.4% of the daily NO3– loading input to the stream network across the entire watershed, whereas the percentage yearly assimilatory NO3– uptake was 9.0% of nitrogen loading to the stream network. This is a maximum because uptake can be revered by mineralization processes. The percentage yearly assimilatory NO3– uptake was lower in the forest-dominated upstream subwatershed (4.8%) than in the lower agriculture dominated subwatershed (13.4%).
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Peipoch M, Gacia E, Bastias E, Serra A, Proia L, Ribot M, Merbt SN, Martí E. Small-scale heterogeneity of microbial N uptake in streams and its implications at the ecosystem level. Ecology 2016; 97:1329-44. [DOI: 10.1890/15-1210.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Marc Peipoch
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
| | - Esperança Gacia
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
| | - Elliot Bastias
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
| | - Alexandra Serra
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
| | - Lorenzo Proia
- Catalan Institute for Water Research; Scientific and Technological Park of the University of Girona; Girona 17003 Spain
| | - Miquel Ribot
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
| | - Stephanie N. Merbt
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
| | - Eugènia Martí
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Blanes 17300 Spain
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Webster JR, Knoepp JD, Swank WT, Miniat CF. Evidence for a Regime Shift in Nitrogen Export from a Forested Watershed. Ecosystems 2016. [DOI: 10.1007/s10021-016-9974-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Lupon A, Martí E, Sabater F, Bernal S. Green light: gross primary production influences seasonal stream N export by controlling fine-scale N dynamics. Ecology 2016; 97:133-44. [DOI: 10.1890/14-2296.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Anna Lupon
- Department d'Ecologia; Facultat de Biologia; Universitat de Barcelona; Av. Diagonal 643 08028 Barcelona Spain
| | - Eugènia Martí
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Accés a la Cala Sant Francesc 14 17300 Blanes Girona Spain
| | - Francesc Sabater
- Department d'Ecologia; Facultat de Biologia; Universitat de Barcelona; Av. Diagonal 643 08028 Barcelona Spain
| | - Susana Bernal
- Department d'Ecologia; Facultat de Biologia; Universitat de Barcelona; Av. Diagonal 643 08028 Barcelona Spain
- Integrative Freshwater Ecology Group; Center for Advanced Studies of Blanes (CEAB-CSIC); Accés a la Cala Sant Francesc 14 17300 Blanes Girona Spain
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von Schiller D, Aristi I, Ponsatí L, Arroita M, Acuña V, Elosegi A, Sabater S. Regulation causes nitrogen cycling discontinuities in Mediterranean rivers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 540:168-177. [PMID: 26233271 DOI: 10.1016/j.scitotenv.2015.07.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 07/04/2015] [Accepted: 07/04/2015] [Indexed: 06/04/2023]
Abstract
River regulation has fundamentally altered large sections of the world's river networks. The effects of dams on the structural properties of downstream reaches are well documented, but less is known about their effect on river ecosystem processes. We investigated the effect of dams on river nutrient cycling by comparing net uptake of total dissolved nitrogen (TDN), phosphorus (TDP) and organic carbon (DOC) in river reaches located upstream and downstream from three reservoir systems in the Ebro River basin (NE Iberian Peninsula). Increased hydromorphological stability, organic matter standing stocks and ecosystem metabolism below dams enhanced the whole-reach net uptake of TDN, but not that of TDP or DOC. Upstream from dams, river reaches tended to be at biogeochemical equilibrium (uptake≈release) for all nutrients, whereas river reaches below dams acted as net sinks of TDN. Overall, our results suggest that flow regulation by dams may cause relevant N cycling discontinuities in rivers. Higher net N uptake capacity below dams could lead to reduced N export to downstream ecosystems. Incorporating these discontinuities could significantly improve predictive models of N cycling and transport in complex river networks.
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Affiliation(s)
- Daniel von Schiller
- Catalan Institut e for Water Research, Carrer d'Emili Grahit, 101, 17003 Girona, Spain.
| | - Ibon Aristi
- Faculty of Science and Technology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain.
| | - Lídia Ponsatí
- Catalan Institut e for Water Research, Carrer d'Emili Grahit, 101, 17003 Girona, Spain.
| | - Maite Arroita
- Faculty of Science and Technology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain.
| | - Vicenç Acuña
- Catalan Institut e for Water Research, Carrer d'Emili Grahit, 101, 17003 Girona, Spain.
| | - Arturo Elosegi
- Faculty of Science and Technology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain.
| | - Sergi Sabater
- Catalan Institut e for Water Research, Carrer d'Emili Grahit, 101, 17003 Girona, Spain; Institute of Aquatic Ecology, University of Girona, Campus de Montilivi 17071, Girona, Spain.
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20
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Zeglin LH. Stream microbial diversity in response to environmental changes: review and synthesis of existing research. Front Microbiol 2015; 6:454. [PMID: 26042102 PMCID: PMC4435045 DOI: 10.3389/fmicb.2015.00454] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 04/27/2015] [Indexed: 01/25/2023] Open
Abstract
The importance of microbial activity to ecosystem function in aquatic ecosystems is well established, but microbial diversity has been less frequently addressed. This review and synthesis of 100s of published studies on stream microbial diversity shows that factors known to drive ecosystem processes, such as nutrient availability, hydrology, metal contamination, contrasting land-use and temperature, also cause heterogeneity in bacterial diversity. Temporal heterogeneity in stream bacterial diversity was frequently observed, reflecting the dynamic nature of both stream ecosystems and microbial community composition. However, within-stream spatial differences in stream bacterial diversity were more commonly observed, driven specifically by different organic matter (OM) compartments. Bacterial phyla showed similar patterns in relative abundance with regard to compartment type across different streams. For example, surface water contained the highest relative abundance of Actinobacteria, while epilithon contained the highest relative abundance of Cyanobacteria and Bacteroidetes. This suggests that contrasting physical and/or nutritional habitats characterized by different stream OM compartment types may select for certain bacterial lineages. When comparing the prevalence of physicochemical effects on stream bacterial diversity, effects of changing metal concentrations were most, while effects of differences in nutrient concentrations were least frequently observed. This may indicate that although changing nutrient concentrations do tend to affect microbial diversity, other environmental factors are more likely to alter stream microbial diversity and function. The common observation of connections between ecosystem process drivers and microbial diversity suggests that microbial taxonomic turnover could mediate ecosystem-scale responses to changing environmental conditions, including both microbial habitat distribution and physicochemical factors.
