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Erdozain M, Cardil A, de-Miguel S. Fire impacts on the biology of stream ecosystems: A synthesis of current knowledge to guide future research and integrated fire management. GLOBAL CHANGE BIOLOGY 2024; 30:e17389. [PMID: 38984506 DOI: 10.1111/gcb.17389] [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: 12/11/2023] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 07/11/2024]
Abstract
Freshwater ecosystems host disproportionately high biodiversity and provide unique ecosystem services, yet they are being degraded at an alarming rate. Fires, which are becoming increasingly frequent and intense due to global change, can affect these ecosystems in many ways, but this relationship is not fully understood. We conducted a systematic review to characterize the literature on the effects of fires on stream ecosystems and found that (1) abiotic indicators were more commonly investigated than biotic ones, (2) most previous research was conducted in North America and in the temperate evergreen forest biome, (3) following a control-impact (CI) or before-after (BA) design, (4) predominantly assessing wildfires as opposed to prescribed fires, (5) in small headwater streams, and (6) with a focus on structural and not functional biological indicators. After quantitatively analyzing previous research, we detected great variability in responses, with increases, decreases, and no changes being reported for most indicators (e.g., macroinvertebrate richness, fish density, algal biomass, and leaf decomposition). We shed light on these seemingly contradicting results by showing that the presence of extreme hydrological post-fire events, the time lag between fire and sampling, and whether the riparian forest burned or not influenced the outcome of previous research. Results suggest that although wildfires and the following hydrological events can have dramatic impacts in the short term, most biological endpoints recover within 5-10 years, and that detrimental effects are minimal in the case of prescribed fires. We also detected that no effects were more often reported by BACI studies than by CI or BA studies, raising the question of whether this research field may be biased by the inherent limitations of CI and BA designs. Finally, we make recommendations to help advance this field of research and guide future integrated fire management that includes the protection of freshwater ecosystems.
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Affiliation(s)
- Maitane Erdozain
- Forest Science and Technology Centre of Catalonia, Solsona, Spain
| | - Adrián Cardil
- Forest Science and Technology Centre of Catalonia, Solsona, Spain
- Department of Agricultural and Forest Sciences and Engineering, University of Lleida, Lleida, Spain
- Technosylva Inc, La Jolla, California, USA
| | - Sergio de-Miguel
- Department of Agricultural and Forest Sciences and Engineering, University of Lleida, Lleida, Spain
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Herring G, Tennant LB, Willacker JJ, Johnson M, Siegel RB, Polasik JS, Eagles-Smith CA. Wildfire burn severity and stream chemistry influence aquatic invertebrate and riparian avian mercury exposure in forested ecosystems. ECOTOXICOLOGY (LONDON, ENGLAND) 2024; 33:131-141. [PMID: 38381206 DOI: 10.1007/s10646-024-02730-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/08/2024] [Indexed: 02/22/2024]
Abstract
Terrestrial soils in forested landscapes represent some of the largest mercury (Hg) reserves globally. Wildfire can alter the storage and distribution of terrestrial-bound Hg via reemission to the atmosphere or mobilization in watersheds where it may become available for methylation and uptake into food webs. Using data associated with the 2007 Moonlight and Antelope Fires in California, we examined the long-term direct effects of wildfire burn severity on the distribution and magnitude of Hg concentrations in riparian food webs. Additionally, we quantified the cross-ecosystem transfer of Hg from aquatic invertebrate to riparian bird communities; and assessed the influence of biogeochemical, landscape variables, and ecological factors on Hg concentrations in aquatic and terrestrial food webs. Benthic macroinvertebrate methylmercury (MeHg) and riparian bird blood total mercury (THg) concentrations varied by 710- and 760-fold, respectively, and Hg concentrations were highest in predators. We found inconsistent relationships between Hg concentrations across and within taxa and guilds in response to stream chemical parameters and burn severity. Macroinvertebrate scraper MeHg concentrations were influenced by dissolved organic carbon (DOC); however, that relationship was moderated by burn severity (as burn severity increased the effect of DOC declined). Omnivorous bird Hg concentrations declined with increasing burn severity. Overall, taxa more linked to in situ energetic pathways may be more responsive to the biogeochemical processes that influence MeHg cycling. Remarkably, 8 years post-fire, we still observed evidence of burn severity influencing Hg concentrations within riparian food webs, illustrating its overarching role in altering the storage and redistribution of Hg and influencing biogeochemical processes.
