Oral Presentation Society for Freshwater Science 2025 Annual Meeting

Co-variation of macrophyte and microbial mat standing stocks along wetland resource gradients (117725)

Paige M Kleindl 1 , Carolina Candelario 1 , Evelyn E Gaiser 1
  1. Institute of Environment, Department of Biological Studies, Florida International University, Miami, Florida, United States

Macrophytes and benthic microbial communities regulate nutrient storage and cycling, soil formation, and higher trophic level resources in wetlands. Hydrologic conditions and nutrient availability can influence macrophyte and benthic microbial community standing stocks, but few studies have evaluated how the two co-vary along resource and stress gradients. We therefore quantified macrophyte and benthic microbial community (mat) standing stocks along Everglades’ hydrologic and nutrient gradients and compared these to values in other shallow freshwater habitats around the world. Macrophyte and microbial mat biomass along with both communities’ carbon, nitrogen, and phosphorus standing stock were measured in three ridge (drier) and three slough (wetter) 1 m2 plots at three sites in Shark River Slough (higher phosphorus) and three sites in Taylor Slough (lower phosphorus) in Everglades National Park, Florida. In this study, macrophyte biomass, phosphorus, and nitrogen standing stocks were on average 50x, 160x, and 23x higher than that of microbial mats, respectively. Macrophyte standing stock was 40% greater in ridges than sloughs while microbial mat standing stock did not differ. In general, macrophyte community biomass and carbon standing stock did not vary along the nitrogen, phosphorus, or hydrologic gradients. Individual macrophyte species, particularly the most common Cladium jamaicense and Eleocharis cellulosa, experienced a significant increase in biomass and carbon stock along the phosphorus and nitrogen gradients. Microbial mat carbon stock and biomass decreased as its phosphorus and nitrogen content increased and hydrologic conditions became wetter. Macrophyte and microbial mat biomass from other Everglades studies followed the same trend along the phosphorus gradient. Everglades’ microbial mat biomass is 4-50x greater than biomass in other shallow freshwater ecosystems while Everglades' macrophyte biomass is comparatively low. Further analysis will reveal the comparison of the co-variation of macrophyte and microbial mat biomass and standing stocks in the Everglades to other freshwater bodies.