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Affiliation(s)
- Lydia H Zeglin
- Division of Biology, Kansas State University Manhattan, KS, USA
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21
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Cross WF, Hood JM, Benstead JP, Huryn AD, Nelson D. Interactions between temperature and nutrients across levels of ecological organization. GLOBAL CHANGE BIOLOGY 2015; 21:1025-40. [PMID: 25400273 DOI: 10.1111/gcb.12809] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 10/06/2014] [Indexed: 05/04/2023]
Abstract
Temperature and nutrient availability play key roles in controlling the pathways and rates at which energy and materials move through ecosystems. These factors have also changed dramatically on Earth over the past century as human activities have intensified. Although significant effort has been devoted to understanding the role of temperature and nutrients in isolation, less is known about how these two factors interact to influence ecological processes. Recent advances in ecological stoichiometry and metabolic ecology provide a useful framework for making progress in this area, but conceptual synthesis and review are needed to help catalyze additional research. Here, we examine known and potential interactions between temperature and nutrients from a variety of physiological, community, and ecosystem perspectives. We first review patterns at the level of the individual, focusing on four traits--growth, respiration, body size, and elemental content--that should theoretically govern how temperature and nutrients interact to influence higher levels of biological organization. We next explore the interactive effects of temperature and nutrients on populations, communities, and food webs by synthesizing information related to community size spectra, biomass distributions, and elemental composition. We use metabolic theory to make predictions about how population-level secondary production should respond to interactions between temperature and resource supply, setting up qualitative predictions about the flows of energy and materials through metazoan food webs. Last, we examine how temperature-nutrient interactions influence processes at the whole-ecosystem level, focusing on apparent vs. intrinsic activation energies of ecosystem processes, how to represent temperature-nutrient interactions in ecosystem models, and patterns with respect to nutrient uptake and organic matter decomposition. We conclude that a better understanding of interactions between temperature and nutrients will be critical for developing realistic predictions about ecological responses to multiple, simultaneous drivers of global change, including climate warming and elevated nutrient supply.
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Affiliation(s)
- Wyatt F Cross
- Department of Ecology, Montana State University, Bozeman, MT, 59717, USA
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23
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Huryn AD, Benstead JP, Parker SM. Seasonal changes in light availability modify the temperature dependence of ecosystem metabolism in an arctic stream. Ecology 2014. [DOI: 10.1890/13-1963.1] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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24
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Humphries P, Keckeis H, Finlayson B. The River Wave Concept: Integrating River Ecosystem Models. Bioscience 2014. [DOI: 10.1093/biosci/biu130] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Northington RM, Webster JR, Benfield EF, Cheever BM, Niederlehner BR. Ecosystem function in Appalachian headwater streams during an active invasion by the hemlock woolly adelgid. PLoS One 2013; 8:e61171. [PMID: 23613803 PMCID: PMC3632569 DOI: 10.1371/journal.pone.0061171] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 03/07/2013] [Indexed: 12/01/2022] Open
Abstract
Forested ecosystems in the southeastern United States are currently undergoing an invasion by the hemlock woolly adelgid (HWA). Previous studies in this area have shown changes to forest structure, decreases in canopy cover, increases in organic matter, and changes to nutrient cycling on the forest floor and soil. Here, we were interested in how the effects of canopy loss and nutrient leakage from terrestrial areas would translate into functional changes in streams draining affected watersheds. We addressed these questions in HWA-infested watersheds at the Coweeta Hydrologic Laboratory in North Carolina. Specifically, we measured stream metabolism (gross primary production and ecosystem respiration) and nitrogen uptake from 2008 to 2011 in five streams across the Coweeta basin. Over the course of our study, we found no change to in-stream nutrient concentrations. While canopy cover decreased annually in these watersheds, this change in light penetration did not translate to higher rates of in-stream primary production during the summer months of our study. We found a trend towards greater heterotrophy within our watersheds, where in-stream respiration accounted for a much larger component of net ecosystem production than GPP. Additionally, increases in rhododendron cover may counteract changes in light and nutrient availability that occurred with hemlock loss. The variability in our metabolic and uptake parameters suggests an actively-infested ecosystem in transition between steady states.
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Affiliation(s)
- Robert M Northington
- Virginia Polytechnic Institute and State University, Department of Biological Sciences, Blacksburg, Virginia, USA.
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Sobota DJ, Johnson SL, Gregory SV, Ashkenas LR. A Stable Isotope Tracer Study of the Influences of Adjacent Land Use and Riparian Condition on Fates of Nitrate in Streams. Ecosystems 2011. [DOI: 10.1007/s10021-011-9489-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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Finlay JC. Stream size and human influences on ecosystem production in river networks. Ecosphere 2011. [DOI: 10.1890/es11-00071.1] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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29
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Brookshire ENJ, Valett HM, Gerber S. Maintenance of terrestrial nutrient loss signatures during in-stream transport. Ecology 2009; 90:293-9. [DOI: 10.1890/08-0949.1] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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