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Responses of freshwater algae to inhibitory vanadium concentrations: The role of phosphorus
... At low levels (<0.01 µg/L) vanadium, which is associated with photosynthesis (Werner, 1977;Nalewajko et al., 1995), encourages growth of certain diatom species (Werner, 1977;). Experimental conditions proposed speciation of vanadium will influence its toxicity for algae with decavanadates being less toxic than orthovanadates (Lee, 1982). ...
... Bacteria present in the water influence the uptake of vanadium by diatoms (Osterholz et al., 2014). Experimental conditions show vanadium competes with phosphates at the binding sites of membrane transporters of certain algal species (including diatoms such as Synedra, Fragilaria and Diatoma; Nalewajko et al., 1995). ...
... Higher concentrations result in blue-green algae thriving to the detriment of the diatoms (Patrick, 1976;Werner, 1977;Nalewajko et al., 1995) but Achnanthidium minutissimum was able to tolerate levels of up to 40 µg/L (Patrick, 1976) with the species richness increasing between 10 and 20 µg/L (Patrick, 1976). ...
ABSTRACT
Shale gas extraction through unconventional means (‘fracking’) poses many environmental risks. Fracking, to recover natural gas, has been proposed for large areas in the Karoo. Covering approximately one third of South Africa, the drought prone semi-arid Karoo region, has many unique ecosystems solely reliant on the underground water, intermittent and ephemeral springs. An accurate and rapid biomonitoring technique is needed in the event of fracking taking place. The aim of the project was to determine whether diatoms could be used as bioindicators of water quality in the Karoo. A total of 56 reservoirs (storing underground water) and 9 fountain sites were sampled. While all waters were mostly alkaline (pH 6.59 to 9.59), there was a wide range in concentrations of most of the measured environmental variables. The water chemistry was rather by localized geology. The 388 diatom taxa encountered from 290 samples were collected from a variety of substrates (tiles, cement, metal, plastic, aquatic plants), in various seasons, from both water body types. There was no significant difference in ecological information gained from the substrates within the same water body. Seasonality analysis revealed the water chemistry rather than temperature affected the distribution of the diatom species. Analysis of deformed diatom cells confirmed outline deformity as the most prolific deformity type but no definite link to a specific environmental variable could be established. The most common variables linked to cell deformities were electrical conductivity, sulphate, oxidized nitrogen, lithium, selenium and strontium. The multivariate analysis of the diatom species and water chemistry variables established the main environmental variables impacting diatom community composition as lithium, oxidized nitrogen, electrical conductivity, and sulphate. TWINSPAN identified groups of indicator species and samples. Two of the five groups (Group 000 and 001) were restricted to the Southern Karoo, Group 000 did not have any specific indicator species. Conditions for Group 001 were indicated by Denticula kuetzingii while Halamphora veneta and Epithemia adnata were indicators for Group 10. Achnanthidium minutissimum, an indicator for Group 01, does not reflect the water chemistry but could be an indicator of habitat disturbance. Water bodies having low flow water with anthropogenic influences (Group 11) are indicated by Eolimna subminuscula, Navicula erifuga, Nitzschia supralitorea and Gomphonema parvulum. Overall, the conclusion can be drawn that diatoms do reflect the water quality in the Karoo and could be useful as bioindicators.
Two in-field experiments were conducted to determine whether the diatom community changes (including possible die-off) when exposed to various contaminants. The effects of the contaminants (sewage, saline solution, fracking fluid and diesel) in water tanks were compared to a control. The diatom community did not respond as expected in both experiments. The diesel contaminated tanks were the only tanks where the diatoms suffered a total die-off. Diatom life-forms and ecological guilds were applied to both diatom community results. It was found that communities in the experimental tanks did not progress further than the pioneer stage.
... Also, based on the previously published study, we can assume that the main fraction of the available vanadium is vanadate(V) [13]. The presence of phosphate may reduce vanadate uptake due to competition [37] and further studies focusing on the interactions between vanadium and phosphorus in soils are required to address this issue. ...
