Thin-layer sediment placement: evaluating an adaptation strategy to enhance coastal marsh resilience across the NERRS
Lead Investigator: Dr. Kenny Raposa, Research Coordinator, Narragansett Bay National Estuarine Reserve
WBNERR Project Contact: Dr. Megan Tyrrell
8 Reserves Included in Project: Great Bay NH, Waquoit Bay MA, Narragansett Bay RI, Chesapeake Bay MD, Chesapeake Bay VA, North Carolina, Grand Bay MS, Elkhorn Slough CA
Tidal marshes provide key ecosystem services, but are threatened by sea level rise. Narragansett Bay and Elkhorn Slough NERRs recently led a project to assess marsh resilience to sea level rise across 16 NERR sites, resulting in a scientific publication, user-friendly summary, and DIY tool. Currently, eight NERR sites across the East, Gulf and West coasts are actively testing strategies to examine the effectiveness of thin-layer sediment placement as a climate adaptation strategy.
Novel aspects of our project include the broad geographic scale, the examination of effectiveness at different marsh elevations, standardized monitoring, and the incorporation of biochar as a soil amendment to enhance carbon sequestration. Beneficial use of dredged sediment to enhance coastal resilience is a concept that resonates in many coastal states, and we have interviewed end-users from eight states interested in funding, permitting, implementation or monitoring of thin-layer sediment projects.
Anna Michel, Zoe Sandwith (WHOI)
Funding Source(s): WHOI
Matthew Long, WHOI
Funding Source(s): WHOI
Robinson W. Fulweiler(Boston University); Teri O’Meara (University of Auckland)
Funding Source(s): Boston University, University of Auckland
PI: Matthew Long, WHOI
Lead Investigator: Wally Fulweiler, Boston University Marine Program
Funding Source: MIT-Seagrant
The negative consequences of excess nutrient loading alter estuarine sediment nutrient cycling in general and the production of methane in particular. On a per molecule basis, the impact of methane on climate is over 20 times greater than carbon dioxide (over a 100 year period). And even though estuaries make up a small portion of the total global ocean area they contribute about 10% of the total ocean methane emissions. Thus, quantifying how the production of methane in estuaries changes seasonally and spatially is an important step in our understanding of coastal systems and future climate. The purpose of this ongoing research is to quantify sediment methane production in Waquoit Bay, MA and to determine how low oxygen conditions alter these rates. To do this we collect sediment cores at four sites exposed to varying oxygen conditions in the Waquoit Bay system and measure methane fluxes across the sediment-water interface. Additionally, we will conduct experimental manipulations where we alter the oxygen conditions in the overlying water to see how this impacts methane fluxes. For more information please go to: www.fulweilerlab.com and follow us @Fulweilerlab.
Collaborative Research: Does Environmental Context Moderate Functional Diversity Effect on Estuarine Sediment Biogeochemistry
PI: Amanda Spivak, WHOI
PI: Camille David, UMASS-Dartmouth, PhD Candidate
Advisor: Brian Howes, UMASS-Dartmouth
Funding: UMASS-Dartmouth, WBNERR collaborative in-kind
Comparing Methods and the Stability of Deep-Driven Rod Elevation Benchmarks and SETs in a Salt Marsh Environment
PIs: Philippe Hensel, National Geodetic Survey
Galen Scott, National Geodetic Survey, University of RI
Jim Lynch, US Geological Survey
WBNERR Staff: Jim Rassman, Jordan Mora, Chris Weidman
Description: Sediment Elevation Tables (SETs) and benchmarks are used to measure change in marsh elevation with millimeter scale accuracy to determine sedimentation rates. This information, combined with accurate water level measures, can assess whether salt marshes are keeping up with sea level rise or risk being “drowned.” Traditionally SETs and benchmarks are installed by driving metal rods deep into the earth until they hit resistance. This can be difficult and costly as each 4’ length of rod is expensive. This project is investigating whether it is necessary to drive the rods that deep, or whether they are just as stable at, say, 20’ depth. Rods have been driven to different depths in the South Cape Beach salt marsh and are being “leveled” regularly – measured against a known point – to see if they have shifted. If not, this research could result in new standards for installation of this infrastructure which would save significant time and money. This is one of a growing number of projects in the new “Climate Change Observatory” in this marsh.
PI: Chris Maio, UMASS-Boston, PhD Candidate.
Advisor: Allan Gontz, UMASS-Boston
Funding: UMASS-Boston, Geological Society of America Research Award, collaborative in-kind-WBNERR
My research looks at coastal changes that have occurred in response to sea-level rise and storminess during the past 4000 years. I use a variety of methods including sediment core analysis, ground penetrating radar, GIS, and radiocarbon dating. Learning about how the Waquoit estuarine system responded to past sea level-rise and storminess will provide needed context for understanding and anticipating future changes.
An ancient red cedar forest was first revealed after a series of storms in 2010 resulted in significant erosion along South Cape Beach revealing 111 subfossil stumps along the beach and into the water. Thirteen stumps were radiocarbon dated and ranged in age from ~413-1200 years old. We assume this age represents the time at which the ancient trees were drowned by marine waters. Shoreline change analysis showed that between 1846 and 2008, the shoreline fronting the paleoforest retreated landward by 70 m at a long-term rate of 0.43 m/yr.
Sediment cores were analyzed to determine storm and sea level history. Radiocarbon dates of bivalve microfossils indicate that Waquoit Bay was first inundated by marine waters approximately 3600 years ago. The ongoing research will help decipher the relationship between sea-level rise, storminess, and the inundation of terrestrial ecosystems and will help to illuminate what caused the drowning of the South Cape Beach paleoforest.
Using Molybdenum Concentration in Estuarine Sediments as a Proxy for Hypoxia Occurrence and Frequency
PI: Warren Boothman (EPA)
Description: With the assistance of the Waquoit Bay Reserve, staff from the Atlantic Ecology Division of the U.S. Environmental Protection Agency’s National Health and Environmental Effects Research Laboratory are examining the relationship between the frequency of hypoxia (low dissolved oxygen) in marine waters and accumulation of molybdenum (Mo) in sediments underlying those waters. Previous research in Narragansett Bay (RI) has shown that Mo accumulates in sediments when the water above becomes low in oxygen and revealed a linear relationship between the total period of hypoxia and concentration of Mo in surface sediment. To test whether the relationship is valid over a wider spatial scale, the same analyses are being done at monitoring sites within Waquoit Bay that have more than a decade of water quality data. Research chemist Warren Boothman (EPA) and Chris Weidman, Research Coordinator at the Waquoit Bay NERR, collected 12 sediment cores from 4 sites in May that will be sliced into 1-cm thick sections and analyzed for Mo. Results of the chemical analyses will be combined with historical records of dissolved oxygen to determine whether the Mo-DO relationship found in RI is also valid in coastal water bodies in MA and presumably elsewhere. In addition to examining the Mo-DO relationship in recent years, vertical profiles of Mo in the cores could develop a historical perspective on the frequency of hypoxia in Waquoit Bay.
For more information on this research, contact Warren Boothman (401-782-3161, firstname.lastname@example.org).