| 1. |
- Arnott, Shelley E., et al.
(författare)
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Widespread variation in salt tolerance within freshwater zooplankton species reduces the predictability of community-level salt tolerance
- 2023
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Ingår i: Limnology and Oceanography Letters. - : John Wiley & Sons. - 2378-2242. ; 8:1, s. 8-18
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Tidskriftsartikel (refereegranskat)abstract
- The salinization of freshwaters is a global threat to aquatic biodiversity. We quantified variation in chloride (Cl-) tolerance of 19 freshwater zooplankton species in four countries to answer three questions: (1) How much variation in Cl- tolerance is present among populations? (2) What factors predict intraspecific variation in Cl- tolerance? (3) Must we account for intraspecific variation to accurately predict community Cl- tolerance? We conducted field mesocosm experiments at 16 sites and compiled acute LC(50)s from published laboratory studies. We found high variation in LC(50)s for Cl- tolerance in multiple species, which, in the experiment, was only explained by zooplankton community composition. Variation in species-LC50 was high enough that at 45% of lakes, community response was not predictable based on species tolerances measured at other sites. This suggests that water quality guidelines should be based on multiple populations and communities to account for large intraspecific variation in Cl- tolerance.
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| 2. |
- Bowes, Rachel E., et al.
(författare)
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Landscape features control river's confluences water quality and tributary fish composition
- 2023
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Ingår i: Rivers Research and Applications. - : John Wiley & Sons. - 1535-1459 .- 1535-1467. ; 39:6, s. 1025-1036
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Tidskriftsartikel (refereegranskat)abstract
- Rivers networks represent hierarchical dendritic habitats within terrestrial landscapes and differences in connectivity and land use influence dispersal, and consequently biodiversity patterns. We, therefore, measured variation in water chemistry and fish abundance and related these to a number of landscape characteristics (e.g., wetland, urban, wooded, and agricultural) in the River Klaralven and its 30 permanently flowing tributaries. We hypothesized that these environmental attributes would differ between tributary and main stem habitat and that these differences would be driven by landscape attributes including land use. We found considerable intertributary variation in temperature and nutrient levels, and between the tributaries and the main stem. Generally, water temperature was lower in the tributaries, whereas nutrient levels were higher in the tributaries. The lower water temperature has implications for coldwater fishes, and we found two fishes, burbot and lamprey, associated with coldwater tributaries. We also found an inverse relationship between water quality and anthropogenic land use. Protecting tributaries with low anthropogenic impact will likely become increasingly important with ongoing global warming as they can function as thermal refugia for coldwater fishes. Hence, this study underscores the need to evaluate water courses at regional scales to identify spatial refuges and ensure connectivity.
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| 3. |
- Dietrich, Anna, 1979-, et al.
(författare)
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The Use of Phytometers for Evaluating Restoration Effects on Riparian Soil Fertility
- 2014
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Ingår i: Journal of Environmental Quality. - : American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.. - 0047-2425 .- 1537-2537. ; 43:6, s. 1916-1925
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Tidskriftsartikel (refereegranskat)abstract
- The ecological restoration of streams in Sweden has become increasingly important to counteract effects of past timber floating. In this study, we focused on the effect on riparian soil properties after returning coarse sediment (cobbles and boulders) to the channel and reconnecting riparian with instream habitats. Restoration increases habitat availability for riparian plants, but its effects on soil quality are unknown. We also analyzed whether the restoration effect differs with variation in climate and stream size. We used standardized plant species to measure the performance of a grass (Phleum pratense L.) and a forb (Centaurea cyanus L.) in soils sampled in the riparian zones of channelized and restored streams and rivers. Furthermore, we analyzed the mass fractions of carbon (C) and nitrogen (N) along with the proportions of the stable isotopes C-13 and N-15 in the soil, as well as its grain size composition. We found a positive effect of restoration on biomass of phytometers grown in riparian soils from small streams, indicating that restoration enhanced the soil properties favoring plant performance. We suggest that changed flooding with more frequent but less severe floods and slower flows, enhancing retention, could explain the observed patterns. This positive effect suggests that it may be advantageous to initiate restoration efforts in small streams, which make up the highest proportion of the stream network in a catchment. Restoration responses in headwater streams may then be transmitted downstream to facilitate recovery of restored larger rivers. If the larger rivers were restored first, a slower reaction would be expected.
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| 4. |
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| 5. |
- Hansen, Henry H., et al.