Vanadium, V, is a redox-sensitive metal that in solution, under aerobic conditions, prevails as the oxyanion vanadate(V). There is little known regarding vanadium toxicity to soil biota and the present study was set up to determine the toxicity of added vanadate to soil organisms and to investigate the relationship between toxicity and vanadium sorption in soils. Five soils with contrasting properties were spiked with 7 different doses (3.2-3200 mg V kg(-1) ) of dissolved vanadate, and toxicity was measured with 2 microbial and 3 plant assays. The EC50 thresholds (50% adverse effect) of the microbial assays ranged from 28 to 690 mg added V kg(-1) and the EC50s in the plant assays ranged from 18 to 510 mg added V kg(-1) . The lower thresholds were in the concentration range of the background vanadium in the untreated control soils (15-58 mg V kg(-1) ). The vanadium toxicity to plants decreased with a stronger soil vanadium sorption strength. The EC50 values for plants expressed on soil solution basis ranged from 0.8 to 15 mg V L(-1) and were less variable among soils than corresponding values based on total vanadium in soil. It is concluded that sorption decreases the toxicity of added vanadate and that soil solution vanadium is a more robust measure to determine critical vanadium concentrations across soils. Environ Toxicol Chem © 2013 SETAC.
... In species of biofouling diatoms, an absolute requirement of the same enzyme for substratum attachment has been reported (Johnson et al. 1995). An elevated concentration of vanadium has also been demonstrated to have an inhibitory effect on the photosynthesis of phytoplankton (Nalewajko et al. 1995). We found a significant regression between the number of dinoflagellate cysts belonging to autotrophic taxa and the concentration of vanadium (p < 0.05, data not shown). ...
Abundance and frequency of dinoflagellate cysts in 19 surface sediment samples from the northern part of the Swedish west coast has been related to physical and chemical characters of the sediment, hydrography of the overlying water column, and plankton species data from the area. Density of cysts varied between 5000 and 101000 cysts g-1 dw, and the most commonly encountered species were Lingulodinium polyedrum and Protoceratium reticulatum. In all, 46 environmental variables were tested for their relation to dinoflagellate cyst densities, proportion of autotrophic and heterotrophic taxa, and individual species distribution and frequency. The outcomes of multivariate analyses, projection to latent structures (PLS) and canonical correspondence analysis (CCA) were consistent with each other and the actual cyst count. The density of the total cyst assemblage (>90% autotrophic taxa) was primarily related to surface temperature, macronutrients, and inversely to phytoplankton competitors, such as diatoms. The abundance of heterotrophic taxa was governed by the preferences of their prey, i.e. diatom-favourable conditions, and, in most cases, higher proportions of heterotrophic taxa were found at well-mixed sites. Some possible effects of anthropogenic contaminants were also noted. Several taxa showed distinct distribution patterns with respect to the environmental variables. A discrepancy between the species constituting the planktonic and the benthic community was revealed when data from 6 yr of plankton monitoring was compared to the data on distribution of dinoflagellate cysts. In particular, cyst-forming species were only a minor part of the plankton, suggesting that these dinoflagellates spend much of their life in the sediments.
... Also, it has been shown to have a nutrient effect at low concentrations and increase photosynthetic activity in green algae and other plants (Meisch and Becker, 1981). However, at higher concentrations, V is toxic to algae by competing for phosphorus and thus inhibiting growth and photosynthesis (Nalewajko et al., 1995), and also by producing ROS (Valko et al., 2005). Vanadium, like Cu, can also undergo Fenton reactions to produce ROS (Shi and Dalal, 1993). ...
The toxicity of metals to organisms is, in-part, related to the formation of reactive oxygen species (ROS) in cells and subsequent oxidative stress. ROS are by-products of normal respiration and photosynthesis processes in organisms, but environmental factors, like metal exposure, can stimulate excess production. Metals involved in several different mechanisms such as Haber-Weiss cycling and Fenton-type reactions can produce ROS. Some metals, such as Cd, may contribute to oxidative stress indirectly by depleting cellular antioxidants. We investigated the measurement of ROS as a sensitive biomarker of metal toxicity (that could possibly be implemented in a biotic ligand model for algae) and we compared ROS induction in response to several contrasting transition metals (Cu, V, Ni, Zn, and Cd). We also compared the ROS response to glutathione and growth toxicity endpoints measured in a previous study. The cell-permeable dye, 2'7'dichlorodihydrofluorescein diacetate, was used as a probe to detect formation of ROS in Chlamydomonas reinhardtii cells. Metal-exposed cells were incubated with the fluorescent dye in a 96-well plate and monitored over 5.5 h. A dose-response of ROS formation was observed with Cu exposure in the range of 20-500 nM. Cu produced more ROS compared with either Zn or Cd (both nonredox active metals). The redox-active metal V produced increased ROS with increased concentration. The measurement of ROS may be a useful indicator of Cu toxicity, but the signal to noise ratio was better for the glutathione endpoint assay. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011.
