Last weekend found us kayaking in one of the most fertile -- and most beautiful -- places on Earth, a coastal Georgia salt marsh. We put in at Crooked River State Park near St. Mary’s and paddled down the river and into a wide tidal creek winding through a sweeping, far-as-the-eye-can-see salt marsh.
The outgoing tide helped float us down the tranquil river. Gentle breezes cooled us on the warm sunny day. As we paddled, our leader, Jessica Aldridge, assistant director of the state park, told us about the amazing fecundity of salt marshes and how they and the tidal creeks, rivers and estuaries together form one of the world’s great ecosystems.
Scientists have found that Georgia's salt marshes produce nearly 20 tons of biomass to the acre, four times more than what the most carefully cultivated farmland yields. Most of the output comes from the marshes' dominant plant, salt-tolerant Spartina alterniflora, or smooth cordgrass. Some 90 percent of Georgia's 400,000 acres of salt marsh is covered by huge swards of Spartina stretching to the horizon like giant, neatly mowed lawns.
The enormous productivity is made possible by tons of nutrients and sediments delivered to the marshes twice daily by the tides. The productivity helps make salt marshes the primary nurseries for more than 80 percent of blue crabs, shrimp and other economically important fish and shellfish. The young creatures not only feed in the marshes, they also use them for shelter and hiding from predators.
As we paddled, we saw some of this abundant life. Zillions of tiny mud snails, resembling masses of olive pits, covered the creek banks. Fiddler crabs darted into their burrows as we passed along. Periwinkle snails clung to Spartina stalks. Mullet flipped out of the placid water. In the shallow water at the marsh’s edge, small sand sharks probed for food.
But the most conspicuous features along the creek were the numerous large oyster reefs, or beds, that harbor hundreds or even thousands of oysters glued tightly together. The mollusks’ razor-sharp shells make walking on an oyster reef dangerous. Nevertheless, the reefs are some of the most ecologically important components of salt marshes, Aldridge said. As it feeds, one adult oyster filters as much as 50 gallons of water per day, thus helping cleanse the water. Also, dozens of species of crabs, fish, shrimp and other creatures live, feed and hide in a reef’s many nooks and crannies.
As we headed back upriver on the incoming tide, a pair of dolphins greeted us -- a fitting end to a glorious day on Georgia's coast. For more information on Crooked River State Park, visit: http://georgiastateparks.org/CrookRiv.
In the sky: The moon will be last quarter on Friday, rising about midnight and setting around midday, says David Dundee, an astronomer with the Tellus Northwest Georgia Science Museum. Mercury is low in the east just before sunrise. Venus is high in the west just after sunset. Mars is high in the west just after dark. Jupiter is low in the east about four hours before sunrise. Saturn rises out of the east before sunset and sets in the west before dawn.
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