Photosynthetic temperature acclimation in two coexisting seagrasses,Zostera marina L. and Ruppia maritima L. |
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Institution: | 1. State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China;2. Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China |
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Abstract: | The physiological responses to temperature were investigated in two coexisting seagrasses, Zostera marina L. and Ruppia maritima L. sensu lato from the lower Chesapeake Bay, Virginia. Seven plant collections were made from March to July, 1983 at ambient temperatures of 8–30°C. Both species maintained relatively constant fresh: dry weight ratios and chlorophyll a:b ratios over the five-month period. Total chlorophyll content remained constant in Z. marina while that of R. maritima doubled from March to July. Pmax values for both species increased with increasing temperature and declined at temperatures above 19 and 23°C (Z. marina and R. maritima, respectively). Pmax values were significantly higher for R. maritima compared to Z. marina at temperatures above 19°C. Both short-term (laboratory) and long-term (in situ) responses to temperature regimes affected estimates of the photosynthetic capacity of both species. Thus, temperature histories of experimental material should be carefully considered when interpreting temperature effects on photosynthesis. This study provides support of the hypothesis that seasonal community dynamics of Z. marina and R. maritima in Chesapeake Bay are regulated in part by different responses to light and temperature. |
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