... In species of biofouling diatoms an absolute requirement of the same enzyme for substratum attachment has been reported (Johnson et al. 1995). An elevated concentration of vanadium has also been demonstrated to have an inhibitory effect on the photosynthesis of phytoplankton (Nalewajko et al. 1995). We found a significant regression between the number of dinoflagellate cysts belonging to 12 autotrophic taxa and the concentration of vanadium (P< 0.05, data not shown). ...
Thesis (doctoral)--Göteborg University, 2002.
... Unlike most transition metals (but like Mo), the most stable form of V in oxic environments is a negatively charged ion, the oxoanion vanadate (H 2 VO 4 Ϫ /H 2 VO 4 2Ϫ ). Vanadate is a structural and electronic analogue of phosphate, and it competes against phosphate for uptake in freshwater algae (24). It is also a potent inhibitor of phosphorylases (11). ...
Vanadium is a cofactor in the alternative V-nitrogenase that is expressed by some N2-fixing bacteria when Mo is not available. We investigated the V requirements, the kinetics of V uptake, and the production
of catechol compounds across a range of concentrations of vanadium in diazotrophic cultures of the soil bacterium Azotobacter vinelandii. In strain CA11.70, a mutant that expresses only the V-nitrogenase, V concentrations in the medium between 10−8 and 10−6 M sustain maximum growth rates; they are limiting below this range and toxic above. A. vinelandii excretes in its growth medium micromolar concentrations of the catechol siderophores azotochelin and protochelin, which bind
the vanadate oxoanion. The production of catechols increases when V concentrations become toxic. Short-term uptake experiments
with the radioactive isotope 49V show that bacteria take up the V-catechol complexes through a regulated transport system(s), which shuts down at high V
concentrations. The modulation of the excretion of catechols and of the uptake of the V-catechol complexes allows A. vinelandii to precisely manage its V homeostasis over a range of V concentrations, from limiting to toxic.
Elevated vanadium (V) concentrations in oil sands coke, which is produced and stored on the site of some major Athabasca Oil Sands companies, could pose a risk to aquatic ecosystems in northern Alberta, Canada, depending on its future storage and utilization. In the present study, V toxicity was determined in reconstituted Athabasca River water to various freshwater organisms, including 2 midge species (Chironomus dilutus and Chironomus riparius; 4-d and 30- to 40-d exposures) and 2 freshwater fish species (Oncorhynchus mykiss and Pimephales promelas; 4-d and 28-d exposures) to facilitate estimation of water quality benchmarks. The acute toxicity of V was 52.0 and 63.2 mg/L for C. dilutus and C. riparius, respectively, and 4.0 and 14.8 mg V/L for P. promelas and O. mykiss, respectively. Vanadium significantly impaired adult emergence of C. dilutus and C. riparius at concentrations ≥16.7 (31.6% reduction) and 8.3 (18.0% reduction) mg/L, respectively. Chronic toxicity in fish presented as lethality, with chronic 28-d estimates of 0.5 and 4.3 mg/L for P. promelas and O. mykiss, respectively. These data were combined with data from the peer-reviewed literature, and separate acute and chronic species sensitivity distributions (SSDs) were constructed. The acute and chronic hazardous concentrations endangering only 5% of species (HC5) were estimated as 0.64 and 0.05 mg V/L, respectively. These new data for V toxicity to aquatic organisms ensure that there are now adequate data available for regulatory agencies to develop appropriate water quality guidelines for use in the Athabasca Oil Sands region and elsewhere. Until then, the HC5 values presented in the present study could serve as interim benchmarks for the protection of aquatic life from exposure to hazardous levels of V in local aquatic environments. This article is protected by copyright. All rights reserved.
