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McDowell R, Kleinman PJA, Haygarth P, McGrath JM, Smith D, Heathwaite L, Iho A, Schoumans O, Nash D. A review of the development and implementation of the critical source area concept: A reflection of Andrew Sharpley's role in improving water quality. JOURNAL OF ENVIRONMENTAL QUALITY 2024. [PMID: 38418931 DOI: 10.1002/jeq2.20551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/21/2024] [Accepted: 01/31/2024] [Indexed: 03/02/2024]
Abstract
Critical source areas (CSAs) are small areas of a field, farm, or catchment that account for most contaminant loss by having both a high contaminant availability and transport potential. Most work on CSAs has focused on phosphorus (P), largely through the work in the 1990s initiated by Dr. Sharpley and colleagues who recognized the value in targeting mitigation efforts. The CSA concept has been readily grasped by scientists, farmers, and policymakers across the globe. However, experiences and success have been mixed, often caused by the variation in where and how CSAs are defined. For instance, analysis of studies from 1990 to 2023 shows that the proportion of the annual contaminant load coming from a CSA decreases from field to farm to catchment scale. This finding is consistent with increased buffering of CSAs and greater contribution of other sources with scale, or variation in the definition of CSAs. We therefore argue that the best application of CSAs to target mitigation actions should be at small areas that truly account for most contaminant loss. This article sheds light on the development and utilization of CSAs, paying tribute to Dr. Sharpley's remarkable contributions to the improvement of water quality, and reflecting upon where the CSA concept has succeeded or not in reducing contaminant (largely P) loss.
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Affiliation(s)
- Richard McDowell
- AgResearch, Lincoln Science Centre, Lincoln, New Zealand
- Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, New Zealand
| | | | | | | | - Douglas Smith
- USDA Agricultural Research Service, Temple, Texas, USA
| | | | - Antti Iho
- LUKE, Natural Resources Institute Finland, Helsinki, Finland
| | - Oscar Schoumans
- Wageningen University and Research, Wageningen, The Netherlands
| | - David Nash
- University of Melbourne, Melbourne, Victoria, Australia
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Lin J, Compton JE, Sabo RD, Herlihy AT, Hill RA, Weber MH, Brooks JR, Paulsen SG, Stoddard JL. The changing nitrogen landscape of United States streams: Declining deposition and increasing organic nitrogen. PNAS NEXUS 2024; 3:pgad362. [PMID: 38213613 PMCID: PMC10783649 DOI: 10.1093/pnasnexus/pgad362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 10/14/2023] [Accepted: 10/26/2023] [Indexed: 01/13/2024]
Abstract
Air quality regulations have led to decreased nitrogen (N) and sulfur deposition across the conterminous United States (CONUS) during the last several decades, particularly in the eastern parts. But it is unclear if declining deposition has altered stream N at large scales. We compared watershed N inputs with N chemistry from over 2,000 CONUS streams where deposition was the largest N input to the watershed. Weighted change analysis showed that deposition declined across most watersheds, especially in the Eastern CONUS. Nationally, declining N deposition was not associated with significant large-scale declines in stream nitrate concentration. Instead, significant increases in stream dissolved organic carbon (DOC) and total organic N (TON) were widespread across regions. Possible mechanisms behind these increases include declines in acidity and/or ionic strength drivers, changes in carbon availability, and/or climate variables. Our results also reveal a declining trend of DOC/TON ratio over the entire study period, primarily influenced by the trend in the Eastern region, suggesting the rate of increase in stream TON exceeded the rate of increase in DOC concentration during this period. Our results illustrate the complexity of nutrient cycling that links long-term atmospheric deposition to water quality. More research is needed to understand how increased dissolved organic N could affect aquatic ecosystems and downstream riverine nutrient export.
