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theses

Due to their persistence, abiotic factors such as industrial waste waters, heavy metals, petrochemicals, and oil dispersants have become a global concern. Effects of such toxicants on aquatic ecosystem health were investigated using photosynthetic characteristics of marine microalgae as an endpoint. Despite progress in understanding the biophysics of the photosystem of marine photoautotrophs, there is a lack of consensus of which photosynthetic reactions are the target of heavy metal and oil pollution. The objective of this work used the model organisms Thalassiosira wessiflogii (diatom) and Symbiodinum spp. (coral symbionts) to: (1) evaluate the toxic effects of metals (Cu, Zn, Pb, and Sn), petrochemicals, and chemically dispersed petrochemicals on photosynthetic light-harvesting processes, photochemistry, and photosynthetic electron transport under different growth irradiance; (2) determine the primary target(s), (3) elucidate the sequence of physiological alterations, and (4) characterize the unique fluorescence signatures of aforementioned compounds on the photosynthetic apparatus using the fluorescence induction and relaxation technique. Parameters reflecting the secondary photosynthetic reactions (Pmax) were influenced first under both growth irradiance when cells were exposed to metals. The exception to this statement is for Pb, which had measurable effects to cell growth rates prior to Pmax under high irradiance. Pmax diverged from the control at the same time except under low irradiance for Cu and Pb. Effects to cell growth rates were the only measured response under low irradiance Zn exposure. I concluded that the primary target for the test metals were sites affecting the secondary photosynthetic reactions. Exposure to petrochemicals and dispersed petrochemicals under both growth irradiances inhibited the same photosynthetic parameters (Pmax, and the connectivity parameter). Corexit alleviated some measurable effects when cells were exposed to benzene and dispersed crude oil under low irradiance. I concluded that the primary targets of petrochemical were to the primary and secondary photosynthetic reactions. Effects to the secondary photosynthetic reactions are assumed to lower the amount of sugar produced, which would lower the organism’s growth rate. Thus, a bottom-up effect on the food web could occur. The unique fluorescence signatures identified between metals and petrochemicals can be utilized as a diagnostic tool for rapid pollution detection.

ETD_4681

Ph.D.

Includes bibliographical references

Includes vita

by Sophia Johnson-Worrell

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000068891

doi:10.7282/T3MC8XMR

ETD doctoral

The author owns the copyright to this work.