Stories from the Bay |
Written by Larry Niles, Niles-Smith Conservation Services For more great info on the Delaware Bay check out Larry's blog about ecology and wildlife conservation, A Rube with a View. A Failure to LearnOur work on Thompson's marsh covers only a tiny patch of the Delaware Bay marsh. One might say our one-acre restoration is too small to have any significant impact, so why do it? Big projects are certainly more important. And ultimately we will need many of them to realize Governor Murphy's recently announced coastal resiliency policy initiative. But big projects can fail big and waste taxpayer dollars. The Delaware Bay has seen a number of these failed expensive projects, like the shoreline restoration of Sea Breeze where $6 million in state-funded cinder blocks lie uselessly on the shore of this now abandoned town. Indeed unfinished protection in the mouth of the Maurice River, where a sunken barge is all that remains of a failed effort to stop the erosion of Basket Flats and the other adjacent wetlands that protect the towns of Port Norris and Heislerville. Working With NatureThese resiliency failures occurred for many reasons, but an important one was failing to take advantage of natural defenses to augment protection. Why defeat the Bay with concrete and steel when you can achieve the same goal with high functioning marsh and well-protected beaches? Easier said than done of course which points to the second reason for recurring failure - no one monitored the projects in order to describe the conditions before during and after the project. Someone engineered the project, someone else got a contract to construct it and then everyone walked away. No one the wiser. Or they did monitor the project but never used the data in a way that described the success or failure of the work and its ultimate ecological impact. Perhaps this is the most the failure because the experience provided no clues on how to carry out the next project. Each new project becomes a gamble or worse useless in the face of an ever-growing threat. Instead, the failed projects speak for themselves, apocalyptic-like reminders of our inability to protect the wildlife and people of Delaware Bay. Start Small and LearnSo our project provides more than a one-acre fix for abandoned salt hay farms. It also helps us understand the most cost-effective way of conducting larger more expensive projects and create innovations that can improve ecological condition. Better to start small and learn. First the problem. Over 10,000 acres of Delaware Bay marsh remains damaged after a wholesale abandonment of at least a century and a half of restricting tidal flow with earthen dikes. The dikes blocked sediment-rich tidal waters to allow salt hay or spartina patens to grow and cut for hay. Each cutting removed vital biomass. Without new sediment or biomass, marsh elevations fell about 2 feet but in some areas as much as 5 feet. Without the dikes, the sea scoured the newly exposed and sparsely vegetated wetlands leaving bare mud as shown in the photos of my previous blog. Thompson Marsh could have turned into a big mud flat like Cox Meadow endangering the people in the town of Heislerville NJ. Instead, the state allowed PSEG to avoid the cost of a new cooling tower by managing wetlands. They hoped the addition of productive marsh would offset the loss of fish killed by increased use of cooling seawater. One can see the work in the following series of photos. The PSEG engineers dredged a new watershed of small creeks allowing a slower draining and flooding of the marsh. It worked. The wetland began recovering slowly over time. New inflow of sediment and the sparse growth of Spartina alterniflora or marsh cord grass built new biomass. The papers of the restoration team spoke of recovery. Unfortunately, sea level rise dashed those hopes. It matched the elevation gained by a renewed marsh. The higher volume of water and more frequent storms scoured mud and sand in the mouth of the creeks. It also eroded creek banks thus increased tidal flow. There is spartina growing over much of the restored area but at a much lower density and slower growing than cordgrass at the proper elevation. A New Start on Thompsons MarshFor Thompsons and many of the once farmed tidal wetlands on Delaware Bay, the only hope is to start rebuilding elevation with new mud. Our wetlands restoration is an experiment with two goals. First how best to manage an old hay farm back to a stable, productive marsh? The second how to do at a practical cost? For example our dikes. In the old days and the PSEG work, workers made new dikes by digging into the marsh. This damaged marsh and created new ditches for water to scour away sediment. We use Coir logs, or 10 feet long 24-inch diameter jute bags of coconut fiber, to form our dikes. They are cheaper than digging and will gradually degrade into the marsh. Most important we avoid damaging the fragile wetland. Managers have used Coir logs elsewhere to confine mud but not in Delaware Bay with its 7-foot tide swing. If successful we will have a low cost and an environmentally friendly solution that can be scaled up to larger areas, one of our top goals.
Restoration Is ExperimentalIn a way all restoration is experimental. Even when done successfully conditions matter enough to make every job different. Restoring a wetland on the gulf coast where tides rise no higher than 2 feet, is far different than Delaware Bay, where the tide can swing 8 feet in a daily cycle. In Florida, winters can serve up a nippy 50's while on Delaware Bay the weather can turn genuinely foul. The bay freezes in most years and thick ice moved by daily tidal cycle can scour and destroy. So previous experience provides some guidance for the wetland biologist, but one must always pursue their restoration as something unique requiring great care and sound monitoring.
This is why we must conduct this experiment in marsh restoration.
0 Comments
Written by Larry Niles, Niles-Smith Conservation Services For more great info on the Delaware Bay check out Larry's blog about ecology and wildlife conservation, A Rube with a View. Centuries of Farming the Marsh has Left an enduring LegacyCenturies of cutting salt marsh vegetation as hay in Delaware Bay left an enduring legacy fraught with danger. Farmer diked the tidal wetlands starving the marsh of sediment and accelerating natural decomposition. Marsh levels fell relative to the tide, so when the farming ended in the 60's the bay rapidly eroded the damaged and fragile marsh. Large areas of the Bayshore were lost and the erosion continues to the day, but now exacerbated by a 4mm yearly rise in sea levels caused by climate change. This week a partnership of experts led by American Littoral Society and Niles Smith Conservation will begin the first restoration of a Delaware Bay marsh damaged by salt hay farming. The goal of the project is to restore 1.8 feet of mud lost by farming with new sediment dredged from an adjacent creek choked with mud from the eroded wetlands it drains. We will create our own dike made of vegetative logs or Coir Logs, and begin to reverse the process started 200 years ago. We intend to bring the marsh height back to it's naturally stable level - marsh vegetation just barely flooded on a normal tide. The productivity of the wetland will improve and more importantly it will be stable providing long-term resiliency. A New Kind of Marsh StewardshipOur second goal is to conduct a restoration experiment. Over the next months, we will slowly raise with the height of this marsh at first to assess our method. Will the Coir Logs provide enough of a barrier to contain the mud? How much drainage is necessary to ensure a gradual dewatering of the slurry of mud and water pumped into the contained area. Finally, how will it resist the winter and then how will it regrow? These questions cannot be answered with just books or judgment. We are farmers assessing conditions for a good crop of spartina alterniflora. This American Littoral Society Project will create structurally sound but ecologically beneficial solution to a complex problem plaguing the bay. Our project offers hope for a long-lasting solution by making new tools to accomplish it. If anyone would like to help with this project, please contact Shane Godshall. |
Archives
April 2021
|