BY KENNETH M. PIERCE
Posted March 30th, 2010 at 9:45 pm
Where has all the seagrass gone?
It sure sounded like a good idea when the Army Corps of Engineers proposed in 2000 to “restore” a trio of bird rookery islands in Roberts Bay. Currents and wakes from the Intracoastal Waterway were eroding their steep sides. The idea: dump tons of boulders into an “L-shaped” breakwater to shield the islands. Eventually, Sarasota County and the Sarasota Bay Estuary Program backed the $1.2 million, year-long construction project, completed in February, 2008.
That same month, helicopters flew over Roberts Bay to scan the bottom for sea-grass, part of a routine check-up. Because seagrass shelters many creatures, its growth tells much about the bay’s health. The grass can’t grow if tiny floating plants prevent sunlight from reaching the bottom, as happens sometimes when too much nitrogen (from fertilizer, say, or wastewater) washes into the bay.
Prior helicopter scans had found great news for Sarasota’s bays: seagrass was increasing, a sign the bays were clearing up. In Roberts Bay, by far the biggest crop of new seagrass between 2001 and 2006 appeared on maps as a growing green blob next to the Bird Colony Islands. It spread from the Intracoastal Waterway to the Bay’s northeast corner.
Unfortunately, as it turned out, that’s about where the construction crew began barging and dumping in 2007 for the Bird Colony Island restoration project. By 2008, scans showed that the big new blob of seagrass had vanished, though gains remained in other parts of Roberts Bay.
Too bad, of course. But wait, it gets worse.
Not long after viewing the 2008 scans, scientists suspected the rookery’s breakwater had caused the blob to vanish. They decided to wait and see if new scans for 2010 show a seagrass comeback near the rookery.
But they didn’t tell the Herald-Tribune, apparently. Several times since May, 2009, the paper has linked the seagrass decline to concern about pollution in Roberts Bay, termed a “troubled water body” by the paper earlier this year. Why hadn’t anybody told the journalists, “It’s the breakwater, stupid?” Finally, a brief article this February did report that Roberts Bay’s seagrass levels were rising, but the paper didn't report that it or anybody else did anything to mislead the public or harm the Bay.
There are some lessons here. First: well-intentioned projects that backers call “restoration” can turn out to cause destruction. A top-level panel on estuaries convened some years ago by the University of Florida’s Sea Grant College Program found that dredging and other “unconsidered” changes in the current flows of bays “may be the most significant threat to the integrity and functionality of Florida’s estuaries in the coming decades.”
From the Bay’s point of view, one might ask: Instead of one giant breakwater, would three little ones have been better? Would a breakwater of a different shape have been kinder to the seagrass? Could less massive methods have stabilized the rookery islands? Was the damage caused by dredging or the shift in currents? Were the currents studied by computer models beforehand, as recommended prior to any such project by that Sea Grant panel?
Answers to these questions were obviously flawed in this case, but I hope such questions were asked, because it’s in the public’s interest to do so. If anyone—even our local newspaper—assails people for questioning a project labeled “restoration,” the best response is, shame on you. Good stewardship requires all of us to ask tough questions about any idea for reshaping (or “restoring”) Sarasota’s 3,000 year-old estuary.
Lesson two: Not all scientists study the same thing (Bird? Land? Water?) and not everything scientists say (or fail to say) is science. Of course science is important to public policy, but so is cost, and so are choices—birds or seagrass, for example, should it come down to that.
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