Written on: December 9th, 2020 in Living Shorelines
By Kenny Smith, Wetland Monitoring & Assessment Program
The Delaware Living Shorelines Committee members are often asked questions by landowners. Many of those questions relate to the suitability of their property for a living shorelines project. For example: is it possible to build a living shoreline on their property? Can a living shoreline protect their property from coastal erosion or create more beneficial habitat for wildlife?
The Delaware Living Shoreline Committee has a smaller sub-committee, the Design and Engineering Sub-Committee, that decided to tackle these questions. They created a document that informs professionals and landowners about the feasibility of a living shoreline for a property. This document is called Site Evaluation for Living Shoreline Projects in Delaware.
The Design and Engineering Sub-Committee consists of individuals from a wide variety of backgrounds, from government employees to private contractors, that are installing living shorelines in Delaware. This diverse group provided the necessary expertise to digest a lot of information into an easy-to-follow document. The guidance highlights important metrics to look at on a shoreline. The document is separated into a desktop analysis and a field visit portion. In total, there are 12 metrics to calculate during the desktop analysis and 5 additional metrics to collect during the field visit.
The desktop analysis portion of site evaluation document explains important environmental parameters that must be calculated to determine the feasibility of a site for a living shoreline. You can calculate these parameters using desktop tools and resources. The list of parameters starts with descriptions of the site, shoreline problem, project goals, dimensions, and body of water. While these descriptor metrics are very basic, they are the basis for all future plans for the site.
The next step is to collect metrics that will steer design plans and feed into calculating some of the more complex metrics. These metrics include shoreline orientation and shoreline change rate. They also include geomorphology of the site, such as upland, shore, and submerged areas. This information is important in classifying current conditions at the site and determining what kind of techniques would be suitable. You will then use the fetch (distance over which wind blows on the water surface to generate waves) and wind metrics to calculate wave climate. From there you can determine expected energy.
The tide metric will provide you with an idea of the range of water your site receives. It will also provide a working window once your project is designed. Delaware has the FEMA maps available online and they are another helpful resource to inform you about the suspected storm energy a site may receive.
Once you have completed the desktop metrics, it is time to visit your site. While it is always better to visit your site multiple times, it is possible to collect the information you need for this evaluation during one visit. While completing the field metrics, you should also be double-checking all of the data that you collected during the desktop analysis. This is an opportunity to fine-tune anything you may have missed or needs to be corrected. In addition, it is a good idea to take as many photographs as possible from various angles and zooms to capture the shoreline.
For site boundaries, you are looking for both physical and jurisdictional boundaries, while for land use/ land cover, you are looking at how the surrounding land is used and what kind of vegetation is present. There is also another metric to capture the geology of your site based on the field visit and fill in any holes from the geomorphology desktop metric. Once again, look in the upland, shore, and submerged areas for sediment types and any other pertinent information. Ecology of your site is split into biotic and abiotic features. Biotic features include plants and animals, whereas abiotic features include water quality, soil type, and sunlight.
It is very important to create site sketches, as they are the best way to quickly assess the spatial relationships among existing features, slopes, and land cover. You should draw a plan view and a profile view to best capture this information for later use during a design. You should also take note of any surrounding healthy shorelines, as they may be a helpful reference for your future site design.
The information you collect in the site evaluation document will help you determine current condition of shoreline. It will also help you figure out the most suitable living shoreline techniques, potential design constraints, and permitting conditions for your site. For instance, your shoreline could be suitable for a planting and coir log design. On the other hand, it could need more protection and need to rely on a sill designed with rock to slow the energy down.
While this document can provide very vital information, it is important that you still consult a professional to create a design based off the information collected in the document. Sites with exposure to extremely high wave energy tend to present challenges when designing a living shoreline. Sites with steep shorelines or very shaded shorelines tend to present challenges as well.
The Design and Engineering Sub-Committee usually hosts a one-day training for roughly 15 participants during the spring months going over the site evaluation guidance and then visiting 4-5 sites to use the information you gained on evaluating sites for living shorelines. Stay tuned for information on this training.
You can find the site evaluation document here. You can also find many other resources on the Delaware Living Shorelines Committee website.
By Erin Dorset, Wetland Monitoring & Assessment Program
The Mid-Atlantic is a sea-level rise hotspot, meaning that rates of sea level rise in the region are relatively high. As such, scientists, outdoor enthusiasts, and coastal communities alike are all worried about the fate of tidal wetlands. Here at Delaware’s WMAP, we’re seeing what we can do to lend tidal wetlands a helping hand.
