2021 Human & Ecosystem Health: Funded Research

Investigating oyster-reef morphodynamics to optimize nature-based infrastructure: Intertidal oyster reefs are commonly incorporated into living-shoreline designs with the reef serving the role of nearshore sill or breakwater oriented parallel to the estuarine shoreline. In contrast, natural fringing reefs develop an elongated morphology oriented perpendicular to shore and the dominant tidal-current direction. Are constructed oyster sills incompatible with the long-term objectives of providing shoreline protection, maximizing the provision of ecosystem services and resilience to climate change, and ensuring a self-sustaining reef in perpetuity? The main objective of this study is to measure the lateral growth rates of oyster reefs and characterize the flow regime where lateral growth is highest. Without a complete understanding of how oyster reefs grow and expand, the effectiveness of using them to enhance shoreline resiliency and reduce storm hazards is severely hampered.

Dr. Antonio Rodriguez and Dr. Joel Fodrie

Image: Collecting a sediment core from Cross Rocks, an elongated oyster reef in the Newport River Estuary, NC. Credit: Joshua Himmelstein.

 Fecal indicator bacteria are monitored in coastal waters to determine if conditions are safe for recreation and shellfish harvest. About 24-48 hours will pass from the time when a sample is collected to when the bacteria data are available, creating long lags that impact management decision-making. This project will investigate how water quality measurements collected in near real-time can be used to nowcast fecal indicator bacteria concentrations, with the goal of enabling more precise, timely, and effective management of coastal waterways.

Dr. Natalie Nelson, Dr. Angela Harris, Dr. Elizabeth Darrow, Dr. Chris Osburn, Dr. Elise Morrison 

Image: Bald Head Creek. Credit: Bald Head Island Conservancy.

Hybrid flood mitigation solutions capitalize on the benefits of both structural measures and natural and nature-based features. However, they have not been commonly adopted in flood risk management, partly because of a lack of technical design guidelines and little understanding of uncertainties in the performance of hybrid solutions. Benefits of Vegetation for Preventing Coastal Flooding Induced by Failure of Seawalls quantifies the extent to which coastal vegetation mitigates wave forces and wave runup on seawalls and develops a probabilistic method for optimized integration of salt marshes with structural measures, without over/underbuilding the solution. The outcome of the project is an advanced understanding of the design and performance of hybrid solutions for coastal flood risk mitigation.

Dr. Reza Marsooli

Image: Sketch of a hybrid salt marsh-seawall flood protection approach. H is wave height; λ is wavelength; l is length (unit area) of salt marsh; m is beach slope; d is water depth in front of the seawall; ηr is wave runup height; FB is freeboard

 Climate change has increased the frequency of operation of the Bonnet Carré Spillway (BCS) which significantly and drastically impacted ecosystems and fisheries of the Mississippi Sound. A coupled modeling framework will be used to evaluate how freshwater and nutrient input from Bonnet Carré spillway openings affects water quality, food webs, and fisheries in the Mississippi Sound and Bight to investigate effects of nutrient-rich freshwater inflow from federally regulated BCS operations in combination with natural river discharge under different atmospheric conditions on coastal ecology and fisheries. The modeling framework will be used to determine ideal habitat for oysters in the Mississippi Sound, nektonic fisheries species biomass and distribution under relevant operational regimes, and the effects of reduced paced BCS openings. Project outcomes will help elucidate where, when, and how inflow of nutrient-rich freshwater can lead to hypoxic events, with subsequent effects on food webs and fisheries.

Dr. Kim de Mutsert and Dr. Kemal Cambazoglu

Image: Model domain for the COAWST/ROMS model application to the Mississippi Sound and Bight. 

 Quantifying the Role of Microcystis Resuspension on HABs in Coastal Lake Erie Using Multidisciplinary Approaches investigates harmful algal blooms (HABs) in Lake Erie that share many of the same drivers as blooms in small lakes - warm temperatures, shallow water, and high phosphorus input - but HABs in Lake Erie are complicated by frequent resuspension caused by currents and waves. The objective of this project is to evaluate resuspension of Microcystis from the sediments using laboratory experiments, ‘omics-enabled methods, and hydrodynamic and statistical modeling. A key benefit of this research could be improved prediction of the conditions leading to bloom initiation.  

Dr. Casey Godwin, Dr. Dmitry Beletsky, Dr. Michael Fraker, and Dr. Subba Rao Chaganti

Image: Sediment core experiment to quantify critical shear for Microcystis resuspension (left) and estimates of currents- and wave-induced stress across western Lake Erie (right). 

