The role of organic acid exudates in liberating phosphorus from seagrass‐vegetated carbonate sediments

• DOI: 10.4319/lo.2008.53.6.2616
• Publication Date: 2010-11-16T08:56:38Z
• Authors: Matthew H. Long; Karen J. McGlathery; Joseph C. Zieman; Peter Berg
• Keywords: Phosphorite

Sediment‐bound phosphorus (P) is a potential nutrient source for P‐limited seagrasses inhabiting carbonate sediments. We explored the role of organic acid (OA) exudation by in liberating mineral P from Organic acids can act to increase available dissolving sediment, competing with binding sites and complexing dissolution end products, also fueling microbial processes that change pore‐water pH. used dialysis tubing placed around individual roots situ quantify dissolved species immediately adjacent (root zone) compared these bulk concentrations vegetated nonvegetated Total OA were highest root zone (29.8 ± 1.8 [mol L −1 ) measures 15.5 1.9 7.5 0.6 sediments, respectively. Phosphate linearly related ( R 2 = 0.63). increased along seagrass productivity gradient, ratios showed significant response gradient P‐limitation seagrasses. found roots, those sediment measures, indicate are OA. Sampling at small spatial scales (mm) critical, because did not capture observed fluctuations caused rapid reaction consumption sediment. Root‐zone liberate considerable quantities P, exudates likely contribute significantly success T. testudinum environments.