A multivariate approach to assess habitat integrity in urban streams using benthic macroinvertebrate metrics

2013 ◽  
Vol 67 (12) ◽  
pp. 2832-2837 ◽  
Author(s):  
S. Canobbio ◽  
A. Azzellino ◽  
R. Cabrini ◽  
V. Mezzanotte
Keyword(s):  
Habitat Loss ◽  
Multiple Stressors ◽  
Synergistic Effects ◽  
Freshwater Ecosystems ◽  
Urban Streams ◽  
Anthropogenic Pressure ◽  
Multivariate Approach ◽  
Urban District ◽  
Morphological Alterations ◽  
Macroinvertebrate Metrics

Benthic macroinvertebrates are widely used as indicators of the health of freshwater ecosystems, responding both to water quality and to the hydromorphological integrity. In urban streams, evaluations can be tricky for the synergistic effects of multiple stressors and confounding factors. In these situations, the most broadly used multimetric indices can be used to assess the overall damage to the invertebrate community and, thus, the overall anthropogenic pressure, but they do not allow to understand the specific causal effects. Particularly, habitat loss due to morphological alterations can be difficult to evaluate, especially due to the often concurrent disturbance caused by water pollution. We used a multivariate approach to focus on the characteristics of the streams and rivers in an urban district and to define which macroinvertebrate metrics should be used to assess the influence of the different kinds of alteration in a severely damaged environment. Some metrics enabling the assessment of habitat loss (ratio of oligochaeta, ratio of filterers) were identified. These metrics may help to raise a better awareness in the evaluation of river restoration success and, thus, in the support of decision-making processes.

scholarly journals Calcium interacts with temperature to influence Daphnia movement rates

2016 ◽  
Vol 3 (12) ◽  
pp. 160537 ◽  
Author(s):  
Gustavo S. Betini ◽  
Jordan Roszell ◽  
Andreas Heyland ◽  
John M. Fryxell
Keyword(s):  
Water Chemistry ◽  
Calcium Concentration ◽  
Synergistic Effects ◽  
Thermal Conditions ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Environmental Stressors ◽  
Ecosystem Dynamics ◽  
Movement Rates ◽  
Projected Changes

Predicting the ecological responses to climate change is particularly challenging, because organisms might be affected simultaneously by the synergistic effects of multiple environmental stressors. Global warming is often accompanied by declining calcium concentration in many freshwater ecosystems. Although there is growing evidence that these changes in water chemistry and thermal conditions can influence ecosystem dynamics, little information is currently available about how these synergistic environmental stressors could influence the behaviour of aquatic organisms. Here, we tested whether the combined effects of calcium and temperature affect movement parameters (average speed, mean turning frequency and mean-squared displacement) of the planktonic Daphnia magna , using a full factorial design and exposing Daphnia individuals to a range of realistic levels of temperature and calcium concentration. We found that movement increased with both temperature and calcium concentration, but temperature effects became considerably weaker when individuals were exposed to calcium levels close to survival limits documented for several Daphnia species, signalling a strong interaction effect. These results support the notion that changes in water chemistry might have as strong an effect as projected changes in temperature on movement rates of Daphnia , suggesting that even sublethal levels of calcium decline could have a considerable impact on the dynamics of freshwater ecosystems.

Environmental flow envelopes: quantifying ecosystem-threatening flow alterations

2021 ◽  
Author(s):  
Vili Virkki ◽  
Elina Alanärä ◽  
Miina Porkka ◽  
Lauri Ahopelto ◽  
Tom Gleeson ◽  
...  
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Human Impacts ◽  
Well Being ◽  
Environmental Flow ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Anthropogenic Pressure ◽  
Basin Scale ◽  
Climate Forcings

<p>The benefits of harnessing rivers into human use should not come with a disproportionate expense on the Earth system. Especially, freshwater ecosystems suffer greatly from direct and indirect human impacts, such as excessive water withdrawals and climate change, which are expected to only increase in the near future. Here, we aim for quantifying the extent and degree of considerable flow alterations that threaten the well-being of freshwater ecosystems, across the world.</p><p>At the global scale, the ecological status of river systems is often assessed using global hydrological models (GHMs) and hydrological environmental flow (EF) methods. These suffer from substantial uncertainties: 1) the GHMs parameterised with variable climate forcings may give highly dispersed discharge estimates and 2) individual hydrological EF methods capture ecosystem water needs poorly. We tackle these sources of uncertainty by introducing a novel methodology: environmental flow envelopes (EFEs). The EFE is an envelope of safe discharge variability between a lower and an upper bound, defined at the sub-basin scale in monthly time resolution. It is based on pre-industrial (1801-1860) discharge and a large ensemble of EF methods, GHMs, and climate forcings, using ISI-MIP2b data. Using the EFE, we can simultaneously assess the frequency and severity of ecosystem-threatening flow alterations.</p><p>Comparing post-industrial (1976-2005) discharge to the EFEs, discharge in 32.7% of the total 3860 sub-basins, covering 28.4% of the global landmass, violates the EFE during more than 10% of all months across four GHMs. These violations are considered as severe threats to freshwater ecosystems. The most impacted regions include areas with high anthropogenic pressure, such as the Middle East, India, Eastern Asia, and Middle America. The violations clearly concentrate on the EFE lower bound during low or intermediate flow seasons. Discharge in 61.4% of sub-basins violates the EFE during more than 10% of low flow season months, average violation being 47.5% below the safe limit denoted by EFE lower bound. Indications of significantly increased flows by violations of the EFE upper bound are fewer and further apart, as well as lower bound violations during high flow season.</p><p>Although fractional discharge allocations alone cannot fully capture the ecosystem water needs, this study is a step towards less uncertainty in global EF assessments. The introduced method provides a novel, globally robust way of estimating ecosystem water needs at the sub-basin scale. The results of this study underline the importance of the low flow season, during which EFE violations are the most prevalent. While only preliminary evidence of significantly increased flows emerges in relatively few areas, the EFE upper bound would benefit from further research. The EFE methodology can be used for exploring macro-regional areas where anthropogenic flow alteration threatens freshwater ecosystems the most. However, case-specific studies incorporating factors beyond quantitative flow only are required for practical implications.</p>

Can Indirect Herbicide Exposure Modify the Response of the Colorado Potato Beetle to an Organophosphate Insecticide?

2019 ◽  
Vol 112 (5) ◽  
pp. 2316-2323 ◽  
Author(s):  
Aigi Margus ◽  
Miia Rainio ◽  
Leena Lindström
Keyword(s):  
Colorado Potato Beetle ◽  
Target Genes ◽  
Multiple Stressors ◽  
Synergistic Effects ◽  
Oxidative Status ◽  
Interactive Effects ◽  
Invasive Pest ◽  
Lipid Hydroperoxides ◽  
Organophosphate Insecticide ◽  
Potato Beetle

AbstractOrganisms live in complex multivariate environments. In agroecosystems, this complexity is often human-induced as pest individuals can be exposed to many xenobiotics simultaneously. Predicting the effects of multiple stressors can be problematic, as two or more stressors can have interactive effects. Our objective was to investigate whether indirect glyphosate-based herbicide (GBH) exposure of the host plant has interactive effects in combination with an insecticide (azinphos-methyl) on an invasive pest Colorado potato beetle (Leptinotarsa decemlineata Say). We tested the effects of GBH and insecticide on the survival, insecticide target genes expression (acetylcholinesterase genes) and oxidative status biomarkers (glutathione S-transferase [GST], glucose-6-phosphate dehydrogenase [G6PDH], glutathione reductase homolog [GR], glutathione peroxidase homolog [GPx], total glutathione [totGSH], glutathione reduced-oxidized [GSH: GSSG], catalase [CAT], superoxide dismutase [SOD], lipid hydroperoxides). We found that exposure to indirect GBH has no single or interactive effects in combination with the insecticide on larval survival. However, prior exposure to GBH inhibits Ldace1 gene expression by 0.55-fold, which is the target site for the organophosphate and carbamate insecticides. This difference disappears when individuals are exposed to both GBH and insecticide, suggesting an antagonistic effect. On the other hand, oxidative status biomarker scores (PCAs of GPx, GR, and CAT) were decreased when exposed to both stressors, indicating a synergistic effect. Overall, we found that indirect GBH exposure can have both antagonistic and synergistic effects in combination with an insecticide, which should be considered when aiming for an ecologically relevant risk assessment of multiple human-induced stressors.

The contamination of inland waters by microplastic fibres under different anthropogenic pressure: Preliminary study in Central Europe (Poland)

2020 ◽  
Vol 38 (11) ◽  
pp. 1231-1238
Author(s):  
Anita Kaliszewicz ◽  
Michał Winczek ◽  
Kamil Karaban ◽  
Dominik Kurzydłowski ◽  
Maria Górska ◽  
...  
Keyword(s):  
High Probability ◽  
Control Sample ◽  
Mesh Size ◽  
Freshwater Ecosystems ◽  
Inland Waters ◽  
Anthropogenic Pressure ◽  
Large Cities ◽  
Field Samples ◽  
Northeastern Poland ◽  
Preliminary Study

The contamination of freshwater ecosystems with microfibres has not yet been studied in Poland. We analysed samples from a river and three lakes located in central and northeastern Poland. A significantly higher number of fibres were reported in the river, which runs through large cities, compared with the lake situated within the Landscape Park. Fibres smaller than 1.0 mm dominated, especially in the river where they constituted 39% of all fibres detected. We found more microplastics (⩽ 4930 fibres·m−3) by using a mesh size of 20 µm compared with other studies of inland waters. The use of Raman spectroscopy allowed us to identify conventional plastic polymers: polyethylene terephthalate, polyester and polyurethane. We estimated that up to 25 g of microplastic in the form of fibres might be in the lake water under the surface. We found microplastic fibres in Majcz Lake situated within the Masurian Landscape Park. This suggests that microfibres are carried by the wind and rain and enter freshwater isolated from sewage outlets. By using the control sample and an air-test of microfibres in the laboratory, we observed that there is a high probability of contamination with microplastic in the field samples (up to 30% of all fibres detected). The contamination risk noted from the samples cannot be ignored; this could be particularly important for analysis of microplastic in remote freshwater ecosystems.

