Sulfide concentration effects on Typha domingensis Pers. (cattail) and Cladium jamaicense Crantz (sawgrass) growth in Everglades marshes

• Sawgrass has been displaced by cattail in eutrophic areas of the Everglades (Florida).
• Prior lab study suggested sulfide toxicity to sawgrass promotes cattail expansion.
• Leaf elongation in the field was not correlated to porewater sulfide levels.
• P-limitation was more important than sulfide for sawgrass and cattail growth.

Displacement of large areas of native Cladium jamaicense Crantz (sawgrass) by Typha domingensis Pers. (cattail) in the Everglades has occurred during the past several decades, and is widely attributed to phosphorus (P) enrichment. In addition, sulfide toxicity to marsh vegetation, particularly Cladium, has been cited as a possible consequence of increased loading of sulfate to the Everglades (USA) from anthropogenic sources, and a potential contributor to the shift from Cladium to Typha. We initiated a plant growth study at three “low P” sites in the Everglades with differing surface water sulfate (1–48 mg L−1) and porewater sulfide (0.09–8.0 mg L−1) concentrations. Leaf elongation (LE) rates of Cladium and Typha were monitored, along with surface and porewater concentrations of iron, nutrients, and inorganic sulfur species. During the course of the study, we observed no reduction in Cladium or Typha LE rates at the two sulfate-impacted locations, relative to LE at a sulfate-unimpacted site. Moreover, across all study sites, we observed a positive, instead of a negative, relationship between Cladium LE rates and porewater sulfide concentrations. This suggests overriding effects of other factors such as P availability and supply on plant growth in these low-P environments, which was supported by a positive relationship between dissolved porewater P concentrations and Cladium LE rates, and by the Typha to Cladium LE ratios.