Coastal communities around the world are adding a tropical twist to shoreline protection, thanks to the humble coconut.
From the sands of the Jersey Shore to the islands of Indonesia, strands of coconut husk, known as coir, are being incorporated into shoreline protection projects.
Often used in conjunction with other measures, coconut material is seen as a cost-effective, readily available and sustainable option. This is especially true in developing countries. But the material is also popular in wealthy nations, where it is considered an important part of so-called “living coasts” that use natural elements instead of hard barriers made of wood, steel or concrete.
One such project is being installed along a section of eroded riverbank in Neptune, New Jersey, about a mile from the ocean on the Shark River. Using a mix of federal grant and local funds, the American Littoral Society, a coastal protection group, is carrying out the $1.3 million project that has already added significantly to what was previously severely eroded shoreline in an area hit by the Superstorm Sandy in 2012.
“We’re always looking to reduce wave energy by shielding the coastline and whenever we can, we like to use nature-based solutions,” said Tim Dillingham, the group’s executive director. “This material is readily available, particularly in developing countries, and is relatively inexpensive compared to harder materials.”
Coir is made from the stringy fibers of the coconut shell and spun into mats or logs, often held together with netting. In developing areas, discarded or torn fishing nets can be incorporated.
Its flexibility allows it to be cast and contoured as needed in uneven areas of shoreline, held in place by wooden stakes.
The coconut-based material biodegrades over time, by design. But before doing so, it is sometimes pre-seeded with shoreline plants and grasses, or these plants are placed in holes that can be drilled into coconut trunks.
The logs hold the plants in place as they root and grow, eventually breaking down and leaving the established plants and sediments around them in place to stabilize the shoreline.
Coconut-based materials are used worldwide for corrosion control projects.
One of them is in Boston, where Julia Hopkins, an assistant professor at Northeastern University, uses coconut fiber, wood chips and other material to create floating mats to soften the force of waves and encourage the growth of aquatic vegetation. A pilot project has four such mats in waterways around Boston. Hopkins envisions a network of hundreds or even thousands of mats linked together to protect larger areas.
She is happy with what she has seen so far.
“Coir is an organic material, it’s relatively cheap and it’s a waste,” he said. “It’s actually recycling something that was going to be thrown away.”
Two projects in East Providence, Rhode Island, used coconut logs in 2020, and 2,400 feet (731 meters) of shoreline in New York’s Jamaica Bay that eroded during Superstorm Sandy was stabilized in 2021 by a project that also included coconut logs.
Cape Cod, Massachusetts, did a similar project last year, and the Delaware Department of Natural Resources and Environmental Control is offering funding to help landowners, homeowner associations and others install living shorelines made of materials that may include coir.
A project in Austin, Texas, stabilized part of the shoreline of Lake Austin. Monitoring from 2009 to 2014 showed reduced erosion and healthy growth of native plants at the water’s edge.
Indonesia is the world’s largest coconut producer, with more than 17 million metric tons in 2021. Scientists from the Oceanography Program of the Bandung Institute of Technology used coconut husk material to help build a sea wall in the village of Karangjaladri, Pangandaran Regency in 2018.
Residents of Diogue Island in Senegal use wooden structures and coconut leaves and sticks to reclaim eroded parts of the beach.
It doesn’t always work, however.
In 2016, the Felix Neck Wildlife Refuge in Edgartown, Massachusetts, on Martha’s Vineyard introduced it to Lake Sengekontacket, where a salt marsh had eroded several feet in previous years. Although it helped reduce erosion for a while, the crusts didn’t last long because of the intense wave action.
“It was blown up several times,” said Suzan Bellincampi, the sanctuary’s director. “We had it in place for a few years and decided not to install it again.
“The project was really interesting in terms of what we wanted to do and how we adapted it,” he said. “It’s not for every site. must be location specific. It works in some places. it doesn’t work in all places.”
Similarly, coconut fiber mats and logs were recently used on Chapel Island in Nova Scotia, Canada, but were damaged by the bad weather.
Another Canadian site, Lac des Battures, a lake on Montreal’s Calogray Island, uses coconut mats to control the growth of invasive reeds along the shoreline.
At the New Jersey site, a few miles south of the musical hotbed of Asbury Park, trucked-in sand has joined with sediment built up by the tides to create a beach that’s noticeably wider than it used to be.
“There are hibernating fiddler crabs under your feet right now,” said Capt. Al Modjeski, Littoral Society restoration specialist. “They’re going to be excited about this new habitat.”
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