TY - JOUR

T1 - Seasonal acclimation in metabolism reduces light requirements of eelgrass (Zostera marina).

AU - Staehr, Peter Anton

AU - Borum, Jens

PY - 2011

Y1 - 2011

N2 - We investigated the ability of eelgrass (Zostera marina) to adjust light requirements to seasonal changes intemperature, light and nutrient conditions through changes in metabolism, pigment and nutrient content. Inagreement with expectations we found that rates of respiration and light saturated photosynthesis of summeracclimated plants peaked at higher temperatures (5 °C and 2 °C higher, respectively), and were lower thanof winter acclimated plants, both at sub- and supra-optimal temperatures. Moreover respiration rates weregenerally more sensitive to increasing temperatures than photosynthetic rates, especially so for coldacclimated plants in February (36% higher Q10-values). These changes were accompanied by a reduction inchlorophyll a and nitrogen concentrations in leaves by 35% and 60% respectively from February to August. Thecritical light requirement (EC) of Z. marina to maintain a positive carbon balance increased exponentially withincreasing temperature but less so for summer-acclimated than for winter-acclimated plants. However,combining EC vs temperature models for whole-plants with data on daily light availability showed thatseasonal acclimation in metabolism increased the annual period, when light requirements were meet at the2–5 m depth interval, by 32–66 days. Hence, acclimation is an important mechanism allowing eelgrass togrow faster and penetrate to deeper waters. Critical depth limits estimated for different combinations ofsummer temperatures and water clarity in a future climate scenario, suggested that expected increases intemperature and nutrient run-off have synergistic negative effects, especially in clear waters, stressing theimportance of continued efforts to improve water clarity of coastal waters.

AB - We investigated the ability of eelgrass (Zostera marina) to adjust light requirements to seasonal changes intemperature, light and nutrient conditions through changes in metabolism, pigment and nutrient content. Inagreement with expectations we found that rates of respiration and light saturated photosynthesis of summeracclimated plants peaked at higher temperatures (5 °C and 2 °C higher, respectively), and were lower thanof winter acclimated plants, both at sub- and supra-optimal temperatures. Moreover respiration rates weregenerally more sensitive to increasing temperatures than photosynthetic rates, especially so for coldacclimated plants in February (36% higher Q10-values). These changes were accompanied by a reduction inchlorophyll a and nitrogen concentrations in leaves by 35% and 60% respectively from February to August. Thecritical light requirement (EC) of Z. marina to maintain a positive carbon balance increased exponentially withincreasing temperature but less so for summer-acclimated than for winter-acclimated plants. However,combining EC vs temperature models for whole-plants with data on daily light availability showed thatseasonal acclimation in metabolism increased the annual period, when light requirements were meet at the2–5 m depth interval, by 32–66 days. Hence, acclimation is an important mechanism allowing eelgrass togrow faster and penetrate to deeper waters. Critical depth limits estimated for different combinations ofsummer temperatures and water clarity in a future climate scenario, suggested that expected increases intemperature and nutrient run-off have synergistic negative effects, especially in clear waters, stressing theimportance of continued efforts to improve water clarity of coastal waters.

U2 - 10.1016/j.jembe.2011.05.031

DO - 10.1016/j.jembe.2011.05.031

M3 - Journal article

VL - 407

SP - 139

EP - 146

JO - Journal of Experimental Marine Biology and Ecology

JF - Journal of Experimental Marine Biology and Ecology

SN - 0022-0981

IS - 2

ER -