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Affiliation(s)
- Jiajia Lin
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
- Oak Ridge Institute for Science and Education, Corvallis, OR 97333, USA
- Oregon Department of Environmental Quality, Water Quality Division, Portland, OR 97232, USA
| | - Jana E Compton
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - Robert D Sabo
- Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, Office of Research and Development, US Environmental Protection Agency, Washington, DC 20004, USA
| | - Alan T Herlihy
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
- Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Ryan A Hill
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - Marc H Weber
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - J Renée Brooks
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - Steve G Paulsen
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
| | - John L Stoddard
- Pacific Ecological Systems Division, Office of Research and Development, US Environmental Protection Agency, Corvallis, OR 97333, USA
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Wan L, Kendall AD, Martin SL, Hamlin QF, Hyndman DW. Important Role of Overland Flows and Tile Field Pathways in Nutrient Transport. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:17061-17075. [PMID: 37871005 PMCID: PMC10634344 DOI: 10.1021/acs.est.3c03741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/23/2023] [Accepted: 09/25/2023] [Indexed: 10/25/2023]
Abstract
Nitrogen and phosphorus pollution is of great concern to aquatic life and human well-being. While most of these nutrients are applied to the landscape, little is known about the complex interplay among nutrient applications, transport attenuation processes, and coastal loads. Here, we enhance and apply the Spatially Explicit Nutrient Source Estimate and Flux model (SENSEflux) to simulate the total annual nitrogen and phosphorus loads from the US Great Lakes Basin to the coastline, identify nutrient delivery hotspots, and estimate the relative contributions of different sources and pathways at a high resolution (120 m). In addition to in-stream uptake, the main novelty of this model is that SENSEflux explicitly describes nutrient attenuation through four distinct pathways that are seldom described jointly in other models: runoff from tile-drained agricultural fields, overland runoff, groundwater flow, and septic plumes within groundwater. Our analysis shows that agricultural sources are dominant for both total nitrogen (TN) (58%) and total phosphorus (TP) (46%) deliveries to the Great Lakes. In addition, this study reveals that the surface pathways (sum of overland flow and tile field drainage) dominate nutrient delivery, transporting 66% of the TN and 76% of the TP loads to the US Great Lakes coastline. Importantly, this study provides the first basin-wide estimates of both nonseptic groundwater (TN: 26%; TP: 5%) and septic-plume groundwater (TN: 4%; TP: 2%) deliveries of nutrients to the lakes. This work provides valuable information for environmental managers to target efforts to reduce nutrient loads to the Great Lakes, which could be transferred to other regions worldwide that are facing similar nutrient management challenges.
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Affiliation(s)
- Luwen Wan
- Department
of Earth and Environmental Sciences, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Anthony D. Kendall
- Department
of Earth and Environmental Sciences, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Sherry L. Martin
- Department
of Earth and Environmental Sciences, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Quercus F. Hamlin
- Department
of Earth and Environmental Sciences, Michigan
State University, East Lansing, Michigan 48824, United States
| | - David W. Hyndman
- Department
of Earth and Environmental Sciences, Michigan
State University, East Lansing, Michigan 48824, United States
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Lassiter MG, Lin J, Compton JE, Phelan J, Sabo RD, Stoddard JL, McDow SR, Greaver TL. Shifts in the composition of nitrogen deposition in the conterminous United States are discernable in stream chemistry. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 881:163409. [PMID: 37044336 PMCID: PMC10332341 DOI: 10.1016/j.scitotenv.2023.163409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/13/2023] [Accepted: 04/06/2023] [Indexed: 04/14/2023]
Abstract
Across the conterminous United States (U.S.), the composition of atmospheric nitrogen (N) deposition is changing spatially and temporally. Previously, deposition was dominated by oxidized N, but now reduced N (ammonia [NH3] + ammonium [NH4+]) is equivalent to oxidized N when deposition is averaged across the entire nation and, in some areas, reduced N dominates deposition. To evaluate if there are effects of this change on stream chemistry at the national scale, estimates of N deposition form (oxidized or reduced) from the National Atmospheric Deposition Program Total Deposition data were coupled with stream measurements from the U.S. Environmental Protection Agency (EPA) National Rivers and Streams Assessments (three stream surveys between 2000 and 2014). A recent fine-scaled N input inventory was used to identify watersheds (<1000 km2) where atmospheric deposition is the largest N source (n = 1906). Within these more atmospherically-influenced watersheds there was a clear temporal shift from a greater proportion of sites dominated by oxidized N deposition to a greater proportion of sites dominated by reduced forms of N deposition. We found a significant positive correlation between oxidized N deposition and stream NO3- concentrations, whereas the correlation between reduced N deposition and stream NO3- concentrations were significant but weaker. Sites dominated by atmospheric inputs of reduced N forms had higher stream total organic N and total N despite lower total N deposition on average. This higher stream concentration of total N is mainly driven by the higher concentration of total organic N, suggesting an interaction between elevated reduced N in deposition and living components of the ecosystem or soil organic matter dynamics. Regardless of the proportion of reduced to oxidized N forms in deposition, stream NH4+ concentrations were generally low, suggesting that N deposited in a reduced form is rapidly immobilized, nitrified and/or assimilated by watershed processes.
