Combined Effects from γ Radiation and Fluoranthene Exposure on Carbon Transfer from Phytoplankton to Zooplankton.
Risk assessment does not usually take into account mixtures of contaminants, thus potentially under- or overestimating environmental effects. We investigated how the transfer of carbon between a primary producer, Pseudokirchneriella subcapitata, and a consumer, Daphnia magna, is affected by acute exposure of γ radiation (GR) in combination with the polycyclic aromatic hydrocarbon fluoranthene (FA). We exposed D. magna to five concentrations of FA and five acute doses of GR as single contaminants and in nine binary combinations. We compared the observed data for three end points (incorporation of carbon by D. magna, D. magna ingestion rates, and growth) to the predicted joint effects of the mixed stressors based on the independent action (IA) concept. There were deviations from the IA predictions, especially for ingestion rates and carbon incorporation by D. magna, where antagonistic effects were observed at the lower doses, while synergism was seen at the highest doses. Our results highlight the importance of investigating the effects of exposure to GR in a multistressor context. In mixtures of GR and FA, the IA-predicted effects seem to be conservative as antagonism between the two stressors was the dominant pattern, possibly due to stimulation of cellular antioxidative stress mechanisms.
Department of Ecology, Environment and Plant Sciences, Stockholm University , 106 91 Stockholm, Sweden.
Francisco J A
FJ
Nascimento
Centre for Ecology and Hydrology , Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, OX10 8BB Oxfordshire, United Kingdom.
Claus
C
Svendsen
Department of Ecology, Environment and Plant Sciences, Stockholm University , 106 91 Stockholm, Sweden.
Clare
C
Bradshaw
D000818:Animals; D002244:Carbon / Q000378:metabolism*; D000460:Chlorophyta / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D003621:Daphnia / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D005449:Fluorenes / Q000633:toxicity*; D005720:Gamma Rays; D010839:Phytoplankton / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity; D015048:Zooplankton / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects
D005449:Fluorenes; D014874:Water Pollutants, Chemical; C007738:fluoranthene; D002244:Carbon