TY - JOUR
T1 - Effect of temperature on photosynthesis, oxygen consumption and sulfide production in an extremely hypersaline cyanobacterial mat
AU - Abed, Raeid M.M.
AU - Polerecky, Lubos
AU - Al Najjar, Mohammad
AU - De Beer, Dirk
PY - 2006/8/16
Y1 - 2006/8/16
N2 - We used microsensors to study short-term temperature effects on gross photosynthesis, oxygen consumption and sulfate reduction in an extremely hypersaline (salinity 200 ‰) cyanobacterial mat. In situ, the mat surface can reach high temperatures (ca. 50°C in summer), and experiences daily temperature fluctuations due to tidal inundation. A mat sample was incubated in the laboratory at 25, 35, 45, 50 and 60°C. Areal rates of gross and net photosynthesis increased with increasing temperature, and maximum rates were detected at 45°C. The photosynthetic zone (i.e. the depth zone in which oxygenic photosynthesis was detectable by the light-dark shift method) decreased from 3 to 1.75 mm with increasing temperature. Above 50°C, photosynthesis was completely inhibited, probably due to high sulfide concentrations. This inhibition was confirmed by the pH profiles, where the peak in the top 2 to 4 mm at 25 to 45°C disappeared at 50 to 60°C. Between 25 and 45°C, areal oxygen consumption rates in the light did not change significantly but showed a decreasing trend in the photosynthetic zone, suggesting a decoupling between photosynthesis and oxygen consumption in the light. In both the light and dark, sulfide production was strongly enhanced by increasing temperature to a maximum flux at 50°C, above which it became inhibited. At 50 to 60°C, the sulfide produced could not be completely removed by sulfide oxidation, resulting in sulfide leakage to the overlying water. Our data demonstrate that these mat ecosystems are well adapted to high ambient temperatures. Photosynthesis, oxygen consumption in the light and sulfide production are differentially controlled by temperature. However, the individual processes in this complex community are not only directly controlled by temperature, but also by the temperature-dependent response of other processes.
AB - We used microsensors to study short-term temperature effects on gross photosynthesis, oxygen consumption and sulfate reduction in an extremely hypersaline (salinity 200 ‰) cyanobacterial mat. In situ, the mat surface can reach high temperatures (ca. 50°C in summer), and experiences daily temperature fluctuations due to tidal inundation. A mat sample was incubated in the laboratory at 25, 35, 45, 50 and 60°C. Areal rates of gross and net photosynthesis increased with increasing temperature, and maximum rates were detected at 45°C. The photosynthetic zone (i.e. the depth zone in which oxygenic photosynthesis was detectable by the light-dark shift method) decreased from 3 to 1.75 mm with increasing temperature. Above 50°C, photosynthesis was completely inhibited, probably due to high sulfide concentrations. This inhibition was confirmed by the pH profiles, where the peak in the top 2 to 4 mm at 25 to 45°C disappeared at 50 to 60°C. Between 25 and 45°C, areal oxygen consumption rates in the light did not change significantly but showed a decreasing trend in the photosynthetic zone, suggesting a decoupling between photosynthesis and oxygen consumption in the light. In both the light and dark, sulfide production was strongly enhanced by increasing temperature to a maximum flux at 50°C, above which it became inhibited. At 50 to 60°C, the sulfide produced could not be completely removed by sulfide oxidation, resulting in sulfide leakage to the overlying water. Our data demonstrate that these mat ecosystems are well adapted to high ambient temperatures. Photosynthesis, oxygen consumption in the light and sulfide production are differentially controlled by temperature. However, the individual processes in this complex community are not only directly controlled by temperature, but also by the temperature-dependent response of other processes.
KW - Arabian Gulf
KW - Cyanobacterial mats
KW - Microsensors
KW - Oxygen consumption
KW - Photosynthesis
KW - Temperature
UR - http://www.scopus.com/inward/record.url?scp=33748750790&partnerID=8YFLogxK
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U2 - 10.3354/ame044021
DO - 10.3354/ame044021
M3 - Article
AN - SCOPUS:33748750790
SN - 0948-3055
VL - 44
SP - 21
EP - 30
JO - Aquatic Microbial Ecology
JF - Aquatic Microbial Ecology
IS - 1
ER -