Dynamics of Selenium in Mercury-Contaminated Experimental Freshwater Ecosystems

1980 ◽  
Vol 37 (5) ◽  
pp. 848-857 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner ◽  
Bruce E. Townsend ◽  
Alison Swick ◽  
Akira Furutani
Keyword(s):  
Water Column ◽  
Aquatic Organisms ◽  
Selenium Concentration ◽  
Freshwater Ecosystems ◽  
Aquatic Herbicides ◽  
Mercury Bioaccumulation ◽  
Simultaneous Movement ◽  
Experimental Treatments ◽  
Aquatic Herbicide ◽  
Rate Of Movement

The simultaneous movement of radiolabeled selenium and mercury was followed in experimental aquatic ecosystems ([Formula: see text] tube enclosures) set into a mercury-contaminated lake. The experimental treatments consisted of increasing stable selenium or sulfate water concentrations, addition of an aquatic herbicide, and isolation of a portion of the water column from contact with sediments. Selenium and mercury did not move together through the ecosystems either geochemically or biologically. Selenium bioaccumulation was rapid by fish, crayfish, and haptobenthos and was enhanced by increased sulfate concentration and in the absence of exposure to bottom sediments. It was reduced in the presence of aquatic herbicides. A selenium concentration of 0.1 mg/L did not affect the rate of movement of mercury out of the water column but it did stabilize the movement of mercury among various compartments in the water column. Elevated selenium appeared to retard the rate of mercury bioaccumulation by fish, crayfish, and haptobenthos. Preliminary observations of selenium toxicity to several aquatic organisms were carried out. The possibility of using selenium as an ameliorating agent for heavy metal polluted freshwater systems is discussed.Key words: selenium, mercury, methylmercury, fish, crayfish

The English–Wabigoon River System: I. A Synthesis of Recent Research with a View towards Mercury Amelioration

1983 ◽  
Vol 40 (12) ◽  
pp. 2206-2217 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner ◽  
Akira Furutani ◽  
Alison L. Swick ◽  
B. E. Townsend
Keyword(s):  
Water Column ◽  
Surface Sediments ◽  
Selenium Concentration ◽  
River System ◽  
Surface Layers ◽  
Advantages And Disadvantages ◽  
Federal Department ◽  
Pollution Problem ◽  
Single Addition ◽  
Mercury Bioaccumulation

Over a 3-yr period, teams from the federal Department of Fisheries and Oceans, the federal Department of the Environment, and the Ontario Ministry of the Environment researched the mercury pollution problem of the English–Wabigoon River system, north-western Ontario, Canada. Mercury methylation and bioaccumulation were occurring mainly in the water column and surface layers of the sediments. Most mercury in the system was buried below the surficial sediments and probably does not contribute substantially to present mercury bioaccumulation. Movement of mercury between geochemical and biological compartments was rapid within the water column and surface sediments. Also, substantial amounts of inorganic and methyl mercury were transported down the river–lake system, having been released from stretches of river upstream of Clay Lake and deposited onto the surfaces of downstream lake sediments. Because of the constant movement of mercury into the water and onto downstream surface sediments, mercury amelioration procedures should concentrate on reducing bioaccumulation rates from both the water column and surface sediments. Treatments such as a single addition of clean clay to the surface sediments of lakes would probably be unsuccessful as long as significant downstream movement of mercury continues. Semicontinuous resuspension of bottom sediments followed by downstream deposition and/or elevation of the selenium concentration in biota by low-level additions of selenite were found to be the two most promising amelioration strategies. Both of these approaches would treat the problem in the water column and surface sediments. We consider advantages and disadvantages of these ideas and some needs for further research.

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.

1.  Toxicity of Fresh and Weathered Sunken Heavy Fuel Oil to the Early Life Stages of Rainbow Trout (Oncorhynchus mykiss) in Simulated Spawning Shoal Environments

2016 ◽  
Author(s):  
Julie Adams
Keyword(s):  
Rainbow Trout ◽  
Water Column ◽  
Aquatic Organisms ◽  
Fuel Oil ◽  
South American ◽  
Benthic Organisms ◽  
Heavy Fuel Oil ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Direct Exposure ◽  
Insight Into

Because the density of heavy fuel oil (HFO) is equal to or greater than that of freshwater, it behaves differently than lighter oils that float. Heavy fuel oil can sink to the bottom or be suspended in the water column and affect aquatic organisms that are not typically exposed to floating oils. Most research on oil spill technologies thus far examines the direct exposure of rainbow trout to floating or submerged oil droplets; there is little knowledge of the impacts of non‐floating heavy fuel oil on the water column and benthic organisms exposed to oil that accumulates in sediments. The toxicity of sunken HFO 6303 and Medium South American (MESA; reference) crude oil, as well as the effects of weathering on toxicity to embryos of rainbow trout were assessed using increasing concentrations of oil on gravel substrate in continuous‐flow desorption columns. Toxicity was assessed by measurement of the rates of mortality and growth, and the prevalence of blue sac disease, a hallmark sign of oil toxicity. The lower median lethal concentration for HFO compared to MESA indicated that HFO is more toxic. Interestingly, the LC50 values for fresh and weathered for both oils were similar, indicating little change in toxicity when the oil weathers naturally. Repetition of this experiment and analysis of PAH content in each treatment will provide more insight into the environmental and health risks associated with sunken heavy fuel oil.   

