Effects of temperature and current discharge on the concentration and photosynthetic activity of the phytoplankton in the upper Mississippi River |
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| Authors: | ALAN L BAKER KATHLEEN KROMER BAKER |
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| Institution: | Department of Botany and Plant Pathology, University of New Hampshire, U.S.A. |
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| Abstract: | SUMMARY. Temperature and current discharge regulated phytoplanktonic concentration, chlorophyll-a concentration, the light-saturated rate of photosynthesis (Pmax), and photosynthetic capacity (Pcap) in the Mississippi River at Prairie Island, Minnesota. The chlorophyll-a maximum was 48 mg m?3 in 1975, a wet year with a high current discharge, and 190 mg m?3 in 1976, a relatively dry year. The highest values of Pmax were 0.37 (mgO2 I?1h?1) in 1975 and 1.60 in 1976. Pcap varied from 3 to 21 (gO2 per g chlorophyll-a h?1) both years, and its value was highly correlated with temperature. The temperature optimum shifted from 16°C for Pcap in the spring, to greater than 28°C in the summer. Multiple regression analysis indicated a second-order relationship of Pcap in the spring to temperature. Other independent variables explained only negligible variation of Pcap. |
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