Christopher G Smith, PhD
As a coastal geologist, my research focuses on the transport, transformation, and deposition of particulate and dissolved constituents within the coastal realm and how system processes will respond to large-scale environmental forcings (e.g., climate change).
Biography
Coastal systems provide a dynamic interface between terrestrial and marine realms; anthropogenic activity and natural processes occurring within terrestrial ecosystems can have a significant impact to the coastal zone and adjacent marine system. Augmentation of coastal systems is inevitable from a human perspective as nearly half of the population of the United States reside within coastal counties. Understanding modern processes (sedimentologic, hydrologic, and geochemical) occurring along this terrestrial-marine continuum is critical in predicting the response associated with natural and anthropogenic perturbations.
My research interests generally fall into two categories: 1) fluid exchange (e.g., surface water – groundwater exchange, submarine and coastal groundwater discharge) and 2) fine-grained sediment dynamics, specifically in marsh and estuarine environments. Linking these two seemingly disparate research topics are naturally-occurring (e.g., U-Th series) and anthropogenically-introduced/spiked (e.g., 137Cs) radionuclides. Particle reactive radionuclides (e.g., 7Be, 234Th, 210Pb, 210Po, and 137Cs) provide excellent tracers to quantify sediment deposition and re-mobilization over time-scales of months to decades. Examining the final sedimentary product in the context of the temporal framework and associated transient changes also provide a breadth of knowledge to environmental conditions that persisted in recent past and the outcome that may be expected if similar conditions persist in the present or future. Alternatively, the more conservative behavior of radon and radium isotopes have proven these as excellent tracers to quantify groundwater discharge in both fresh and marine environments.
Over the last three decades, groundwater discharge to the coastal zone has received increasing recognition as a substantial material vector, influencing water quality and nutrient fluxes. Quantification of fresh and marine groundwater end-members and the processes that drive the exchange (e.g., seasonal recharge cycles, hurricanes and tropical cyclones) are critical to assess the overall importance of coastal groundwater and has been at the forefront of my research.
Science and Products
Estuarine and MaRsh Geology Research Project
The goal of the Estuarine and MaRsh Geology (EMRG) Research Project is to study how and where short- and long-term marsh and estuarine coastal processes interact, how they influence coastal accretion or erosion, and how they pre-condition a marsh’s resiliency to storms, sea-level change, and human alterations along the northern Gulf of Mexico (Grand Bay and Point aux Chenes, Mississippi and St...
Submarine Groundwater Discharge
We define submarine groundwater discharge (SGD) to consist either of fresh groundwater, re-circulated seawater, or a composite thereof. We evaluate and present SGD in terms of a vector for nutrient delivery to coastal waters.
Alabama Barrier Island Restoration Assessment
This project is a collaborative effort between the USGS, U.S. Army Corps of Engineers (USACE), and the State of Alabama funded by National Fish and Wildlife Foundation (NFWF) to investigate viable, sustainable restoration options that protect and restore the natural resources of Dauphin Island, Alabama. The project is focused on restoration options that protect and restore habitat and living...
Hurricane Sandy Response- Linking the Delmarva Peninsula's Geologic Framework to Coastal Vulnerability
The Delmarva Peninsula is a 220-kilometer-long headland, spit, and barrier island complex that was significantly affected by Hurricane Sandy. In order to better constrain controls on coastal vulnerability and evolution, the region’s sediment sources, transport pathways and sediment sinks must be identified. This project defines the geologic framework of the Delmarva coastal system through...
Sea-level and Storm Impacts on Estuarine Environments and Shorelines (SSIEES)
This project assesses the physical controls of sediment and material exchange between wetlands and estuarine environments along the northern Gulf of Mexico (Grand Bay Alabama/Mississippi and Vermilion Bay, Louisiana) and the Atlantic coast (Chincoteague Bay, Virginia/Maryland).
Alabama Barrier Island Restoration Study
Scientists are collecting geologic data and developing a numerical model framework to understand the evolution of Dauphin Island over the last 15-20 years and assess the future evolution of the island over the next 15-50 years, including the impacts of potential restoration scenarios.