scholarly journals Potential impacts to freshwater ecosystems caused by flow regime alteration under changing climate conditions in Taiwan

2008 ◽  
Vol 5 (6) ◽  
pp. 3005-3032 ◽  
Author(s):  
J.-P. Suen
Keyword(s):  
Climate Change ◽  
Flow Regime ◽  
River Flow ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Climate Conditions ◽  
Regime Changes ◽  
Changing Climate ◽  
Extreme Flood ◽  
Precautionary Measures

Abstract. Observed increases in the Earth's surface temperature bring with them associated changes in precipitation and atmospheric moisture that consequentially alter river flow regimes. This paper uses the Indicators of Hydrologic Alteration approach to examine climate-induced flow regime changes that can potentially affect freshwater ecosystems. Analyses of the annual extreme water conditions at 23 gauging stations throughout Taiwan reveal large alterations in recent years; extreme flood and drought events were more frequent in the period after 1991 than from 1961–1990, and the frequency and duration of the flood and drought events also show high fluctuation. Climate change forecasts suggest that such flow regime alterations are going to continue into the foreseeable future. Aquatic organisms not only feel the effects of anthropogenic damage to river systems, but they also face on-going threats of thermal and flow regime alterations associated with climate change. This paper calls attention to the issue, so that water resources managers can take precautionary measures that reduce the cumulative effects from anthropogenic influence and changing climate conditions.

scholarly journals Simple quality control technique to identify dissolved oxygen diffusion issues with biochemical oxygen demand bottle incubations

2017 ◽  
Author(s):  
Johnathan Daniel Maxey ◽  
Neil David Hartstein ◽  
Dorathy Penjinus ◽  
Alan Kerroux
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Biochemical Oxygen Demand ◽  
Oxygen Demand ◽  
Freshwater Ecosystems ◽  
Control Technique ◽  
Community Respiration ◽  
Parallel Diffusion ◽  
Quality Control Technique

Stratified estuaries are home to expanding aquaculture activities whose ecological footprints can be observed through trends in microbial community respiration in the water column. Bottle incubations are widely used to measure water column community respiration in marine and freshwater ecosystems by measuring the flux of dissolved oxygen occurring in the bottle over a period of time. When in situ dissolved oxygen (DO) concentrations are markedly different than DO concentration of the incubation medium the potential for diffusion of oxygen across the bottle opening is great and may be especially pronounced in strongly stratified systems with relatively low rates of pelagic oxygen consumption. We incubated 60 Biochemical Oxygen Demand (BOD) bottles filled with sterilized water with DO concentrations ranging from 2.51 mg O2 L-1 to 10.03 mg O2 L-1 for 24 hours in a temperature controlled water bath. There was a significant relationship when DO flux was set as a function of initial DO (DO Flux = -0.0017x + 0.0085, r2 = 0.72, p < 2.2 e-16). DO fluxes ranged from -0.012 mg O2 L-1 hour-1 to 0.005 mg O2 L-1 hour-1 for bottles incubated with initial DO ranging from 10.03 mg O2 L-1 to 3.31 mg O2 L-1, respectively. These results suggest that diffusion across the ground glass seal of BOD bottles is possible and that extra precaution through parallel diffusion controls should be considered when measuring pelagic respiration using BOD bottle incubations in systems with relatively low or relatively high in situ DO concentrations.

scholarly journals The role of methanotrophy in the microbial carbon metabolism of temperate lakes

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Paula C. J. Reis ◽  
Shoji D. Thottathil ◽  
Yves T. Prairie
Keyword(s):  
Water Column ◽  
Carbon Metabolism ◽  
Volume Fraction ◽  
Specific Activity ◽  
Freshwater Ecosystems ◽  
Carbon Consumption ◽  
Temperate Lakes ◽  
Relative Contribution ◽  
Methane Oxidizing Bacteria ◽  
Microbial Carbon

