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Time-averaged copper concentrations from continuous exposures predicts pulsed exposure toxicity to the marine diatom, Phaeodactylum tricornutum: Importance of uptake and elimination.
Aquat Toxicol. 2015 Jul; 164:1-9.AT

Abstract

Intermittent, fluctuating and pulsed contaminant discharges result in organisms receiving highly variable contaminant exposures. Current water quality guidelines are predominantly derived using data from continuous exposure toxicity tests, and most frequently applied by regulators with the assumption that concentrations from a single sampling event will provide a meaningful approach to assessing potential effects. This study investigated the effect of single and multiple (daily) dissolved copper pulses on the marine diatom, Phaeodactylum tricornutum, including measurements of copper uptake and elimination to investigate the toxic mechanism. Copper pulses of between 0.5 and 24h and continuous exposures with equivalent 72-h time-averaged concentrations (TACs) resulted in similar biomass inhibition of P. tricornutum, with continuous exposures often being marginally more toxic. Rates of cell division generally recovered to control levels within 24h of the copper pulse removal. Upon resuspension in clean seawater, the extracellular copper per cell decreased rapidly, whereas the intracellular copper per cell decreased slowly. Negligible loss of copper from the total algal biomass indicated that P. tricornutum did not have an effective mechanism for eliminating copper from cells, rather the intracellular copper decreased as a result of dilution by cellular division as the algal growth rate recovered. The measurement of copper uptake after 72-h exposure and kinetics of elimination thereafter suggest that continuous exposures are marginally more toxic to P. tricornutum than pulsed copper exposures with equivalent TACs because slow internalization and saturation of algal membrane transport sites results in less copper uptake into pulse-exposed cells than continuously-exposed cells coupled with dilution of internalized copper via cellular division in the post-exposure period. In the case of P. tricornutum, the results indicate that water quality guidelines for copper based on continuous exposure will be conservative when applied to short-term discharges.

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Publisher Full Text (DOI)

Authors+Show Affiliations

Angel BM
Centre for Environmental Contaminants Research, CSIRO Land and Water Locked Bag 2007, Kirrawee, NSW 2232, Australia. Electronic address: brad.angel@csiro.au.
Simpson SL
Centre for Environmental Contaminants Research, CSIRO Land and Water Locked Bag 2007, Kirrawee, NSW 2232, Australia.
Chariton AA
CSIRO Oceans and Atmosphere, Locked Bag 2007, Kirrawee, NSW 2232, Australia.
Stauber JL
Centre for Environmental Contaminants Research, CSIRO Land and Water Locked Bag 2007, Kirrawee, NSW 2232, Australia.
Jolley DF
School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.

MeSH

BiomassCopperDiatomsSeawaterTime FactorsToxicity TestsWater Pollutants, Chemical

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25911575

Citation

Angel, Brad M., et al. "Time-averaged Copper Concentrations From Continuous Exposures Predicts Pulsed Exposure Toxicity to the Marine Diatom, Phaeodactylum Tricornutum: Importance of Uptake and Elimination." Aquatic Toxicology (Amsterdam, Netherlands), vol. 164, 2015, pp. 1-9.
Angel BM, Simpson SL, Chariton AA, et al. Time-averaged copper concentrations from continuous exposures predicts pulsed exposure toxicity to the marine diatom, Phaeodactylum tricornutum: Importance of uptake and elimination. Aquat Toxicol. 2015;164:1-9.
Angel, B. M., Simpson, S. L., Chariton, A. A., Stauber, J. L., & Jolley, D. F. (2015). Time-averaged copper concentrations from continuous exposures predicts pulsed exposure toxicity to the marine diatom, Phaeodactylum tricornutum: Importance of uptake and elimination. Aquatic Toxicology (Amsterdam, Netherlands), 164, 1-9. https://doi.org/10.1016/j.aquatox.2015.04.008
Angel BM, et al. Time-averaged Copper Concentrations From Continuous Exposures Predicts Pulsed Exposure Toxicity to the Marine Diatom, Phaeodactylum Tricornutum: Importance of Uptake and Elimination. Aquat Toxicol. 2015;164:1-9. PubMed PMID: 25911575.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Time-averaged copper concentrations from continuous exposures predicts pulsed exposure toxicity to the marine diatom, Phaeodactylum tricornutum: Importance of uptake and elimination. AU - Angel,Brad M, AU - Simpson,Stuart L, AU - Chariton,Anthony A, AU - Stauber,Jenny L, AU - Jolley,Dianne F, Y1 - 2015/04/09/ PY - 2014/11/11/received PY - 2015/03/12/revised PY - 2015/04/07/accepted PY - 2015/4/26/entrez PY - 2015/4/26/pubmed PY - 2016/3/5/medline KW - Accumulation KW - Chronic toxicity KW - Dissolved metal KW - Fluctuating KW - Intermittent KW - Recovery SP - 1 EP - 9 JF - Aquatic toxicology (Amsterdam, Netherlands) JO - Aquat Toxicol VL - 164 N2 - Intermittent, fluctuating and pulsed contaminant discharges result in organisms receiving highly variable contaminant exposures. Current water quality guidelines are predominantly derived using data from continuous exposure toxicity tests, and most frequently applied by regulators with the assumption that concentrations from a single sampling event will provide a meaningful approach to assessing potential effects. This study investigated the effect of single and multiple (daily) dissolved copper pulses on the marine diatom, Phaeodactylum tricornutum, including measurements of copper uptake and elimination to investigate the toxic mechanism. Copper pulses of between 0.5 and 24h and continuous exposures with equivalent 72-h time-averaged concentrations (TACs) resulted in similar biomass inhibition of P. tricornutum, with continuous exposures often being marginally more toxic. Rates of cell division generally recovered to control levels within 24h of the copper pulse removal. Upon resuspension in clean seawater, the extracellular copper per cell decreased rapidly, whereas the intracellular copper per cell decreased slowly. Negligible loss of copper from the total algal biomass indicated that P. tricornutum did not have an effective mechanism for eliminating copper from cells, rather the intracellular copper decreased as a result of dilution by cellular division as the algal growth rate recovered. The measurement of copper uptake after 72-h exposure and kinetics of elimination thereafter suggest that continuous exposures are marginally more toxic to P. tricornutum than pulsed copper exposures with equivalent TACs because slow internalization and saturation of algal membrane transport sites results in less copper uptake into pulse-exposed cells than continuously-exposed cells coupled with dilution of internalized copper via cellular division in the post-exposure period. In the case of P. tricornutum, the results indicate that water quality guidelines for copper based on continuous exposure will be conservative when applied to short-term discharges. SN - 1879-1514 UR - https://www.unboundmedicine.com/medline/citation/25911575/Time_averaged_copper_concentrations_from_continuous_exposures_predicts_pulsed_exposure_toxicity_to_the_marine_diatom_Phaeodactylum_tricornutum:_Importance_of_uptake_and_elimination_ DB - PRIME DP - Unbound Medicine ER -