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Boardman L. Cross-talk between low temperature and other environmental factors. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101193. [PMID: 38490451 DOI: 10.1016/j.cois.2024.101193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 03/07/2024] [Accepted: 03/11/2024] [Indexed: 03/17/2024]
Abstract
Low temperatures are rarely experienced in isolation. The impacts of low temperatures on insects can be exacerbated or alleviated by the addition of other environmental factors, including, for example, desiccation, hypoxia, or infection. One way in which environmental factors can interact is through cross-talk where different factors enact common signaling pathways. In this review, I highlight the breadth of abiotic and biotic factors that can interact with low-temperature tolerance in both natural and artificial environments; and discuss some of the candidate pathways that are possibly responsible for cross-talk between several factors. Specifically, I discuss three interesting candidates: the neurohormone octopamine, circadian clock gene vrille, and microbes. Finally, I discuss applications of cross-talk studies, and provide recommendations for researchers.
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Affiliation(s)
- Leigh Boardman
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA.
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2
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Seli DA, Prendergast A, Ergun Y, Tyagi A, Taylor HS. High NaCl Concentrations in Water Are Associated with Developmental Abnormalities and Altered Gene Expression in Zebrafish. Int J Mol Sci 2024; 25:4104. [PMID: 38612913 PMCID: PMC11012806 DOI: 10.3390/ijms25074104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 03/20/2024] [Accepted: 03/26/2024] [Indexed: 04/14/2024] Open
Abstract
Salt is frequently introduced in ecosystems, where it acts as a pollutant. This study examined how changes in salinity affect the survival and development of zebrafish from the two-cell to the blastocyst stage and from the blastocyst to the larval stage. Control zebrafish embryos were cultured in E3 medium containing 5 mM Sodium Chloride (NaCl), 0.17 mM Potassium Chloride (KCL), 0.33 mM Calcium Chloride (CaCl2), and 0.33 mM Magnesium Sulfade (MgSO4). Experiments were conducted using increasing concentrations of each individual salt at 5×, 10×, 50×, and 100× the concentration found in E3 medium. KCL, CaCl2, and MgSO4 did not result in lethal abnormalities and did not affect early embryo growth at any of the concentrations tested. Concentrations of 50× and 100× NaCl caused embryonic death in both stages of development. Concentrations of 5× and 10× NaCl resulted in uninflated swim bladders in 12% and 65% of larvae, compared to 4.2% of controls, and caused 1654 and 2628 genes to be differentially expressed in blastocysts, respectively. The ATM signaling pathway was affected, and the Sonic Hedgehog pathway genes Shh and Ptc1 implicated in swim bladder development were downregulated. Our findings suggest that increased NaCl concentrations may alter gene expression and cause developmental abnormalities in animals found in affected ecosystems.
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Affiliation(s)
- Denis A. Seli
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT 06520, USA
| | - Andrew Prendergast
- Yale Zebrafish Phenotyping Core, Yale School of Medicine, New Haven, CT 06520, USA
| | - Yagmur Ergun
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT 06520, USA
- IVIRMA Global Research Alliance, IVIRMA New Jersey, Marlton, NJ 08053, USA
| | - Antariksh Tyagi
- Department of Genetics, Yale School of Medicine, New Haven, CT 06520, USA
| | - Hugh S. Taylor
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT 06520, USA
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Moyano Salcedo AJ, Prat N, Bertrans-Tubau L, Piñero-Fernandez M, Cunillera-Montcusí D, López-Doval JC, Abril M, Proia L, Cañedo-Argüelles M. What happens when salinization meets eutrophication? A test using stream microcosms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168824. [PMID: 38030007 DOI: 10.1016/j.scitotenv.2023.168824] [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: 08/08/2023] [Revised: 10/25/2023] [Accepted: 11/22/2023] [Indexed: 12/01/2023]
Abstract
Nutrient and salt pollution often co-occur in rivers and streams due to human activities (e.g., agriculture, urbanization). Thus, understanding the interactive effects of nutrients and salinity on freshwater ecosystems is critical for environmental management. We experimentally assessed the interactive effects of nutrient and salt pollution on stream microcosms using biofilm and macroinvertebrates as model systems. Six treatments were performed in triplicate: control (C: N-NH4+ = 0.05; P- PO43- = 0.037; Cl- = 33.5 mg L-1), intermediate nutrient (IN: N-NH4+ = 0.4; P- PO43- = 0.271; Cl- = 33. 5 mg L-1), high nutrient (HN: N-NH4+ = 0.84; P- PO43- = 0.80; Cl- = 33.5 mg L-1), salt (S: N-NH4+ = 0.05; P- PO43- = 0.037; Cl- = 3000 mg L-1), salt with intermediate nutrient (SIN: N-NH4+ = 0.4; P- PO43- = 0.27; Cl- = 3000 mg L-1) and salt with high nutrient (SHN: N-NH4+ = 0.84; P- PO43- = 0.80; Cl- = 3000 mg L-1). After 14 days of exposure, biofilm chlorophyll-a increased across all treatments, with cyanobacteria replacing diatoms and green algae. Treatments with no added nutrients (C and S) had more P uptake capacity than the rest. The indicator species analysis showed 8 significant taxa, with Orthocladius (Orthocladius) gr. Wetterensis and Virganytarsus significantly associated with the salinity treatment. Overall, salt pollution led to a very strong decline in macroinvertebrate richness and diversity. However, salt toxicity seemed to be ameliorated by nutrient addition. Finally, both structural equation models and biotic-abiotic interaction networks showed that complex biological interactions could be modulating the response of the biological communities to our treatments. Thus, our study calls for species-level assessments of salt and nutrient effects on river ecosystems and advocates for better management of co-occurring pollutants.
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Affiliation(s)
- Alvaro Javier Moyano Salcedo
- FEHM-Lab (Freshwater Ecology, Hydrology and Management), Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Geohazards and Civil Engineering Research Group, Department of Civil Engineering, Saint Thomas Villavicencio University, C/22 No 1a, 500003 Villavicencio, Colombia; Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Carrer de Jordi Girona, 18-26, 08034 Barcelona, Spain.
