During summer months, Chesapeake Bay waters become home to a range of bacteria. One of the most talked-about bacteria is Vibrio, which occurs naturally in warm estuarine waters and can infect those who eat contaminated shellfish or swim with open wounds in contaminated waters. But illness can be avoided. Learn about the bacteria—and how to avoid infection—with this list of five Vibrio facts.
Image courtesy CDC/Wikimedia Commons
1. Vibrio is a naturally occurring bacteria. There are more than 80 species of Vibrio, which occur naturally in brackish and saltwater. Not all species can infect humans, but two strains that can have raised concern in the Bay watershed: Vibrio vulnificus and Vibrio parahaemolyticus. The bacteria are carried on the shells and in the bodies of microscopic animals called copepods.
2. The presence of Vibrio in surface waters is affected by water temperature, salinity and chlorophyll. Because Vibrio prefers warm waters, it is not found in the Bay during winter months. Instead, it is common in the summer and early fall. When water temperatures are warm, algae blooms form, fed by nutrients in the water. These blooms feed the copepods that carry the Vibrio bacteria. When the copepods die, Vibrio bacteria are shed into the water. As climate change increases the temperature of the Bay, both algae blooms and Vibrio could persist later in the season.
3. Vibrio infections can occur in people who eat raw or undercooked shellfish or who swim with open wounds or punctures in contaminated waters. While infections are rare, they do take place and can be particularly dangerous for people with compromised immune systems. The ingestion of Vibrio can cause vomiting, diarrhea and abdominal pain, and in some cases can infect the bloodstream. If an open wound or puncture comes into contact with the bacteria, the area around the wound can experience swelling, redness, pain, blistering and ulceration of the skin.
4. Infection can be avoided. To avoid Vibrio infection, follow these tips:
5. Vibrio symptoms can start 12 to 72 hours after exposure. If you think you’ve been infected with Vibrio, seek medical attention. Make sure to let your doctor know that you have eaten raw or undercooked shellfish or crabs or have come into contact with brackish or saltwater.
The R/V Rachel Carson is docked on Solomons Island. At 81 feet long, the red and blue research vessel stands out against the deadrise workboats that share the Patuxent River marina. Her mission today is to lead researchers from the University of Maryland Center for Environmental Science (UMCES) to the Chesapeake Bay’s dead zone.
Every summer, this so-called “dead zone” forms in the main stem of the Bay. The area of low-oxygen water is created by bacteria as they feed on algae blooms growing in nutrient-rich water. The dead zone persists through the warm summer months because the Bay is stratified into two layers: a surface layer of lighter, fresher water that mixes with the atmosphere, and a bottom layer of denser, saltier water, where oxygen depletion persists. These layers won’t mix until the cooler temperatures of autumn allow the surface waters to sink.
To find the dead zone, Director of Marine Operations and Rachel Carson Captain Michael H. Hulme takes us to one of the deep troughs that run down the center of the Bay. Geologic remnants of the ancient Susquehanna River, these troughs can reach up to 174 feet deep in an estuary whose average depth is just 21 feet. Hulme anchors offshore of Calvert Cliffs State Park.
The boat is equipped with a dynamic positioning system, which holds it in place regardless of wind or waves. This allows the captain to step away from the helm and offer his hands on deck. “Being able to hover over that [specific] latitude and longitude is what makes the Rachel Carson so unique,” said Hulme. It’s also one of the reasons the vessel is so useful to scientists, who often return to the same sampling site again and again over time.
UMCES Senior Faculty Research Assistant David Loewensteiner drops a CTD overboard. The oceanography instrument takes eight measurements per second, tracking conductivity, temperature and depth as it is lowered through the water. Connected to the ship with a cable, the CTD sends data to a laptop in the boat’s dry lab. We measure 2.04 mg/L of dissolved oxygen in surface water, and just 0.33 mg/L at 98 feet deep. Critters need concentrations of 5 mg/L or more to thrive; these are “classic dead zone” conditions.
Dead zones are bad for the Bay. Like animals on land, underwater critters need oxygen to survive. In a dead zone, immobile shellfish suffocate and those fish that can swim are displaced into more hospitable waters. “If you were a self-respecting fish and oxygen was [low], what would you do?” asked Bill Dennison, Vice President for Science Applications and Professor at UMCES. “Swim away.”
First reported in the 1930s, the appearance of the dead zone in the Bay is linked to our actions on land: as we replace forests with cities, suburbs and farms, we increase the amount of nutrients entering rivers and streams. This fuels the growth of algae blooms that lead to dead zones. “Hypoxia [or low-oxygen conditions] is driven by what we do on the watershed,” said UMCES Assistant Professor Jeremy Testa. “The Bay is naturally set up to generate hypoxia because of that [stratification] feature. That said… when there were no people here, there was not much hypoxia.”