AbstractPrevious stable isotope and biomarker evidence has indicated that methanotrophy is an important pathway in the microbial loop of freshwater ecosystems, despite the low cell abundance of methane-oxidizing bacteria (MOB) and the low methane concentrations relative to the more abundant dissolved organic carbon (DOC). However, quantitative estimations of the relative contribution of methanotrophy to the microbial carbon metabolism of lakes are scarce, and the mechanism allowing methanotrophy to be of comparable importance to DOC-consuming heterotrophy remained elusive. Using incubation experiments, microscopy, and multiple water column profiles in six temperate lakes, we show that MOB play a much larger role than their abundances alone suggest because of their larger cell size and higher specific activity. MOB activity is tightly constrained by the local methane:oxygen ratio, with DOC-rich lakes with large hypolimnetic volume fraction showing a higher carbon consumption through methanotrophy than heterotrophy at the whole water column level. Our findings suggest that methanotrophy could be a critical microbial carbon consumption pathway in many temperate lakes, challenging the prevailing view of a DOC-centric microbial metabolism in these ecosystems.

scholarly journals Effects of Cyanobacteria on Phosphorus Cycling and Other Aquatic Organisms in Simulated Eutrophic Ecosystems

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2265
Author(s):  
Peng Gu ◽  
Qi Li ◽  
Hao Zhang ◽  
Xin Luo ◽  
Weizhen Zhang ◽  
...  
Keyword(s):  
Nutrient Management ◽  
Lake Taihu ◽  
Cyanobacterial Bloom ◽  
Aquatic Organisms ◽  
Pilot Scale ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Eutrophic Lakes ◽  
P Concentration ◽  
Bloom Formation

Cyanobacterial blooms caused by eutrophication in Lake Taihu have led to ecological threats to freshwater ecosystems. A pilot scale experiment was implemented to investigate the relationship between cyanobacteria and other aquatic plants and animals in simulated eutrophic ecosystems under different phosphorus (P) regimes. The results of this study showed that cyanobacteria had two characteristics favorable for bloom formation in eutrophic ecosystems. One is the nutrient absorption. The presence of alkaline phosphatase was beneficial for algal cells in nutrition absorption under low P concentration. Cyanobacteria exhibited a stronger ability to absorb and store P compared to Vallisneria natans, which contributed to the fast growth of algal cells between 0.2 and 0.5 mg·L−1 of P (p < 0.05). However, P loads affected only the maximum biomass, but not the growth phases. The growth cycle of cyanobacteria remained unchanged and was not related to P concentration. P cycling indicated that 43.05–69.90% of the total P existed in the form of sediment, and P content of cyanobacteria showed the highest increase among the organisms. The other is the release of microcystin. Toxic microcystin-LR was released into the water, causing indirectly the growth inhibition of Carassius auratus and Bellamya quadrata and the reduction of microbial diversity. These findings are of importance in exploring the mechanism of cyanobacterial bloom formation and the nutrient management of eutrophic lakes.

scholarly journals Inhibition of Extracellular Enzymes Exposed to Cyanopeptides

2020 ◽  
Vol 74 (3) ◽  
pp. 122-128
Author(s):  
Christine M. Egli ◽  
Regiane S. Natumi ◽  
Martin R. Jones ◽  
Elisabeth M.-L. Janssen
Keyword(s):  
Extracellular Enzymes ◽  
Heterotrophic Bacteria ◽  
Hydrolytic Enzymes ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Biologically Relevant ◽  
Metabolic Functions ◽  
Harmful Cyanobacterial Blooms ◽  
Quality Assessments

Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive secondary metabolites including cyanopeptides that pose ecological and human health risks. Only adverse effects of one class of cyanopeptides, microcystins, have been studied extensively and have consequently been included in water quality assessments. Inhibition is a commonly observed effect for enzymes exposed to cyanopeptides and has mostly been investigated for human biologically relevant model enzymes. Here, we investigated the inhibition of ubiquitous aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are utilized in the metabolism of aquatic organisms and extracellularly by heterotrophic bacteria to obtain assimilable substrates. The ubiquitous occurrence of hydrolytic enzymes leads to the co-occurrence with cyanopeptides especially during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkaline phosphatase were exposed to cyanopeptide extracts of different cyanobacterial strains ( Microcystis aeruginosa wild type and microcystin-free mutant, Planktothrix rubescens) and purified cyanopeptides. We observed inhibition of aminopeptidase and phosphatase upon exposure, especially to the apolar fractions of the cyanobacterial extracts. Exposure to the dominant cyanopeptides in these extracts confirmed that purified microcystins, aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg L–1 range while the phosphatase was less affected. Inhibition of aquatic enzymes can reduce the turnover of nutrients and carbon substrates and may also impair metabolic functions of grazing organisms.

scholarly journals Dispersal of invasive species by drifting

2011 ◽  
Vol 57 (6) ◽  
pp. 818-827 ◽  
Author(s):  
M.C. Van Riel ◽  
G. Van Der Velde ◽  
A. Bij De Vaate
Keyword(s):  
Invasive Species ◽  
Water Column ◽  
Aquatic Organisms ◽  
Aquatic Macroinvertebrates ◽  
Winter Period ◽  
River Rhine ◽  
Summer Period ◽  
Diel Patterns ◽  
Dispersal Mechanism ◽  
Dispersal Vectors

Abstract Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium curvispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a dispersal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range.

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