Search for: All records

Abstract Biogenic mangrove wetlands rely on trapping and burying organic production in soil to pace sea-level rise. However, the fate and role of allochthonous marine wrack in regulating carbon processing and wetland elevation in fringe mangrove forest soils remain unclear. We quantified long-term changes in tidal hydrology and surface soil elevation (2011–2024) across two representative fringe mangrove forest sites (BISC-1, BISC-2) in Biscayne National Park (Florida, USA). To test the influence of marine wrack deposition, we measured the spatiotemporal variation of monthly wrack deposition, litter breakdown rates, soil organic carbon, and stable isotope δ¹³C and δ¹⁵N content along landward transects (2022–2024). Our results indicate that relative sea-level rise (annual rate ± SE: 8.5 ± 0.4 mm yr^− 1) was greater than annual rates of surface elevation change at either site (BISC-1 2.1 ± 2.6 mm yr^− 1; BISC-2 3.9 ± 3.2 mm yr^− 1).Rhizophora manglelitter breakdown rates (mean ± SE: BISC-1 0.011 ± 0.001kd^− 1; BISC-2 0.008 ± 0.001kd^− 1) were greater thanThalassia testudinum(BISC-1 0.009 ± 0.001kd^− 1; BISC-2 0.005 ± 0.001kd^− 1), suggesting that wrack deposition can potentially enhance elevations gains more than mangrove litter. Stable isotope content in soil, mangrove, and seagrass tissue suggested that allochthonous marine wrack contributed between 36.1% ± 0.8% and 53% ± 3.6% to the soil organic carbon content. Our findings emphasize the importance of ecological connectivity in transporting wrack as a marine subsidy that can enhance blue carbon storage and elevation increases by reducing breakdown rates and promoting peat formation in fringe mangrove forests. 

Abstract Abundance-weighted averaging is a simple and common method for estimating taxon preferences (optima) for phosphorus (P) and other environmental drivers of freshwater-ecosystem health. These optima can then be used to develop transfer functions to infer current and/or past environmental conditions of aquatic ecosystems in water-quality assessments and/or paleolimnological studies. However, estimates of species’ environmental preferences are influenced by the sample distribution and length of environmental gradients, which can differ between datasets used to develop and apply a transfer function. Here, we introduce a subsampling method to ensure a uniform and comparable distribution of samples along a P gradient in two similar ecosystems: the Everglades Protection Areas (EPA) and Big Cypress National Preserve (BICY) in South Florida, USA. Diatom optima were estimated for both wetlands using weighted averaging of untransformed and log-transformed periphyton mat total phosphorus (mat TP) values from the original datasets. We compared these estimates to those derived from random subsets of the original datasets. These subsets, referred to as “SUD” datasets, were created to ensure a uniform distribution of mat TP values along the gradient (both untransformed and log-transformed). We found that diatom assemblages in BICY and EPA were similar, dominated by taxa indicating oligotrophic conditions, and strongly influenced by P gradients. However, the original BICY datasets contained more samples with elevated mat TP concentrations than the EPA datasets, introducing a mathematical bias and resulting in a higher abundance of taxa with high mat TP optima in BICY. The weighted averaged mat TP optima of BICY and EPA taxa were positively correlated across all four dataset types, with taxa optima of SUD datasets exhibiting higher correlations than in the original datasets. Equalizing the mat TP sample distribution in the two datasets confirmed consistent mat TP estimates for diatom taxa between the two wetland complexes and improved transfer-function performance. Our findings suggest that diatom environmental preferences may be more reliable across regional scales than previously suggested and support the application of models developed in one region to another nearby region if environmental gradient lengths are equalized and data distribution along gradients is uniform. 

{"Abstract":["Environmental and diatom data were collected from sites in the Big Cypress National Preserve (BICY) by the South Florida/Caribbean Inventory and Monitoring Network of the National Park Service and from sites in the Everglades Protection Area (EPA) as part of the Monitoring and Assessment Program of the Comprehensive Everglades Restoration Plan. Samples from years 2012, 2013, 2019, 2019, and 2020 are included in this dataset. Environmental data include drier variables that have been found to influence diatom assemblage composition in the greater Everglades ecosystem, including periphyton mat total phosphorus (a proxy for phosphorus in the environment), water column pH, water column conductivity, water depth, days since last dry, and hydroperiod. Diatom data include diatom species composition as percent relative abundances. Code included is pertinent to the methods described in "Robust species optima estimates from non-uniformly sampled environmental gradients" by Solomon et al. 2025, Journal of Paleolimnology."]}