While it is our actions on land that created the dead zone, it is our actions on land that can make the dead zone go away. Research has shown that certain pollution-reducing practices—like upgrading wastewater treatment plants, lowering vehicle and power plant emissions and reducing runoff from farmland—can improve the health of local rivers and streams. Scientists have also traced a decline in the duration of the dead zone from five months to four, which suggests that conservation practices gaining traction across the watershed could have very real benefits for the entire Bay.
To view more photos, visit the Chesapeake Bay Program Flickr page.
Images by E. Guy Stephens/Southern Maryland Photography. Captions by Catherine Krikstan.
Eight of the top 10 U.S. cities that have seen an increase in “nuisance flooding” alongside rising seas are on the East Coast, according to a new report from the National Oceanic and Atmospheric Administration (NOAA).
Four of the top 10 cities are in the Chesapeake Bay watershed. Annapolis and Baltimore lead the list with a 925 and 920 percent increase in their average number of nuisance floods since 1960. Washington, D.C., has seen a 373 percent increase, while Norfolk has seen a 325 percent increase.
According to the report, nuisance flooding—or minor flooding that closes roads, overwhelms storm drains and compromises infrastructure never designed to withstand inundation or saltwater exposure—will worsen as sea level rise accelerates. Indeed, nuisance flooding has become “more noticeable and widespread” because of rising seas, sinking land and the loss of natural flood barriers.
“As relative sea level increases, it no longer takes a strong storm or a hurricane to cause flooding,” said William Sweet, oceanographer and lead author of the report, in a media release. “Flooding now occurs with high tides.”
Image courtesy rwillia533/Flickr
The study was conducted by scientists at the Center for Operational Oceanographic Products and Services, who compared data from 45 tide gauges with reports of nuisance floods; whether or not a nuisance flood has taken place is determined at the local level by a National Weather Service threshold. It is hoped the findings will “heighten awareness of a growing problem” and “encourage resiliency efforts in response to” sea level rise.
An understanding of where floods are occurring is integral to building climate resiliency. Once coastal communities know where environmental threats and vulnerabilities lie, they can take steps to move growth and development away from the coast, enhance preparedness efforts to protect human health and protect and restore wetlands, buffers and barrier islands that might shield the shoreline from strong wind and waves.
The Chesapeake Bay Program has set a goal to increase the climate resiliency of the watershed’s living resources and public infrastructure, using monitoring, assessment and adaptation to ensure the region withstands the impacts of a changing climate.
Every once in a while, one is struck by the power of a new idea. At a recent event held by the Maryland Department of Natural Resources (DNR) to kick off a public education campaign about invasive catfish in the Chesapeake Bay, I learned about an initiative called the Wide Net Project. The concept of the Wide Net Project is elegant in its simplicity and its brilliance.
Image courtesy Virginia Sea Grant
Neither blue nor flathead catfish are native to the Chesapeake Bay. Unfortunately, the invasive species have become apex predators that feed voraciously on other fish and shellfish. In some areas of the watershed, they represent a significant percentage of a tributary’s total fish biomass. But they are also a good source of lean protein.
In this invasive catfish problem, Wide Net Project co-founders Sharon Feuer Gruber and Wendy Stuart saw a solution: the catfish could be fished out of local tributaries and used to provide low-cost protein to hunger relief organizations.
Wide Net Project staff work with J.J. McDonnell, a large seafood company, to process and distribute the catch from area anglers. Staff sell the fish to restaurants, grocers, hospitals, universities and other institutions at market price. A significant portion of these sales is used to lower the price of the fish staff then sell to hunger relief agencies, which normally can’t afford healthy, local foods. To address the health concern related to the potential accumulation of toxins in older and larger fish, the Wide Net Project markets and sells only younger and smaller blue catfish. J.J. McDonnell also recycles fish waste produced during processing into pet food.
At the DNR event, which was held at Smallwood State Park on the Mattawoman Creek, chefs cooked up samples of blue catfish. While I enjoy eating fish, I don’t think I had ever tasted catfish before that day. I tried some, and found it had a flakey white meat and a light and delicate taste. I thought to myself, one should never underestimate the power of a great idea or the ability of a few dedicated individuals to get things done. Sharon and Wendy connected the dots and inspired us all.
Note: The opinions expressed above are those of the author and do not necessarily reflect U.S. EPA policy endorsement or action.