Abstract—Protection of ecological health of aquatic ecosystems is a primary focus of water quality programs globally. Of special concern is the degradation impact from urban stormwater. Urban storm runoff is highly variable in both physical and chemical stressors, and can impact by changing the structure and physiology of ecological communities. We propose the use of photosystem II (PSII) activity of local periphyton communities for detecting impacts on the ecological health of aquatic ecosystems. This study evaluated the sensitivity of PSII response of periphyton communities to environmental stress in the field and stress (copper toxicity) simulated in the laboratory. The field study was done on natural periphyton communities at two sites in the Swan River estuary, Western Australia receiving urban stormwater discharge. Natural community at a non-receiving upstream site was used as the control. The laboratory study involved a chronic and an acute exposure to copper using periphyton community collected at the control upstream site. Both the laboratory and field studies indicated that PSII response was a sensitive indicator to the different exposures than the response in biomass, chlorophyll a content, or in-vivo chlorophyll fluorescence. Response in PSII also correlated strongly with the structural changes of the communities in total individuals (N) and species number (S) (Pearson’s coefficient 0.9 at sig < 0.01). Communities pre-exposed to chronic copper, exhibited enhanced PSII activity that correlated positively with the increased community tolerance to copper toxicity. The PSII activity of communities receiving urban stormwater was indicative of the stormwater quality in that lower activity corresponded to poorer water quality. The results demonstrated that community PSII response to be sufficiently sensitive to environmental stress, including urban stormwater that is episodic and highly variable.

Index Terms—PSII quantum yield, periphyton community, ecological impact, variable exposure, urban stormwater.

C. K. Tan is with the Universiti Tunku Abdul Rahman, Faculty of Engineering and Green Technology, Malaysia (e-mail: tckhunr@utar.edu.my).
C. Oldham is with the University of Western Australia, Western Australia, Australia. (e-mail: carolyn.oldham@uwa.edu.au). L. Evans was with Curtin University, Western Australia, Australia, is now retired.

 

Cite:Tan C. Khun, Carolyn Oldham, and Louis Evans, "PSII Activity as An Ecological Indicator for Assessing Impact from Variable Exposure at Community-Level," International Journal of Bioscience, Biochemistry and Bioinformatics vol. 3, no. 3, pp. 232-238, 2013.