Improving Our Ability to Forecast Tidal Marsh Response to Sea Level Rise
Our overall objective is to understand what controls the vulnerability of coastal marshes to risks associated with global change drivers and rising sea levels. Fundamental questions pertaining to coastal wetland vulnerability still need to be addressed. What factors explain spatial and geographic variation in tidal wetland vulnerability? How do short term climatic events (storms) influence the...
Gulf of Mexico blue hole harbors high levels of novel microbial lineages
Exploration of oxygen-depleted marine environments has consistently revealed novel microbial taxa and metabolic capabilities that expand our understanding of microbial evolution and ecology. Marine blue holes are shallow karst formations characterized by low oxygen and high organic matter content. They are logistically challenging to sample, and...
Patin, N.V.; Dietrich, Z.A.; Stancil, A.; Quinan, M.; Beckler, J.S.; Hall, E.R.; Culter, J; Smith, Christopher; Taillefert, Martial; Stewart, F.J.Using multiple environmental proxies and hydrodynamic modeling to investigate Late Holocene climate and coastal change within a large Gulf of Mexico estuarine system (Mobile Bay, Alabama, USA)
A high degree of uncertainty exists for understanding and predicting coastal estuarine response to changing climate, land-use, and sea-level conditions, leaving geologic records as a best-proxy for constraining potential outcomes. With the majority of the world's population focused in coastal regions, understanding how local systems respond to...
Smith, Christopher; Jones, Miriam C.; Osterman, Lisa; Passeri, Davina L.Council Monitoring and Assessment Program (CMAP): Inventory of existing water quality and habitat monitoring, and mapping metadata for Gulf of Mexico Programs
Under the Council-Selected Restoration Component of the RESTORE Act, the Council develops Funded Priority Lists (FPLs) that describe the projects and programs it will fund. Projects and programs funded through this component must be in furtherance of the goals and objectives of the Council’s Comprehensive Plan and address at least one of the...
Meyers, Michelle; Bosch, Julie; Burkart, Heidi; Clement, Chris; Enwright, Nicholas; Giordano, Steve; Jeffery, Chris; Hart, Rheannon; Hile, Sarah; Howell, Jacob; Lee, Michael; Laurenzano, Claudia ; McCloskey, Terrance; Mize, Scott; Monaco, Mark E.; Owen, Kevin; Rebich, Richard; Sample, Thomas; Steyer, Gregory D.; Suir, Kevin J.; Smith, Christopher G.; Watson, Katie; Bosch, Julie; Burkart, Heidi; Chivoiu, Bogdan; Clark, Randy; Clement, Chris; Enwright, Nicholas; Giordano, Steve; Jeffrey, Chris; Johnson, Edward; Hart, Rheannon M.; Hile, Sarah; Howell, Jacob; Laurenzano, Claudia ; Lee, Michael T.; McCloskey, Terrence A.; McTigue, Terry; Meyers, Michelle B.; Mize, Scott; Monaco, Mark E.; Owen, Kevin; Rebich, Richard A.; Rendon, Samuel H.; Robertson, Ali; Sample, Thomas; Steyer, Gregory D.; Suir, Kevin J.; Swarzenski, Christopher M.; Watson, KatieTemperature mediates secondary dormancy in resting cysts of Pyrodinium bahamense (Dinophyceae)
High‐biomass blooms of the toxic dinoflagellate Pyrodinium bahamense occur most summers in Tampa Bay, Florida, USA, posing a recurring threat to ecosystem health. Like many dinoflagellates, P. bahamense forms immobile resting cysts that can be deposited on the seafloor—creating a seed bank that can retain the organism within...
Lopez, Cary B.; Karim, Aliza; Murasko, Susan; Marot, Marci E.; Smith, Christopher G.; Corcoran, Alina A.Distribution of modern salt-marsh Foraminifera from the eastern Mississippi Sound, U.S.A.
This study documented surface distributions of live and dead foraminiferal assemblages in the low-gradient tidal marshes of the barrier island and estuarine complex of the eastern Mississippi Sound (Grand Bay, Pascagoula River, Fowl River, Dauphin Island). A total of 71,833 specimens representing 38 species were identified from a gradient of...
