Retreived from Bay Daily http://cbf.typepad.com/bay_daily/2010/11/exciting-news-from-a-troubled-river.html
Chesapeake Bay Foundation (CBF) scientists are finding lots of healthy, fast-growing oysters in Norfolk’s Lafayette River, a tributary of the Elizabeth River. The discovery bodes well for improving water quality – and restoring a thriving oyster population – in this historic river.
but troubled waterway whose four branches (Western Branch, Eastern Branch, Southern Branch and Lafayette) drain four cities and some of South Hampton Roads’ most industrialized areas. As a result, the Elizabeth system is among the Bay’s worst pollution “hot spots,” with some areas containing bottom sediments laden with toxic chemicals from decades-old pollution.The Lafayette River, bordered largely by homes, museums, marinas, and marshes, is less severely polluted but remains among the most urbanized rivers in the Bay watershed. It suffers from many of the Bay’s classic problems: too much runoff, too many algal blooms, too much bacteria, and too little oxygen.
CBF, the Elizabeth River Project, the City of Norfolk, and other partners are working with theVirginia Institute of Marine Science to restore water quality in the river. All believe that oyster restoration will be integral to success.
To that end, CBF is expanding the number of volunteer citizen oyster gardeners in the Lafayette. Additionally, last summer we placed 50 concrete reef balls, many of them coated with a skin of living baby oysters, or spat, in the river to create a manmade reef. We hoped the reef balls would prove suitable homes for the baby oysters as well as attract and grow more wild oysters.
CBF scientists also began a comprehensive survey of the oyster population in the Lafayette, examining 22 miles of shoreline to look for oysters. We also recruited scores of waterfront residents to participate in a “spat catcher” program.
Spat catchers — small cages containing 50 recycled oyster shells – were suspended from more than 80 residents’ backyard piers and docks. We wanted to see how many free-floating baby oysters in the river would attach to the shells. By later comparing the numbers of spat in the various shell cages, CBF oyster scientists hoped to determine which parts of the Lafayette may hold the greatest potential for future oyster restoration efforts.
Last weekend, a CBF team of scientists, interns, and volunteers pulled up the spat catchers and tallied the results. Here is how CBF Oyster Restoration and Fisheries Scientist Tommy Leggett described it:
“This is one of the most exciting things I think we’ve ever done…We had some of the most remarkable spat sets on the shells that I’ve ever seen in the wild, and especially for the Elizabeth River system. Some shells had spat numbers that rivaled what we produce in our spat-on-shell tanks (at CBF’s oyster farm). “ For example, the shell in the photo at left had a remarkable 28 spat attached (photo by Chip Finch).
A few days later, Leggett, CBF Oyster Restoration Specialist Jackie Shannon, and CBF Reef Ball Technician Laura Engelund inspected the concrete reef balls CBF placed in the Lafayette last June.
“We’ve been anxiously wondering how the oyster spat on the reef balls fared over the summer and didn’t quite know what to expect once we got back this week,” Engelund said. “We were amazed at the size of the oysters! In four months they have grown from baby spat to near market size. They are significantly larger than we anticipated and cover the reef balls nearly 100 percent. We put in a couple of reef balls without spat and were pleased to find a natural set growing quite nicely on those as well. The reef balls we planted without spat are easy to recognize in the photographs: smaller oysters and fewer in number. But they all got there by themselves!”
Pictures are worth a thousand blogging words, so take a look at what’s happening in the Lafayette.
What does it all mean for the river’s future? The preliminary data suggest there’s a healthy oyster population in the Lafayette River, says Leggett (below, center, with Jackie Shannon, left, and Laura Engelund, right, and one of the Lafayette reef balls).
“But the river has limited habitat for baby oysters to settle upon. Most of the natural oyster bars/rocks are gone, silted over, or have sunk beneath the river bottom. What the river needs now is more oyster shell or hard substrate like reef balls for oysters to attach to.”
And Leggett added, “Efforts to improve water quality by reducing nitrogen from sewage treatment plants and runoff from lawns and storm drains will provide better conditions for a recovering oyster population.”
CBF and its Lafayette River partners will be working to address these issues in the months and years to come. Stay tuned for more good news!
By Chuck Epes
Chesapeake Bay Foundation