Effects of ultraviolet light on photosynthesis and pigments of Antarctic marine phytoplankton /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Recent reports of drastic decreases in stratospheric ozone observed over Antarctic regions and the lack of information on the effects of concomitant increases in UV radiation on phytoplankton in that area prompted this investigation. This field study was conducted at Palmer Station, Anvers Island, Antarctica, during November-December, 1987. The main objectives were to quantify the effects on photosynthetic rates and pigmentation of short-term (4-hour) and long-term (24-hour) exposures of Antarctic phytopiankton to different levels of UV radiation. Phytopiankion and ice algae were exposed to four levels of UV radiation in outdoor incubation chambers: near ambient UV; UV enhanced by approximately 5% over ambient levels; reduced UV-B; and essentially no UV. Both total solar irradiance and its spectral quality varied throughout each day, as well as from day to day. The ratio of UV to total irradiance was especially variable throughout each day. Results of 4-hour studies showed that rates of phytopiankton photosynthesis were generally inversely related to UV exposure. Higher photosynthetic rates were maintained over a greater range of irradiance levels when UV was removed in photosynthesis-irradiance studies. Photosynthetic pigments (chlorophyll a and fucoxanthin) did not change with variations in either visible or UV light. However, the ratio of non-photosynthetic pigments diatoxanthin:diadinoxanthin was greatest at the highest visible irradiance level tested. After adaptation for 24 hours, photosynthetic rate measured under conditions of essentially no UV was approximately twice that measured under near ambient UV conditions. Results of photosynthesis-irradiance experiments indicate that photosynthetic efficiencies (α), maximum photosynthetic rates (Pmax) and the index of inhibition (lb) were inversely related to UV levels, probably due at least in part to the loss of chlorophyll a. In contrast to free-living phytopiankton, results of 4 hour photosynthesis-irradiance studies conducted using ice algae (composed mainly of Navicula glacei) seem to indicate that they were able to adapt to some degree both to high visible light and to natural levels of UV light. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Oceanography." |
| Physical Description: | xiii, 121 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |