| 11. |
- Dahllöf, Ingela, 1963, et al.
(författare)
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Long-term effects of tri-n-butyltin on the function of a marine sediment system
- 1999
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Ingår i: Marine Ecology Progress Series. ; 188, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The effect of tri-n-butyl-tin (TBT) was studied in a 5 mo experiment using intact coastal sediment communities in a boxcosm system. TBT-spiked sediment was added in a geometrical series between 0.0065 and 300 mu mol TBT m(-2) to a sediment that already had a background TBT concentration. Fluxes of ammonium, nitrate, phosphate, silicate and oxygen were used as effect indicators for the entire sediment system, integrating the function of all fauna and micro-organisms present. Changes in flux patterns were analysed in order to evaluate the effect of TBT on the whole sediment system using a non-parametric analysis of similarities (ANOSIM), based on Bray-Curtis similarity indices. Effects were seen at the lowest additions of 6.5 nmol TBT m(-2) as changes in flux pattern compared to the control sediments. The separate nutrient fluxes were also evaluated, showing an early response in a reduced ammonium flux and a stimulated nitrate flux for most of the TBT additions. The initial response indicated immediate effects on the microbial part of the sediment community. The fluxes changed with time in all sediment boxes, but the changes were different in sediments with added TBT compared to the control sediment. These changes showed that the heterotrophic capability to degrade organic matter and autotrophic nitrification was reduced during the 5 mo of the experiment. In the 3 highest additions, the abundance of macrofauna was reduced at the very beginning of the experiment, whereas fauna in the intermediate additions seemed to become stressed with time as indicated by an increased oxygen consumption. This study shows that minute additions of fresh TBT to an already contaminated sediment have effects on the function of the sediment system at nominal concentrations of nmol of TBT added per square metre. These additions were well below the current detection limits for TBT in sediments.
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| 12. |
- Dahllöf, Ingela, 1963, et al.
(författare)
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The Effect of TBT on the Structure of a Marine Sediment Community - a Boxcosm Study
- 2001
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Ingår i: Marine Pollution Bulletin. - 0025-326X .- 1879-3363. ; 42:8, s. 689-695
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Tidskriftsartikel (refereegranskat)abstract
- The effect of tri-n-butyl tin (TBT) on an intact marine sediment community after five months exposure was investigated. Changes in the structure of macro- and meiofauna communities were determined, as well as the functional diversity of the microbial community using BIOLOG microplates for Gram negative bacteria. Development of tolerance in the microbial community was investigated using Pollution Induced Community Tolerance (PICT) experiments with fluxes of nutrients as effect indicators. TBT affected the structure and recruitment of the macro- and meiofauna at nominal additions of 30137 mol TBT/m2 sediment. Number of species, diversity, biomass and community similarity was reduced at these concentrations compared to control. Species that molt seemed to be the most tolerant since they were predominant in boxes that had received the highest TBT addition and echinoderms were the most sensitive species. Renewed addition of TBT in PICT experiments with sediment from each boxcosm showed that TBT had an effect on individual nutrient fluxes from all sediments. Analyses of the flux patterns revealed a memory of previous TBT exposure, either due to induced tolerance or other community conditioning.
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| 13. |
- Eriksson, Martin, 1970, et al.
(författare)
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A phylogenetic approach to detect selection on the target site of the antifouling compound irgarol in tolerant periphyton communities
- 2009
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 11, s. 2065-2077
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Tidskriftsartikel (refereegranskat)abstract
- Using DNA sequence data for phylogenetic assessment of toxicant targets is a new and promising approach to study toxicant-induced selection in communities. Irgarol 1051 is a photosystem (PS) II inhibitor used in antifouling paint. It inhibits photosynthesis through binding to the D1 protein in PS II, which is encoded by the psbA gene found in genomes of chloroplasts, cyanobacteria and cyanophages. psbA mutations that alter the target protein can confer tolerance to PS II inhibitors. We have previously shown that irgarol induces community tolerance in natural marine periphyton communities and suggested a novel tolerance mechanism, involving the amino acid sequence of a turnover-regulating domain of D1, as contributive to this tolerance. Here we use a large number of psbA sequences of known identity to assess the taxonomic affinities of psbA sequences from these differentially tolerant communities, by performing phylogenetic analysis. We show that periphyton communities have high psbA diversity and that this diversity is adversely affected by irgarol. Moreover, we suggest that within tolerant periphyton the novel tolerance mechanism is present among diatoms only, whereas some groups of irgarol-tolerant cyanobacteria seem to have other tolerance mechanisms. However, it proved difficult to identify periphyton psbA haplotypes to the species or genus level, which indicates that the genomic pool of the attached, periphytic life forms is poorly studied and inadequately represented in international sequence databases. © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.
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| 14. |
- Eriksson, Martin, 1970, et al.
(författare)
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Community-Level Analysis of psbA Gene Sequences and Irgarol Tolerance in Marine Periphyton
- 2009
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Ingår i: Applied and Environmental Microbiology. - Washington, D.C. : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 75:4, s. 897-906
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Tidskriftsartikel (refereegranskat)abstract
- This study analyzes psbA gene sequences, predicted D1 protein sequences, species relative abundance, and pollution-induced community tolerance in marine periphyton communities exposed to the antifouling compound Irgarol 1051. The mechanism of action of Irgarol is the inhibition of photosynthetic electron transport at photosystem II by binding to the D1 protein. The metagenome of the communities was used to produce clone libraries containing fragments of the psbA gene encoding the D1 protein. Community tolerance was quantified with a short-term test for the inhibition of photosynthesis. The communities were established in a continuous flow of natural seawater through microcosms with or without added Irgarol. The selection pressure from Irgarol resulted in an altered species composition and an inducted community tolerance to Irgarol. Moreover, there was a very high diversity in the psbA gene sequences in the periphyton, and the composition of psbA and D1 fragments within the communities was dramatically altered by increased Irgarol exposure. Even though tolerance to this type of compound in land plants often depends on a single amino acid substitution (Ser(264)-> Gly) in the D1 protein, this was not the case for marine periphyton species. Instead, the tolerance mechanism likely involves increased degradation of D1. When we compared sequences from low and high Irgarol exposure, differences in nonconserved amino acids were found only in the so-called PEST region of D1, which is involved in regulating its degradation. Our results suggest that environmental contamination with Irgarol has led to selection for high-turnover D1 proteins in marine periphyton communities at the west coast of Sweden.
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| 15. |
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| 16. |
- Eriksson, Martin, 1970, et al.
(författare)
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Long-term effects of lowered pH on marine periphyton communities
- 2011
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Ingår i: SETAC (Society of environmental Toxicology and Chemistry) Europe, 21st Annual Meeting.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The phenomenon of Ocean Acidification has been identified as a potential threat to several marine organisms and might lead to adverse disturbances of marine ecosystems. Although the knowledge about effects of rising acidity in the oceans is increasing for some species, the knowledge of these effects on the community level of biological complexity is very scarce. Still, community-level effect indicators are needed in order to predict direct and indirect effects of Ocean Acidification on marine ecosystems. In a community the organisms live in their realized niche with important ecological interactions (e.g. competition, grazing and predation) present. This gives community approaches in ecotoxicological tests high ecological relevance. Since lowered pH might eliminate species or strains that are sensitive to such stress, and select for the ones that are more competitive under this condition, a community approach have the potential to detect any pH-induced change in community structure or function. We have used marine periphyton communities in a long-term study of effects of increased partial pressure of CO2 in the water and the accompanied lowering of pH. Periphyton was allowed to colonize and grow on glass substrata for 3.5 weeks in flow-through microcosms. The pH in the microcosms was either that of the incoming natural surface water or was manipulated by bubbling of CO2 down to approximately 7.7. We used Pulse Amplitude Modulation (PAM) to detect effects on photosynthetic electron transport and estimate induced community tolerance to low pH. In addition, we used confocal microscopy to trace effects on biofilm architecture and biofilm thickness. We have also estimated microbial diversity and composition of trace elements in periphyton using PCR-TGGE and X-ray fluorescence respectively. First results indicate that long-term effects of lowered pH change the capacity of communities to tolerate further changes in pH, making them more sensitive to pH-stress. However, no long-term effects on photosynthetic electron transport or trace element composition was detected.