Back in 2013, we worked closely with DNREC’s Shoreline and Waterway Management Section (SWMS) to apply a thin layer of dredge material to a struggling marsh at Piney Point along Pepper Creek. We have since monitored the site every year until 2019. Elevation sufficiently increased from the sediment application such that we saw plant life rebound and thrive in the years after. Seeing how successful the Piney Point project was, we were eager to try another similar project in Delaware.
In 2019, we identified a candidate project site along the Indian River in Millsboro. We saw in aerial imagery that what used to be coastal forest and tidal wetland has since eroded and retreated. Now, there is an intertidal mudflat that is completely devoid of plant life. The remaining marsh is likely to continue retreating if we don’t help the marsh recover.
By rebuilding this former tidal wetland, we will be recreating important wildlife habitat and better protecting nearby public infrastructure from storms and rising seas. We will also be testing a new method of tidal wetland restoration in Delaware involving thick sediment application. Previously at Piney Point, we applied a much thinner sediment layer to an existing marsh. For this project, we will apply a thicker layer to recreate a marsh that has been lost. We will be learning important new lessons about tidal wetland restoration by using this different method.
To ensure the success of this beneficial use project, we have been working closely with DNREC’s SWMS every step of the way, just as with Piney Point. The SWMS dredges the Indian River annually to maintain the navigation channel. Usually, they place dredged sediment near the project area in what is called a confined disposal facility (CDF) in a nearby upland. The SWMS will divert dredged sediments to the mudflat for this project instead of to the CDF. We will use that sediment to rebuild the former marsh.
We collected important baseline field data before applying any sediment in order to create an accurate design plan. Baseline data included current site elevation, water levels, and elevations where different plants in the area are growing.
We used the water level data to accurately predict tides at the site, which is necessary for performing fieldwork. We were also able to determine mean high water (MHW) and mean low water (MLW) at our site, both of which are important to know for permitting and for planting.
Additionally, we were able to use plant elevation readings to figure out our target elevation to rebuild the marsh. Our goal is to encourage the growth of the low marsh plant, saltmarsh cordgrass (Spartina alterniflora), and discourage the growth of the invasive European reed (Phragmites australis). Therefore, we chose a target elevation that is optimal for saltmarsh cordgrass, but not for European reed. We then calculated approximately how much sediment we will need to achieve that target elevation by using the mudflat elevation data.
We plan to apply dredged sediments to the project site over 2 winters (winter 2020/2021, and winter 2021/2022) to account for the high sediment need. Once sediment application is complete, we will plant the site with native seeds to help it recover.
Recovery will likely take several years, after which we hope to have achieved the following goals:
As with any wetland restoration project, it’s important to monitor the area over time. Monitoring allows scientists to determine if project goals are being met. For our monitoring plan, we paired our project site with a ‘reference marsh’. The reference marsh is a nearby salt marsh that is in relatively good condition that will not receive sediment. The reference site will help us see if conditions at the project site eventually approach natural salt marsh conditions.
We have recently collected a variety of data at both the project and reference sites before any sediment has been applied. The fieldwork we performed at both sites to collect these data include marsh bird surveys and nekton (free-swimming organisms) surveys. We also performed vegetation surveys, bearing capacity (marsh stability) surveys, and benthic infauna surveys. In addition, we installed several sediment plates to test them as methods of measuring accretion and erosion at our project site. Finally, we established several permanent photo points at the project site that will help us visually document changes over time.
We will collect data in the same fashion after sediment is applied to the project site for several years. By comparing the project site and the reference marsh both before and after sediment application, we will better be able to attribute any changes we see to our wetland restoration methods instead of to natural variability.
Stay tuned for more updates!
This project is being conducted in partnership with DNREC’s Shoreline and Waterway Management Section. For more information or questions about this project, please contact Alison Rogerson at firstname.lastname@example.org or 302-739-9939.
Written on: December 9th, 2020 in Wetland Assessments
Guest Student Writer: Sandra Demberger, M.S., recent graduate,
Boaters, kayakers, and bird watchers are drawn to salt marshes for their quiet beauty. Wildlife, ranging from great blue herons to tiny fiddler crabs, and marsh grasses rustling in the soothing breeze, all draw recreators to these coastal systems. But did you know, these seemingly tranquil systems are hard at work providing valuable ecosystem services?