| | - Narcís Prat
- FEHM-Lab (Freshwater Ecology, Hydrology and Management), Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Lluís Bertrans-Tubau
- BETA Technological Center, University of Vic-Central University of Catalonia (UVic-UCC), Vic, Barcelona, Spain
| | - Martí Piñero-Fernandez
- FEHM-Lab (Freshwater Ecology, Hydrology and Management), Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - David Cunillera-Montcusí
- FEHM-Lab (Freshwater Ecology, Hydrology and Management), Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; WasserCluster Lunz - Biologische Station GmbH, Lunz am See, Austria
| | - Julio C López-Doval
- BETA Technological Center, University of Vic-Central University of Catalonia (UVic-UCC), Vic, Barcelona, Spain
| | - Meritxell Abril
- BETA Technological Center, University of Vic-Central University of Catalonia (UVic-UCC), Vic, Barcelona, Spain
| | - Lorenzo Proia
- BETA Technological Center, University of Vic-Central University of Catalonia (UVic-UCC), Vic, Barcelona, Spain
| | - Miguel Cañedo-Argüelles
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Carrer de Jordi Girona, 18-26, 08034 Barcelona, Spain
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4
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Cochran JK, Funk DH, Buchwalter DB. Physiological and life history responses in a mayfly (Callibaetis floridanus) inhabiting ponds with saltwater intrusion. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1135924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
Freshwater salinity varies in natural systems and plays a role in species distribution. Anthropogenic alterations to freshwater salinity regimes include sea level rise and subsequent intrusion of saline waters to inland habitats. While mayflies are generalized to be sensitive to increasing salinity, we still know remarkably little about the physiological processes (and their plasticity) that determine the performance of species in a changing world. Here, we explored life-history outcomes and physiological plasticity in a population of Callibaetis floridanus (Ephemeroptera: Baetidae) from a coastal pond that routinely experiences saltwater intrusion. We reared naiads from egg hatch to adulthood across a gradient of increasing salinities (113, 5,020, 9,921 μS/cm). Radiotracer flux studies (22Na, 35SO4, and 45Ca) were conducted in naiads reared at each salinity, revealing a positive association between ionic concentration and uptake rates. However, the influence of rearing history on ionic influx rates was apparent when naiads were transferred from their respective rearing water to the other experimental conditions. For example, we observed that naiads reared in the low salinity treatment (113 μS/cm) had 10.8-fold higher Na uptake rates than naiads reared at 9,921 μS/cm and transferred to 113 μS/cm. Additionally, naiads acclimated to the higher salinity water exhibited reduced uptake in ion-rich water relative to those reared in more dilute conditions (e.g., in 9,921 μS/cm water, 113 and 5,020 μS/cm acclimated naiads had 1.5- and 1.1-fold higher Na uptake rates than 9,921 μS/cm acclimated naiads, respectively). We found no significant changes in survival (80 ± 4.4%, mean ± s.e.m.) or naiad development time (24 ± 0.3 days, mean ± s.e.m.) across these treatments but did observe a 27% decrease in subimago female body weight in the most dilute condition. This reduction in female weight was associated with higher oxygen consumption rates in naiads relative to the other rearing conditions. Collectively, these data suggests that saline adapted C. floridanus may be more energetically challenged in dilute conditions, which differs from previous observations in other mayfly species.
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Kaushal SS, Mayer PM, Likens GE, Reimer JE, Maas CM, Rippy MA, Grant SB, Hart I, Utz RM, Shatkay RR, Wessel BM, Maietta CE, Pace ML, Duan S, Boger WL, Yaculak AM, Galella JG, Wood KL, Morel CJ, Nguyen W, Querubin SEC, Sukert RA, Lowien A, Houde AW, Roussel A, Houston AJ, Cacopardo A, Ho C, Talbot-Wendlandt H, Widmer JM, Slagle J, Bader JA, Chong JH, Wollney J, Kim J, Shepherd L, Wilfong MT, Houlihan M, Sedghi N, Butcher R, Chaudhary S, Becker WD. Five state factors control progressive stages of freshwater salinization syndrome. LIMNOLOGY AND OCEANOGRAPHY LETTERS 2023; 8:190-211. [PMID: 37539375 PMCID: PMC10395323 DOI: 10.1002/lol2.10248] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 02/21/2022] [Indexed: 08/05/2023]
Abstract
Factors driving freshwater salinization syndrome (FSS) influence the severity of impacts and chances for recovery. We hypothesize that spread of FSS across ecosystems is a function of interactions among five state factors: human activities, geology, flowpaths, climate, and time. (1) Human activities drive pulsed or chronic inputs of salt ions and mobilization of chemical contaminants. (2) Geology drives rates of erosion, weathering, ion exchange, and acidification-alkalinization. (3) Flowpaths drive salinization and contaminant mobilization along hydrologic cycles. (4) Climate drives rising water temperatures, salt stress, and evaporative concentration of ions and saltwater intrusion. (5) Time influences consequences, thresholds, and potentials for ecosystem recovery. We hypothesize that state factors advance FSS in distinct stages, which eventually contribute to failures in systems-level functions (supporting drinking water, crops, biodiversity, infrastructure, etc.). We present future research directions for protecting freshwaters at risk based on five state factors and stages from diagnosis to prognosis to cure.
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Affiliation(s)
- Sujay S. Kaushal
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Paul M. Mayer
- Pacific Ecological Systems Division, US Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Corvallis, Oregon
| | - Gene E. Likens
- Cary Institute of Ecosystem Studies, Millbrook, New York
- University of Connecticut, Storrs, Connecticut
| | - Jenna E. Reimer
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Carly M. Maas
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Megan A. Rippy
- Occoquan Watershed Monitoring Laboratory, The Charles E. Via Jr Department of Civil and Environmental Engineering, Virginia Tech, Manassas, Virginia
- Center for Coastal Studies, Virginia Tech, Blacksburg, Virginia
| | - Stanley B. Grant
- Occoquan Watershed Monitoring Laboratory, The Charles E. Via Jr Department of Civil and Environmental Engineering, Virginia Tech, Manassas, Virginia
- Center for Coastal Studies, Virginia Tech, Blacksburg, Virginia
| | - Ian Hart
- Chatham University, Gibsonia, Pennsylvania
| | | | - Ruth R. Shatkay
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Barret M. Wessel
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland
| | - Christine E. Maietta
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland
| | - Michael L. Pace
- Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia
| | - Shuiwang Duan
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Walter L. Boger
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Alexis M. Yaculak
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Joseph G. Galella
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Kelsey L. Wood
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Carol J. Morel
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - William Nguyen
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Shane Elizabeth C. Querubin
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Rebecca A. Sukert
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Anna Lowien
- Environmental Science & Policy Program, University of Maryland, College Park, Maryland
| | - Alyssa Wellman Houde
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland
| | - Anaïs Roussel
- Department of Biology, Georgetown University, Washington, District of Columbia
| | - Andrew J. Houston
- Department of Geology, University of Maryland, College Park, Maryland
| | - Ari Cacopardo
- Department of Geology, University of Maryland, College Park, Maryland
| | - Cristy Ho
- Department of Geology, University of Maryland, College Park, Maryland
| | | | - Jacob M. Widmer
- Department of Geology, University of Maryland, College Park, Maryland
| | - Jairus Slagle
- Department of Geology, University of Maryland, College Park, Maryland
| | - James A. Bader
- Department of Geology, University of Maryland, College Park, Maryland
| | - Jeng Hann Chong
- Department of Geology, University of Maryland, College Park, Maryland
| | - Jenna Wollney
- Department of Geology, University of Maryland, College Park, Maryland
| | - Jordan Kim
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland
| | - Lauren Shepherd
- Department of Geology, University of Maryland, College Park, Maryland
| | - Matthew T. Wilfong
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland
| | - Megan Houlihan
- Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland
| | - Nathan Sedghi
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland
| | - Rebecca Butcher
- Department of Geology, University of Maryland, College Park, Maryland
| | - Sona Chaudhary
- Department of Geology, University of Maryland, College Park, Maryland
| | - William D. Becker
- Department of Geology, University of Maryland, College Park, Maryland
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Kefford BJ, Nichols SJ, Duncan RP. The cumulative impacts of anthropogenic stressors vary markedly along environmental gradients. GLOBAL CHANGE BIOLOGY 2023; 29:590-602. [PMID: 36114730 PMCID: PMC10087255 DOI: 10.1111/gcb.16435] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/21/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
Understanding the cumulative effects of multiple stressors on biodiversity is key to managing their impacts. Stressor interactions are often studied using an additive/antagonistic/synergistic typology, aimed at identifying situations where individual stressor effects are reduced or amplified when they act in combination. Here, we analysed variation in the family richness of stream macroinvertebrates in the groups Ephemeroptera, Plecoptera and Trichoptera (EPT) at 4658 sites spanning a 32° latitudinal range in eastern Australia in relation to two largely human-induced stressors, salinity and turbidity, and two environmental gradients, temperature and slope. The cumulative and interactive effect of salinity and turbidity on EPT family richness varied across the landscape and by habitat (edge or riffle) such that we observed additive, antagonistic and synergistic outcomes depending on the environmental context. Our findings highlight the importance of understanding the consistency of multiple stressor impacts, which will involve higher-order interactions between multiple stressors and environmental factors.
