2006/09/01 by Patrick W. Inglett, K. R. Reddy, K. Ramesh Reddy · 2 citations
Environmental Science · Earth and Planetary Sciences · #Coastal wetland ecosystem dynamics #Isotope Analysis in Ecology #Geology and Paleoclimatology Research
paper · pdf · doi:10.4319/lo.2006.51.5.2380
We investigated the use of stable C and N isotopic ratios as indicators of shifts in nutrient limitation of aquatic macrophytes in native Typha (Typha domingensis Pers.) and Cladium (Cladium jamaicense Crantz) communities growing along the well-established phosphorus enrichment gradient of Water Conservation Area 2A of the Florida Everglades. Both Typha and Cladium had significantly different Δ15N (~4‰ and 6‰, respectively) in affected areas, with live leaves of Typha showing elevated Δ15N up to 7 km from nutrient inflows. In contrast, changes in Δ13C were inconsistent, with an ~2‰ increase in Typha and a corresponding 2‰ decrease in Cladium of nutrient-affected areas. The isotopic patterns of live leaves were well represented in standing dead leaves of Cladium, but not for Typha, indicating a significant alteration of isotopic signature during senescence for this emergent species. Correlations of isotopic values with tissue nutrients (total C, N, and P) indicated a greater effect of P on the Δ13C of both plants and the Δ15Nof Typha, and a greater importance of N content in determiningΔ15N of Cladium. These results support the use of macrophyte biomass Δ13C and Δ15N as an indicator of eutrophication and shifts between N and P limitation. However, the results also highlight potential pitfalls arising from differences in species-specific response to nutrient enrichment.