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Affiliation(s)
- Garth Herring
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, 97331, USA.
| | - Lora B Tennant
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, 97331, USA
- Nez Perce Tribe, Department of Fisheries Resource Management, Joseph, OR, 97846, USA
| | - James J Willacker
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, 97331, USA
| | - Matthew Johnson
- National Park Service, Inventory & Monitoring Division, Southern Colorado Plateau Network, Flagstaff, AZ, 86001, USA
| | - Rodney B Siegel
- The Institute for Bird Populations, Petaluma, CA, 94953, USA
| | - Julia S Polasik
- The Institute for Bird Populations, Petaluma, CA, 94953, USA
- Teton Raptor Center, Wilson, WY, 83014, USA
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, 97331, USA
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Negrazis L, Kidd KA, Erdozain M, Emilson EJS, Mitchell CPJ, Gray MA. Effects of forest management on mercury bioaccumulation and biomagnification along the river continuum. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 310:119810. [PMID: 35940481 DOI: 10.1016/j.envpol.2022.119810] [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: 02/07/2022] [Revised: 07/15/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
Forest management can alter the mobilization of mercury (Hg) into headwater streams and its conversion to methylmercury (MeHg), the form that bioaccumulates in aquatic biota and biomagnifies through food webs. As headwater streams are important sources of organic materials and nutrients to larger systems, this connectivity may also increase MeHg in downstream biota through direct or indirect effects of forestry on water quality or food web structure. In this study, we collected water, seston, food sources (biofilm, leaves, organic matter), five macroinvertebrate taxa and fish (slimy sculpin; Cottus cognata) at 6 sites representing different stream orders (1-5) within three river basins with different total disturbances from forestry (both harvesting and silviculture). Methylmercury levels were highest in water and some food sources from the basin with moderate disturbance (greater clearcutting but less silviculture). Water, leaves, stoneflies and fish increased in MeHg or total Hg along the river continuum in the least disturbed basin, and there were some dissipative effects of forest management on these spatial patterns. Trophic level (δ15N) was a significant predictor of MeHg (and total Hg in fish) within food webs across all 18 sites, and biomagnification slopes were significantly lower in the basin with moderate total disturbance but not different in the other two basins. The elevated MeHg in lower trophic levels but its reduced trophic transfer in the basin with moderate disturbance was likely due to greater inputs of sediments and of dissolved organic carbon that is more humic, as these factors are known to both increase transport of Hg to streams and its uptake in primary producers but to also decrease MeHg bioaccumulation in consumers. Overall, these results suggest that the type of disturbance from forestry affects MeHg bioaccumulation and trophic transfer in stream food webs and some longitudinal patterns along a river continuum.
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Affiliation(s)
- Lauren Negrazis
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Karen A Kidd
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada; School of Earth, Environment and Society, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada.
| | - Maitane Erdozain
- Canadian Rivers Institute and Biology Department, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada
| | - Erik J S Emilson
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Carl P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | - Michelle A Gray
- Canadian Rivers Institute, Faculty of Forestry and Environmental Management, University of New Brunswick, 28 Dineen Drive, Fredericton, New Brunswick E3B 5A3, Canada
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Roon DA, Dunham JB, Bellmore JR, Olson DH, Harvey BC. Influence of riparian thinning on trophic pathways supporting stream food webs in forested watersheds. Ecosphere 2022. [DOI: 10.1002/ecs2.4219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- David A. Roon
- Department of Fisheries, Wildlife, and Conservation Sciences Oregon State University Corvallis Oregon USA
- Department of Forest Engineering, Resources and Management Oregon State University Corvallis Oregon USA
| | - Jason B. Dunham
- Forest and Rangeland Ecosystem Science Center US Geological Survey Corvallis Oregon USA
| | - J. Ryan Bellmore
- Pacific Northwest Research Station USDA Forest Service Juneau Alaska USA
| | - Deanna H. Olson
- Pacific Northwest Research Station USDA Forest Service Corvallis Oregon USA
| | - Bret C. Harvey
- Pacific Southwest Research Station USDA Forest Service Arcata California USA