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Affiliation(s)
- Meredith G Lassiter
- United States Environmental Protection Agency (U.S. EPA), Office of Research and Development, Center for Public Health and Environmental Assessment, Health and Environmental Effects Assessment Division, 109 T.W. Alexander Dr. Research Triangle Park, NC 27709, United States.
| | - Jiajia Lin
- Oak Ridge Institute for Science and Education, Postdoctoral Participant, Corvallis, OR 97333, United States; U.S. EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - Jana E Compton
- U.S. EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - Jennifer Phelan
- RTI International, P.O. Box 12194, 3040 Cornwallis Rd., RTP, NC 27709, United States.
| | - Robert D Sabo
- US EPA Headquarters, Office of Research and Development, Center for Public Health and Environmental Assessment, Health and Environmental Effects Assessment Division, 1200 Penn Ave NW, Mailcode 8623-P, Washington, DC 20460, United States.
| | - John L Stoddard
- U.S. EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - Stephen R McDow
- United States Environmental Protection Agency (U.S. EPA), Office of Research and Development, Center for Public Health and Environmental Assessment, Health and Environmental Effects Assessment Division, 109 T.W. Alexander Dr. Research Triangle Park, NC 27709, United States.
| | - Tara L Greaver
- United States Environmental Protection Agency (U.S. EPA), Office of Research and Development, Center for Public Health and Environmental Assessment, Health and Environmental Effects Assessment Division, 109 T.W. Alexander Dr. Research Triangle Park, NC 27709, United States.
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5
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Severe E, Errigo IM, Proteau M, Sayedi SS, Kolbe T, Marçais J, Thomas Z, Petton C, Rouault F, Vautier C, de Dreuzy JR, Moatar F, Aquilina L, Wood RL, LaBasque T, Lécuyer C, Pinay G, Abbott BW. Deep denitrification: Stream and groundwater biogeochemistry reveal contrasted but connected worlds above and below. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 880:163178. [PMID: 37023812 DOI: 10.1016/j.scitotenv.2023.163178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 03/25/2023] [Accepted: 03/26/2023] [Indexed: 05/27/2023]
Abstract
Excess nutrients from agricultural and urban development have created a cascade of ecological crises around the globe. Nutrient pollution has triggered eutrophication in most freshwater and coastal ecosystems, contributing to a loss in biodiversity, harm to human health, and trillions in economic damage every year. Much of the research conducted on nutrient transport and retention has focused on surface environments, which are both easy to access and biologically active. However, surface characteristics of watersheds, such as land use and network configuration, often do not explain the variation in nutrient retention observed in rivers, lakes, and estuaries. Recent research suggests subsurface processes and characteristics may be more important than previously thought in determining watershed-level nutrient fluxes and removal. In a small watershed in western France, we used a multi-tracer approach to compare surface and subsurface nitrate dynamics at commensurate spatiotemporal scales. We combined 3-D hydrological modeling with a rich biogeochemical dataset from 20 wells and 15 stream locations. Water chemistry in the surface and subsurface showed high temporal variability, but groundwater was substantially more spatially variable, attributable to long transport times (10-60 years) and patchy distribution of the iron and sulfur electron donors fueling autotrophic denitrification. Isotopes of nitrate and sulfate revealed fundamentally different processes dominating the surface (heterotrophic denitrification and sulfate reduction) and subsurface (autotrophic denitrification and sulfate production). Agricultural land use was associated with elevated nitrate in surface water, but subsurface nitrate concentration was decoupled from land use. Dissolved silica and sulfate are affordable tracers of residence time and nitrogen removal that are relatively stable in surface and subsurface environments. Together, these findings reveal distinct but adjacent and connected biogeochemical worlds in the surface and subsurface. Characterizing how these worlds are linked and decoupled is critical to meeting water quality targets and addressing water issues in the Anthropocene.