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Affiliation(s)
- Ben J. Kefford
- Centre for Applied Water ScienceInstitute for Applied Ecology, University of CanberraCanberraAustralian Capital TerritoryAustralia
| | - Susan J. Nichols
- Centre for Applied Water ScienceInstitute for Applied Ecology, University of CanberraCanberraAustralian Capital TerritoryAustralia
| | - Richard P. Duncan
- Centre for Conservation Ecology and GenomicsInstitute for Applied Ecology, University of CanberraCanberraAustralian Capital TerritoryAustralia
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Venâncio C, Caon K, Lopes I. Cation Composition Influences the Toxicity of Salinity to Freshwater Biota. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1741. [PMID: 36767106 PMCID: PMC9914514 DOI: 10.3390/ijerph20031741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
The effects of salinization on freshwater ecosystems have been estimated by testing sodium chloride (NaCl) since it is the most widely used salt as a deicing agent and Na+ and Cl- ions are the most representative in seawater composition. However, calcium, magnesium, and/or potassium are starting to be proposed as potential surrogates for NaCl, but for which ecotoxicological effects are less explored. This study aimed to identify (i) the less toxic salt to freshwater biota to be suggested as a safer alternative deicer and (ii) to contribute to the lower tiers of salinity risk assessment frameworks by identifying a more suitable surrogate salt than NaCl. The battery of ecotoxicity assays with five key trophic level species showed that among the tested salts (MgCl2, CaCl2, and KCl), KCl and CaCl2 seemed to induce the highest and lowest toxicity, respectively, compared with NaCl. CaCl2 is suggested as a safer alternative for use as a deicer and KCl as a surrogate for the risk assessment of seawater intrusion in coastal regions. These results enrich the salt toxicity database aiming to identify and propose more suitable surrogate salts to predict the effects of salinization to a broader extent.
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Orr SE, Collins LB, Jima DD, Buchwalter DB. Salinity-induced ionoregulatory changes in the gill proteome of the mayfly, Neocloeon triangulifer. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 316:120609. [PMID: 36368556 DOI: 10.1016/j.envpol.2022.120609] [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: 08/11/2022] [Revised: 10/06/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Ecologists have observed declines in the biodiversity of sensitive freshwater organisms in response to increasing concentrations of major ions (salinization). Yet, how changing salinities physiologically challenge aquatic organisms, such as mayflies, remains remarkably understudied. Moreover, it is not well understood the degree to which species respond and acclimate to salinity changes. Our lab is developing the Baetid mayfly, N. triangulifer, as a model organism for physiological research. We have previously described acclimatory changes in both ion flux rates and altered mRNA transcript levels in response to chronic exposures to elevated major ion concentrations at the whole animal level. In the present study, we use shotgun proteomics to identify the specific proteins associated with apical ion transport and how their abundance changes in response to chronic salinity exposures in gills. Gills were isolated from the penultimate nymphal stage of N. triangulifer reared under control culture conditions, elevated NaCl (157 mg L-1 Na), elevated CaCl2 (121 mg L-1 Ca), elevated Ca/MgSO4 (735 mg L-1 SO4). These conditions mirrored those from previously published physiological work. We also acutely exposed nymphs to dilute (50% dilution of culture water with deionized water) to explore proteomic changes in the gills in response to dilute conditions. We report 710 unique peptide sequences among treatment groups, including important apical ion transporters such as Ca-ATPase, Na/K ATPase, and V-ATPase. Treatment with elevated NaCl and Ca/MgSO4 appeared to cause more significant differential protein expression (452 and 345, respectively) compared to CaCl2 and dilute groups (134 and 17, respectively). Finally, we demonstrated the breadth of physiological functions in gills by exploring non-transport related pathways found in our dataset, including ATP synthesis, calcium signaling, and oxidative stress response. We discuss our results in the context of freshwater salinization and the challenges of working with non-model species without fully sequenced and annotated genomes.
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Affiliation(s)
- Sarah E Orr
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, USA
| | - Leonard B Collins
- Molecular Education, Technology and Research Innovation Center, North Carolina State University, Raleigh, NC, 27695, USA
| | - Dereje D Jima
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, 27695, USA; Bioinformatics Research Center, North Carolina State University, Raleigh, NC, 27695, USA
| | - David B Buchwalter
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, USA.
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9
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Rossi ML, Kremer P, Cravotta CA, Scheirer KE, Goldsmith ST. Long-term impacts of impervious surface cover change and roadway deicing agent application on chloride concentrations in exurban and suburban watersheds. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:157933. [PMID: 35987233 DOI: 10.1016/j.scitotenv.2022.157933] [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: 05/23/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Roadway deicing agents, including rock salt and brine containing NaCl, have had a profound impact on the water quality and aquatic health of rivers and streams in urbanized areas with temperate climates. Yet, few studies evaluate impacts to watersheds characterized by relatively low impervious surface cover (ISC; < 15 %). Here, we use long-term (1997-2019), monthly streamwater quality data combined with daily streamflow for six exurban and suburban watersheds in southeastern Pennsylvania to examine the relations among chloride (Cl-) concentrations and ISC. Both flow-normalized Cl- concentrations and ISC increased over time in each of the six watersheds, consistent with changes in watershed management (e.g., ISC, road salt application, etc.). The watersheds that experienced the greatest changes in percent ISC (e.g., agriculture replaced by residential and commercial development) experienced the greatest changes in flow-normalized Cl- concentrations. We also utilized a comprehensive mass-balance model (2011-2018) that indicated Cl- inputs exceeded the outputs for the study watersheds. Road salt applied to state roads, non-state roads, and other impervious surfaces accounted for the majority of Cl- inputs to the six watersheds. Furthermore, increasing Cl- concentrations during baseflow conditions confirm impacts to shallow groundwater. Although flow-normalized Cl- concentrations are below the U.S. Environmental Protection Agency's chronic threshold value for impacts to aquatic organisms, year-round exceedances may result before the end of this century based on current trends. Though reduced Cl- loading to streams may be achieved by limiting the expansion of impervious surfaces in exurban and suburban watersheds, changes in baseflow concentrations are likely to be gradual because of the accumulated Cl- in groundwater.
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Affiliation(s)
- Marissa L Rossi
- Department of Geography and the Environment, Villanova University, Villanova, PA 19085, United States of America
| | - Peleg Kremer
- Department of Geography and the Environment, Villanova University, Villanova, PA 19085, United States of America
| | - Charles A Cravotta
- U.S. Geological Survey, Pennsylvania Water Science Center, 215 Limekiln Road, New Cumberland, PA 17070, United States of America
| | - Krista E Scheirer
- Aqua Pennsylvania, Inc., 762 W. Lancaster Ave, Bryn Mawr, PA 19010, United States of America
| | - Steven T Goldsmith
- Department of Geography and the Environment, Villanova University, Villanova, PA 19085, United States of America.
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10
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Fanelli RM, Cashman MJ, Porter AJ. Identifying Key Stressors Driving Biological Impairment in Freshwater Streams in the Chesapeake Bay Watershed, USA. ENVIRONMENTAL MANAGEMENT 2022; 70:926-949. [PMID: 36207606 PMCID: PMC9622507 DOI: 10.1007/s00267-022-01723-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
Biological communities in freshwater streams are often impaired by multiple stressors (e.g., flow or water quality) originating from anthropogenic activities such as urbanization, agriculture, or energy extraction. Restoration efforts in the Chesapeake Bay watershed, USA seek to improve biological conditions in 10% of freshwater tributaries and to protect the biological integrity of existing healthy watersheds. To achieve these goals, resource managers need to better understand which stressors are most likely driving biological impairment. Our study addressed this knowledge gap through two approaches: 1) reviewing and synthesizing published multi-stressor studies, and 2) examining 303(d) listed impairments linked to biological impairment as identified by jurisdiction regulatory agencies (the states within the watershed and the District of Columbia). Results identified geomorphology (i.e., physical habitat), salinity, and toxic contaminants as important for explaining variability in benthic community metrics in the literature review. Geomorphology (i.e., physical habitat and sediment), salinity, and nutrients were the most reported stressors in the jurisdictional impairment analysis. Salinity is likely a major stressor in urban and mining settings, whereas geomorphology was commonly reported in agricultural settings. Toxic contaminants, such as pesticides, were rarely measured; more research is needed to quantify the extent of their effects in the region. Flow alteration was also highlighted as an important urban stressor in the literature review but was rarely measured in the literature or reported by jurisdictions as a cause of impairment. These results can be used to prioritize stressor monitoring by managers, and to improve stressor identification methods for identifying causes of biological impairment.
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Affiliation(s)
- Rosemary M Fanelli
- U.S. Geological Survey, South Atlantic Water Science Center, Raleigh, NC, USA.
| | - Matthew J Cashman
- U.S. Geological Survey, Maryland-D.C.-Delaware Water Science Center, Baltimore, MD, USA
| | - Aaron J Porter
- U.S. Geological Survey, Virginia-West Virginia Water Science Center, Richmond, VA, USA
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Haake DM, Krchma S, Meyners CW, Virag R. Impacts of urbanization on chloride and stream invertebrates: A 10-year citizen science field study of road salt in stormwater runoff. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2022; 18:1667-1677. [PMID: 35199928 PMCID: PMC9790684 DOI: 10.1002/ieam.4594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
The use of deicing agents during the winter months is one of many stressors that impact stream ecosystems in urban and urbanizing watersheds. In this study, a long-term data set collected by citizen scientists with the Missouri Stream Team was used to evaluate the relationships between watershed urbanization metrics and chloride metrics. Further, these data were used to explore the effects of elevated chloride concentrations on stream invertebrate communities using quantile regression. While the amount of road surface in a watershed was a dominant factor in predicting the maximum chloride measurement, the median chloride concentration was also strongly related to the amount of medium-to-high density development in the watershed, suggesting that nonmunicipal salt use is an important contributor to increases in base flow chloride concentrations. Additionally, chloride concentration appears to be one of the many factors that impact invertebrate density and diversity measurements, with decreases in invertebrate diversity corresponding with the US Environmental Protection Agency water quality criteria. Our findings suggest that the use of chloride-based road salt on municipal roads as well as on nonmunicipal settings is contributing to a loss of diversity and density of aquatic invertebrate communities in urban regions. Integr Environ Assess Manag 2022;18:1667-1677. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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Affiliation(s)
- Danelle M. Haake
- National Great Rivers Research and Education CenterLewis and Clark Community CollegeEast AltonIllinoisUSA
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12
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Soucek DJ, Dickinson A, Norberg-King TJ. Influence of Test Method Variables on Sensitivity of Neocloeon Triangulifer to a Reference Toxicant in Short-Term, Effluent Style Evaluations. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:2758-2768. [PMID: 35959890 DOI: 10.1002/etc.5463] [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: 04/05/2022] [Revised: 05/22/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Recent literature has demonstrated the sensitivity of mayflies to environmental contaminants. However, to date, there are no methods approved by the US Environmental Protection Agency for using sensitive insects like mayflies in whole-effluent toxicity or receiving water toxicity tests. The parthenogenetic mayfly Neocloeon triangulifer has been shown to be amenable to continuous culture in the laboratory, and methods have been described for its use in both acute and chronic toxicity studies. The goal of the present study was to investigate aspects of N. triangulifer testing and culturing methods that might require adjustment so that they are applicable for testing effluents and receiving waters in a short-term exposure. To this end, the influence of organism age, test duration, and test temperature on sensitivity to NaCl as a reference toxicant were tested (concentrations ranging from 182 to 2489 mg/L). Further studies were conducted to assess the utility of commercially available diets and the influence of nutrient amendment of water on organism growth and sensitivity. Seven-day NaCl tests started with less than 24-h-old larvae were similar in sensitivity to 14-day and full life chronic tests, and were much more sensitive than those started with 7-day-old organisms. Reducing test temperature from 25 °C to 22 °C had a minor influence on culture timing, and little impact on sensitivity to NaCl. In other experiments, reconstituted test water supplemented with nutrients to potentially improve in-test food quality had minimal effect on growth at 7 days and did not significantly alter acute sensitivity to NaCl relative to unamended reconstituted water. A suitable commercially available, ready-to-feed diet substitute for cultured diatoms was not found. Testing N. triangulifer in effluents or receiving waters with the methods recommended will complement similar methods for Ceriodaphnia dubia. Environ Toxicol Chem 2022;41:2758-2768. © 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- David J Soucek
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri, USA
| | - Amy Dickinson
- Prairie Research Institute, Illinois Natural History Survey, Champaign, Illinois, USA
| | - Teresa J Norberg-King
- Retired, Great Lakes Toxicology and Ecology Division, Center for Computational Toxicology and Exposure, Office of Research and Development, US Environmental Protection Agency, Duluth, Minnesota, USA
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13
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Hills KA, Hyne RV, Kefford BJ. Bicarbonate alone does not totally explain the toxicity from major ions of coal bed derived waters to freshwater invertebrates. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:967-975. [PMID: 35701565 PMCID: PMC9300549 DOI: 10.1007/s10646-022-02552-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Concentrations of major ions in coal mine discharge waters and unconventional hydrocarbon produced waters derived from coal bed methane (CBM) production, are potentially harmful to freshwater ecosystems. Bicarbonate is a major constituent of produced waters from CBM and coal mining. However, little is known about the relative toxicity of differing ionic proportions, especially bicarbonate, found in these CBM waters. As all freshwater invertebrates tested are more acutely sensitive to sodium bicarbonate (NaHCO3) than sodium chloride (NaCl) or synthetic sea water, we tested the hypotheses that toxicity of CBM waters are driven by bicarbonate concentration, and waters containing a higher proportion of bicarbonate are more toxic to freshwater invertebrates than those with less bicarbonate. We compared the acute (96 h) lethal toxicity to six freshwater invertebrate species of NaHCO3 and two synthetic CBM waters, with ionic proportions representative of water from CBM wells across New South Wales (NSW) and Queensland (Qld), in Australia. The ranking of LC50 values expressed as total salinity was consistent with the hypotheses. However, when toxicity was expressed as bicarbonate concentration, the hypothesis that the toxicity of coal bed waters would be explained by bicarbonate concentration was not well supported, and other ionic components were either ameliorating or exacerbating the NaHCO3 toxicity. Our findings showed NaHCO3 was more toxic than NaCl and that the NaHCO3 proportion of synthetic CBM waters drives toxicity, however other ions are altering the toxicity of bicarbonate.
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Affiliation(s)
- Kasey A Hills
- Centre for Applied Water Sciences, Institute for Applied Ecology, University of Canberra, Bruce, ACT, 2601, Australia
- New South Wales Environmental Protection Authority, Locked Bag 5022, Parramatta, NSW, 2124, Australia
| | - Ross V Hyne
- Department of Planning, Industry and Environment, Environment Protection Science, Lidcombe Laboratories, Lidcombe, NSW, 2141, Australia
| | - Ben J Kefford
- Centre for Applied Water Sciences, Institute for Applied Ecology, University of Canberra, Bruce, ACT, 2601, Australia.
