December 1998: Vol. 78, No. 1December 1998: Vol. 78, No. 1
More bacteria on earth than stars in the sky
You can't see them, but they're there. They're why you wash your hands before you eat, cook meat thoroughly, and sometimes need a doctor's prescription for antibiotics.
In fact, five million trillion trillion bacteria roam the earth, according to a study led by UGA microbiologist William Whitman. That's a five with 30 zeroes after it--more bacteria on earth than stars in the universe. But bacteria aren't necessarily a bad thing. In fact, we can't live without them.
"Bacteria are essential for life on Earth," says Whitman. "They make up the biosphere more than any other group of organisms. Without bacteria, we'd die very quickly."
Still, why count them? Because no one else had, say Whitman and fellow UGA researchers David Coleman and William Wiebe.
"There simply hadn't been any estimates of the number of bacteria on Earth," says Whitman. "Because they are so diverse and important, we thought it made sense to get a picture of their magnitude."
To get that picture, Whitman searched scientific literature for separate measurements of bacteria from different habitats. He then used various calculations to estimate the number of bacteria in the subsurface, which is the sediment below 30 feet on land and below four inches in marine environments. Whitman added these numbers together to arrive at five million trillion trillion.
Bacteria produce the air we breathe, clean the water we drink, and create fertile soil. Yes, some cause disease when they infiltrate humans and animals, but those bacteria make up less than one percent of the total.
Still stuck on the stars metaphor? Consider that if all of those five million trillion trillion bacteria were the size of a penny and were stacked one on top of the other, they would reach a trillion light-years away. If the dry weight of all the bacteria on earth were added up, it would roughly equal the total weight of France to a depth of one meter.
Freeman keeps watch on eels, endangered fish
Kudzu and honeysuckle define Georgia as much as peaches and peanuts, yet neither plant is indigenous to the South. They are invaders introduced from other continents.
Now a new kind of invader is transgressing Georgia's waterways--and it doesn't possess the southern charm of honeysuckle and kudzu. Not even close.
Asian rice eels, Monopterus albus, have slithered into three ponds at the Chattahoochee Nature Center north of Atlanta, and UGA's Bud Freeman is keeping a close eye on them.
"These things look like slippery snakes," he says. "They're about two feet long, and they were probably imported as pets from Southeast Asia and then released into the wild."
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Ecology professor Bud Freeman sends his lab assistants to gather data (upper left) at a spawning site of the endangered robust red-horse fish (lower left). Freeman also studies the Asian rice eel, an exotic invader threatening the Chattahoochee River (above). |
Freeman, an ichthyologist and taxonomist in UGA's Institute of Ecology, studies the eels to determine whether they have the potential to upset the Chattahoochee's natural ecosystem.
"Whenever you introduce a species to a new area, you don't know what the eventual impact is going to be," says Freeman. "Some things that seemed to be benign introductions have had serious impacts."
Whether the Asian rice eel will become a kudzu of the waterways remains to be seen, but Freeman suspects they have already entered the river. So far, he's captured 15 eels around the nature center with an electric shocker. He and his assistants are now trying to trap them--a difficult task since the eels slither out of even the smallest openings.
Working both ends of the equation, Freeman studies fish driven from their homes by other exotic invaders--in particular, the robust redhorse. Today the fish is limited to two Georgia rivers due to sedimentation, extensive damming, and the feeding habits of the flathead catfish, another alien species that has made a home in Georgia's waterways.
Freeman is trying to establish a recovery program for the robust redhorse, which is teetering on the brink of the federal government's endangered species list.
"It's a tough concept to get across why we should care about what we introduce," Freeman says. "I don't think people get the connection between what they do and what ends up in the creek."
Section by Stacie Sutton