Roman A. Danilov

Effects of Cu2+, Ni2+, Pb2+, Zn2+ and pentachlorophenol on photosynthesis and motility in Chlamydomonas reinhardtii in short-term exposure experiments

BackgroundHeavy metals, especially copper, nickel, lead and zinc, have adverse effects on terrestrial and in aquatic environments. However, their impact can vary depending on the nature of organisms. Taking into account the ability of heavy metals to accumulate in sediments, extended knowledge of their effects on aquatic biota is needed. In this context the use of model organisms (often unicellular), which allows for rapid assessment of pollutants in freshwater, can be of advantage. Pentachlorophenol has been extensively used for decades as a bleaching agent by pulp- and paper industry. Pentachlorophenol tends to accumulate in the nature. We aim to determine if photosynthesis and motility can be used as sensitive physiological parameters in toxicological studies of Chlamydomonas reinhardtii, a motile green unicellular alga. It is discussed if photosynthesis and motility can be used as sensitive physiological parameters in toxicological studies.ResultsThe concentrations studied ranged from 0.1 to 2.0 mg l-1 for copper, nickel, lead and zinc, and from 0.1 to 10.0 mg l-1 for pentachlorophenol. Exposure time was set to 24 h. Copper and pentachlorophenol turned out to be especially toxic for photosynthetic efficiency (PE) in C. reinhardtii.ConclusionCopper and pentachlorophenol turned out to be especially toxic for PE in C. reinhardtii. Zinc has been concluded to be moderately toxic while nickel and lead had stimulatory effects on the PE. Because of high variance, motility was not considered a reliable physiological parameter when assessing toxicity of the substances using C. reinhardtii.

Comparison of usefulness of three types of artificial substrata (glass, wood and plastic) when studying settlement patterns of periphyton in lakes of different trophic status.

Usefulness of three types of artificial substrata (glass, wood and plastic) was tested when studying settlement patterns of periphyton in lakes of different trophic status. Strictly eu-, meso- and oligotrophic lakes in central Sweden were chosen as objects of the study. Glass slides, glass tubes, pieces of plastic (PVC) and pieces of wood of similar dimensions were placed for 9 weeks in July-August vertically 3 cm above bottom at a total depth of ca. 30 cm. Substrata were located at well-illuminated places without any other submerged objects (like macrophytes and stones), which could potentially affect colonisation patterns by algae. Periphyton communities, which colonised both the glass tubes and the pieces of wood tested, were specific enough to enable a clear classification of the lakes studied in eu-, meso- and oligotrophic. Glass tubes turned out to be the most favourable substratum when investigating settlement patterns of periphyton in this study. Although also colonised by periphytic species, wood did not support the same diversity and abundance of species as glass did. No algae were detected on the plastics studied. The plastics were covered entirely by a slime layer of bacteria. It is discussed if the nature of plastics could have some inhibitory effects on algal growth or the slime layer itself may have prevented settlement of algal spores.

The efficiency of seven diversity and one similarity indices based on phytoplankton data for assessing the level of eutrophication in lakes in central Sweden

Abstract Seven diversity and one similarity indices calculated on the basis of phytoplankton data were studied for their usefulness for eutrophication studies in lakes in central Sweden. The lakes of different eutrophication levels (eutrophic, mesotrophic and eutrophic) were investigated monthly during autumn 1998. All of the diversity indices calculated (Hurlbert’s, Margalef’s, Menhinick’s, Shannon’s, Simpson’s, McNaughton’s and Species Number) failed to distinguish between different levels of eutrophication. However, the use of similarity index based on presence–absence matrices of phytoplankton species proved its high efficiency for eutrophication studies in the lakes in central Sweden. The consideration of abundance, additionally to presence–absence data, was concluded not to be as efficient as only presence–absence matrices. We recommend the use of similarity index based on presence–absence matrices of phytoplankton species as a good tool for the assessment of the level of eutrophication in the lakes studied.

Comparative studies on the usefulness of seven ecological indices for the marine coastal monitoring close to the shore on the swedish east coast

The simultaneous behaviour of seven ecological indices(Hurlbert’s, Margalef’s, Menhinick’s, Shannon’s,species number, Jaccard’s and saprobic index) wasstudied based on phytoplankton data close to the shoreon the East coast of Sweden during the summer 1998.The sampling stations had a similar eutrophicationlevel and were located in bays. Standard phytoplanktondatabases were used in calculating the indices, whichwere later compared using cluster analysis.Hurlbert’s, Margalef’s, Menhinick’s, Shannon’s andspecies number indices, as measure of communitydiversity, produced similar trends which oftendiffered from those based on Jaccard’s index ofsimilarity. However, the simultaneous use of theseindices was found meaningful as a possible part of themonitoring close to the shore. The application of asaprobic index lead to erroneous conclusions in thestudied case.

Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis

The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry.

