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Influence of light, temperature and salinity on dissolved organic carbon exudation rates in Zostera marina L.
Citation:
KALDY, III, J. E. Influence of light, temperature and salinity on dissolved organic carbon exudation rates in Zostera marina L. Aquatic Biosystems. BioMed Central Ltd, London, Uk, 8(19):pgs 12, (2012).
Impact/Purpose:
Seagrass carbon budgets provide valuable insight on the minimum requirements needed to maintain this valuable resource.
Description:
Seagrass carbon budgets provide valuable insight on the minimum requirements needed to maintain this valuable resource. Carbon budgets are a balance between C fixation, storage and loss rates, most of which are well characterized. However, relatively few measurements of dissolved organic carbon (DOC) exudation rates exist for most seagrass species. Here I evaluate how eelgrass (Zostera marina L.) DOC exudation and photosynthetic parameters are affected by a gradient of a single stressor (light, temperature or salinity). Replicate eelgrass plants were exposed to treatments in experimental chambers (separate leaf and rhizome/root compartments) with artificial seawater media (AFSW). Regression analysis of changes in the DOC concentration through time was used to calculate DOC exudation rates. There were no consistent patterns in the exudation of DOC from leaf versus rhizome. For all experiments leaf DOC exudation ranged between 0.032 and 0.069 mg C gdw-1 h-1, while rhizodeposition ranged between 0.024 and 0.045 mg C gdw-1 h-1. Leaf DOC exudation rates were consistent with previous work and leaf exudation + rhizodeposition accounted for 1.5 to 6% of gross primary production. Experimental treatments did not have a large effect on DOC exudation; however, increased salinity did appear to increase Rd and decrease Pmax but differences were not statistically significant. Zostera marina carbon losses from either leaf exudation or rhizodeposition account for a small proportion of gross primary production and appear to be insensitive to short-term environmental variations in chamber experiments.
