Many answers lurk at the bottom

ON THE BAY

February 19, 1994|By TOM HORTON

In writing about the health of the modern-day Chesapeake, I often recall an old Latin textbook's vivid scene from Rome of more than 2,000 years ago.

It describes the haruspices, literally "lookers at guts." Soothsayers, they divined future events by closely observing natural phenomena, including the entrails of specially sacrificed beasts.

And millennia later, I often find myself waiting on river banks and aboard boats, notebook and pencil poised to record the utterances of some haruspex, who is more likely to be called a biologist or ecologist now.

A surprising amount of our information about the environment still begins with netting the shallows to count the spawn of fish; with grappling up oyster shells to see the state of the summer's spat set; with collecting the baby crabs in a square meter of sea grass bed -- counting, weighing, feeling the life and holding it up to the light (though it may be the light of an electron microscope).

Vastly more sophisticated and powerful in its divinations, the process, in form and spirit, often seems not a dime removed from those old lookers at guts.

On the Chesapeake Bay, as we invest more years and millions in trying to heal the estuary, and require ever more changes of society in the name of saving the bay, documenting and #F evaluating the results become critical.

Are we emphasizing the right problems? Are we making a difference yet? What will we call "saved," and how clean is clean enough?

Not surprisingly, we are looking intensely for answers in the bay's "guts," which are beginning to yield some fascinating reports on our progress. Those guts may be said to lie, as much as anywhere, in the sands and clays and muddy ooze of the bay bottom, and more specifically, in the 300-odd species of worm and sponge and coral and mollusk, what we call the benthos, or bottom dwellers.

The only famous member of the benthic community is the oyster (and perhaps a couple of species of clam). But, collectively, the benthos are a better indicator of progress than are better-known groups of bay species like fish and waterfowl.

"The benthos occupy a nice niche," explains Steve Weisberg, a scientist at Versar, a private environmental group in Columbia that monitors the bay bottom for Maryland and the U.S. Environmental Protection Agency.

Mr. Weisberg says benthic creatures don't live long or move around much, compared with a rockfish that may spend 20 years traveling annually as far as Nova Scotia. The bottom-dwellers are more representative of what's happening, at any given time, wherever they occur in the bay.

From the other end of the scale, the Versar scientists say, examining the benthos can tell you more than knowing the actual levels of pollutants in the water and bottom sediments. "We measure 'what's out there' with toxics, but the real question is, 'what's that mean -- what's that level of contamination doing,' and the benthos can tell you," says Mr. Weisberg's colleague, Ananda Ranasinghe.

And the benthos, which can include thousands of tiny critters per square foot of bottom, have a more direct link to the health of BTC higher-level species than you might think. They are a major munchie for white perch, spot, eels, croakers, flounder and the young of rockfish and sea trout; also blue crabs and canvasback ducks. A study in the Patuxent river showed that such predators were eating, at times, an astounding 70 percent of everything growing on the river bottom.

The ultimate goals of the benthic-monitoring program are to develop a simple index, say one through five, with a one representing a highly degraded environment, and a five something close to pollution-free.

Then bay managers could explain to the general public, or a legislative committee debating the budget, where things are looking up, where they are deteriorating, whether progress is being made, and so on.

The process is not as easy as just collecting and counting bottom organisms. Before the messages in the bottom can be "read," a proper alphabet has to be worked out. For example, sheer abundance of organisms is no clue to environmental health at all, but diversity of species is important.

The ratio of "opportunist" vs. "equilibrium" benthos is a key -- the former being like weeds, representative of chaotic conditions; the latter more akin to oaks and the stability of the forest.

After nearly a decade of Maryland's monitoring the benthos in earnest, Mr. Weisberg is gaining confidence that an answer to the "how's the bay" question will emerge.

For example, of 26 areas of bottom sampled throughout the Maryland bay and its tidal rivers, the benthos in nine areas made a three or better on the index of one through five. Based on comparisons with areas of known good water quality, that is deemed good enough to meet bay restoration goals.

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