An ecosystem service is a natural process that contributes directly or indirectly to the well-being of the human population¹. Salt marshes provide many ecosystem services. Some of these services include coastal protection from storm events, water filtration, and nursery habitat for economically important fish species. Additionally, scientists increasingly recognize salt marshes for their role in removing carbon from the atmosphere and storing it long-term in their soils. That process is called carbon sequestration.
All these valuable services are provided by the marsh free of charge!
Carbon dioxide is a major contributor to global climate change because it functions as a greenhouse gas. Greenhouse gases trap heat in our atmosphere, much like a garden greenhouse does. Consequently, these gases warm up our planet at an unnatural pace. This process results in what is commonly referred to as global warming, and, in turn, global climate change (a shift in climate as a result of warmer temperatures). Unfortunately, all of us are releasing carbon dioxide into the atmosphere by doing daily activities like driving our cars and heating/cooling our homes.
While we humans are putting carbon dioxide into the atmosphere, salt marshes are working hard to remove it!
Carbon sequestration is a valuable ecosystem service, naturally removing carbon from the atmosphere and locking it away in plant material for generations. While many ecosystems can sequester carbon, salt marshes have proven to be the experts. Salt marshes can sequester carbon at rates 10 times higher than other terrestrial wetland systems². Less carbon in the atmosphere means less greenhouse gases, and, ultimately, reduced global warming.
Carbon sequestration is a cycle with three key components: plant material, suspended sediments (think mud and sand particles floating in the water), and very slow natural sea level rise. Here is the basic carbon sequestration cycle:
1. Salt marsh plants need sunlight, water, and carbon dioxide to grow. This process is called photosynthesis. The carbon absorbed during photosynthesis is stored in the plant matter.
2. Over time, marsh plants will die and their plant matter, still full of carbon, will build up on the marsh surface. While some of this plant material will be decomposed by microbes in the marsh, a portion will remain.
3. Twice a day the tidal waters will bring suspended sediments onto the marsh surface during high tide. The still living plants will slow tidal waters, allowing suspended sediments to settle out of the water column onto the marsh surface.
4. These suspended sediments will bury the plant material (from step 2) as well as the carbon stored within it, and elevate the marsh surface.
5. Slow, natural sea level rise allows the marsh to gain elevation at a pace that can keep up. This cycle has continued over millennia to form deep carbon deposits.
Over thousands of years, this cycle has formed carbon-rich deposits reaching six meters in depth³. The rates of salt marsh carbon sequestration may vary by region due to factors like the length of the plant growing season and the amount of suspended sediments deposited on the marsh surface. Regardless of the pace of carbon sequestration, salt marshes are worth protecting for this important ecosystem service.
It is often challenging to convince non-salt marsh lovers of the importance of these systems. To many, salt marshes are buggy and muddy areas with no real use. Defining ecosystem services–in particular, their monetary value–helps people understand their importance.
Therefore, some economists have dedicated their careers to estimating the monetary value of ecosystem services. They have developed the social cost of carbon as a way to measure the monetary value of carbon sequestration in salt marshes. The social cost of carbon is the sum of all the costs of one additional ton of carbon dioxide being emitted into the atmosphere. Some of these costs may include more severe storms and wildfires, which destroy communities and reduced agricultural yields straining our food supply. The exact value may vary due to different assumptions and uncertainties about the impacts of climate change in the future (click here for more information).
My Master’s research was related to this idea of valuing ecosystem services of salt marshes. Specifically, I focused on carbon sequestration in the Delaware Estuary. I found that the Delaware Estuary sequesters over 306,000 Mg Carbon dioxide annually. In other words, the Delaware Estuary removes the equivalent of carbon dioxide emitted from 66,109 passenger cars in one year. But this is still hard to comprehend. So, let’s apply the social cost of carbon!
The Delaware Estuary prevents about $18.32 million in damages every year by sequestering carbon from the atmosphere (using a $ 59.83 social cost of carbon value). If salt marshes stopped sequestering carbon tomorrow, society could expect to endure over $18 million in damages per year. This is pretty impactful!
This basic monetary valuation, in this case just for a single ecosystem service, helps provide context to an otherwise complex natural process.
Accelerated sea level rise is a serious threat the salt marshes. Marshes unable to gain elevation at a pace that keeps up will drown and erode away. That, in turn, would cause large carbon deposits to be released back into the environment, contributing, once again, to global climate change.
Living shorelines, beneficial reuse of dredge material, and other restoration projects are essential to protecting marshes, and the large amounts of carbon stored within them, from accelerated sea level rise. Valuing carbon sequestration and other ecosystem services may help land managers and practitioners gain funding and support for these types of conservation efforts. Additionally, understanding the value of carbon sequestration, and the many other ecosystem services, may help conservationists discourage the development of retail and housing on these valuable landscapes.