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14
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Zhang VM, Martin RL, Murray RL. Chronic Road Salt Exposure Across Life Stages and The Interactive Effects of Warming and Salinity in a Semiaquatic Insect. ENVIRONMENTAL ENTOMOLOGY 2022; 51:313-321. [PMID: 35348654 DOI: 10.1093/ee/nvac014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Indexed: 06/14/2023]
Abstract
The salinization of freshwater habitats from winter road salt application is a growing concern. Understanding how taxa exposed to road salt run-off respond to this salinity exposure across life history transitions will be important for predicting the impacts of increasing salinity. We show that Leucorrhinia intacta Hagen, 1861 (Odonata: Libellulidae) dragonflies are robust to environmentally relevant levels of salt pollution across intrinsically stressful life history transitions (hatching, growth, and metamorphosis). Additionally, we observed no carry-over effects into adult dragonfly morphology. However, in a multiple-stressor setting, we see negative interactive effects of warming and salinity on activity, and we found that chronically warmed dragonfly larvae consumed fewer mosquitoes. Despite showing relatively high tolerance to salinity individually, we expect that decreased dragonfly performance in multiple-stressor environments could limit dragonflies' contribution to ecosystem services such as mosquito pest control in urban freshwater environments.
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Affiliation(s)
- Vicki M Zhang
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd. L5L 1C6, Mississauga, Ontario, Canada
- Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. M5S 3B2, Toronto, Ontario, Canada
| | - Rosemary L Martin
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd. L5L 1C6, Mississauga, Ontario, Canada
- Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. M5S 3B2, Toronto, Ontario, Canada
| | - Rosalind L Murray
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd. L5L 1C6, Mississauga, Ontario, Canada
- Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. M5S 3B2, Toronto, Ontario, Canada
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15
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Moulding BJG, Kon Kam King G, Shenton M, Bray JP, Nichols SJ, Kefford BJ. Assessing the Relative Toxicity of Different Road Salts and Effect of Temperature on Salinity Toxicity: LC x Values versus No-Effect Concentration (NEC) Values. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 82:281-293. [PMID: 35091822 DOI: 10.21203/rs.3.rs-580126/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/02/2021] [Indexed: 05/26/2023]
Abstract
Freshwater biota are at risk globally from increasing salinity, including increases from deicing salts in cold regions. A variety of metrics of toxicity are used when estimating the toxicity of substances and comparing the toxicity between substances. However, the implications of using different metrics are not widely appreciated. Using the mayfly Colobruscoides giganteus (Ephemeroptera: Colobruscoidea), we compare the toxicity of seven different salts where toxicity was estimated using two metrics: (1) the no-effect concentrations (NEC) and (2) the lethal concentrations for 10, 25 and 50% of the test populations (LCx). The LCx values were estimated using two different models, the classic log-logistic model and the newer toxicokinetic-toxicodynamic (TKTD) model. The NEC and both types of LCx values were estimated using Bayesian statistics. We also compared the toxicity of two salts (NaCl and CaCl2) for C. giganteus at water temperatures of 4 °C, 7 °C and 15 °C using the same metrics of toxicity. Our motivation for using a mayfly to assess salinity toxicity was because mayflies are generally salt sensitive, are ecologically important and are common in Australian (sub-)alpine streams. The temperature ranges were chosen to mimic winter, spring and summer water temperatures for Australian (sub-)alpine streams. Considering 144-h classical LCx values, we found toxicity differed between various salts, i.e., the lowest 144-h LC50 (8 mS/cm) for a salt used by a ski resort was half that of the highest 144-h LC50 from artificial marine salts and CaCl2 applied to roads (16 mS/cm). The analytical grade NaCl (as shown by 144-h LC50 value at 7 °C) was substantially more toxic (7.3 mS/cm) compared to analytical grade CaCl2 (12.5 mS/cm). Yet for NEC values, there were comparably fewer differences in toxicity between salts and none between the same salts at different temperatures. We conclude that LCx values are better suited to compare the difference in toxicity between substances or between the same substance at different test temperatures, while NEC values are better suited to estimating concentrations of substances that have no effect to the test species and endpoint measured under laboratory conditions.
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Affiliation(s)
- Benjamin J G Moulding
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.
| | | | - Mark Shenton
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Jon P Bray
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
- Gisborne District Council, PO Box 747, Gisborne, 4010, New Zealand
| | - Susan J Nichols
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Ben J Kefford
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
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16
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Moulding BJG, Kon Kam King G, Shenton M, Bray JP, Nichols SJ, Kefford BJ. Assessing the Relative Toxicity of Different Road Salts and Effect of Temperature on Salinity Toxicity: LC x Values versus No-Effect Concentration (NEC) Values. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 82:281-293. [PMID: 35091822 DOI: 10.1007/s00244-021-00908-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/02/2021] [Indexed: 06/14/2023]
Abstract
Freshwater biota are at risk globally from increasing salinity, including increases from deicing salts in cold regions. A variety of metrics of toxicity are used when estimating the toxicity of substances and comparing the toxicity between substances. However, the implications of using different metrics are not widely appreciated. Using the mayfly Colobruscoides giganteus (Ephemeroptera: Colobruscoidea), we compare the toxicity of seven different salts where toxicity was estimated using two metrics: (1) the no-effect concentrations (NEC) and (2) the lethal concentrations for 10, 25 and 50% of the test populations (LCx). The LCx values were estimated using two different models, the classic log-logistic model and the newer toxicokinetic-toxicodynamic (TKTD) model. The NEC and both types of LCx values were estimated using Bayesian statistics. We also compared the toxicity of two salts (NaCl and CaCl2) for C. giganteus at water temperatures of 4 °C, 7 °C and 15 °C using the same metrics of toxicity. Our motivation for using a mayfly to assess salinity toxicity was because mayflies are generally salt sensitive, are ecologically important and are common in Australian (sub-)alpine streams. The temperature ranges were chosen to mimic winter, spring and summer water temperatures for Australian (sub-)alpine streams. Considering 144-h classical LCx values, we found toxicity differed between various salts, i.e., the lowest 144-h LC50 (8 mS/cm) for a salt used by a ski resort was half that of the highest 144-h LC50 from artificial marine salts and CaCl2 applied to roads (16 mS/cm). The analytical grade NaCl (as shown by 144-h LC50 value at 7 °C) was substantially more toxic (7.3 mS/cm) compared to analytical grade CaCl2 (12.5 mS/cm). Yet for NEC values, there were comparably fewer differences in toxicity between salts and none between the same salts at different temperatures. We conclude that LCx values are better suited to compare the difference in toxicity between substances or between the same substance at different test temperatures, while NEC values are better suited to estimating concentrations of substances that have no effect to the test species and endpoint measured under laboratory conditions.
