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Monsters in Our Water

What were your biggest motivators?
Vogelbein: “Curiosity about the beauty and workings of the natural world. Discovery of the new creativity of work in the scientific disciplines.”

Read Wolfgang Vogelbein's
full Q&A
»

Rhodes: “My interest in science was inspired by a couple of wonderful high school biology and chemistry instructors who took a special interest in me.”

Read Martha Rhodes'
full Q&A »

Hoenig: “I might have studied birds, insects, plants or some other area of ecology but one professor excited me by showing how we could quantify and model impacts.”

Read John Hoenig's full Q&A »

A man sits on a bank of the Chesapeake Bay, enjoying a day of fishing. Suddenly, he feels a tug on his line and happily reels in his catch. What he sees at the end of the line is more ghastly than appetizing. Portions of the striped bass’s flesh can be seen through its skin, as if some creature took a few bites then simply moved on to gnaw on other victims. What is this flesh-eating monster?

To answer that mystery, fish pathologist Wolfgang Vogelbein, microbiologist Martha Rhodes and statistician John Hoenig from the Virginia Institute of Marine Science in Gloucester, Virginia, join forces to solve the mystery. By testing infected fish cells, they revealed the monsters were a nasty group of bacteria called Mycobacterium. Mycobacterium includes members that can cause tuberculosis and leprosy in humans. The particular strain infecting the stripers causes extensive damage to internal organs, skin ulcers and eventual death. Plus, in those unfortunate anglers who handle infected fish, they can cause unsightly red welts and create achy joints.

According to Vogelbein, the mycobacterial species lurking in the Chesapeake are widespread. But that’s not all. They appear to have accomplices, organisms that can indirectly weaken the stripers and make them easy prey for bacterial attacks. Here’s how it works. Throughout the estuary, masses of microscopic plants and algae called phytoplankton make up an essential part of the marine food web. If given too much fertilizer, however, they can rapidly reproduce and wreck havoc on the ecosystem. When excess phytoplankton die, their decomposition rapidly sucks oxygen out the water. Those animals or plants unlucky enough to be trapped in these suffocating areas die. Such low-oxygen regions are called dead zones. These have tripled in the bay during the past few decades and are extending now into deeper waters that provide refuge from the debilitating heat of summer surface waters and so are crucial for striper survival. Without these cool refuges, stripers can become stressed and therefore weakened, becoming easy pickings for opportunistic, flesh-devouring mycobacteria.

Vogelbein and his team are finding that human actions can play a large role in such mycobacterial epidemics as well as the algal blooms. Excess nitrogen and phosphorous fertilizers from our lands and feedlots wash into rivers, bays and the ocean. They build up and provide excess nutrients to phytoplankton fueling massive blooms. In the past, healthy populations of filter-feeding animals like oysters and menhaden fish in the Chesapeake could have helped keep such blooms in check. But past overfishing has wiped out these populations, further confounding the problem.

More worrisome is that excess nutrients aren’t just a problem in the Chesapeake. According to biologist Robert Diaz of the Virginia Institute of Marine Science, more than 300 dead zones have emerged worldwide, up from 148 just a few years ago. This increase, Diaz admits, is largely because an overload of human-produced nitrogen is entering our water systems.

Now that we have identified the problem, what can we do? A number of effective measures can stem the flow of excess nutrients into our waters. Here’s how you can help:

  • Reduce the use of harmful fertilizers and pesticides around your home.
  • Volunteer to help restore wetlands that act as natural filters of groundwater.
  • Support policies that encourage innovative farming practices that limit fertilizer and manure runoff into streams and rivers.

For even more solutions visit: What can we do?

References
»

Shogren, S. (2006). Scientists probe cause of death of east coast fish, All Things Considered, National Public Radio, http://www.npr.org/templates/story/story.php?storyId=5162318 Off-site Link

 
»

Blankenship, K. (June, 2004). Mycobacteriosis infection rate in Bay’s striped bass increasing, Bay Journal, http://www.bayjournal.com/article.cfm?article=1252. Off-site Link

 
»

Rhodes, M.W., Kator, H., Kotob, S., van Berkum, P., Kaattari, I., Vogelbein, W.K., Quinn, F., Floyd, M.M., Butler, W.R., Ottinger, C.A. Mycobacterium shottsii sp. nov., a slowly growing species isolated from Chesapeake Bay striped bass (Morone saxatilis), International Journal of the Society of Environmental Microbiology, Published on-line: August 16 2002.

 

For more topic references check out the Resources section


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