1. U.S. Environmental Protection Agency. 2009. Valuing the protection of ecological systems and services. A report of the EPA Science Advisory Board. EPA, Washington, D.C., USA.
2. Bridgham, Scott D., Patrick J. Megonigal, Jason Keller, Norman Bliss, and Carl Trettin. 2006. The carbon balance of North American wetlands. Wetlands. 26:889–916. https://link.springer.com/article/10.1672/0277-5212(2006)26[889:TCBONA]2.0.CO;2
3. Chmura, Gail L. 2013. What do we need to assess the sustainability of the tidal salt marsh carbon sink? Ocean and Coastal Management83: 25–31. doi.org/10.1016/j.ocecoaman.2011.09.006
Written on: December 9th, 2020 in Outreach
Guest Writer: Kate Fleming, Delaware Sea Grant
When crab pots* are lost or abandoned at sea, they remain in the water, free to continue to capture blue crabs as they are designed to do. They can also capture other animals like diamondback terrapin and summer flounder. Since derelict crab pots are not tended by anyone, the animals that become trapped inside will eventually die. As such, these forgotten pots can lead to continued and needless mortality in our ecosystem in a process called ghost fishing.
Gear loss and abandonment is fairly common in pot-based fisheries. That’s because pots are designed to be placed in the water and left alone for days at a time before being checked on. This comes with some inherent risk for accidental loss and sometimes obstacles can come up that hinder a timely return.
Here in Delaware, blue crabbing is an important commercial industry. It is also a popular recreational past-time that leads to the capture of over 1 million blue crabs each year. Could it be that we have ghost crab pots scattered across the bottom of Delaware’s Inland Bays, where only recreational crabbing takes place? Based on the work I have been doing with University of Delaware Professor, Dr. Art Trembanis, I can say with confidence that the answer is yes, yes we do.
This shouldn’t be particularly surprising given the ubiquitous nature of this type of marine debris. However, the shallow murky waters of our Inland Bays offer an effective hiding place. Last winter** we used a commercial-grade side scan sonar to document over 560 derelict crab pots submerged beneath the surface of just under 250 acres of Rehoboth Bay. This represents some of the highest densities of derelict crab pots that have been estimated in Chesapeake Bay, which supports one of the largest blue crabbing fisheries in the nation. We followed our surveys up with a pilot removal effort. We recovered about 100 derelict crab pots in just a couple days. (Read more about our pilot removal project here!).
Today our project team has grown to include University of Delaware graduate student Jen Repp. It also includes Delaware Sea Grant’s Fisheries and Aquaculture Specialist, Dr. Ed Hale. Our sights are now set on Indian River Bay. Jen and Art are initiating side-scan sonar surveys any day now. Plus, I am in the thick of planning Derelict Crab Pot Round-Ups across three days this January and/or February 2021. The whims of the weather will determine the specific dates!
Compared to last year’s pilot project, we plan to quadruple our survey area. We will be removing 10 times the number of derelict crab pots over the next two years, aided by volunteers with boats that are willing to wield a grappling hook and help us on the water. We’ll be staging out of Holts Landing State Park and keeping our fingers crossed for flat calm seas and the balmiest of winter temperatures!
Interested in helping out? We are targeting volunteers that can bring and crew their own boats. Click here for more information and to register a team, or contact me at email@example.com with any questions!
If you don’t have a boat but would still like to contribute, there are a couple other volunteer opportunities that will likely come up with this project:
– We will be giving a subset of our recovered pots to the Partnership for Delaware Estuary (PDE) to be repurposed in a living shoreline experiment. Following the removal, the Center for Inland Bays (CIB) will be coordinating volunteers to transport these pots to Wilmington, DE where PDE is located. Interested volunteers can contact CIB Volunteer Coordinator, Nivette Perez-Perez at firstname.lastname@example.org.
– I will likely be looking for volunteer assistance to refurbish any remaining crab pots this spring or summer so that they can be reused for education and outreach. If that sounds like fun (I think it does), please reach out (email@example.com) and I’ll get you on my list.
One of the most common questions I get when I talk about derelict crab pots in Delaware’s recreational blue crab fishery is: Why? Why would a recreational crabber abandon their pots? Our work doesn’t actually focus on answering that question. But, I often like to point out that DNREC-Enforcement has an existing program to curb crab pot abandonment in our state. The program issues notices and then seizes pots that have not been tended within three days as is required in Delaware. They actually let me collect data through this program. It has been an outstanding opportunity to learn about recreational crab pot abandonment rates. I’ve also learned a lot about Turtle Bycatch Reduction Device (TBRD) compliance (a little more on TBRD’s below).
