The role of ocean tides on groundwater-surface water exchange in a mangrove-dominated estuary: Shark River Slough, Florida Coastal Everglades, USA

Christopher G. Smith; Rene M. Price; Peter W. Swarzenski; Jeremy C. Stalker

doi:10.1007/s12237-016-0079-z

Home/Archive/USGS

USGS · 70169031

The role of ocean tides on groundwater-surface water exchange in a mangrove-dominated estuary: Shark River Slough, Florida Coastal Everglades, USA

Christopher G. Smith·Rene M. Price·Peter W. Swarzenski·Jeremy C. Stalker

View original source ↗Export metadata ↓

Abstract

Low-relief environments like the Florida Coastal Everglades (FCE) have complicated hydrologic systems where surface water and groundwater processes are intimately linked yet hard to separate. Fluid exchange within these lowhydraulic-gradient systems can occur across broad spatial and temporal scales, with variable contributions to material transport and transformation. Identifying and assessing the scales at which these processes operate is essential for accurate evaluations of how these systems contribute to global biogeochemical cycles. The distribution of 222 Rn and 223,224,226 Ra have complex spatial patterns along the Shark River Slough estuary (SRSE), Everglades, FL. High-resolution time-series measurements of 222 Rn activity, salinity, and water level were used to quantify processes affecting radon fluxes out of the mangrove forest over a tidal cycle. Based on field data, tidal pumping through an extensive network of crab burrows in the lower FCE provides the best explanation for the high radon and fluid fluxes. Burrows are irrigated during rising tides when radon and other dissolved constituents are released from the mangrove soil. Flushing efficiency of the burrows—defined as the tidal volume divided by the volume of burrows— estimated for the creek drainage area vary seasonally from 25 (wet season) to 100 % (dry season) in this study. The tidal pumping of the mangrove forest soil acts as a significant vector for exchange between the forest and the estuary. Processes that enhance exchange of O2 and other materials across the sediment-water interface could have a profound impact on the environmental response to larger scale processes such as sea level rise and climate change. Compounding the material budgets of the SRSE are additional inputs from groundwater from the Biscayne Aquifer, which were identified using radium isotopes. Quantification of the deep groundwater component is not obtainable, but isotopic data suggest a more prevalent signal in the dry season. These findings highlight the important role that both tidal- and seasonal-scale forcings play on groundwater movement in low-gradient hydrologic systems.

Explore related subjects

Estuaries and Coasts Article

Source-reported bounding extent: 25.175116531621764° to 25.76526690492097° latitude; -81.3482666015625° to -80.4364013671875° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Christopher G. Smith, Rene M. Price, Peter W. Swarzenski, Jeremy C. Stalker. 2016-05-26. The role of ocean tides on groundwater-surface water exchange in a mangrove-dominated estuary: Shark River Slough, Florida Coastal Everglades, USA. https://doi.org/10.1007/s12237-016-0079-z

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Drivers of ecosystem metabolism in an anthropogenically modified delta

Estuaries are under threat globally from a wide range of stressors, with rates of ecosystem metabolism – respiration (R), gross primary production (GPP), and net ecosystem metabolism (NEM) – representing a way for resource managers to quantify their impacts. In this study, we assessed how natural and anthropogenic stressors have altered metabolism within the extensively modified Sacramento-San Joaquin Delta (“Delta”) in California, USA. Metabolism was estimated using a diel open-water technique utilizing dissolved oxygen measurements from a high frequency (15 min) water quality monitoring array, and spanned 6 sites across 11 years (2014–2025). Our analyses were driven by a conceptual model of Delta carbon (C) cycling focused on 1) Invasive aquatic vegetation (IAV), 2) Phytoplankton, 3) Wastewater treatment plant (WWTP) upgrades, 4) Large-scale flow alterations, and 5) Wet vs. dry years. We found that allochthonous C fuels net heterotrophy in the outer riverine sections of the Delta, while the heavily vegetated central Delta produces autochthonous C remineralized elsewhere in the system. IAV were the dominant primary producers, with low phytoplankton production except during a historic bloom. WWTP upgrades imparted negligible changes to metabolism, with low chlorophyll a (< 5 µg L −1 ) both before and after. Introduction of a flow barrier – a management response to drought – hydrodynamically isolated deep-water channels from nearby shallow areas, resulting in decreased metabolism indicative of changes to C transport. Contrary to past research, low rainfall years were associated with increased metabolism. This study demonstrates how multi-sensor arrays can be used to quantify ecosystem responses to major environmental stressors.

California↗

USGS2026

Forecasting marsh resilience in the Plum Island Estuary: Integrating uncertainty to inform coastal management

Salt marshes provide critical ecosystem services yet face increasing threats from accelerated relative sea-level rise (SLR). The long-term persistence of these habitats depends on their ability to vertically accrete and laterally migrate into adjacent uplands. Predicting the location and viability of these future marsh corridors is therefore a primary challenge for coastal managers; one often hindered by uncertainties in future water levels and topographic data accuracy, particularly in vegetated wetlands where light detection and ranging (lidar) data systematically overestimate elevation. This study applies an uncertainty-informed modeling framework to forecast marsh resilience in the Plum Island Estuary, Massachusetts. We integrated the Sea Level Affecting Marshes Model (SLAMM) with a Monte Carlo error analysis, generating an ensemble of bias-corrected digital elevation models (DEMs) alongside three probabilistic SLR scenarios (Intermediate, Intermediate High, High) through 2100. We synthesized these simulations into a “marsh fate” classification map to distinguish between resilient core habitats, vulnerable zones requiring intervention, and likely migration corridors. While the marsh platform exhibits resilience under Intermediate scenarios, a critical tipping point emerges under the High SLR scenario. In this case, accelerating inundation overwhelms accretion capacities, driving a landscape-scale regime shift. By integrating the interacting uncertainties of SLR trajectories and initial marsh elevation, we project 2100 net marsh coverage outcomes ranging from a 10.5% gain to a 23.2% loss. These results demonstrate that incorporating elevation uncertainty is essential for detecting non-linear threshold behaviors that deterministic models often miss. The resulting framework empowers managers with a spatially explicit tool to prioritize land acquisition and restoration efforts in the face of climate uncertainty.

Massachusetts↗

USGS2026

Incorporating wetland drowning thresholds to assess the spatiotemporal variability in potential wetland migration and submergence from sea-level rise

In the coming decades sea-level rise rates could exceed the upper bounds of coastal wetland vertical movement leading to wetland submergence. Consequently, understanding the spatiotemporal variability of wetland migration and submergence at regional and national scales can inform decision making. In this study, we developed an approach that addresses elevation error in digital elevation models for wetlands, incorporates uncertainty in current and future water levels, and utilizes recent literature on coastal wetland drowning thresholds. We used our framework to predict wetland change with sea-level rise for the middle and upper Texas coast—a region that is experiencing some of the highest relative sea-level rise rates in the United States. Our elevation-based approach produced contemporary wetland maps that had a high level of agreement (> 87–91%) with existing national wetland maps. For the intermediate relative sea-level rise scenario, extensive change is predicted within the study area by 2100, including a net decrease in coverage of irregularly oceanic-flooded wetlands (-37%) and regularly oceanic-flooded wetlands (-23%). The wetland migration space of these two wetland zones is largely made up of existing wetlands (> 70%), but also includes other upland areas, such as pasture/hay and grassland. By breaking down our results for the full region and two distinct focal areas, we highlight the spatiotemporal variability of wetland change. Our scalable approach provides natural resource managers with information for developing location-specific strategies for balancing the trade-offs associated with wetland change from sea-level rise.

Texas↗