James W. Fourqurean1, Joseph C. Zieman1, George V. N. Powell2
1Department of Environmental Sciences, University of Virginia, Charlottesville, 22903
2National Audubon Society, 115 Indian Mound Trail, Tavemier, Florida 33070
Tóm tắt
Florida Bay is a shallow, seagrass‐dominated embayment on the southern tip of Florida. Variation of C, N, and P content of leaves of Thalassia testudinum was measured on two spatial scales: locally (10–100 m) in relation to a point source of nutrients associated with a bird colony in eastern Florida Bay and regionally (10– 100 km) across all of the bay. Locally, the P content of leaves decreased from a high of 0.16% P (wt/wt) 30 m from the nutrient source to a low of 0.08% 120 m from the source; the C and N content (34.9 and 2.1%) was independent of distance from the nutrient source. Due to variations in P content, C : P and N : P, but not C : N, varied locally. Regionally, P content varied greatly, from 0.05 to 0.20%; C (29.4–39.5%) and N (1.7–2.7%) showed considerably less variation. Variation in C : P and N : P across the bay encompassed a range nearly as great as reported for all seagrasses around the world combined; C : N showed little variation. Local variation around the nutrient point source indicated that C : P and N : P were indicators of P availability, and trend analysis of the regional spatial variation in C : P and N : P showed that P availability was greatest in northwest, and least in eastern, Florida Bay. This pattern mirrored abundance of seagrasses and productivity in the bay. T. testudinum from the bay appears to be P limited and N saturated, even in the sparsest seagrass communities.