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Charbonneau KL, Kidd KA, Kreutzweiser DP, Sibley PK, Emilson EJS, O'Driscoll NJ, Gray MA. Are There Longitudinal Effects of Forest Harvesting on Carbon Quality and Flow and Methylmercury Bioaccumulation in Primary Consumers of Temperate Stream Networks? ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:1490-1507. [PMID: 35297511 DOI: 10.1002/etc.5330] [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: 11/07/2021] [Revised: 12/23/2021] [Accepted: 03/12/2022] [Indexed: 06/14/2023]
Abstract
Forest harvesting affects dissolved organic matter (DOM) and aqueous mercury inputs as well as the food web structure in small-headwater streams, but how these upstream changes manifest downstream is unclear. To address this uncertainty, we examined DOM quality, autochthony in the caddisfly Hydropsychidae (using δ2 H), and methylmercury (MeHg) concentrations in stream water and the caddisfly along a longitudinal gradient (first- to fourth-order streams, subcatchments of 50-1900 ha) in paired partially harvested and reference catchments in central Ontario, Canada. Although measures of DOM quality (specific ultraviolet absorbance at 254 nm 2.20-11.62) and autochthony in caddisflies (4.9%-34.0%) varied among sites, no upstream-to-downstream differences in these measures were observed between the paired harvested and reference catchments. In contrast, MeHg levels in stream water (0.06-0.35 ng/L) and caddisflies (29.7-192 µg/kg dry wt) were significantly higher in the upstream sites but not the farthest downstream sites in the harvested catchments compared to the reference catchments. This suggests that while current mitigation measures used by forestry companies did not prevent elevated MeHg in water and invertebrates at smaller spatial scales (subcatchments of 50-400 ha), these upstream impacts did not manifest at larger spatial scales (subcatchments of 800-1900 ha). The present study advances our understanding of spatially cumulative impacts within harvested catchments, which is critical to help forest managers maintain healthy forest streams and their provisioning of aquatic ecosystem services. Environ Toxicol Chem 2022;41:1490-1507. © 2022 SETAC.
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Affiliation(s)
- Kelli L Charbonneau
- Department of Biological Sciences & Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, Canada
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Karen A Kidd
- Department of Biological Sciences & Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, Canada
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
- School of Earth, Environment and Society, McMaster University, Hamilton, Ontario, Canada
| | - David P Kreutzweiser
- Great Lakes Forestry Centre, Canadian Forest Service, Natural Resources Canada, Sault Ste. Marie, Ontario, Canada
| | - Paul K Sibley
- School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Erik J S Emilson
- Great Lakes Forestry Centre, Canadian Forest Service, Natural Resources Canada, Sault Ste. Marie, Ontario, Canada
| | - Nelson J O'Driscoll
- Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada
| | - Michelle A Gray
- Faculty of Forestry and Environmental Management & Canadian Rivers Institute, University of New Brunswick, Fredericton, New Brunswick, Canada
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Elevated Allochthony in Stream Food Webs as a Result of Longitudinal Cumulative Effects of Forest Management. Ecosystems 2021; 25:1311-1327. [PMID: 36187364 PMCID: PMC9519712 DOI: 10.1007/s10021-021-00717-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/27/2021] [Indexed: 11/13/2022]
Abstract
The river continuum concept (RCC) predicts a downstream shift in the reliance of aquatic consumers from terrestrial to aquatic carbon sources, but this concept has rarely been assessed with longitudinal studies. Similarly, there are no studies addressing how forestry related disturbances to the structure of headwater food webs manifest (accumulate/dissipate) downstream and/or whether forest management alters natural longitudinal trends predicted by the RCC. Using stable isotopes of carbon, nitrogen and hydrogen, we investigated how: 1) autochthony in macroinvertebrates and fish change from small streams to larger downstream sites within a basin with minimal forest management (New Brunswick, Canada); 2) longitudinal trends in autochthony and food web length compare among three basins with different forest management intensity [intensive (harvest and replanting), extensive (harvest only), minimal] to detect potential cumulative/dissipative effects; and 3) forest management intensity and other catchment variables are influencing food web dynamics. We showed that, as predicted, the reliance of some macroinvertebrate taxa (especially collector feeders) on algae increased from small streams to downstream waters in the minimally managed basin, but that autochthony in the smallest shaded stream was higher than expected based on the RCC (as high as 90% for some taxa). However, this longitudinal increase in autochthony was not observed within the extensively managed basin and was weaker within the intensively managed one, suggesting that forest management can alter food web dynamics along the river continuum. The dampening of downstream autochthony indicates that the increased allochthony observed in small streams in response to forest harvesting cumulates downstream through the river continuum.