Haller, Christian; Smith, Christopher; Hallock, Pamela; Hine, Albert C.; Osterman, Lisa; McCloskey, TerrenceRecent outer-shelf foraminiferal assemblages on the Carnarvon Ramp and Northwestern Shelf of Western Australia
The carbonate sediments of the Western Australian shelf in the Indian Ocean host diverse assemblages of benthic foraminifera. Environments of the shelf are dominated by the southward-flowing Leeuwin Current, which impacts near-surface circulation and influences biogeographic ranges of Indo-Pacific warm-water foraminifera. Analyses of outer ramp to...
Christian Haller; Pamela Hallock; Albert C. Hine; Smith, ChristopherAssessing the impact of open-ocean and back-barrier shoreline change on Dauphin Island, Alabama, at multiple time scales over the last 75 years
Dauphin Island and Little Dauphin Island, collectively, make up a geomorphically complex barrier island system located along Alabama’s southern coast, separating Mississippi Sound from the Gulf of Mexico and Mobile Bay. The barrier island system provides numerous economical (tourism, fisheries) and natural (habitat for migratory birds, natural...
Smith, Christopher G.; Long, Joseph W.; Henderson, Rachel E.; Nelson, Paul R.The effects of tropical cyclone-generated deposition on the sustainability of the Pearl River marsh, Louisiana: The importance of the geologic framework
Shoreline retreat is a tremendously important issue along the coast of the northern Gulf of Mexico, especially in Louisiana. Although this marine transgression results from a variety of causes, the crucial factor is the difference between marsh surface elevation and rising sea levels. In most cases, the primary cause of a marsh's inability to keep...
McCloskey, Terrence A.; Smith, Christopher G.; Liu, Kam-Biu; Nelson, Paul R.The foraminifera of Chincoteague Bay, Assateague Island, and the surrounding areas: A regional distribution study
Foraminiferal census data from Chincoteague Bay, Newport Bay, the salt marshes of Assateague Island, adjacent mainland salt marshes, and the inner-shelf, were assessed to determine the current assemblages in Chincoteague Bay, and how the different environments surrounding the bay, and the gradients within the bay, influence the microfossil...
Smith, Christopher G.; Ellis, Alisha M.; Shaw, Jaimie E.; Osterman, Lisa E.; Smith, Christopher G.Barrier-island and estuarine-wetland physical-change assessment after Hurricane Sandy
IntroductionThe Nation’s eastern coast is fringed by beaches, dunes, barrier islands, wetlands, and bluffs. These natural coastal barriers provide critical benefits and services, and can mitigate the impact of storms, erosion, and sea-level rise on our coastal communities. Waves and storm surge resulting from Hurricane Sandy, which made landfall...
Plant, Nathaniel G.; Smith, Kathryn E.L.; Passeri, Davina L.; Smith, Christopher G.; Bernier, Julie C.The sedimentological characteristics and geochronology of the marshes of Dauphin Island, Alabama
In August 2015, scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center collected 11 push cores from the marshes of Dauphin Island and Little Dauphin Island, Alabama. Sample site environments included high marshes, low salt marshes, and salt flats, and varied in distance from the shoreline. The sampling efforts...
Ellis, Alisha M.; Smith, Christopher G.; Marot, Marci E.How could a freshwater swamp produce a chemical signature characteristic of a saltmarsh?
Reduction–oxidation (redox) reaction conditions, which are of great importance for the soil chemistry of coastal marshes, can be temporally dynamic. We present a transect of cores from northwest Florida wherein radical postdepositional changes in the redox regime has created atypical geochemical profiles at the bottom of the sedimentary column....
McCloskey, Terrence A.; Smith, Christopher G.; Liu, Kam-biu; Marot, Marci E.; Haller, ChristianPre-USGS Publications
Research Geologist Christopher G. Smith to be featured in episode of Changing Seas titled, "Florida's Blue Holes: Oases in the Sea"
PBS’s Changing Seas docuseries will be airing an original episode on blue holes, featuring research being conducted by USGS and partners on the West Florida Shelf. Blue holes are submerged sinkholes off the coast of Florida that are considered ecological hotspots for marine biodiversity.
Collaborative research will advance knowledge on coastal erosion hazards of marsh shorelines and the impact of living shorelines
Coastal wetland loss has been well documented and attributed to many factors, including increased shoreline erosion from human activities, sea level rise, and storms.
USGS Measures Flooding in Arizona
U.S. Geological Survey field crews are measuring flooding after heavy rainfall occurred in northern portions of Maricopa County, Arizona.