Scientists: Runoff is killing marine life 

Two decades of unique research at the Skidaway Institute of Oceanography has provided dramatic evidence that increased development on Georgia’s coast is a clear and present danger to marine life.

Specifically, say researchers, runoff from development promotes the spread of algae. In turn, bacteria feeding on the algae’s waste devour oxygen in the water available for other creatures.

“Nutrients that feed the growth of algae are arriving in increasing amounts that exceed the ability of the rivers and estuaries to accept them,” says Institute research scientist Dr. Peter Verity.

“Oxygen integrates all activities adjacent to waterways. The combination of those activities is now overwhelming the capacity of system to handle what’s coming off the land.”

Verity says the likely culprits are fertilizers from farms, golf courses and lawns, and sewage.

“When you fertilize your lawn, pay for golf fees or flush your toilet, ultimately you are responsible for the injection of nutrients into local aquifers, rivers and estuaries,” he says.

Once that nutrient-rich effluent reaches water, algae feed on it and grow.

“Think of what happens to your body if you regularly consume more food than you burn off in your daily activities – you get bigger,” Verity says. “Well, so does the amount of algae in whatever water bodies receive extra nutrients.”

Verity says the data is so consistent that there’s little room for ambiguity in drawing a conclusion.

“Concentrations of algae have been increasing rather steadily each year we’ve done the research. It’s remarkable how each summer the highest concentrations of algae are greater than the summer before.”

When oxygen levels fall below two to three milligrams per liter, water is hypoxic -- meaning it doesn’t contain enough oxygen to support healthy marine life. Over the last decade, the catches of commercially important fish and shellfish have declined by more than 50 percent; blue crabs by 90 percent.

The algae manifest in blooms that are sometimes aggravated by rainfall.

“As one example, there has been a steady increase in algae and bacteria in the Skidaway estuary with especially large blooms during the summer,” Verity says. “These blooms are associated with large rainfall events that wash larger amounts of fertilizer and other nutrients into the water.”

Verity says that right now the Georgia coast is not experiencing the kind of toxic algae blooms common in the Gulf of Mexico.

“I think that has to do with the very high tidal ranges in the coastal area. We have a higher tidal range than anywhere between Cape Hatteras and southwest of Miami. So when blooms of a toxic kind start to form, vertical mixing tends to dissipate those blooms.”

Still, the outlook is dire for the coast of Georgia if steps aren’t taken. The worst-case scenario, Verity says, is for bacteria to consume all the oxygen needed by marine organisms.

“Parts of Coastal Georgia are heading in the direction of Chesapeake Bay and Boston Harbor,” he says. “It may take a few more years to get there, but if it does, history shows that it will take many generations to get it back.”

Because of its 19 years of consistency, the work at Skidaway -- an autonomous research unit of the University System of Georgia -- is possibly the most unique of its kind in the U.S.

“It’s highly unique -- at least that’s what my peers tell me,” Verity says.

“We’ve used the same approaches as when we began in August 1986. Of course, we’ve made certain improvements with regards to sensitivity, because of the better technology available today. But that won’t change any issue regarding the quality of the data.”

Verity says coastal Georgia’s relatively recent discovery by developers has increased the quality of his research.

“In most parts of the country this kind of data wasn’t collected until a problem was recognized,” he says. “That coastal Georgia was relatively late to be developed is a boon.”

Verity says what makes the Skidaway research so unique is primarily the high frequency of sampling.

“It’s a very labor-intensive process. There’s often a tradeoff between frequency and cost. The fact that we have data collected weekly is highly unusual.”

Still -- and perhaps most amazingly of all in these cash-strapped times -- Verity stresses that all of his research has been done so far without state or federal funds.

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About The Author

Jim Morekis

Jim Morekis

A native Savannahian, Jim has been editor-in-chief of Connect Savannah for ten years. The University of Georgia graduate is also a travel writer, authoring regional guides in the Moon handbook series... more

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Connect Today 10.22.2016

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