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Erdozain M, Kidd KA, Emilson EJS, Capell SS, Luu T, Kreutzweiser DP, Gray MA. Forest management impacts on stream integrity at varying intensities and spatial scales: Do biological effects accumulate spatially? THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 763:144043. [PMID: 33383512 DOI: 10.1016/j.scitotenv.2020.144043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
The effects of forest harvesting on headwaters are quite well understood, yet our understanding of whether impacts accumulate or dissipate downstream is limited. To address this, we investigated whether several biotic indicators changed from smaller to larger downstream sites (n = 6) within three basins that had intensive, extensive or minimal forest management in New Brunswick (Canada). Biofilm biomass and grazer abundance significantly increased from upstream to downstream, whereas organic matter decomposition and the autotrophic index of biofilms decreased. However, some spatial trends differed among basins and indicated either cumulative (macroinvertebrate abundance, predator density, sculpin GSI) or dissipative (autotrophic index, cotton decomposition) effects downstream, potentially explained by sediment and nutrient dynamics related to harvesting. No such among-basin differences were observed for leaf decomposition, biofilm biomass, macroinvertebrate richness or sculpin condition. Additionally, results suggest that some of the same biological impacts of forestry observed in small headwaters also occurred in larger systems. Although the intensive and extensive basins had lower macroinvertebrate diversity, there were no other signs of biological impairment, suggesting that, overall, current best management practices protect biological integrity downstream despite abiotic effects.
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Affiliation(s)
- Maitane Erdozain
- Canadian Rivers Institute and Biology Department, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada.
| | - Karen A Kidd
- Canadian Rivers Institute and Biology Department, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada; Department of Biology and School of Earth, Environment and Society, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Erik J S Emilson
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Scott S Capell
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Taylor Luu
- Department of Biology and School of Earth, Environment and Society, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - David P Kreutzweiser
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Michelle A Gray
- Canadian Rivers Institute and Faculty of Forestry and Environmental Management, University of New Brunswick, 28 Dineen Drive, Fredericton, New Brunswick E3B 5A3, Canada
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Kuglerová L, Hasselquist EM, Sponseller RA, Muotka T, Hallsby G, Laudon H. Multiple stressors in small streams in the forestry context of Fennoscandia: The effects in time and space. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 756:143521. [PMID: 33243494 DOI: 10.1016/j.scitotenv.2020.143521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/29/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
In this paper we describe how forest management practices in Fennoscandian countries, namely Sweden and Finland, expose streams to multiple stressors over space and time. In this region, forestry includes several different management actions and we explore how these may successively disturb the same location over 60-100 year long rotation periods. Of these actions, final harvest and associated road construction, soil scarification, and/or ditch network maintenance are the most obvious sources of stressors to aquatic ecosystems. Yet, more subtle actions such as planting, thinning of competing saplings and trees, and removing logging residues also represent disturbances around waterways in these landscapes. We review literature about how these different forestry practices may introduce a combination of physicochemical stressors, including hydrological change, increased sediment transport, altered thermal and light regimes, and water quality deterioration. We further elaborate on how the single stressors may combine and interact and we consequently hypothesise how these interactions may affect aquatic communities and processes. Because production forestry is practiced on a large area in both countries, the various stressors appear multiple times during the rotation cycles and potentially affect the majority of the stream network length within most catchments. We concluded that forestry practices have traditionally not been the focus of multiple stressor studies and should be investigated further in both observational and experimental fashion. Stressors accumulate across time and space in forestry dominated landscapes, and may interact in unpredictable ways, limiting our current understanding of what forested stream networks are exposed to and how we can design and apply best management practices.
