A little development can cause big harm


Science: Emerging studies find real wetlands protection means preserving larger buffers of undeveloped open space.

February 11, 2005|By Tom Horton | Tom Horton,SUN STAFF

Finally, growth in your county is coming to the peninsula where you've lived in bucolic bliss, fishing and crabbing and bird-watching along the edges of tidal river and bay.

As local officials and developers explain their plans, your spirits rise. They're showing more environmental sensitivity then anyone expected.

They promise not to touch any of the extensive wetlands. But what's more, they will maintain an inviolable buffer of open space around them of a thousand feet - far more than required.

All commercial development will be sited so that it's invisible from any shoreline. State-of-the-art controls will be used by homebuilders to control runoff during and after construction.

And when it's all built out, the peninsula will remain at least 75 percent farms and forests.

Not nearly as bad as you thought.

But think again, this time armed with emerging studies from the Smithsonian Environmental Research Center (SERC) near Edgewater.

For the first time, the center is relating the ways we use land to specific changes in the tidewater environment, based on four years of research at dozens of locations the length of the Chesapeake.

And its work suggests that with the seemingly rosy development scenario above, you could still get:

A sharp reduction in young blue crabs, and declines in the number of fish and their overall numbers.

A precipitous decline in marsh birds.

A rise in toxic PCB levels in tasty white perch so steep you'd be advised to limit severely how many you ate.

Water so cloudy that sea grasses are no longer able to get enough light to survive.

Overall, SERC found that developing as little as 14 percent of tidewater regions triggered a drastic decline in marsh-dwelling birds like rails and herons.

A minimum buffer of some 1,500 feet was needed to protect marsh birds. Where development was as much as 25 percent, a 3,000-foot buffer was needed.

Even a 10 percent level of development was enough to push PCBs in perch up tenfold. Once development reached 35 percent, the fish were often so contaminated that Environmental Protection Agency guidelines advise no consumption.

The production of PCBs has been banned for years, "but this suggests they are persisting more widely in the environment than we realized," said Dennis Whigham, one of the SERC researchers.

The relationship of development to reduced water clarity was surprisingly strong, said Charles Gallegos, a SERC ecologist.

He said modern storm-water controls capture the great bulk of sediment by weight. But the very light, fine particles that escape developed land stay suspended in the water for days, reducing light to sea grasses.

Young blue crabs, for which the tidal shallows are a critical habitat, were largely absent in areas with development and agriculture - even when wetlands remained intact, the studies showed.

The good news - and one of the points of the research - is it can show planners and decision-makers better ways to minimize impact of human land use around the estuary. For example, the location of development in the SERC studies often was more important than the amount - generally, the closer it was to shorelines or marshes, the greater its impact.

"Certainly it argues for giving far fewer exemptions to Maryland's Critical Area Act," the law restricting development along the edges of the bay and tidal rivers, said Whigham.

Preserving forested, non-bulkheaded waterfronts appears a key to maintaining little blue crabs. They, along with many fish, depend on the woody debris from trees falling into the water for refuge.

Commercial development was even more strikingly linked to elevated PCBs than residential - and again, the closer it was to the water's edge, the greater its impact.

And real wetlands protection clearly means preserving larger buffers of undeveloped open space (including farms) than most jurisdictions require.

The SERC studies, part of a larger EPA effort around the U.S. coastline, also aim to increase our ability to quickly survey present and planned land patterns, and predict their consequences for water quality and wildlife.

Doing the same thing by going into every place and monitoring, measuring and sampling is so time-consuming and costly it never gets done.

A lot of science is still needed to tease out exactly why and how development does its damage. This could lead to sounder ways to develop. Meanwhile, the evidence is we ought to stay back from the natural edge a lot more than we do now.

The real challenge is to translate such science into governments' decision-making. With our satellites, our ecological understanding, our computer modeling and graphics, we've become awfully good at describing what ails the bay - far less good at acting like it matters.

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