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The USGS Mendenhall Research Fellowship Program is a prestigious opportunity for early career geoscientists to enhance their scientific stature and credentials. The fellowships are limited to a two-year appointment, making them time-sensitive by nature. While this is typically adequate time to complete their research, a global pandemic has posed new challenges for Mendenhall fellows at USGS.

A man writes on a long metal cyllinder in a marsh environment
Mendenhall postdoctoral fellow Daniel Ciarletta labels a sediment core obtained from Mullet Key, a barrier island along the Gulf coast of Central Florida. 

Dr. Daniel “Dan” Ciarletta began his fellowship with the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center in August 2019. Shortly after getting settled into his position, Dan was faced with a challenge like many others across the world: learning how to accomplish his work during a global pandemic.

Prior to joining USGS, Dr. Dan Ciarletta used historical maps and U.S. Coast Survey T-sheets to investigate changes in barrier island morphology on the Virginia coast over the past hundred years. He noticed dramatic shifts in shoreline position over time, sparking questions that would seed his Mendenhall project: What drivers are responsible for barrier island change? How do sea-level rise and sediment flux affect island structure and vulnerability to change? What will happen to these protective barrier islands in the long term?

For his Mendenhall postdoctoral research at the USGS St. Petersburg Coastal and Marine Science Center in Pinellas County, Florida, Dan uses a combination of field and modeling approaches to study barrier island sensitivity to drivers such as sediment flux, sea-level rise, and storms. He proposed to collect field data on the shape and structure of Fire Island, New York and Cat Island, Mississippi – building upon partial existing USGS datasets. He would then compare these data with historical records and use sediment cores to reconstruct the geologic history of the islands. By studying the barrier island system holistically, from the back barrier to the waterline and even out to the continental shelf, Dan planned to incorporate the data into numerical models of barrier island evolution to identify the interactions and drivers of barrier island evolution and predict future change.

Two scientists operate a motorized cylindrical object as it penetrates a sandy marsh environment
Dan Ciarletta (right) working alongside Julie Bernier (left) to collect a sediment core on Mullet Key in Pinellas County, Florida. The core will be used to reconstruct the geologic history of the island.

In early 2020, Dan was preparing to travel to Fire Island to begin his first round of data collection. On March 13, the USGS began operating at maximum telework while limiting fieldwork to mission essential and critical functions. These changes resulted in a delay, and sometimes complete loss, of field operations across the USGS, including Dan’s Mendenhall work. His postdoctoral research halted in its tracks.

The original intent was for Dan’s field data to inform his modeling approaches. However, instead of waiting on the field data, he decided to get a head start on the modeling component of his project—taking an innovative, observationally inspired approach to develop the models.  Drawing on conceptual models of barrier landscape evolution and measured rates of change in barriers located around the world, Dan produced a numerical model to simulate coastal change driven by sediment fluxes and rate of sea-level rise. Dan’s innovation and creativity resulted in a publication with a broader, conceptual overview of the various processes that influence how barrier islands evolve over time – leading to models with global implications rather than a geographically specific focus. Dan described this opportunity as “life giving lemons.”

Eventually, new safety procedures enabled USGS field operations to resume, ensuring maximum safety of USGS employees and communities. The procedures incorporated guidance from the White House, Department of the Interior, Centers for Disease Control and Prevention, and state and local authorities.

An aerial view of several thin, sandy barrier islands lining a populated coastline behind an embayment
Barrier islands off the coast of northern Pinellas County, Florida including Anclote Key, Three Rooker Island, and the northern tip of Honeymoon Island. These barriers protect a highly populated coastline. 

