Effects of in situ CO₂ enrichment on the structural and chemical characteristics of the seagrass Thalassia testudinum
2013
Campbell, Justin E. | Fourqurean, James W.
Seagrasses commonly display carbon-limited photosynthetic rates. Thus, increases in atmospheric pCO₂, and consequentially oceanic CO₂₍ₐq₎ concentrations, may prove beneficial. While addressed in mesocosms, these hypotheses have not been tested in the field with manipulative experimentation. This study examines the effects of in situ CO₂₍ₐq₎ enrichment on the structural and chemical characteristics of the tropical seagrass, Thalassia testudinum. CO₂₍ₐq₎ availability was manipulated for 6 months in clear, open-top chambers within a shallow seagrass meadow in the Florida Keys (USA), reproducing forecasts for the year 2100. Structural characteristics (leaf area, leaf growth, shoot mass, and shoot density) were unresponsive to CO₂₍ₐq₎ enrichment. However, leaf nitrogen and phosphorus content declined on average by 11 and 21 %, respectively. Belowground, non-structural carbohydrates increased by 29 %. These results indicate that increased CO₂₍ₐq₎ availability may primarily alter the chemical composition of seagrasses, influencing both the nutrient status and resilience of these systems.
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