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Effect of multiple stressors on eelgrass Zostera marina L. from the Pacific Northwest, USA: Manipulation of temperature and nutrients - November 2011
KALDY, III, J. E. Effect of multiple stressors on eelgrass Zostera marina L. from the Pacific Northwest, USA: Manipulation of temperature and nutrients - November 2011. Presented at 21st Bieenial Coastal and Estuarine Research Federation Meeting, Daytona, FL, November 06 - 10, 2011.
Estuarine eelgrass beds in the Pacific Northwest (PNW) are being exposed to a range of natural and anthropogenic stressors and climate change.
Estuarine eelgrass beds in the Pacific Northwest (PNW) are being exposed to a range of natural and anthropogenic stressors and climate change. The purpose of the current study was to examine the effects of temperature and nutrient quantity on Z. marina growth and physiology. Manipulations were conducted in acrylic chambers and spanned a range of temperature and nutrient concentrations. Single factor range finding experiments were conducted to evaluate physiological tolerances to temperature and nitrogen concentrations. Eelgrass exhibited a significant, linear increase in specific growth with increasing NH4 from 10 to 1000 µM; there was no relationship between specific growth rate and NO3 over the same concentration range. Leaf growth and specific growth all exhibited strong linear relationships with increasing water temperature (range 4-25 ºC). The factorial experiment used 3 temperatures (10, 18 and 25 ºC) and 3 nitrate concentrations (10, 30 and 100 µM) with 3 replicate chambers per treatment combination. Most growth metrics exhibited a significant temperature effect indicating the importance of temperature on metabolic rates. Tissue δ15N and C:N values generally exhibited a significant nutrient effect and in some cases a significant temperature effect. Non-structural carbohydrate content of eelgrass exhibited no significant differences with respect to either temperature or nitrate concentration. The results indicate that Z. marina in the PNW may be insensitive to high N, but extremely sensitive to increased temperatures. The results also suggest that increased temperatures may predispose Z. marina to secondary stressors such as wasting disease, potentially impacting estuarine seagrass beds.