Incorporating Uncertainty in a Wetland Soil Accretion Model (NUMAN 2.0) to Test Generality Across Coastal Environmental Settings of South Florida
Estuarine, Coastal and Shelf Science2025
Understanding the relative contributions of aboveground and belowground processes to soil accretion and carbon density may explain carbon sequestration rates in mangroves across different coastal environmental settings. We reformulated the nutrient mangrove model (NUMAN) by improving algorithms and uncertainty analysis using literature values and site-specific observations from literature to evaluate the relative contributions of organic and inorganic sedimentation for three mangrove sites with marked soil fertility gradients reflected by nitrogen-to-phosphorus (N: P) ratios including Shark River (N: P= 28), Rookery Bay (N: P= 54-78), and Taylor Slough (N: P= 102) in south Florida. NUMAN 2.0 considers cellulose as a refractory organic-matter sub-pool and simultaneously incorporates coarse-root inputs to soil formation. The model simulation also captures root necromass accumulation.
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Patterns and mechanisms of wetland change in the Breton sound estuary, Mississippi River delta: A review
Estuarine, Coastal and Shelf Science2025
The Breton Sound Estuary, located within the Mississippi River Delta, has experienced significant wetland loss over the past century due to a combination of natural and anthropogenic factors. This study examines the patterns and mechanisms driving wetland change in the upper Breton Sound Basin and focuses on the impacts of riverine isolation, hydrological alterations, and human activities. Prior to human interventions, the basin received regular large riverine input via overbank flooding and crevasse channels. Levee construction began in the 18th century, but it wasn't until the great Mississippi River flood of 1927 that continuous levees were built that completely isolated the river from the upper Breton Sound Basin. The reduction of riverine input led to replacement of fresh and low salinity marshes by more salt-tolerant species.
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Patterns of marsh surface accretion rates along salinity and hydroperiod gradients between active and inactive coastal deltaic floodplains
Estuarine, Coastal and Shelf Science2024
High subsidence rates are inherent to coastal deltas worldwide, contributing to rapid rates of relative sea-level rise and compromising the sustainability of coastal wetlands. Different parts of river deltas, however, experience accretion or erosion, depending on the coupling between ecological and morphological processes. Wetland expansion occurs in active deltaic coastal basins that are connected to riverine sedimentation. In contrast, wetland degradation occurs in inactive deltaic coastal basins where river engineering strategies associated with flood control restrict river connectivity. Here, we investigated the relative role of inorganic and organic loading to marsh accretion rates spanning fresh to brackish to saline zones between active and inactive coastal deltaic floodplains of the Mississippi River Delta.
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Hurricane Effects on Benthic Nitrogen Cycling in an Emerging Coastal Deltaic Floodplain Within the Mississippi River Delta Plain
Estuaries and Coasts2024
Hurricanes are one of the most common natural events that disturb estuarine and coastal wetlands along the Gulf of Mexico. The episodic and energetic events of hurricanes modify wetland hydrodynamics, sedimentation, and vegetation structure, which can impact the connectivity of coastal deltaic floodplains in processing riverine nutrients. Hurricane effects on benthic nitrogen dynamics and their fluxes during ecosystem recovery following an event were investigated at three experimental sites with distinct sediment organic matter (SOM) concentrations (lower-, intermediate-, and higher-SOM) in Wax Lake Delta (WLD), Louisiana. Intact sediment cores were incubated with 15NO3− enrichment prior to, 1 month, 2 years, and 3 years post Hurricane Barry.
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Net evaporation-induced mangrove area loss across low-lying Caribbean islands
Environmental Research: Climate2024
Although mangroves provide many beneficial ecosystem services, such as blue carbon storage and coastal protection, they are currently under threat due to changes in climate conditions, such as prolonged drought exposure. Under drought conditions, evaporation exceeds precipitation and high soil salinities can lead to stunted growth and die-back. To quantify this interplay, we developed a database for low-lying and uninhabited mangrove islands in the Caribbean under various evaporation and precipitation regimes. We extracted physical and biological information from each island using remote sensing techniques and coupled it with a process-based model. We used this database to develop a model that explains both the spatial variability in vegetated area across the Caribbean—as a function of rates of evaporation and precipitation—and porewater salinity concentration and dispersion from island edge towards the interior of mangrove islands.
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Co-evolution of wetland landscapes, flooding, and human settlement in the Mississippi River Delta Plain
Sustainability Science2016
River deltas all over the world are sinking beneath sea-level rise, causing significant threats to natural and social systems. This is due to the combined effects of anthropogenic changes to sediment supply and river flow, subsidence, and sea-level rise, posing an immediate threat to the 500–1,000 million residents, many in megacities that live on deltaic coasts. The Mississippi River Deltaic Plain (MRDP) provides examples for many of the functions and feedbacks, regarding how human river management has impacted source-sink processes in coastal deltaic basins, resulting in human settlements more at risk to coastal storms. The survival of human settlement on the MRDP is arguably coupled to a shifting mass balance between a deltaic landscape occupied by either land built by the Mississippi River or water occupied by the Gulf of Mexico. We developed an approach to compare 50 % L:W isopleths (L:W is ratio of land to water) across the Atchafalaya and Terrebonne Basins to test landscape behavior over the last six decades to measure delta instability in coastal deltaic basins as a function of reduced sediment supply from river flooding.
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