Search

Water depth and flow effects on growth and nutrient content of three marsh plants ( Cladium jamaicense Crantz, Eleocharis cellulosa Torr., and Nymphaea odorata Aiton) and on soil-building were estimated in the Loxahatchee Impoundment Landscape Assessment where macrocosms contain habitats distinguished by relative water depth (deep slough, shallow slough, and mid-ridge) but that differ in flow. We hypothesized that optimal growth would vary with water depth and species, paralleling distributions in the natural environment, and that growth and tissue nutrients would be positively affected by flow. In addition, we hypothesized that plant morphology would influence sediment deposition with the dense growth of C. jamaicense supporting greatest accretion. Our hypotheses were partly supported. Cladium jamaicense unexpectedly grew best in deep sloughs at depths greater than previously reported. Eleocharis cellulosa had a wide depth tolerance and grew best in flowing conditions. Nymphaea odorata grew best in slough habitats. Nutrient contents differed among species and plant parts but were not affected by flow. Soil accretion did not vary with biomass but partially varied with depth and flow, both key factors in conceptual models of vegetation and soil dynamics in wetlands, especially in the Everglades ridge-and-slough topography. [ABSTRACT FROM AUTHOR]

The Florida Everglades is a mosaic of short and long-hydroperiod marshes that differ in the depth, duration, and timing of inundation. Algae are important primary producers in widespread Everglades’ periphyton mats, but relationships of algal production and community structure to hydrologic variability are poorly understood. We quantified differences in algal biomass and community structure between periphyton mats in 5 short and 6 long-hydroperiod marshes in Everglades National Park (ENP) in October 2000. We related differences to water depth and total phosphorus (TP) concentration in the water, periphyton and soils. Long and short-hydroperiod marshes differed in water depth (73 cm vs. 13 cm), periphyton TP concentrations (172 μg g−1 vs. 107 μg g−1, respectively) and soil TP (284 μg g−1 vs. 145 μg g−1). Periphyton was abundant in both marshes, with short-hydroperiod sites having greater biomass than long-hydroperiod sites (2936 vs. 575 grams ash-free dry mass m−2). A total of 156 algal taxa were identified and separated into diatom (68 species from 21 genera) and “soft algae” (88 non-diatom species from 47 genera) categories for further analyses. Although diatom total abundance was greater in long-hydroperiod mats, diatom species richness was significantly greater in short- hydroperiod periphyton mats (62 vs. 47 diatom taxa). Soft algal species richness was greater in long-hydroperiod sites (81 vs. 67 soft algae taxa). Relative abundances of individual taxa were significantly different among the two site types, with soft algal distributions being driven by water depth, and diatom distributions by water depth and TP concentration in the water and periphyton. Periphyton communities differ between short and long-hydroperiod marshes, but because they share many taxa, alterations in hydroperiod could rapidly promote the alternate community. [ABSTRACT FROM AUTHOR]