TY - JOUR

T1 - Combined impact of water column oxygen and temperature on internal oxygen status and growth of Zostera marina seedlings and adult shoots

AU - Raun, Ane-Marie Løvendahl

AU - Borum, Jens

PY - 2013

Y1 - 2013

N2 - Eelgrass (Zostera marina L.) occasionally experiences severe die-offs during warm summer periods with variable water column oxygen partial pressures (pO). Eelgrass is known to be very intolerant to tissue anoxia with reduced growth and increasing mortality after ≤12h anoxia in the dark at temperatures of ≥25°C. In the present study we experimentally examine the impact of combined water column oxygen and temperature on oxygen dynamics in leaf meristems of seedlings and adult shoots to better understand how stressful environmental conditions affect eelgrass oxygen dynamics and subsequent growth and mortality. There was a strong interaction between water column oxygen and temperature on meristem pO implying that eelgrass is rather resistant to unfavorable oxygen conditions in winter but becomes increasingly vulnerable in summer, especially at high temperatures. At 25°C meristems became anoxic at a water column pO of 12kPa corresponding to 60% of air saturation, and leaf growth was negatively affected after 24h exposure to water column pO below 7kPa. Temperature had in itself a substantial impact on meristem pO both in light and in the dark as a result of increasing tissue respiration. Seedlings were less prone to meristem anoxia than adult shoots suggesting that seedlings would better tolerate unfavorable combinations of water column oxygen conditions and temperature. The results suggest that eelgrass die-offs will occur more frequently in eutrophied coastal areas with the more frequent periods of unusually high temperatures expected in the future as a result of global warming.

AB - Eelgrass (Zostera marina L.) occasionally experiences severe die-offs during warm summer periods with variable water column oxygen partial pressures (pO). Eelgrass is known to be very intolerant to tissue anoxia with reduced growth and increasing mortality after ≤12h anoxia in the dark at temperatures of ≥25°C. In the present study we experimentally examine the impact of combined water column oxygen and temperature on oxygen dynamics in leaf meristems of seedlings and adult shoots to better understand how stressful environmental conditions affect eelgrass oxygen dynamics and subsequent growth and mortality. There was a strong interaction between water column oxygen and temperature on meristem pO implying that eelgrass is rather resistant to unfavorable oxygen conditions in winter but becomes increasingly vulnerable in summer, especially at high temperatures. At 25°C meristems became anoxic at a water column pO of 12kPa corresponding to 60% of air saturation, and leaf growth was negatively affected after 24h exposure to water column pO below 7kPa. Temperature had in itself a substantial impact on meristem pO both in light and in the dark as a result of increasing tissue respiration. Seedlings were less prone to meristem anoxia than adult shoots suggesting that seedlings would better tolerate unfavorable combinations of water column oxygen conditions and temperature. The results suggest that eelgrass die-offs will occur more frequently in eutrophied coastal areas with the more frequent periods of unusually high temperatures expected in the future as a result of global warming.

UR - http://www.scopus.com/inward/record.url?scp=84873310111&partnerID=8YFLogxK

U2 - 10.1016/j.jembe.2013.01.014

DO - 10.1016/j.jembe.2013.01.014

M3 - Journal article

AN - SCOPUS:84873310111

VL - 441

SP - 16

EP - 22

JO - Journal of Experimental Marine Biology and Ecology

JF - Journal of Experimental Marine Biology and Ecology

SN - 0022-0981

ER -