Influence of increasing temperature and salinity on herbicide toxicity in estuarine phytoplankton
Article first published online: 27 MAY 2011
Copyright © 2011 Wiley Periodicals, Inc.
Volume 28, Issue 7, pages 359–371, July 2013
How to Cite
DeLorenzo, M. E., Danese, L. E. and Baird, T. D. (2013), Influence of increasing temperature and salinity on herbicide toxicity in estuarine phytoplankton. Environ. Toxicol., 28: 359–371. doi: 10.1002/tox.20726
- Issue published online: 24 JUN 2013
- Article first published online: 27 MAY 2011
- Manuscript Accepted: 21 MAR 2011
- Manuscript Revised: 15 MAR 2011
- Manuscript Received: 20 JAN 2011
- National Science Foundation Research Experiences for Undergraduates Program. Grant Numbers: DBI-0552828, IOS-0725245
- climate change;
Ecological risk assessments are, in part, based on results of toxicity tests conducted under standard exposure conditions. Global climate change will have a wide range of effects on estuarine habitats, including potentially increasing water temperature and salinity, which may alter the risk assessment of estuarine pollutants. We examined the effects of increasing temperature and salinity on the toxicity of common herbicides (irgarol, diuron, atrazine, and ametryn) to the phytoplankton species Dunaliella tertiolecta. Static 96-h algal bioassays were conducted for each herbicide under four exposure scenarios: standard temperature and salinity (25°C, 20 ppt), standard temperature and elevated salinity (25°C, 40 ppt), elevated temperature and standard salinity (35°C, 20 ppt), and elevated temperature and elevated salinity (35°C, 40 ppt). The endpoints assessed were algal cell density at 96 h, growth rate, chlorophyll a content, lipid content, and starch content. Increasing exposure temperature reduced growth rate and 96-h cell density but increased the cellular chlorophyll and lipid concentrations of the control algae. Exposure condition did not alter starch content of control algae. Herbicides were found to decrease growth rate, 96 h cell density, and cellular chlorophyll and lipid concentrations, while starch concentrations increased with herbicide exposure. Herbicide effects under standard test conditions were then compared with those observed under elevated temperature and salinity. Herbicide effects on growth rate, cell density, and starch content were more pronounced under elevated salinity and temperature conditions. To encompass the natural variability in estuarine temperature and salinity, and to account for future changes in climate, toxicity tests should be conducted under a wider range of environmental conditions. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013.