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Affiliation(s)
- Benjamin J G Moulding
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.
| | | | - Mark Shenton
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Jon P Bray
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
- Gisborne District Council, PO Box 747, Gisborne, 4010, New Zealand
| | - Susan J Nichols
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Ben J Kefford
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
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17
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Venâncio C, Ribeiro R, Lopes I. Seawater intrusion: an appraisal of taxa at most risk and safe salinity levels. Biol Rev Camb Philos Soc 2021; 97:361-382. [PMID: 34626061 DOI: 10.1111/brv.12803] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 09/23/2021] [Accepted: 09/27/2021] [Indexed: 11/30/2022]
Abstract
Seawater intrusion into low-lying coastal ecosystems carries environmental risks. Salinity levels at these coastal ecosystems may vary substantially, causing ecological effects from mortality to several sublethal endpoints, such as depression of rates of feeding, somatic growth, or reproduction. This review attempts to establish safe salinity levels for both terrestrial and freshwater temperate ecosystems by integrating data available in the literature. We have four specific objectives: (i) to identify the most sensitive ecological taxa to seawater intrusion; (ii) to establish maximum acceptable concentrations-environmental quality standards (MAC-EQSs) for sea water (SW) from species sensitivity distributions (SSDs); (iii) to compile from the literature examples of saline intrusion [to be used as predicted environmental concentrations (PECs)] and to compute risk quotients for the temperate zone; and (iv) to assess whether sodium chloride (NaCl) is an appropriate surrogate for SW in ecological risk assessments by comparing SSD-derived values for NaCl and SW and by comparing these with field data. Zooplankton, early life stages of amphibians and freshwater mussels were the most sensitive ecological receptors for the freshwater compartment, while soil invertebrates were the most sensitive ecological receptors for the terrestrial compartment. Hazard concentration 5% (HC5 ) values, defined as the concentration (herein measured as conductivity) that affects (causes lethal or sublethal effects) 5% of the species in a distribution, computed for SW were over 22 and 40 times lower than the conductivity of natural SW (≈ 52 mS/cm) for the freshwater and soil compartment, respectively. This sensitivity of both compartments means that small increments in salinity levels or small SW intrusions might represent severe risks for low-lying coastal ecosystems. Furthermore, the proximity between HC5 values for the soil and freshwater compartments suggests that salinized soils might represent an additional risk for nearby freshwater systems. This sensitivity was corroborated by the derivation of risk quotients using real saline intrusion examples (PECs) collected from the literature: risk was >1 in 34 out of 37 examples. By contrast, comparisons of HC5 values obtained from SSDs in field surveys or mesocosm studies suggest that natural communities are more resilient to salinization than expected. Finally, NaCl was found to be slightly more toxic than SW, at both lethal and sublethal levels, and, thus, is suggested to be an acceptable surrogate for use in risk assessment.
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Affiliation(s)
- Cátia Venâncio
- Department of Life Sciences, Centre for Functional Ecology, University of Coimbra, Calçada Martim de Freitas, Coimbra, 3000-456, Portugal
| | - Rui Ribeiro
- Department of Life Sciences, Centre for Functional Ecology, University of Coimbra, Calçada Martim de Freitas, Coimbra, 3000-456, Portugal
| | - Isabel Lopes
- CESAM & Department of Biology, University of Aveiro, Aveiro, 3810-193, Portugal
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18
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Orr SE, Negrão Watanabe TT, Buchwalter DB. Physiological plasticity and acclimatory responses to salinity stress are ion-specific in the mayfly, Neocloeon triangulifer. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 286:117221. [PMID: 33975217 DOI: 10.1016/j.envpol.2021.117221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/09/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
Freshwater salinization is a rapidly emerging ecological issue and is correlated with significant declines in aquatic biodiversity. It remains unclear how changing salinity regimes affect the physiology of sensitive aquatic insects. We used the parthenogenetic mayfly, Neocloeon triangulifer, to ask how ionic exposure history alters physiological processes and responses to subsequent major ion exposures. Using radiotracers (22Na, 35SO4, and 45Ca), we observed that mayflies chronically reared in elevated sodium or sulfate (157 mg L-1 Na or 667 mg L-1 SO4) had 2-fold (p < 0.0001) and 8-fold (p < 0.0001) lower ion uptake rates than mayflies reared in dilute control water (16 mg L-1 Na and 23 mg L-1 SO4) and subsequently transferred to elevated salinities, respectively. These acclimatory ion transport changes provided protection in 96-h toxicity bioassays for sodium, but not sulfate. Interestingly, calcium uptake was uniformly much lower and minimally influenced by exposure history, but was poorly tolerated in the toxicity bioassays. With qRT-PCR, we observed that the expression of many ion transporter genes in mayflies was influenced by elevated salinity in an ion-specific manner (general upregulation in response to sulfate, downregulation in response to calcium). Elevated sodium exposure had minimal influence on the same genes. Finally, we provide novel light microscopic evidence of histomorphological changes within the epithelium of the Malpighian tubules (insect primary excretory system) that undergoes cellular degeneration and necrosis secondary to calcium toxicity. We conclude that physiological plasticity to salinity stress is ion-specific and provide evidence for ion-specific toxicity mechanisms in N. triangulifer.
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Affiliation(s)
- Sarah E Orr
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27607, USA
| | - Tatiane Terumi Negrão Watanabe
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, 27607, USA
| | - David B Buchwalter
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27607, USA.
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19
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Delaune KD, Nesich D, Goos JM, Relyea RA. Impacts of salinization on aquatic communities: Abrupt vs. gradual exposures. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117636. [PMID: 34380226 DOI: 10.1016/j.envpol.2021.117636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/15/2021] [Accepted: 06/19/2021] [Indexed: 06/13/2023]
Abstract
Increasing chloride concentrations from road salt applications are an emerging threat to freshwater diversity in cold weather regions. Few studies have focused on how road salt affects freshwater biota and even fewer have focused on how the rate of exposure alters organism responses. We hypothesized that road salt concentrations delivered gradually would result in slower population declines and more rapid rebounds due to evolved tolerance. To test this hypothesis, we examined the responses of freshwater lake organisms to four environmentally relevant salt concentrations (100, 230, 860, and 1600 mg Cl-/L) that differed in application rate (abrupt vs. gradual). We used outdoor aquatic mesocosms containing zooplankton, filamentous algae, phytoplankton, periphyton, and macroinvertebrates. We found negative effects of road salt on zooplankton and macroinvertebrate abundance, but positive effects on phytoplankton and periphyton, likely resulting from reduced grazing. Only rarely did we detect a difference between abrupt vs gradual salt applications and the directions of those differences were not consistent. This affirms the need for additional research on how road salt pollution entering ecosystems at different frequencies and magnitudes will alter freshwater communities.
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Affiliation(s)
- Kelbi D Delaune
- Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, Troy, NY, 12980, USA
| | - David Nesich
- Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, Troy, NY, 12980, USA
| | - Jared M Goos
- Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, Troy, NY, 12980, USA
| | - Rick A Relyea
- Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, Troy, NY, 12980, USA.
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20
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Le TDH, Schreiner VC, Kattwinkel M, Schäfer RB. Invertebrate turnover along gradients of anthropogenic salinisation in rivers of two German regions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 753:141986. [PMID: 32911168 DOI: 10.1016/j.scitotenv.2020.141986] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
Rising salinity in freshwater ecosystems can affect community composition. Previous studies mainly focused on changes in freshwater communities along gradients of absolute levels of electrical conductivity (EC). However, both geogenic and anthropogenic drivers contribute to the EC level and taxa may regionally be adapted to geogenic EC levels. Therefore, we examined the turnover in freshwater invertebrates along gradients of anthropogenic EC change in two regions of Germany. The anthropogenic change of EC was estimated as the difference between the measured EC and the modeled background EC driven by geochemical and climate variables. Turnover in freshwater invertebrates (β-diversity) was estimated using the Jaccard index (JI). We found that invertebrate turnover between EC gradient categories is generally greater than 47%, with a maximum of approximately 70% in sites with a more than 0.4 mS cm-1 change compared to the baseline (i.e. no difference between predicted and measured EC). The invertebrates Amphinemura sp., Anomalopterygella chauviniana and Leuctra sp. were reliable indicators of low EC change, whereas Potamopyrgus antipodarum indicated sites with the highest EC change. Variability within categories of EC change was slightly lower than within categories of absolute EC. Elevated nutrient concentrations that are often linked to land use may have contributed to the observed change of the invertebrate richness and can exacerbate effects of EC on communities in water. Overall, our study suggests that the change in EC, quantified as the difference between measured EC and modeled background EC, can be used to examine the response of invertebrate communities to increasing anthropogenic salinity concentrations in rivers. However, due to the strong correlation between EC change and observed EC in our study regions, the response to these two variables was very similar. Further studies in areas where EC change and observed EC are less correlated are required. In addition, such studies should consider the change in specific ions.