Considering the risks of travel and the myriad challenges surrounding the ongoing pandemic, Dan shifted his focus locally. Pinellas County, Florida—where the USGS St. Petersburg Coastal and Marine Science Center is located—is a highly populated coastal area protected by a system of barrier islands. He organized a team to visit local islands including Mullet Key, Honeymoon Island, and Caladesi Island. The team used vibracore equipment to collect sediment cores at each site ranging from 2.1 to over 3m long. The layers of sediment within the cores will allow Dan to reconstruct the geologic history of each barrier, as far back as several hundred years. Radiological techniques are used to estimate the age of each layer, and clues from each layer indicate the type of environment that existed at one location through time. For instance, the presence of peat (comprised of decomposed organic matter) indicates a marsh environment was present there, while white sandy sediment may indicate that a beach or dune was present. The change in these environments through time allows scientists to see how the island has moved and changed over decades to millennia. The team also collected Ground-Penetrating Radar (GPR) data to visualize the various sediment layers beneath the surface of the islands and investigate the processes that led to their modern structure.

A flatbed trailer with scientific equipment strapped down
Scientific equipment on a flatbed truck at the St. Petersburg Coastal and Marine Science Center in St. Petersburg, Florida. The equipment is to be shipped up to the New York Water Science Center to a group of scientists who will help assist in data collection at Fire Island, New York.

These data are important for understanding change in all barrier systems, including Pinellas County. However, opportunities to collect data in some environments is quickly eroding away – in some places, literally. Dan’s original location of interest at Fire Island, New York is part of a barrier system that protects a highly populated area from the impacts of storms, waves, and erosion. In 2012, Hurricane Sandy re-opened an inlet that had not been present since the 1830’s. Since the inlet reappeared, the island has been prone to rapid erosion. Although the pandemic offered an opportunity to shift his focus, Dan developed yet another innovative solution to collect valuable data in New York before the study site is altered by these extreme erosional processes, or disappears completely. He partnered with the USGS New York Water Science Center to collect data from the island – including the same core and GPR data he collected in Florida. This involved shipping large equipment up to New York and providing detailed instructions and training for the team to assist in data collection without the need for air travel. “These are data that this team has never collected before, but we couldn’t collect it without them,” said Dan. “I’m really grateful we have these opportunities at USGS to work together and create innovative solutions, even in the midst of a pandemic.” This creative thinking and dedicated partnership are allowing Dan to obtain important information about the geologic history of Fire Island before the information is lost forever.

Working in the geosciences provides many opportunities to foster resiliency and innovation. Research plans are often altered due to obstacles such as unexpected weather and equipment malfunctions. The pandemic has been yet another challenge that scientists have had to face over the past year. Despite this challenge slowing research efforts, scientists like Dan are pushing through it.

Dan’s research has a direct connection to current, ongoing challenges like coastal resilience and vulnerability of habitats and economic resources. Millions of people live and work on barrier islands, and in the coastal areas protected by them. Investigating how these systems change is critical for predicting what the next few decades will look like. Postponement of research efforts could lead to a delay in our understanding of coastal change impacts, and therefore hinder our abilities to predict and prepare for resultant coastal hazards. This could translate into increased monetary and physical risk to taxpayers and coastal communities.

“Climate change and sea-level rise aren’t slowing down, even if research and monitoring efforts are,” said Dan. “The research we do really has an impact. Decisions could be delayed, or not made at all, because the science isn’t there to inform our elected leaders. There will be consequences, but we plan to continue our work to provide the information needed to reduce them.”

A plot with numerous lines showing the shape of sediment layers beneath the surface of a barrier island
Provisional ground penetrating radar (GPR) data collected from a transect running North to South on Saint Jean Key in Fort De Soto Park, Pinellas County, Florida. The bold lines near the top of the plot indicate the position of the ground surface, with the colors below indicating reflections of radio waves from underground sediments. The reflections indicate the shape of historical island morphology as far back as several hundred years ago. Shown here, a u-shaped feature in the radar profile suggests the presence of a buried channel that was filled in by sediments that came from a northerly direction (diagonal lines filling the inside of the channel). Once the channel filled, sediment continued to deposit uniformly over this section of the island, forming the relatively flat surface seen today.

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