scholarly journals Multiple Stressors Determine Community Structure and Estimated Function of River Biofilm Bacteria

2020 ◽  
Vol 86 (12) ◽  
Author(s):  
Ferran Romero ◽  
Vicenç Acuña ◽  
Sergi Sabater
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Pesticide Exposure ◽  
Multiple Stressors ◽  
Bacterial Community Composition ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Hydrological Stress ◽  
The Individual

ABSTRACT Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress, and pesticide exposure. We used 24 artificial streams on which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e., a simulated low-flow situation) was the most relevant, since it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57 to 89% of all significant interactions), followed by synergisms (11 to 43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities. IMPORTANCE Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g., toxic chemicals, increased water temperatures, and hydrological alterations) cooccurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.

Multiple stressors in freshwater ecosystems

2010 ◽  
Vol 55 ◽  
pp. 1-4 ◽  
Author(s):  
S. J. ORMEROD ◽  
M. DOBSON ◽  
A. G. HILDREW ◽  
C. R. TOWNSEND
Keyword(s):  
Multiple Stressors ◽  
Freshwater Ecosystems

scholarly journals Synergistic impacts of habitat loss and fragmentation on model ecosystems

2016 ◽  
Vol 283 (1839) ◽  
pp. 20161027 ◽  
Author(s):  
Lewis J. Bartlett ◽  
Tim Newbold ◽  
Drew W. Purves ◽  
Derek P. Tittensor ◽  
Michael B. J. Harfoot
Keyword(s):  
Land Use ◽  
Habitat Loss ◽  
Plant Biomass ◽  
Synergistic Effects ◽  
Ecosystem Model ◽  
Ecosystem Structure ◽  
Population Declines ◽  
Ecosystem Responses ◽  
Habitat Loss And Fragmentation ◽  
Biomass Loss

Habitat loss and fragmentation are major threats to biodiversity, yet separating their effects is challenging. We use a multi-trophic, trait-based, and spatially explicit general ecosystem model to examine the independent and synergistic effects of these processes on ecosystem structure. We manipulated habitat by removing plant biomass in varying spatial extents, intensities, and configurations. We found that emergent synergistic interactions of loss and fragmentation are major determinants of ecosystem response, including population declines and trophic pyramid shifts. Furthermore, trait-mediated interactions, such as a disproportionate sensitivity of large-sized organisms to fragmentation, produce significant effects in shaping responses. We also show that top-down regulation mitigates the effects of land use on plant biomass loss, suggesting that models lacking these interactions—including most carbon stock models—may not adequately capture land-use change impacts. Our results have important implications for understanding ecosystem responses to environmental change, and assessing the impacts of habitat fragmentation.

scholarly journals Warmer temperatures interact with salinity to weaken physiological facilitation to stress in freshwater fishes

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Richard H Walker ◽  
Geoffrey D Smith ◽  
Spencer B Hudson ◽  
Susannah S French ◽  
Annika W Walters
Keyword(s):  
Stress Reactivity ◽  
Multiple Stressors ◽  
Cutthroat Trout ◽  
Freshwater Fishes ◽  
Freshwater Ecosystems ◽  
Negative Effects ◽  
Temperature Dependent ◽  
Glucose Levels ◽  
Baseline Concentrations ◽  
Underlying Mechanisms

Abstract Management of stressors requires an understanding of how multiple stressors interact, how different species respond to those interactions and the underlying mechanisms driving observed patterns in species’ responses. Salinization and rising temperatures are two pertinent stressors predicted to intensify in freshwater ecosystems, posing concern for how susceptible organisms achieve and maintain homeostasis (i.e. allostasis). Here, glucocorticoid hormones (e.g. cortisol), responsible for mobilizing energy (e.g. glucose) to relevant physiological processes for the duration of stressors, are liable to vary in response to the duration and severity of salinization and temperature rises. With field and laboratory studies, we evaluated how both salinity and temperature influence basal and stress-reactive cortisol and glucose levels in age 1+ mottled sculpin (Cottus bairdii), mountain sucker (Catostomus platyrhynchus) and Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus). We found that temperature generally had the greatest effect on cortisol and glucose concentrations and the effect of salinity was often temperature dependent. We also found that when individuals were chronically exposed to higher salinities, baseline concentrations of cortisol and glucose usually declined as salinity increased. Reductions in baseline concentrations facilitated stronger stress reactivity for cortisol and glucose when exposed to additional stressors, which weakened as temperatures increased. Controlled temperatures near the species’ thermal maxima became the overriding factor regulating fish physiology, resulting in inhibitory responses. With projected increases in freshwater salinization and temperatures, efforts to reduce the negative effects of increasing temperatures (i.e. increased refuge habitats and riparian cover) could moderate the inhibitory effects of temperature-dependent effects of salinization for freshwater fishes.

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