The Effects of an Herbicide and Antibiotic Mixture on Aquatic Primary Producers and Grazers
Widespread use of agrochemicals increases their likelihood of entering aquatic systems in mixture. Despite different modes of action, atrazine (herbicide) and tetracycline (antibiotic) adversely affect non-target photosynthetic organisms individually, but the effects of simultaneous exposure to both contaminants are untested. We created microcosms containing microalgae (Chlorella sp.), floating macrophytes (Lemna minor), and a zooplankton grazer (Daphnia magna). Microcosms were exposed to environmentally relevant concentrations of atrazine and tetracycline, alone and together, for 10 days. Atrazine decreased Chlorella sp. abundance, but not enough to reduce food availability to D. magna whose reproduction and mortality were unaffected. In contrast, tetracycline and atrazine appeared to have additive effects on L. minor abundance and growth inhibition. These additive adverse effects suggest increased potential for L. minor population decline over the long term, and potential for altered species interactions in aquatic systems receiving agricultural runoff.
KeywordsAquatic community Duckweed Ecotoxicology Phytoplankton Zooplankton
We thank the Chandler Foundation, the Department of Biology, the Georgia Southern University Honors Program Undergraduate Research Fund, and the Student Government Association for funding awards to the first author who completed this study under the mentorship of the second author. We also thank C. R. Chandler for statistical advice and J. Duff, L. Latzsch and A. Wagner for assistance with the experiment.
- Arar EJ, Collins GB (1997) In vitro determination of chlorophyll a and pheophytin a in marine and freshwater algae by fluorescence. EPA Method 445Google Scholar
- Ebert D (2005) Ecology, epidemiology, and evolution of parasitism in Daphnia. National Library of Medicine (US), National Center for Biotechnology, Bethesda, MDGoogle Scholar
- Forney DR, Davis DE (1981) Effects of low concentrations of herbicides on submersed aquatic plants. Weed Sci 29:677–685Google Scholar
- Fuhrer G (1999) The quality of our nation’s waters: nutrients and pesticides. DIANE Publishing, Darby, pp 57–79Google Scholar
- Hoberg JR (1991) Atrazine technical—toxicity to the duckweed (Lemna gibba). In: SLI Report 93-11-5053. Springborn Laboratories, WarehamGoogle Scholar
- Marshall GC (2009) Assessing the behavioral and physiological responses of three aquatic invertebrates to tributyltin and atrazine in a multi-species, early warning biomonitoring technology. Dissertation, Ryerson UniversityGoogle Scholar
- Munch JW (1995) Determination of nitrogen- and phosphorous-containing pesticides in water by gas chromatography with a nitrogen-phosphorous detector. EPA Method 507Google Scholar
- Okomoda VT, Solomon SG, Ataguba GA (2012) Potential uses of the family Lemnaceae. J Agric Vet Sci 4:1–14Google Scholar
- Powell KW, Cope WG, LePrevost CE, Augspurger T, McCarthy AM, Shea D (2017) A retrospective analysis of agricultural herbicides in surface water reveals risk plausibility for declines in submerged aquatic vegetation. Toxics 5(21):1–13Google Scholar
- United States Environmental Protection Agency (1996) Prevention, Pesticides and Toxic Substances (7101), EPA712-C-96-156, Ecological Effects Test Guidelines OPPTS 850.4400, Aquatic Plant Toxicology Test Using Lemna spp., Tiers I and IIGoogle Scholar