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Affiliation(s)
- Emilee Severe
- Lancaster Environmental Centre, Lancaster University, Lancaster, UK; Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, USA
| | - Isabella M Errigo
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, USA; Grupo de Investigación en Biodiversidad, Medio Ambiente y Salud (BIOMAS), Facultad de Ingenierías y Ciencas Aplicadas, Universidad de Las Américas, Quito, Ecuador
| | - Mary Proteau
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, USA
| | - Sayedeh Sara Sayedi
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, USA
| | - Tamara Kolbe
- Section of Hydrogeology and Hydrochemistry, Institute of Geology, Faculty of Geoscience, Geoengineering and Mining, TU Bergakademie Freiberg, Freiberg, Germany
| | - Jean Marçais
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAe), RiverLy, Centre de Lyon-Villeurbanne, 69625 Villeurbanne, France
| | - Zahra Thomas
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAe), Sol Agro et Hydrosystème Spatialisation, UMR 1069, Agrocampus Ouest, 35042 Rennes, France
| | - Christophe Petton
- Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, 35000 Rennes, France
| | - François Rouault
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAe), Sol Agro et Hydrosystème Spatialisation, UMR 1069, Agrocampus Ouest, 35042 Rennes, France
| | - Camille Vautier
- Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, 35000 Rennes, France
| | - Jean-Raynald de Dreuzy
- Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, 35000 Rennes, France; Univ Rennes, CNRS, OSUR (Observatoire des sciences de l'univers de Rennes), UMS 3343, 35000 Rennes, France
| | - Florentina Moatar
- RiverLy, INRAE, Centre de Lyon-Grenoble Auvergne-Rhône-Alpes, Lyon, France
| | - Luc Aquilina
- Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, 35000 Rennes, France
| | - Rachel L Wood
- Department of Biology, Brigham Young University, Provo, UT, USA
| | - Thierry LaBasque
- Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, 35000 Rennes, France
| | | | - Gilles Pinay
- Environnement, Ville & Société (EVS UMR5600), Centre National de la Recherche Scientifique (CNRS), Lyon, France
| | - Benjamin W Abbott
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, USA.