Oregon Coastal Dune Management – Physical Mechanics and Community Perception: The Oregon coast consists predominantly of unmanaged foredunes occupied by invasive beachgrasses, with a smaller fraction of foredunes heavily managed for human benefits near population centers. The geomorphological and ecological evolution of unmanaged foredunes populated by invasive beachgrasses is reasonably well understood. However, the evolution of dunes that are managed for human benefit, where dunes are graded for views and re-planted with beach grasses is understudied. In Oregon, there is an expressed need for this specific knowledge of best practices for Oregon coastal dune management. We are currently following the evolution of Oregon foredune geomorphology in six Oregon communities that grade or have graded their dunes for views. The goal is to provide science based foredune management guidance for the state of Oregon via a community accessible Oregon Coastal Dunes Management Guidebook. The Guidebook will be a living resource for community managers that will incorporate integrated observations and recommendations on short- and long-time scales using both native and invasive grasses for dune evolution.

Dr. Meagan Wengrove and Dr. Flaxen Conway

Image: left – Unmanaged foredune in Pacific City, OR. Right – Graded foredune in Pacific City, OR.

Identification of sources of fecal pollution in populated estuaries by a combination of monitoring and numerical modeling: Conventional survey techniques are inadequate in identifying the sources of fecal pollution in soil and estuaries, making it crucial to devise a framework that merges microbial source tracking with numerical models to improve septic system identification. The project proposes to couple a groundwater model with a hydrodynamic model to model the advection-diffusion-decay of fecal bacteria in soil and surface waters, which will be tested in the Guana-Tolomato-Matanzas lagoonal system. The aim is to provide GTM estuary managers with information about the relative contribution of human fecal pollution from septic systems under different scenarios. The results will offer pointers to the locations where septic systems have the greatest impact on water quality, and where alternative wastewater treatment options should be prioritized.

Dr. Alberto Canestrelli

Image: Example of fecal contaminants plumes computed with the groundwater model. 

  Plastics underpin modern human life, and their accumulation in natural environments poses a significant threat to biological organisms and foodwebs. Microplastics(R)Us – Sources and transport pathways of microplastics in a coastal estuary combines 3D hydrodynamic modeling with field measurements to deliver a detailed model of microplastics flow in a coastal estuary during normal conditions and storm disturbance. Outcomes from this project will contribute to an understanding of the various sources of microplastics, knowledge on their watershed and estuarine transport pathways and processing, and on their global flux to the oceans.

Dr. Karl Kaiser, Dr. Jiabi Du, Dr. Kyeong Park, Emily Summers

Image: Model results showing microplastic particle tracks during the first 60 days after release. 

 Wave attenuation is often one of the primary objectives of living shorelines projects; however, two recent studies of an oyster castle pilot project in New Jersey have documented wave amplification. These amplification events mostly occur when the structures are submerged. This project looks to expand upon these initial observations by studying four different living shorelines projects, each designed to attenuate waves. The research question is, are these amplification events common across different types of living shorelines projects in different settings, or isolated to this specific location? To answer the question, a combination of field measurements and numerical modeling will be employed. Given the fact that sea level rise will make submergence of low-crested living shoreline structures more common in the future, the research promises to offer insight into the design of future projects and the management of existing projects. 

Dr. Jon Miller

Image: Gauges being deployed at Forked River NJ at a Hesco basket breakwater. 

Salt marshes are essential to nutrient removal, carbon sequestration, and wildlife habitats, as well as defense from coastal flooding. Salt marsh health relies on fluid exchange and sediment supply from tidal inlets, tributaries, inundation or wave-driven flooding. However, barrier systems that include human-built grey infrastructure (e.g., roads) can severely limit natural the natural overwash process resulting from inundation or wave-driven flooding. This project investigates the response of salt marsh systems to overwash events in the presence and absence of grey infrastructure in barrier systems through a combination of numerical modeling and field surveys at two different salt marshes.

Dr. Diane Foster and Dr. Matthew Florence (Post-doc)

Images: Left – Example of PIT tag movement as a result of overwash highlighting the nutrient exchange and sediment transport process. Top right – GPS survey to for topography data for numerical modeling. Bottom right – Bathymetry data colinear to the black line in the GPS survey for use in numerical modeling.

Microplastic presence and circulation in Galveston, Corpus Christi, and Matagorda Bays aims to generate robust baseline data on microplastic concentrations in Corpus Christi, Matagorda, and Galveston Bays to assess their circulation and potential impacts of dredging. Objectives include consolidating existing data, developing a cost-effective Open Source Raman Spectrometer for broader research access, and combining the data with hydrodynamics models to predict microplastic transport and fate within these bays.

Dr. Hussain Abdulla and Dr. Darek Bogucki and Dr. Gombojav Ariunbold (Mississippi State University) 

Image: The distribution of the surface currents within the Matagorda Bay on June 21, 2021, at 0 h. The interpolated and time dependent currents will be used to predict the MPs fate.