(författare)
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Resilient rivers and connected marine systems : A review of mutual sustainability opportunities
- 2022
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Ingår i: Global Sustainability. - : Cambridge University Press. - 2059-4798. ; 6, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- Rivers are crucial to the water cycle, linking the landscape to the sea. Human activities, including effluent discharge, water use, and fisheries, have transformed the resilience of many rivers around the globe. SDG 14 prioritizes addressing many of the same issues in marine ecosystems. This review illustrates how rivers contribute directly and indirectly to SDG 14 outcomes, but also provides ways to potentially address them through a river to sea view on policy, management, and research. The United Nations initiated the sustainable development goals (SDGs) to produce "a shared blueprint for peace and prosperity for people and the planet, now and into the future."Established in 2015, progress of SDGs directed at the aquatic environment is slow despite an encroaching 2030 deadline. The modification of flow regimes combined with other anthropogenic pressures underpin ecological impacts across aquatic ecosystems. Current SDG 14 targets (Life Below Water) do not incorporate the interrelationships of rivers and marine systems systematically, nor do they provide recommendations on how to improve existing management and policy in a comprehensive manner. Therefore, this review aims to illustrate the linkages between rivers and marine ecosystems concerning the SDG 14 targets and to illustrate land to sea based strategies to reach sustainability goals. We provide an applied case study to show how opportunities can be explored. We review three major areas where mutual opportunities are present: 1) rivers contribute to marine and estuary ecosystem resilience (targets 14.1, 14.2, 14.3, 14.5); (2) resilient rivers are part of the global fisheries sustainability concerns (targets 14.4, 14.6, 14.7, 14.B); and (3) enhancing marine policy and research from a river and environmental flows perspective (targets 14.A, 14.C). Social Media Summary (100 characters max): Restoring resilience to rivers and their environmental flows helps fulfill SDG 14.
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| 6. |
- Hansson, Mattias, et al.
(författare)
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The suitability of Hester–Dendy macroinvertebrate samplers in fluctuating flows
- 2021
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Ingår i: Rivers Research and Applications. - Hoboken : John Wiley & Sons. - 1535-1459 .- 1535-1467. ; 37:6, s. 859-899
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Tidskriftsartikel (refereegranskat)abstract
- Reliable methods for assessing the ecological status of degraded rivers are essential for evaluating restoration efforts in lotic habitats. Several methods are based on biological indicators, such as benthic macroinvertebrates. The Hester–Dendy multi‐plate sampler is a commonly used tool for sampling macroinvertebrates, but its performance under different environmental conditions is not well understood. In a laboratory experiment, we assessed if fluctuating and increasing water velocity influences the performance of Hester–Dendy samplers, by studying colonization of the samplers in relation to a pre‐determined composition of benthic macroinvertebrates. Biodiversity (Shannon‐Wiener index) of colonizing macroinvertebrates was higher in a constant than in a fluctuating flow treatment, but there was no effect on the number of colonizing individuals. The results suggest a potential bias in the interpretation of biodiversity data from sites with sub‐daily flow changes, for example, downstream of hydropeaking power plants.
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| 7. |
- Hasselquist, Eliza Maher, et al.
(författare)
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Time for recovery of riparian plants in restored northern Swedish streams : A chronosequence study
- 2015
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 25:5, s. 1373-1389
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Tidskriftsartikel (refereegranskat)abstract
- A lack of ecological responses in stream restoration projects has been prevalent throughout recent literature with many studies reporting insufficient time for recovery. We assessed the relative importance of time, site variables, and landscape setting for understanding how plant species richness and understory productivity recover over time in riparian zones of northern Swedish streams. We used a space-for-time substitution consisting of 13 stream reaches restored 5-25 years ago, as well as five unrestored channelized reference reaches. We inventoried the riparian zone for all vascular plant species along 60-m study reaches and quantified cover and biomass in plots. We found that while species richness increased with time, understory biomass decreased. Forbs made up the majority of the species added, while the biomass of graminoids decreased the most over time, suggesting that the reduced dominance of graminoids favored less productive forbs. Species richness and density patterns could be attributed to dispersal limitation, with anemochorous species being more associated with time after restoration than hydrochorous, zoochorous, or vegetatively reproducing species. Using multiple linear regression, we found that time along with riparian slope and riparian buffer width (e.g., distance to logging activities) explained the most variability in species richness, but that variability in total understory biomass was explained primarily by time. The plant community composition of restored reaches differed from that of channelized references, but the difference did not increase over time. Rather, different time categories had different successional trajectories that seemed to converge on a unique climax community for that time period. Given our results, timelines for achieving species richness objectives should be extended to 25 years or longer if recovery is defined as a saturation of the accumulation of species over time. Other recommendations include making riparian slopes as gentle as possible given the landscape context and expanding riparian buffer width for restoration to have as much impact as possible.
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| 8. |
- Hebert, Marie-Pier, et al.
