A new method for evaluating defense of microalgae against protozoan grazing. (June 2017)

• Record Type: Journal Article
• Authors: Wang, Zheng; Xu, Guangjian; Zhao, Lu; Gao, Yangyang; Al, Mamun Abdullah; Xu, Henglong
• Is Part Of: Ecological indicators. Volume 77(2017)
• Page Start: 261
• Page End: 266
• Publication Date: 2017-06
• Subjects: Bioassay -- Body-size distinctness -- Protozoan community -- Nannochloropsis oceanica -- Chlorella sp.; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2017.02.026
• Languages: English
• ISSNs: 1470-160X

Abstract

Highlights: Two algal species represented strong defense effects on the test protozoan community system. The body-size distinctness of the protozoa showed a sharp decrease at high concentration level. Paired body-size distinctness showed a departure from the expectation due to algal defense. Body-size spectrum of protozoa is a potential indicator to identify the defense of microalgae. Abstract: Body-size spectrum has proved to be a highly informative indicator to summarize the functional structure of a community at taxon-free resolution. In this study, an approach based on body-size spectrum of protozoan communities was used to detect the defense of microalgae against protozoan grazing. The biofilm-dwelling protozoan communities were used as a test predator system, and two algal species, Chlorella sp. and Nannochloropsis oceanica, were employed as test microalgae. A nine-day bioassay test was carried out by exposing biofilm-dwelling protozoan communities to a gradient of concentrations 10 0 (control), 10 4, 10 5, 10 6, and 10 7 cell ml −1 of both microalgae, respectively. Results showed that both algal species represented strong defense effects on the test predator system at different levels of concentration. The body-size distinctness of the protozoan assemblages showed a sharp decrease at high concentration level more than 10 6 cell ml −1 in both algal treatments. Based on the paired body-size distinctness indices of the protozoa, ellipse tests demonstrated that the body-size spectrum showed an increasing trend of departure from the expected pattern with increasing concentrations of both test algae. Thus, it is suggested that the body-size spectrum of protozoa may be used as a useful indicator to identify the defense of microalgae against protozoan grazing.