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Herbicides interfere with antigrazer defenses in Scenedesmus obliquus
- Source :
- Chemosphere. 162
- Publication Year :
- 2016
-
Abstract
- The extensive application of herbicides has led to a serious threat of herbicide contamination to aquatic ecosystem. Herbicide exposure affects aquatic communities not only by exerting toxicity on single species but also by changing interspecific interactions. This study investigated the antigrazer defenses of the common green alga Scenedesmus obliquus against different herbicides [glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D), and atrazine] at various concentrations (0–2.0 mg L−1). In the presence of grazer (Daphnia)-derived cues, S. obliquus populations without herbicides formed high proportions of multicelled (e.g., four- and eight-celled) colonies. This result confirms that S. obliquus exhibits a morphological defense against grazing risk. At the low concentration range of 0.002–0.02 mg L−1, the three herbicides exerted no influence on the growth and photosynthetic efficiency of S. obliquus, and multicelled colonies showed constant proportions. At the high concentration range of 0.20–2.0 mg L−1, atrazine significantly inhibited the algal growth and photosynthesis whereas glyphosate or 2,4-D did not. Nonetheless, these levels of glyphosate or 2,4-D remarkably decreased the proportion of multicelled colonies, with reduced numbers of cells per particle in Daphnia filtrate-treated population. No eight-celled colony was formed after treatment with atrazine at 0.20–2.0 mg L−1 despite the addition of Daphnia filtrate. These results suggest that herbicide exposure impairs antigrazer colonial morphs in phytoplankton although it is not sufficient to hamper algal growth. This phenomenon can increase the risk of predation by herbivores, thereby disrupting the inducible phytoplankton community. Furthermore, the predator-prey interactions between herbivores and phytoplankton can be potentially changed more seriously than previously considered.
- Subjects :
- 0106 biological sciences
Environmental Engineering
Health, Toxicology and Mutagenesis
Population
010501 environmental sciences
Biology
Photosynthetic efficiency
01 natural sciences
Daphnia
chemistry.chemical_compound
Phytoplankton
Botany
Environmental Chemistry
Animals
Atrazine
Photosynthesis
education
Ecosystem
0105 earth and related environmental sciences
education.field_of_study
Dose-Response Relationship, Drug
Herbicides
010604 marine biology & hydrobiology
Aquatic ecosystem
fungi
Public Health, Environmental and Occupational Health
General Medicine
General Chemistry
Interspecific competition
biology.organism_classification
Pollution
Biodegradation, Environmental
chemistry
Glyphosate
Water Pollutants, Chemical
Scenedesmus
Subjects
Details
- ISSN :
- 18791298
- Volume :
- 162
- Database :
- OpenAIRE
- Journal :
- Chemosphere
- Accession number :
- edsair.doi.dedup.....d0f2b89ba95f1324231a6beaf1726082