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Lee RM, Griffin N, Jones E, Abbott BW, Frei RJ, Bratsman S, Proteau M, Errigo IM, Shogren A, Bowden WB, Zarnetske JP, Aanderud ZT. Bacterioplankton dispersal and biogeochemical function across Alaskan Arctic catchments. Environ Microbiol 2022; 24:5690-5706. [PMID: 36273269 DOI: 10.1111/1462-2920.16259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 10/21/2022] [Indexed: 01/12/2023]
Abstract
In Arctic catchments, bacterioplankton are dispersed through soils and streams, both of which freeze and thaw/flow in phase, seasonally. To characterize this dispersal and its potential impact on biogeochemistry, we collected bacterioplankton and measured stream physicochemistry during snowmelt and after vegetation senescence across multiple stream orders in alpine, tundra, and tundra-dominated-by-lakes catchments. In all catchments, differences in community composition were associated with seasonal thaw, then attachment status (i.e. free floating or sediment associated), and then stream order. Bacterioplankton taxonomic diversity and richness were elevated in sediment-associated fractions and in higher-order reaches during snowmelt. Families Chthonomonadaceae, Pyrinomonadaceae, and Xiphinematobacteraceae were abundantly different across seasons, while Flavobacteriaceae and Microscillaceae were abundantly different between free-floating and sediment-associated fractions. Physicochemical data suggested there was high iron (Fe+ ) production (alpine catchment); Fe+ production and chloride (Cl- ) removal (tundra catchment); and phosphorus (SRP) removal and ammonium (NH4 + ) production (lake catchment). In tundra landscapes, these 'hot spots' of Fe+ production and Cl- removal accompanied shifts in species richness, while SRP promoted the antecedent community. Our findings suggest that freshet increases bacterial dispersal from headwater catchments to receiving catchments, where bacterioplankton-mineral relations stabilized communities in free-flowing reaches, but bacterioplankton-nutrient relations stabilized those punctuated by lakes.
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Affiliation(s)
- Raymond M Lee
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Natasha Griffin
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvalis, Oregon, USA
| | - Erin Jones
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Benjamin W Abbott
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Rebecca J Frei
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Samuel Bratsman
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Mary Proteau
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Isabella M Errigo
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Arial Shogren
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, USA
| | - William B Bowden
- The Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont, USA
| | - Jay P Zarnetske
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, Michigan, USA
| | - Zachary T Aanderud
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
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Brain RA, Prosser RS. Human induced fish declines in North America, how do agricultural pesticides compare to other drivers? ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:66010-66040. [PMID: 35908028 PMCID: PMC9492596 DOI: 10.1007/s11356-022-22102-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/14/2022] [Indexed: 06/15/2023]
Abstract
Numerous anthropogenic factors, historical and contemporary, have contributed to declines in the abundance and diversity of freshwater fishes in North America. When Europeans first set foot on this continent some five hundred years ago, the environment was ineradicably changed. Settlers brought with them diseases, animals, and plants via the Columbian Exchange, from the old world to the new, facilitating a process of biological globalization. Invasive species were thus introduced into the Americas, displacing native inhabitants. Timber was felled for ship building and provisioning for agriculture, resulting in a mass land conversion for the purposes of crop cultivation. As European colonization expanded, landscapes were further modified to mitigate against floods and droughts via the building of dams and levees. Resources have been exploited, and native populations have been overfished to the point of collapse. The resultant population explosion has also resulted in wide-spread pollution of aquatic resources, particularly following the industrial and agricultural revolutions. Collectively, these activities have influenced the climate and the climate, in turn, has exacerbated the effects of these activities. Thus, the anthropogenic fingerprints are undeniable, but relatively speaking, which of these transformative factors has contributed most significantly to the decline of freshwater fishes in North America? This manuscript attempts to address this question by comparing and contrasting the preeminent drivers contributing to freshwater fish declines in this region in order to provide context and perspective. Ultimately, an evaluation of the available data makes clear that habitat loss, obstruction of streams and rivers, invasive species, overexploitation, and eutrophication are the most important drivers contributing to freshwater fish declines in North America. However, pesticides remain a dominant causal narrative in the popular media, despite technological advancements in pesticide development and regulation. Transitioning from organochlorines to organophosphates/carbamates, to pyrethroids and ultimately to the neonicotinoids, toxicity and bioaccumulation potential of pesticides have all steadily decreased over time. Concomitantly, regulatory frameworks designed to assess corresponding pesticide risks in Canada and the USA have become increasingly more stringent and intensive. Yet, comparatively, habitat loss continues unabated as agricultural land is ceded to the frontier of urban development, globalized commerce continues to introduce invasive species into North America, permanent barriers in the form of dams and levees remain intact, fish are still being extracted from native habitats (commercially and otherwise), and the climate continues to change. How then should we make sense of all these contributing factors? Here, we attempt to address this issue.
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Affiliation(s)
| | - Ryan Scott Prosser
- School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
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