It looks like a paint factory has exploded, spewing millions of gallons of stain to stripe the river. The location is the Monitor-Merrimack Bridge, where Route 664 crosses the James near Hampton Roads.
But the stain is actually a massive algal bloom, fed by excessive amounts of nitrogen and phosphorus pollution. The photo was taken from an airplane on August 30 by Virginia Institute of Marine Science Professor Wolfgang K. Vogelbein. Dr. Vogelbein said in an email that the bloom is likely a potentially harmful species of algae, Cochlodinium polykrikoides. It’s a marine dinoflagellate known to cause fish kills around the world. Sometimes it’s called “red tide,” although Dr. Vogelbein prefers the term "mahogany tide," because of its darker tint.
"These types of blooms are an indication of eutrophication -- excessive nutrients," meaning too much nitrogen and phosphorus pollution from fertilizers, sewage plants, and other sources, Dr. Vogelbein said. “Nutrients are the biggest pollutant concern in the Bay.”
Dr. Vogelbein said that he and his fellow researchers at VIMS were inspired to start flying over the Bay to determine the extent of algal blooms in 2007. That was when they discovered a different kind of “mahogany tide” or “red tide,” called Alexandrium monilatum, that was irritating the skin of oyster aquaculture workers and killing cownose rays and sea snails (whelks) in Virginia’s York River.
One theory that Dr. Vogelbein and colleagues are trying to explore by tracking “red tide” blooms is whether Alexandrium monilatum, which is common farther south in the Gulf of Mexico, has shifted north into the Chesapeake Bay because of global warming.
“The question is whether this organism (Alexandrium) has been able to move up the coast and establish new habitat in the Chesapeake Bay," Dr. Vogelbein said.
He said he has flown twice over the southern Bay and its tributaries since August to photograph and document algal blooms, and may fly again soon. A colleague of his at VIMS, Professor Kim Reece, conducted an aerial survey last summer. The blooms last summer may have been even worse than this summer, Dr. Vogelbein said.
Algae respond to the same conditions that encourage plant growth on land, and thus are most likely to form blooms when waters are warm and rich with phosphorus and nitrogen pollution, according to VIMS.
“There are three main ingredients for an algal bloom,” Dr. Reece said on the VIMS website. “Warm waters that favor rapid growth of algal cells, abundant nutrients to fertilize that growth, and wind and tidal-driven currents to confine the cells into a dense aggregation.”
The most important way to prevent these harmful algal blooms is to reduce phosphorus and nitrogen pollution from all sources, including rainwater running off of fertilized land.
In December 2010, the federal government imposed limits on nitrogen and phosphorus in the Chesapeake Bay and its tributaries, and threatened penalties to states, including Virginia, that fail to meet these limits. The states are now following pollution reduction plans called the Chesapeake Clean Water Blueprint.
Meeting these pollution reduction targets over the next 12 years will require investments, innovation, and cooperation between the federal government, states, and counties.
But the payoff will be beautiful to behold: A Bay with a lot fewer stains like the ones shown in these pictures.
By Tom Pelton
Chesapeake Bay Foundation
(Photo courtesy of Virginia Institute of Marine Science Professor Wolfgang K. Vogelbein)