May 11, 2020

Monitoring Marsh Elevation in Barnegat Bay

by S-FX.com

emily ssim

Every year, usually starting in April, the Barnegat Bay Partnership wetlands research team begins collecting data for our Site Specific Intensive Monitoring (SSIM) program. SSIM is part of the Mid-Atlantic Coastal Wetlands Assessment (MACWA) program, which was developed in collaboration with the Partnership for the Delaware Estuary and other federal, state and academic partners to study the condition of our coastal wetlands.

During our SSIM field work, we collect data on elevation, vegetation, water quality, and soils at four salt marsh sites throughout the Barnegat Bay. In order to determine marsh elevation, we use a couple of different techniques to get a good picture of how things are changing in the marsh. In addition to conducting elevation surveys with very precise GPS units, we also install a series of Surface Elevation Tables (SETs). SETs are long rods driven down far into the marsh platform. The rod is cemented in place so it doesn’t move, and connects to a receiver that allow us to measure relative elevation in the exact same location year after year.

In close proximity to these SETs, we install marker horizon plots. These plots are small squares where we put down white feldspar clay, which does not degrade and tends to stay in place. As time goes on, and sediment builds up, we are able to cut out a small section of marsh, which we call a ‘’marsh brownie,” and measure the amount of sediment accretion (build-up) in that location. 

Emilys Blog Marsh Brownie.docx 2
“Marsh brownie”

By coupling SET and marker horizon data, we are able to determine if there are shallow below-ground processes that are causing the marsh to sink. For example, if we see accretion rates of 5mm per year but are only seeing an elevation change of 3mm per year, then we know there is 2mm per year of shallow subsidence (downward settling of land).

Knowing changes in marsh elevation is critical when planning wetland restoration and protection projects. Geological changes along the mid-Atlantic coast are causing land to sink at the same time that sea levels are rising. There are two reasons for this land subsidence. The weight of ice from glaciers during the last ice age caused the east coast to rise up a bit. Once the glaciers melted, the land along the coast began to gradually sink back down. A second factor is the pumping of groundwater in coastal communities, resulting in sediments settling and land subsiding.

Last week was scheduled to be the opening of the field sampling season for our wetlands research team. However, due to COVID-19 precautions, we have had to adjust our field schedule and procedures to ensure that our team remains safe during these challenging times. With these adjustments, we will still be able to continue our important ongoing studies of Barnegat Bay coastal wetlands this year.

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UNKNOWN

There is limited data available to quantify Wetland and Riparian Buffer Preservation, or updated data to quantify Wetland Acreage. The BBP has obtained funding and will begin assessment efforts for both targets, in the next few years.

 

 Hard Clam abundance has not been updated since 2012. Recovery of the stock will be guided by the Fishery Management Plan for Hard Clams, which is under development with the NJDEP, BBP, and other organizations. Reclam the Bay and other partners have continued to plant clams for restoration purposes. Continued plantings in strategic locations which maximize survival and reproduction is one strategy to pursue in the coming years. This work can use a model developed by Rutgers with BBP funding which identified areas where planted clams could have the greatest dispersal of their larvae and thus potentially maximally contribute to the recovery of the stock.

 Water Withdrawals were over the target in the 2021 report; USGS has not yet completed its latest update, so a definitive determination of status is not available. However, additional NJDEP data show that it is likely that we continue to not meet the target. Per capita water use has gone down, demonstrating the effectiveness of water-saving appliances and practices, but that decrease has been offset by population gains. 


IN PROGRESS

New maps quantifying Submerged Aquatic Vegetation extent were developed, but poor image clarity resulted in a high degree of uncertainty in the total acreage. NJDEP and Rutgers are working to resolve the uncertainty of these maps, and improve the total acreage estimate. Funding has also been obtained for further research and restoration activities. Several groups are developing potential restoration actions.

The USGS has completed the first phase of its study to identify minimum ecological flows in select Barnegat Bay tributaries. USGS scientists compared streamflow statistics between historical and current time periods to better understand trends in watershed flow conditions. This work provides a foundation for developing ecological flow targets in the Barnegat Bay watershed.  Similar to SAV extent, funding (approximately $450K) has been obtained by the BBP to complete the remaining phases necessary for threshold determination.

 

TARGETS ACHIEVED

No targets can be considered “Achieved” at this time.

 

NOT ACHIEVING

Several Public Swimming Beaches exceeded their safe swimming standards more frequently than during their baseline time period (2016-2018).

While most beaches are routinely safe for swimming, several problematic areas such as Beachwood, Hancock, Windward, and several lake beaches need track-down studies and restoration to pinpoint and address sources of bacteria.

Acres of Approved Shellfish Waters decreased from the last report. While this decrease was small, it represents a loss of previously approved waters. Similar to public beaches, track-down studies and restoration work are needed to pinpoint and address sources of bacteria.

 

Monitoring Marsh Elevation in Barnegat Bay

Every year, usually starting in April, the Barnegat Bay Partnership wetlands research team begins collecting data for our Site Specific Intensive Monitoring (SSIM) program. SSIM is part of the Mid-Atlantic Coastal Wetlands Assessment (MACWA) program, which was developed in collaboration with the Partnership for the Delaware Estuary and other federal, state and academic partners to study the condition of our coastal wetlands.

During our SSIM field work, we collect data on elevation, vegetation, water quality, and soils at four salt marsh sites throughout the Barnegat Bay. In order to determine marsh elevation, we use a couple of different techniques to get a good picture of how things are changing in the marsh. In addition to conducting elevation surveys with very precise GPS units, we also install a series of Surface Elevation Tables (SETs). SETs are long rods driven down far into the marsh platform. The rod is cemented in place so it doesn’t move, and connects to a receiver that allow us to measure relative elevation in the exact same location year after year.

In close proximity to these SETs, we install marker horizon plots. These plots are small squares where we put down white feldspar clay, which does not degrade and tends to stay in place. As time goes on, and sediment builds up, we are able to cut out a small section of marsh, which we call a ‘’marsh brownie,” and measure the amount of sediment accretion (build-up) in that location. 

Emilys Blog Marsh Brownie.docx 2
“Marsh brownie”

By coupling SET and marker horizon data, we are able to determine if there are shallow below-ground processes that are causing the marsh to sink. For example, if we see accretion rates of 5mm per year but are only seeing an elevation change of 3mm per year, then we know there is 2mm per year of shallow subsidence (downward settling of land).

Knowing changes in marsh elevation is critical when planning wetland restoration and protection projects. Geological changes along the mid-Atlantic coast are causing land to sink at the same time that sea levels are rising. There are two reasons for this land subsidence. The weight of ice from glaciers during the last ice age caused the east coast to rise up a bit. Once the glaciers melted, the land along the coast began to gradually sink back down. A second factor is the pumping of groundwater in coastal communities, resulting in sediments settling and land subsiding.

Last week was scheduled to be the opening of the field sampling season for our wetlands research team. However, due to COVID-19 precautions, we have had to adjust our field schedule and procedures to ensure that our team remains safe during these challenging times. With these adjustments, we will still be able to continue our important ongoing studies of Barnegat Bay coastal wetlands this year.

Contact Monitoring Marsh Elevation in Barnegat BayContact Monitoring Marsh Elevation in Barnegat Bay
emily ssim