Vanadium (V) is an abundant trace metal present in bitumen from the Athabasca Oil Sands (AOS) region in Alberta, Canada. The upgrading of bitumen can result in the production of large volumes of a carbonaceous material referred to as petroleum coke that contains V at elevated levels compared to the native bitumen. Previous studies have shown that coke has the capacity to leach ecotoxicologically relevant levels of V into water it contacts, yet limited data are available on the toxicity of aqueous V to planktonic organisms. Therefore, this study set out to evaluate the acute and chronic toxicity of V (as vanadate oxyanions) to freshwater zooplankton and phytoplankton species that are either commonly-used laboratory species, or species more regionally-representative of northern Alberta. Four cladoceran (2-d and 21-d tests) and two algal (3-d tests) species were exposed to V to obtain both acute and chronic toxicity estimates. Acute V toxicity (LC50s) ranged from 0.60 mg V/L for Ceriodaphnia quadrangula to 2.17 mg V/L for Daphnia pulex. Chronic toxicity estimates (EC50s) for cladoceran survival and reproduction were nearly identical within species and ranged from a low of 0.13 to a high of 0.46 mg V/L for Daphnia dentifera and D. pulex, respectively. The lack of sublethal V toxicity in daphnia suggests a direct mechanism of toxicity through ion imbalance. Growth inhibition (EC50) of green algae occurred at concentrations of 3.24 and 4.12 mg V/L for Pseudokirchneriella subcapitata and Scenedesmus quadricauda, respectively. Overall, cladocerans were more sensitive to V than green algae, with survival of the field-collected D. dentifera being approximately 2.5 to 3.5 times more sensitive to acute and chronic V exposure than the standard test species D. pulex. However, there were no significant differences in V toxicity between the field-collected cladocerans Simocephalus serrulatus and C. quadrangula, compared to the respective standard species D. pulex and Ceriodaphnia dubia. Similarly, there were no significant differences in sensitivity to V in the two algal species evaluated. Based on V concentrations reported in laboratory-generated coke leachates, zooplankton survival could be adversely impacted under conditions of chronic leachate exposure if V concentrations in the environment exceed 0.1 mg/L. Furthermore, toxicity thresholds from commonly-used planktonic test species would likely have sufficed for derivation of a V water quality guideline (WQG) for protection of local aquatic communities near oil sands operations, but the new data presented here on V toxicity to more regionally-representative species will strengthen the database for WQG derivation.
Carbon uptake in the green macroalga Cladophora glomerata (L.) Kütz. from the brackish Baltic Sea was studied by recording changes in pH, alkalinity, and inorganic carbon concentration of the seawater medium during photosynthesis. The use of specific inhibitors identified three uptake mechanisms: 1) dehydration of HCO3− into CO2 by periplasmic carbonic anhydrase, followed by diffusion of CO2 into the cell; 2) direct uptake of HCO3− via a 4,4′-diisothiocyanato-stilbene-2,2′-disulfonate-sensitive mechanism; and 3) uptake of inorganic carbon by the involvement of a vanadate-sensitive P-type H+-ATPase (proton pump). A decrease in the alkalinity of the seawater medium during carbon uptake, except when treated with vanadate, indicated a net uptake of the ionic species contributing to alkalinity (i.e. HCO3−, CO32−, and OH−) from the medium, where OH− influx is equivalent to H+ efflux. This would suggest that the proton pump is involved in HCO3− transport. We also show that the proton pump can be induced by carbon limitation. The inducibility of carbon uptake in C. glomerata may partly explain why this species is so successful in the upper littoral zone of the Baltic Sea. Usually, carbon limitation is not a problem in the upper littoral of the sea. However, it may occur frequently within dense Cladophora belts with high photosynthetic rates that create high pH and low carbon concentrations in the alga's microenvironment.
Phosphorus(P)-starved cells of the cyanobacterium Phormidium laminosum have been investigated in relation to their phosphate uptake characteristics. P-deficient cells showed much higher phosphate uptake rates from ultrapure water supplemented with this anion than P-sufficient ones. After 9 days of starvation in P-free medium, the total cellular P content of P-deficient cells was approximately five times lower than that of cells grown in the presence of phosphate. Phosphate uptake by P-deficient cells occurred in both light and dark under aerobic conditions. In anaerobiosis, light was required for uptake, suggesting that the necessary energy could be derived from the respiratory electron transport chain. Phosphate uptake in P-deficient cells was sensitive to vanadate, suggesting the involvement of a plasma membrane ATPase.
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