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Affiliation(s)
- Trong Dieu Hien Le
- iES Landau, Institute for Environmental Sciences, University Koblenz-Landau, Fortstraße 7, 76829 Landau in der Pfalz, Germany; Faculty of Resources & Environment, University of Thu Dau Mot, 06 Tran Van On street, Thu Dau Mot City, Binh Duong, Viet Nam.
| | - Verena C Schreiner
- iES Landau, Institute for Environmental Sciences, University Koblenz-Landau, Fortstraße 7, 76829 Landau in der Pfalz, Germany
| | - Mira Kattwinkel
- iES Landau, Institute for Environmental Sciences, University Koblenz-Landau, Fortstraße 7, 76829 Landau in der Pfalz, Germany
| | - Ralf B Schäfer
- iES Landau, Institute for Environmental Sciences, University Koblenz-Landau, Fortstraße 7, 76829 Landau in der Pfalz, Germany
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21
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Dong Y, Peng W, Liu Y, Wang Z. Photochemical origin of reactive radicals and halogenated organic substances in natural waters: A review. JOURNAL OF HAZARDOUS MATERIALS 2021; 401:123884. [PMID: 33113752 DOI: 10.1016/j.jhazmat.2020.123884] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 08/14/2020] [Accepted: 08/23/2020] [Indexed: 06/11/2023]
Abstract
Halogenated organic compounds, also termed organohalogens, were initially regarded to be of almost exclusively anthropogenic origin. However, recent research has demonstrated that photochemical reactions are important abiotic sources of organohalogen compounds in sunlit surface waters. Halide ions (X-, X represents Cl, Br and I) are common anions in natural waters and might be oxidized by reactive species originated from photochemistry of dissolved organic matter (DOM) or inorganic photoactive species. The resulting reactive halogen species may react with organic substances with diverse bimolecular reaction rate constants, depending on the complexity and structure of organic substances. Therefore, the chemical mechanism of halogenation remains challenging to be fully elucidated. To better understand the trends in the existing data and to identify the knowledge gaps that may merit further investigation, this review gives an integrative summary on the sources of reactive oxygen species (ROS) and halogen radicals (X/X2-). Photochemical halogenation of phenolic compounds and formation of methyl halide and brominated organic pollutants are highlighted. By evaluating existing literature and identifying some uncertainties, this review emphasizes the environmental significance of sunlight-driven halogenation and proposes further research directions on mechanistic investigation and rational experimental design close to natural systems.
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Affiliation(s)
- Yongxia Dong
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China
| | - Wenya Peng
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China
| | - Yunjiao Liu
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China
| | - Zhaohui Wang
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, Shanghai 200241, China; Technology Innovation Center for Land Spatial Eco-restoration in Metropolitan Area, Ministry of Natural Resources, 3663 N. Zhongshan Road, Shanghai 200062, China.
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Transcriptomic and life history responses of the mayfly Neocloeon triangulifer to chronic diel thermal challenge. Sci Rep 2020; 10:19119. [PMID: 33154410 PMCID: PMC7644658 DOI: 10.1038/s41598-020-75064-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 10/08/2020] [Indexed: 01/31/2023] Open
Abstract
To better understand the effects of transient thermal stress in an aquatic insect, we first identified static temperatures associated with fitness deficits, and then reared larvae from egg hatch to adulthood under diurnally variable regimens including daily forays into deleterious temperatures. We sampled mature larvae at the coolest and warmest portions of their respective regimens for RNA-seq analysis. Few transcripts (28) were differentially expressed when larvae oscillated between favorable temperatures, while 614 transcripts were differentially expressed when experiencing daily transient thermal stress. Transcripts associated with N-glycan processing were downregulated while those associated with lipid catabolism and chitin turnover were significantly upregulated in heat stressed larvae. An across-regimen comparison of differentially expressed transcripts among organisms sampled at comparable temperatures demonstrated that the effects of daily thermal stress persisted even when larvae were sampled at a more optimal temperature (806 differentially expressed transcripts). The chronically stressed population had reduced expression of transcripts related to ATP synthesis, mitochondrial electron chain functions, gluconeogenesis and glycolytic processes while transcripts associated with cell adhesion, synaptic vesicle transport, regulation of membrane potential and lipid biosynthesis increased. Comparisons of constant vs. variable temperatures revealed that the negative consequences of time spent at stressful temperatures were not offset by more time spent at optimal temperatures.
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23
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Verberk WC, Buchwalter DB, Kefford BJ. Energetics as a lens to understanding aquatic insect's responses to changing temperature, dissolved oxygen and salinity regimes. CURRENT OPINION IN INSECT SCIENCE 2020; 41:46-53. [PMID: 32682316 DOI: 10.1016/j.cois.2020.06.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/04/2020] [Accepted: 06/08/2020] [Indexed: 05/12/2023]
Abstract
Assemblages of aquatic insects are structured by multiple biotic and abiotic conditions, including temperature, salinity and oxygen. Here we highlight recent developments in our understanding of how high temperatures, elevated salinities and low oxygen levels affect physiological processes, responses at the organismal level, and impacts on species interaction and community assembly. As aquatic insects may be exposed to multiple stressors, we review their sensitivity to interactive effects of multiple stressors. While each of these stressors may operate via different physiological mechanisms, they all influence the overall energy budget as well as the allocation of energy to competing functions such as homeostatic maintenance, growth, development and reproduction. As such, there is potential for interaction whereby one stressor may exacerbate the effect of another stressor. Integrating research on these stressors can provide a powerful approach for delineating the sensitivity of aquatic insects to multiple stressors and developing sound management practices.
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Affiliation(s)
- Wilco Cep Verberk
- Department of Animal Ecology and Ecophysiology, Radboud University, P.O. Box 9010, 6500 GL Nijmegen, the Netherlands.
| | - David B Buchwalter
- Department of Biological Sciences, North Carolina State University. Box 7633, Raleigh, NC 27695, USA
| | - Ben J Kefford
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, ACT 2601, Australia
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24
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Orr SE, Buchwalter DB. It's all about the fluxes: Temperature influences ion transport and toxicity in aquatic insects. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 221:105405. [PMID: 32014642 DOI: 10.1016/j.aquatox.2020.105405] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 12/30/2019] [Accepted: 01/04/2020] [Indexed: 06/10/2023]
Abstract
Many freshwater ecosystems are becoming saltier and/or warmer, but our understanding of how these factors interact and affect the physiology and life history outcomes of most aquatic species remain unknown. We hypothesize that temperature modulates ion transport rates. Since ion transport is energetically expensive, increases in salinity and/or temperature may influence ion flux rates and ultimately, organismal performance. Radiotracer (22Na+, 35SO4-2, and 45Ca2+) experiments with lab-reared mayflies (N. triangulifer) and other field-collected insects showed that increasing temperature generally increased ion transport rates. For example, increasing temperature from 15 °C to 25 °C, increased 22Na+ uptake rates by two-fold (p < 0.0001) and 35SO4-2 uptake rates by four-fold (p < 0.0001) in the caddisfly, Hydropsyche sparna. Smaller changes in 22Na+ and 35SO4-2 uptake rates were observed in the mayflies, Isonychia sayi and Maccaffertium sp., suggesting species-specific differences in the thermal sensitivity of ion transport. Finally, we demonstrated that the toxicity of SO4 was influenced by temperature profoundly in a 96-h bioassay. Under the saltiest conditions (1500 mg L-1 SO4), mayfly survival was 78 % at 15 °C, but only 44 % at 25 °C (p < 0.0036). Conceivably, the energetic cost of osmoregulation in warmer, saltier environments may cause significant major ion toxicity in certain freshwater insects.