With that program in place, I prefer to ponder the issue of accidental pot loss. I suspect it is an important contributor to the presence of derelict crab pots in our Inland Bays. If gear is rigged with old, degrading line it can be more susceptible to breakage by rough weather or boat propellers. Likewise, buoys assembled from hollow materials are more likely to fill up with water and sink if punctured. We have recovered quite a few derelict crab pots that had bleach bottle and bumper “floats” still attached that were no longer doing their jobs.
These are accidents of course. But, I do think there are things that recreational crabbers and boaters can do to minimize the potential to lose a pot. These are things like:
-Use those white foam bullet floats in lieu of bleach bottles or bumpers
-Change out your lines each year
-Use line that sinks
-Keep your eye on the weather forecast before you set your pots
-Update your tending plan if it looks like a storm is coming or you have to go out of town
Likewise, boaters should:
-Stay vigilant for buoys on the water
-Wear polarized sunglasses to make spotting them a little easier
-Slow down and give buoys plenty of berth to avoid a line strike. The pot lines can be hard to see and are often times longer than you think.
Then there are things you can do to minimize impacts in the event that a pot does go missing. The first is to simply remember that the limit for recreational crabbers in Delaware is two pots per person. We know that some amount of pot loss is unavoidable. Therefore, keeping the number of pots fished to the required limits can reduce the overall quantity that end up on the Missing in Action list.
In Delaware, crabbers are required to install Turtle Bycatch Reduction Devices on all funnel entrances of a recreational crab pot. They help keep diamondback terrapins from getting inside the pots, where they will eventually drown. For more information on TBRD’s, or Terrapin Excluder Devices as they are often called, check out DNREC’s TBRD Pamphlet.
Cull rings are not actually required in Delaware. However, they have been shown to allow sublegal crabs (crabs you wouldn’t be able to keep anyway) and other small organisms to escape. They are required in some of our neighboring states, so should be fairly easy to find if you want to go the extra mile. A juvenile blue crab will thank you.
I want to wrap up by offering some acknowledgement and thanks to those that have helped us with our past and current projects. It truly takes a village.
Delaware Sea Grant provided the seed funding to get our initial side-scan sonar surveys going to confirm the prevalence of derelict crab pots in Rehoboth Bay. We received additional funding from the University of Delaware School of Marine Science and Policy. Subsequently, we have received funding from Delaware Coastal Programs and the NOAA Marine Debris Program.
Delaware Coastal Programs and several sections within the Delaware Division of Fish and Wildlife (Enforcement, Fisheries, and Wildlife) have provided support to this project. They have provided a boat and labor on clean-up days, permitting support, technical assistance, and more. Rehoboth Bay Marina allowed us to stage our removal at their private boat ramp. This was invaluable to being able to work in Bay Cove, behind Dewey Beach last year.
Dave Beebe with Rehoboth Bay Oyster Company and Rich King from Delaware Surf-fishing.com joined us on the water and were a big help (that is how I discovered the magic of a trash pump!). We couldn’t have done this work without the many University of Delaware staff and students that joined us from Art’s CSHEL Lab, Delaware Sea Grant, and others that simply volunteered to help. Vince Capone with Black Laster Learning has provided a lot of help to Art’s lab in the processing of side-scan sonar data.
We are looking forward to this year’s efforts. We’ve already had so much support from partners that have helped out in recruiting or have expressed a willingness to join us with field operations. In addition to partners already mentioned, thank you to the Center for Inland Bays, the U.S. Environmental Protection Agency, Delaware Mobile Surf Fisherman Club, Ducks Unlimited, Partnership for Delaware Estuary, Delaware Cooperative Extension, The Nature Conservancy. Also, thank you to all the volunteers that have reached out to express interest in helping out this winter. We’re grateful for your support and looking forward to a successful Derelict Crab Pot Round-Up!
*Commercial or Chesapeake-style crab pots are often referred to as crab traps, though crab pots is also technically appropriate. I prefer to use the term crab pots to differentiate them from recreational crab traps that have collapsible sides and are incapable of ghost fishing.
**Why do we work in the winter? Our work has to take place between December 1 and the end of February each year to coincide with the closed blue crab season. This ensures that the pots we find and remove are in fact derelict!