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| 17. |
- Eriksson, Martin, 1970, et al.
(författare)
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Long-term effects of the antibacterial agent triclosan on marine periphyton communities
- 2015
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 34:9, s. 2067-2077
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Tidskriftsartikel (refereegranskat)abstract
- Triclosan is a widely used antibacterial agent that has become a ubiquitous contaminant in freshwater, estuary, and marine environments. Concerns about potential adverse effects of triclosan have been described in several recent risk assessments. Its effects on freshwater microbial communities have been well studied, but studies addressing effects on marine microbial communities are scarce. In the present study, the authors describe short- and long-term effects of triclosan on marine periphyton (microbial biofilm) communities. Short-term effects on photosynthesis were estimated after 60min to 210min of exposure. Long-term effects on photosynthesis, chlorophyll a fluorescence, pigment content, community tolerance, and bacterial carbon utilization were studied after exposing periphyton for 17d in flow-through microcosms to 0.316nM to 10000nM triclosan. Results from the short-term studies show that triclosan is toxic to periphyton photosynthesis. Half maximal effective concentration (EC50) values of 1080nM and 3000nM were estimated using (CO2)-C-14-incorporation and pulse amplitude modulation (PAM) fluorescence measurements, respectively. After long-term triclosan exposure in flow-through microcosms, photosynthesis estimated using PAM fluorometry was not inhibited by triclosan concentrations up to 1000nM but instead increased with increasing triclosan concentration. Similarly, at exposure concentrations of 31.6nM and higher, triclosan caused an increase in photosynthetic pigments. At 316nM triclosan, the pigment amounts were increased by a factor of 1.4 to 1.9 compared with the control level. Pollution-induced community tolerance was observed for algae and cyanobacteria at 100nM triclosan and higher. Despite the widespread use of triclosan as an antibacterial agent, the compound did not have any effects on bacterial carbon utilization after long-term exposure.
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| 18. |
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| 19. |
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| 20. |
- Eriksson, Martin, 1970, et al.
(författare)
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Triclosan changes community composition and selects for specific bacterial taxa in marine periphyton biofilms in low nanomolar concentrations
- 2020
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Ingår i: Ecotoxicology. - : Springer Science and Business Media LLC. - 0963-9292 .- 1573-3017. ; 29:7, s. 1083-1094
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Tidskriftsartikel (refereegranskat)abstract
- The antibacterial agent Triclosan (TCS) is a ubiquitous environmental contaminant due to its widespread use. Sensitivity to TCS varies substantially among eu- and pro-karyotic species and its risk for the marine environment remains to be better elucidated. In particular, the effects that TCS causes on marine microbial communities are largely unknown. In this study we therefore used 16S amplicon rDNA sequencing to investigate TCS effects on the bacterial composition in marine periphyton communities that developed under long-term exposure to different TCS concentrations. Exposure to TCS resulted in clear changes in bacterial composition already at concentrations of 1 to 3.16 nM. We conclude that TCS affects the structure of the bacterial part of periphyton communities at concentrations that actually occur in the marine environment. Sensitive taxa, whose abundance decreased significantly with increasing TCS concentrations, include the Rhodobiaceae and Rhodobacteraceae families of Alphaproteobacteria, and unidentified members of the Candidate division Parcubacteria. Tolerant taxa, whose abundance increased significantly with higher TCS concentrations, include the families Erythrobacteraceae (Alphaproteobacteria), Flavobacteriaceae (Bacteroidetes), Bdellovibrionaceae (Deltaproteobacteria), several families of Gammaproteobacteria, and members of the Candidate phylum Gracilibacteria. Our results demonstrate the variability of TCS sensitivity among bacteria, and that TCS can change marine bacterial composition at concentrations that have been detected in the marine environment.
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