Protecting Our Beaches From an Unlikely Foe.

Mallin, M.A., M.I.H, Turner, M.R. McIver, B.R. Toothman, and H.C. Freeman. 2016. Significant Reduction of Fecal Bacteria and Suspended Solids Loading by Coastal Best Management Practices. Journal of Coastal Research 32: 923 – 931.

https://doi.org/10.2112/JCOASTRES-D-15-00195.1

To Swim or Not To Swim.

Summertime dips in the ocean are a fond memory for many.  The cool feel of the ocean water provides a refreshing antidote to many sun-baked beach-goers.  With worry slipping away in a relaxed state of mind, the last thing beach-goers are likely to consider is the quality of the water they are swimming in.  Water quality can be greatly impacted as more people visit and move to coastal areas, and beach-goers aren’t the only ones affected by polluted coastal waters.  Seafood lovers, shellfish fishermen, resource managers, and resorts can all be impacted by one particular type of pollution: fecal bacteria.

Shellfishing area closure sign due to harvested shellfish posing a health hazard upon consumption. Photo Credit: N.C. Division of Marine Fisheries.

Did You Say, Fecal Bacteria?

I know what you’re thinking.  Fecal bacteria?  As in the bacteria in our feces?  Won’t that make me sick?  How does that even end up in our coastal waterways and the ocean? To start, fecal bacteria refers to bacteria from the intestine of humans or other animals.  The bacteria itself don’t actually make us sick, but they can indicate the presence of viruses and diseases that will.  Fecal bacteria end up in our waterways when it rains and runoff washes over the land, collecting pet and wildlife waste into storm drains that empty into coastal waters.  This stormwater runoff becomes a big problem in areas that have growing populations with lots of roads, driveways, and sidewalks, as these surfaces can direct lots of pollution into the water.  This type of pollution is known as nonpoint source pollution because it lacks a clearly distinguishable source and can be very challenging to address.

Fecal bacteria colonies (in dark blue) grown in a laboratory from collected water samples to determine amount present in water. Photo Credit: Massachusetts Institute of Technology.

Impacting Human Health and Our Wallets.

Fecal bacteria pollution can cause problems in many different ways.  Beach-goers can get sick by swimming in and getting in contact with the water.  Shellfish filter the water for food, and can become contaminated by fecal pollution, posing a significant health risk to consumers.  Shellfishing areas can be closed due to excessive pollution, which results in economic losses to fishermen and restaurants.  Resorts, hotels, and recreational activities by the water can also suffer as tourists and locals avoid all water related activities.  With so much at stake, researchers have been working to find solutions that can be applied to developing coastal areas.

Teamwork Makes the Dream Work!

The Town of Wrightsville Beach in North Carolina was one place in need of a solution to its fecal bacteria woes.  Excessive fecal bacteria loads had been plaguing their local swimming and shellfishing waters, threatening the livelihood of many who live and work on the resort island.  A taskforce including researchers, engineers, and activists got together to study the area and devise a plan to reduce the amount of fecal bacteria making its way into the water.  Their strategy was to install a series of devices aimed to capture or divert polluted water from entering the surrounding waterways.  One device, known as an infiltration chamber, consisted of a long, punctured pipe that was buried underground.  It was designed to collect water when it rained, and slowly allow that water to seep into the ground instead of a waterway.  Other infrastructure included amended street curbs and stormwater drains to route water into grassy areas known as swales.  These designs were also intended to allow polluted water to slowly infiltrate into the ground, instead of washing it into a waterway.

Infiltration chamber (top) and punctured pipe of infiltration chamber (bottom). Photo Credit: Dr. Michael Mallin, UNCW.

 

Amended street curb (top) and storm drain directing stormwater runoff into grassy swale (bottom). Photo Credit: Dr. Michael Mallin, UNCW.

Did It Work?

The goal of the researchers was to see how effectively the infiltration chamber, amended street curbs, grassy swales, and other installations were at reducing the pollution load to waterways.  The key was to collect water samples after a rainfall.  Collecting samples after a storm allowed the researchers to see what the runoff from rain was collecting from streets and sidewalks.  The researchers collected water samples before the installation of the devices, and afterwards, to get a ‘before and after’ state of the pollution loads.  What they found was that the infiltration chamber helped to reduce an astonishing 96% of the fecal bacteria load that would have otherwise ended up in the waterway!  The amended street curbs, grassy swales, and other infrastructure had similar effective results in reducing fecal bacterial loads, helping to save the beach area from being contaminated with pollution.

Safe Beaches for You and Me!

It’s important to remember that coastal areas may all be slightly different, and that their needs and financial flexibility will determine what types of stormwater filtration infrastructure they invest in.  That being said, this study demonstrates successful ways other beach towns can address their fecal bacteria pollution problems.  This allows beach-goers to continue making wonderful summertime memories, and for those relying on coastal areas for their livelihood to put their worries at ease.

References.

Mallin, M.A., M.I.H, Turner, M.R. McIver, B.R. Toothman, and H.C. Freeman. 2016. Significant Reduction of Fecal Bacteria and Suspended Solids Loading by Coastal Best Management Practices. Journal of Coastal Research 32: 923 – 931.

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Nick Iraola

Nick has a Master of Science in Marine Science from UNC Wilmington. He has worked in the Aquatic Ecology Laboratory since 2015, and which monitors the water quality in the Lower Cape Fear River Basin. His master's thesis research pertained to eutrophication and nutrient cycling within a freshwater lake in Wilmington, NC. When he's not sciencing, Nick enjoys running, swimming, cooking, sailing, and catching up with friends and family. His favorite candy is Reese's pb cups, because what is there not to like!?

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