National Geographic : 1972 Jun
an important part in the ecology of the marsh. They consume the algae and food particles in the mud; then, in turn, they serve as food for birds, raccoons, and other creatures that range the marsh. We watched the female fiddlers work the small pincers on their forelegs, vigorously shoveling food into their mouths, like a small hungry child using both hands on a plate of spaghetti. The male, who has one claw much larger than the other, does not use his large pincer in feeding, but makes do with a single foreleg. A major purpose of his big claw is to lure female fiddlers into his burrow. He sits at the entrance, waving his claw enticingly; if the female responds, they mate. Spartina Keeps Grasshoppers Hopping Fiddlers do not eat the living spartina. In fact, only about 10 percent of it is grazed on. One of the grazers is the salt-marsh grass hopper, which finds the grass a lifesaver in more ways than one. On a later visit to Sapelo, canoeing through the marsh at high tide, I saw that the grass hoppers had climbed up the spartina stems to escape the rising waters, perching like squirrels in a tree. They jumped from stem to stem, inches above the hungry lurking fish. One brave hopper even ventured to swim across the creek, climbed a grass stem, and with a jump disappeared into the jungle. The spartina leaves that are not eaten even tually die and fall into the marsh. There bac teria and fungi reduce them to organic detri tus. The marsh exports great quantities of this detritus to the sea. Georgia's Spartina alternifloramarshes produce five to nine tons of plant material an acre a year; Virginia's, three; and Delaware's, two. About half of all this flows into estuaries to nourish the animals of the sea. Some of the most productive acreage on earth lies untended in our marshlands. Its yield cannot be estimated in bushels an acre or in so many head of cattle, for its ultimate consumption takes place miles from its source of origin. (See the diagrams explaining the ecology of a salt marsh on pages 737-8.) Are there ways for man to make even great er use of this food-rich detritus? It could become the basis of a new sea agriculture. Biologists have already started raising clams and oysters indoors in their early stages, so they can control breeding, growth, disease, and predators. But, as the shellfish mature, they must be moved to an estuary to feed on Mud bath aids science at the University of Geor gia Marine Institute on Sapelo Island. Biology student Jennifer Jewitt brings up a sample of tidal flat sediment to determine the types and distri bution of marsh organisms. Underwater at high tide, an adventurous peri winkle (left) rests atop a blade of cordgrass (Spar tina alterniflora).The algae-eating snail and its kin provide nutrient-rich droppings that bolster growth of the all-important marsh plant.