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Affiliation(s)
- Sarah E Orr
- North Carolina State University, United States
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25
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Kolpas A, Funk DH, Jackson JK, Sweeney BW. Phenological modeling of the parthenogenetic mayfly Neocloeon triangulifer (Ephemeroptera: Baetidae) in White Clay Creek. Ecol Modell 2020. [DOI: 10.1016/j.ecolmodel.2019.108892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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26
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Cañedo-Argüelles M, Kefford B, Schäfer R. Salt in freshwaters: causes, effects and prospects - introduction to the theme issue. Philos Trans R Soc Lond B Biol Sci 2018; 374:rstb.2018.0002. [PMID: 30509904 DOI: 10.1098/rstb.2018.0002] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2018] [Indexed: 01/07/2023] Open
Abstract
Humans are globally increasing the salt concentration of freshwaters (i.e. freshwater salinization), leading to significant effects at the population, community and ecosystem level. The present theme issue focuses on priority research questions and delivers results that contribute to shaping the future research agenda on freshwater salinization as well as fostering our capacity to manage salinization. The issue is structured along five topics: (i) the estimation of future salinity and evaluation of the relative contribution of the different drivers; (ii) the physiological responses of organisms to alterations in ion concentrations with a specific focus on the osmophysiology of freshwater insects and the responses of different organisims to seawater intrusion; (iii) the impact of salinization on ecosystem functioning, also considering the connections between riparian and stream ecosystems; (iv) the role of context in moderating the response to salinization. The contributions scrutinise the role of additional stressors, biotic interactions, the identify of the ions and their ratios, as well as of the biogeographic and evolutionary context; and (v) the public discourse on salinization and recommendations for management and regulation. In this paper we introduce the general background of salinization, outline research gaps and report key findings from the contributions to this theme issue.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.
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Affiliation(s)
- Miguel Cañedo-Argüelles
- Grup de recerca FEHM (Freshwater Ecology, Hydrology and Management), Departament de Biologia Evolutiva, Ecologia i Ciència Ambientals, Universitat de Barcelona, Avda Diagonal 643, 08028 Barcelona, Spain
| | - Ben Kefford
- Institute for Applied Ecology, University of Canberra, Australian Capital Territory 2601, Australia
| | - Ralf Schäfer
- Department of Quantitative Landscape Ecology, University Koblenz-Landau, Fortstr. 7, 76829 Landau, Germany
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27
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Velasco J, Gutiérrez-Cánovas C, Botella-Cruz M, Sánchez-Fernández D, Arribas P, Carbonell JA, Millán A, Pallarés S. Effects of salinity changes on aquatic organisms in a multiple stressor context. Philos Trans R Soc Lond B Biol Sci 2018; 374:20180011. [PMID: 30509913 PMCID: PMC6283958 DOI: 10.1098/rstb.2018.0011] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2018] [Indexed: 12/29/2022] Open
Abstract
Under global change, the ion concentration of aquatic ecosystems is changing worldwide. Many freshwater ecosystems are being salinized by anthropogenic salt inputs, whereas many naturally saline ones are being diluted by agricultural drainages. This occurs concomitantly with changes in other stressors, which can result in additive, antagonistic or synergistic effects on organisms. We reviewed experimental studies that manipulated salinity and other abiotic stressors, on inland and transitional aquatic habitats, to (i) synthesize their main effects on organisms' performance, (ii) quantify the frequency of joint effect types across studies and (iii) determine the overall individual and joint effects and their variation among salinity-stressor pairs and organism groups using meta-analyses. Additive effects were slightly more frequent (54%) than non-additive ones (46%) across all the studies (n = 105 responses). However, antagonistic effects were dominant for the stressor pair salinity and toxicants (44%, n = 43), transitional habitats (48%, n = 31) and vertebrates (71%, n = 21). Meta-analyses showed detrimental additive joint effects of salinity and other stressors on organism performance and a greater individual impact of salinity than the other stressors. These results were consistent across stressor pairs and organism types. These findings suggest that strategies to mitigate multiple stressor impacts on aquatic ecosystems should prioritize restoring natural salinity concentrations.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.
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Affiliation(s)
- Josefa Velasco
- Department of Ecology and Hydrology, University of Murcia, Murcia, Spain
| | - Cayetano Gutiérrez-Cánovas
- Grup de Recerca Freshwater Ecology and Management (FEM), Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona (UB), Diagonal 643, 08028 Barcelona, Catalonia, Spain
| | - María Botella-Cruz
- Department of Ecology and Hydrology, University of Murcia, Murcia, Spain
| | - David Sánchez-Fernández
- Department of Ecology and Hydrology, University of Murcia, Murcia, Spain
- Instituto de Ciencias Ambientales (ICAM), Universidad de Castilla-La Mancha, Toledo, Spain
| | - Paula Arribas
- Island Ecology and Evolution Research Group, Instituto de Productos Naturales y Agrobiología (IPNA-CSIC), c/Astrofísico Francisco Sánchez 3, 38206 La Laguna, Islas Canarias, Spain
| | | | - Andrés Millán
- Department of Ecology and Hydrology, University of Murcia, Murcia, Spain
| | - Susana Pallarés
- Instituto de Ciencias Ambientales (ICAM), Universidad de Castilla-La Mancha, Toledo, Spain
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28
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Bray JP, Reich J, Nichols SJ, Kon Kam King G, Mac Nally R, Thompson R, O'Reilly-Nugent A, Kefford BJ. Biological interactions mediate context and species-specific sensitivities to salinity. Philos Trans R Soc Lond B Biol Sci 2018; 374:rstb.2018.0020. [PMID: 30509919 DOI: 10.1098/rstb.2018.0020] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2018] [Indexed: 12/21/2022] Open
Abstract
Toxicants have both sub-lethal and lethal effects on aquatic biota, influencing organism fitness and community composition. However, toxicant effects within ecosystems may be altered by interactions with abiotic and biotic ecosystem components, including biological interactions. Collectively, this generates the potential for toxicant sensitivity to be highly context dependent, with significantly different outcomes in ecosystems than laboratory toxicity tests predict. We experimentally manipulated stream macroinvertebrate communities in 32 mesocosms to examine how communities from a low-salinity site were influenced by interactions with those from a high-salinity site along a gradient of salinity. Relative to those from the low-salinity site, organisms from the high-salinity site were expected to have greater tolerance and fitness at higher salinities. This created the potential for both salinity and tolerant-sensitive organism interactions to influence communities. We found that community composition was influenced by both direct toxicity and tolerant-sensitive organism interactions. Taxon and context-dependent responses included: (i) direct toxicity effects, irrespective of biotic interactions; (ii) effects that were owing to the addition of tolerant taxa, irrespective of salinity; (iii) toxicity dependent on sensitive-tolerant taxa interactions; and (iv) toxic effects that were increased by interactions. Our results reinforce that ecological processes require consideration when examining toxicant effects within ecosystems.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.
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Affiliation(s)
- J P Bray
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - J Reich
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - S J Nichols
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - G Kon Kam King
- Università degli Studi di Torino, Torino, Italy.,Collegio Carlo Alberto, Moncalieri, Italy
| | - R Mac Nally
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - R Thompson
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - A O'Reilly-Nugent
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - B J Kefford
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
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