Good news, for once

The New York Times has an editorial about the resurgence of Chesapeake oysters:

Good news from the waters of Chesapeake Bay is a rarity, especially when it concerns oysters— the basis of a once-flourishing, but now nearly defunct, fishery. Over the years, the Chesapeake— a broad, shallow estuary— has become contaminated by agricultural and other polluted runoff from the dozens of rivers and creeks that feed it, wreaking havoc on water quality and aquatic life. This, plus overfishing, has virtually destroyed a species that helped filter and cleanse the bay’s water.
So it comes as a welcome surprise to learn that scientists working near the mouth of Virginia’s Great Wicomico River have established surprisingly healthy beds of native oysters. The experiment, which began in 2004, uses broad, tall beds of oyster shells as artificial reefs for new oyster seedlings. The height of the reefs— a foot or more— raises the new oysters above the sediment, which seems to improve their health. The reefs are big, some as much as twenty acres in size. Scientists believe that this, too, is important to reproduction.
These experimental oyster cities— 185 million oysters on about 80 acres total— are believed to contain the largest re-established population of native oyster species in the world. Scientists think they could be a model for experiments elsewhere.
One big question is whether these reefs help protect oysters from disease. But if they work as well as they seem to, the reefs offer enormous promise. They also present an enormous engineering problem— how to build them over tens of thousands of acres, re-creating a time when the Chesapeake was paved with oysters.