(författare)
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Lake salinization drives consistent losses of zooplankton abundance and diversity across coordinated mesocosm experiments
- 2023
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Ingår i: Limnology and Oceanography Letters. - : John Wiley & Sons. - 2378-2242. ; 8:1, s. 19-29
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Tidskriftsartikel (refereegranskat)abstract
- Human-induced salinization increasingly threatens inland waters; yet we know little about the multifaceted response of lake communities to salt contamination. By conducting a coordinated mesocosm experiment of lake salinization across 16 sites in North America and Europe, we quantified the response of zooplankton abundance and (taxonomic and functional) community structure to a broad gradient of environmentally relevant chloride concentrations, ranging from 4 to ca. 1400 mg Cl- L-1. We found that crustaceans were distinctly more sensitive to elevated chloride than rotifers; yet, rotifers did not show compensatory abundance increases in response to crustacean declines. For crustaceans, our among-site comparisons indicate: (1) highly consistent decreases in abundance and taxon richness with salinity; (2) widespread chloride sensitivity across major taxonomic groups (Cladocera, Cyclopoida, and Calanoida); and (3) weaker loss of functional than taxonomic diversity. Overall, our study demonstrates that aggregate properties of zooplankton communities can be adversely affected at chloride concentrations relevant to anthropogenic salinization in lakes.
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| 9. |
- Hintz, William D., et al.
(författare)
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Current water quality guidelines across North America and Europe do not protect lakes from salinization
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:9
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Tidskriftsartikel (refereegranskat)abstract
- Human-induced salinization caused by the use of road deicing salts, agricultural practices, mining operations, and climate change is a major threat to the biodiversity and functioning of freshwater ecosystems. Yet, it is unclear if freshwater ecosystems are protected from salinization by current water quality guidelines. Leveraging an experimental network of land-based and in-lake mesocosms across North America and Europe, we tested how salinization—indicated as elevated chloride (Cl−) concentration—will affect lake food webs and if two of the lowest Cl− thresholds found globally are sufficient to protect these food webs. Our results indicated that salinization will cause substantial zooplankton mortality at the lowest Cl− thresholds established in Canada (120 mg Cl−/L) and the United States (230 mg Cl−/L) and throughout Europe where Cl− thresholds are generally higher. For instance, at 73% of our study sites, Cl− concentrations that caused a ≥50% reduction in cladoceran abundance were at or below Cl− thresholds in Canada, in the United States, and throughout Europe. Similar trends occurred for copepod and rotifer zooplankton. The loss of zooplankton triggered a cascading effect causing an increase in phytoplankton biomass at 47% of study sites. Such changes in lake food webs could alter nutrient cycling and water clarity and trigger declines in fish production. Current Cl− thresholds across North America and Europe clearly do not adequately protect lake food webs. Water quality guidelines should be developed where they do not exist, and there is an urgent need to reassess existing guidelines to protect lake ecosystems from human-induced salinization.
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| 10. |
- Hintz, William D., et al.
(författare)
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Salinization triggers a trophic cascade in experimental freshwater communities with varying food-chain length
- 2017
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Ingår i: Ecological Applications. - : John Wiley & Sons. - 1051-0761 .- 1939-5582. ; 27:3, s. 833-844
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Tidskriftsartikel (refereegranskat)abstract
- The application of road deicing salts in northern regions worldwide is changing the chemical environment of freshwater ecosystems. Chloride levels in many lakes, streams, and wetlands exceed the chronic and acute thresholds established by the United States and Canada for the protection of freshwater biota. Few studies have identified the impacts of deicing salts in stream and wetland communities and none have examined impacts in lake communities. We tested how relevant concentrations of road salt (15, 100, 250, 500, and 1000mgCl(-)/L) interacted with experimental communities containing two or three trophic levels (i.e., no fish vs. predatory fish). We hypothesized that road salt and fish would have a negative synergistic effect on zooplankton, which would then induce a trophic cascade. We tested this hypothesis in outdoor mesocosms containing filamentous algae, periphyton, phytoplankton, zooplankton, several macroinvertebrate species, and fish. We found that the presence of fish and high salt had a negative synergistic effect on the zooplankton community, which in turn caused an increase in phytoplankton. Contributing to the magnitude of this trophic cascade was a direct positive effect of high salinity on phytoplankton abundance. Cascading effects were limited with respect to impacts on the benthic food web. Periphyton and snail grazers were unaffected by the salt-induced trophic cascade, but the biomass of filamentous algae decreased as a result of competition with phytoplankton for light or nutrients. We also found direct negative effects of high salinity on the biomass of filamentous algae and amphipods (Hyalella azteca) and the mortality of banded mystery snails (Viviparus georgianus) and fingernail clams (Sphaerium simile). Clam mortality was dependent on the presence of fish, suggesting a non-consumptive interactive effect with salt. Our results indicate that globally increasing concentrations of road salt can alter community structure via both direct and indirect effects.
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