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Affiliation(s)
- Lenka Kuglerová
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
| | - Eliza Maher Hasselquist
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden; Water Quality Impacts Unit, Natural Resources Institute Finland, Helsinki, Finland
| | | | - Timo Muotka
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland; Finnish Environment Institute, Freshwater Centre, Oulu, Finland
| | - Göran Hallsby
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Hjalmar Laudon
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
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Erdozain M, Kidd KA, Emilson EJS, Capell SS, Kreutzweiser DP, Gray MA. Forest management impacts on stream integrity at varying intensities and spatial scales: Do abiotic effects accumulate spatially? THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 753:141968. [PMID: 32911166 DOI: 10.1016/j.scitotenv.2020.141968] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/21/2020] [Accepted: 08/23/2020] [Indexed: 06/11/2023]
Abstract
Though effects of forest harvesting on small streams are well documented, little is known about the cumulative effects in downstream systems. The hierarchical nature and longitudinal connectivity of river networks make them fundamentally cumulative, but lateral and vertical connectivity and instream processes can dissipate the downstream transport of water and materials. To elucidate such effects, we investigated how a suite of abiotic indicators changed from small streams to larger downstream sites (n = 6) within three basins ranging in forest management intensity (intensive, extensive, minimal) in New Brunswick (Canada) in the summer and fall of 2017 and 2018. Inorganic sediments, the inorganic/organic ratios and water temperatures significantly increased longitudinally, whereas nutrients and the fluorescence index of dissolved organic carbon (DOC; indication of terrestrial source) decreased. However, some longitudinal trends differed across basins and indicated downstream cumulative (inorganic sediments, the inorganic/organic ratios and to a lesser extent DOC concentration and humification) as well as dissipative (temperatures, nutrients, organic sediments) effects of forest management. Overall, we found that the effects previously reported for small streams with managed forests also occur at downstream sites and suggest investigating whether different management practices can be used within the extensive basin to reduce these cumulative effects.
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Affiliation(s)
- Maitane Erdozain
- Canadian Rivers Institute and Biology Department, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada.
| | - Karen A Kidd
- Canadian Rivers Institute and Biology Department, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada; Department of Biology, School of Earth, Environment and Society, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Erik J S Emilson
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Scott S Capell
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - David P Kreutzweiser
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Michelle A Gray
- Canadian Rivers Institute, Faculty of Forestry and Environmental Management, University of New Brunswick, 28 Dineen Drive, Fredericton, New Brunswick E3B 5A3, Canada
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Chételat J, Ackerman JT, Eagles-Smith CA, Hebert CE. Methylmercury exposure in wildlife: A review of the ecological and physiological processes affecting contaminant concentrations and their interpretation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 711:135117. [PMID: 31831233 DOI: 10.1016/j.scitotenv.2019.135117] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/15/2019] [Accepted: 10/21/2019] [Indexed: 05/12/2023]
Abstract
Exposure to methylmercury (MeHg) can result in detrimental health effects in wildlife. With advances in ecological indicators and analytical techniques for measurement of MeHg in a variety of tissues, numerous processes have been identified that can influence MeHg concentrations in wildlife. This review presents a synthesis of theoretical principals and applied information for measuring MeHg exposure and interpreting MeHg concentrations in wildlife. Mercury concentrations in wildlife are the net result of ecological processes influencing dietary exposure combined with physiological processes that regulate assimilation, transformation, and elimination. Therefore, consideration of both physiological and ecological processes should be integrated when formulating biomonitoring strategies. Ecological indicators, particularly stable isotopes of carbon, nitrogen, and sulfur, compound-specific stable isotopes, and fatty acids, can be effective tools to evaluate dietary MeHg exposure. Animal species differ in their physiological capacity for MeHg elimination, and animal tissues can be inert or physiologically active, act as sites of storage, transformation, or excretion of MeHg, and vary in the timing of MeHg exposure they represent. Biological influences such as age, sex, maternal transfer, and growth or fasting are also relevant for interpretation of tissue MeHg concentrations. Wildlife tissues that represent current or near-term bioaccumulation and in which MeHg is the predominant mercury species (such as blood and eggs) are most effective for biomonitoring ecosystems and understanding landscape drivers of MeHg exposure. Further research is suggested to critically evaluate the use of keratinized external tissues to measure MeHg bioaccumulation, particularly for less-well studied wildlife such as reptiles and terrestrial mammals. Suggested methods are provided to effectively use wildlife for quantifying patterns and drivers of MeHg bioaccumulation over time and space, as well as for assessing the potential risk and toxicological effects of MeHg on wildlife.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada.
| | - Joshua T Ackerman
- U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA 95620, United States
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, United States
| | - Craig E Hebert
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada
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