Applicability of growth rate, cell shape, and motility of Euglena gracilis as physiological parameters for bioassessment at lower concentrations of toxic substances: An experimental approach

The responses of the growth rate, motility, and cell shape in the green flagellate Euglena gracilis to different concentrations of waste water substances from the pulp and paper industry were tested in a long‐term study (7 days). Samples before (uncleaned sample) and after (cleaned sample) the treatment in a cleaning system were studied. The influence of different doses of UV‐B radiation on cell shape and motility was also investigated. No statistically significant effects of increasing concentrations of the waste substances both before and after the cleaning process (except inhibition by the undiluted uncleaned effluent) on the growth rate in E. gracilis were observed. Cell shape turned out to be an unreliable physiological parameter for assessing the toxicity at lower concentrations of waste water substances. No significant patterns could be observed in the response of the cell shape to the different concentrations of the waste water substances or to UV‐B radiation. Motility has been concluded to be a more sensitive parameter than cell shape. However, no clear patterns were observed in the response of the motility to the different concentrations of the waste water substances studied. Increasing concentrations of the uncleaned sample demonstrated a defense against UV‐B radiation, due to the high absorbance in the UV‐B range, when effects on motility were examined. We conclude that contrary to the results reported in the literature earlier, cell shape and motility of E. gracilis are not universal physiological parameters for bioassessment at lower concentrations of toxic substances, including metals such as copper and zinc from the pulp and paper industry. The long‐duration tests had, in general, higher significance than those of short duration. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 78–83, 2001

Responses of Photosynthetic Efficiency, Cell Shape and Motility in Euglena gracilis (Euglenophyceae) to Short-Term Exposure to Heavy Metals and Pentachlorophenol

Euglena gracilis was exposed for 24 hr to concentrationsof copper, nickel, lead and zinc ranging from 0.1 to 2.0 mg L-1 and to pentachlorophenol ranging from 0.1 to 10.0 mg L-1. Photosynthetic efficiency (PE) was inhibited by increasing concentrations of the heavy metals. Nickel was foundto be the least toxic of the metals to E. gracilis, whilethe other three metals exhibited similar levels of toxicity. Treatment with pentachlorophenol caused unusual responses of the photosynthetic apparatus probably due to the especially high toxicity of this substance. Both cell shape and motility turned out to be insensitive physiological parameters for the toxicity testing of the substances studied.

The use of epiphyton and epilithon data as a base for calculating ecological indices in monitoring of eutrophication in lakes in central Sweden.

Eutrophication was monitored with the aid of one similarity and seven diversity indices in the lakes of different trophic levels (eutrophic, mesotrophic and oligotrophic) in central Sweden. The ecological indices were applied separately to epiphyton and epilithon communities. Epiphyton turned out to be inappropriate for assessing eutrophication in the lakes studied. On the other hand, Hurlberts, Simpsons and the similarity indices turned out to be promising environmental tools when applied to the data of epilithon.

Effects of pH on the growth rate, motility and photosynthesis in Euglena gracilis

The influence of pH 3–10 on the growth, motility and photosynthesis inEuglena gracilis was demonstrated during a 7-d cultivation. The cells did not survive at pH<4 and >8, highest growth rate being detected at pH 7. Motility followed a similar patterns as growth rate. Photosynthetic response curves were shown to be of the same type over the whole pH range. High respiration was characteristic for cells grown at pH 5 and 6, the lowest one at 7. At high and also at low pH more active respiration was found which can be considered as a protective response on proton stress. Respiration was not completely inhibited with potassium cyanide. Photosynthesis was the most effective at pH 6; lower and higher pH decreased photosynthetic efficiency. pH affected more the growth rate than the photosynthesis.

Effects of solar radiation, humic substances and nutrients on phytoplankton biomass and distribution in Lake Solumsjö, Sweden

Impacts of solar radiation, humic substances and nutrients on phytoplankton abundance at different depths were investigated in a temperate dimictic lake, Lake Solumsjö. Penetration of solar radiation profiles at different depths, represented as light attenuation coefficient (Kd) were examined. Water sampling and downward irradiance of photosynthetically active radiation (PAR), ultraviolet-A (UV-A, 320–400 nm) and ultraviolet-B (UV-B, 280–320 nm) radiation were performed once a week and at three different times of the day (08.00, 12.00 and 16.00 hrs, local time) between September 13 and November 1, 1999. During the period of investigation, solar radiation above the water surface declined from 474 to 94 μmol m−2 s−1 for PAR, from 1380 to 3.57 W m−2 for UV-A and from 13.1 to 0.026 W m−2 for UV-B, respectively. The attenuation coefficient (Kd) for UV-B radiation ranged from 3.7 to 31 m−1 and UV-B radiation could not be detected at depths greater than 0.25 m. Humic substances measured at 440 nm ranged from 35.5 to 57.7 Pt mg l−1. Mean values of biomass, estimated from chlorophyll a, in the whole water column (0–10 m) varied between 2.3 and 5.6 μg l−1 and a diel fluctuation was observed. During stratified conditions, high levels of iron (1.36 mg l−1) and manganese (4.32 mg l−1) were recorded in the hypolimnion, suggesting that the thermocline played a major role in the vertical distribution of phytoplankton communities in Lake Solumsjö. The high levels of iron and manganese stimulated the growth of Trachelomonas volvocinopsis in the hypolimnion at a depth of 10 m. Negative impacts of UV-B radiation on phytoplankton in lake Solumsjö are reduced due to the high levels of humic substances and the high degree of solar zenith angle at the latitude studied.