Ul 



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period. These monetary estimates do not include the value of primary 

 production in terms of food for wildlife or in terms of the animals, in- 

 cluding furbearers, that it supports. < 



Wetlands have long been associated with the production of water- _] 



fowl (Alexander et al. 1953; Linduska 1964). They are recognized as > 



the Nation's "duck factories. " The pothole country, for example, S 



which represents only 109£ of our wetlands, produces over 50*% of our C/5 



ducks. Every year 300,000 ducklings fly off the western marshes along 

 the Pacific Flyway. The 14 southern states add another 700,000, and 

 the eastern coastal marshes add 200,000 more during the best years. 

 Some wetlands are more important as the actual breeding areas. 

 Others are essential as wintering grounds and as feeding and resting 

 areas scattered along the major flyways (Errington 1966; Niering 

 1966). 



Studies of the primary producers in the Tinicum Marshes by McCor- 

 mick ( 1970) provide insight into higher plant productivity. Among the 

 eight vegetation types represented, common reed grass, wild rice, cat- 

 tail, and mixed aquatic types were most important. They produced a 

 standing crop of 4.2, 6.9, 3.9, and 4.0 tons/acre, respectively. 



In general, wetlands exhibit a distinctive flora and fauna adapted to 

 hydric conditions or to periodic flooding. Some of the plant species are 

 of special interest for their unique features. These include the insec- 

 tivorous plants, orchids, and ericads of the bogs and species typical of 

 the vernal pools that change morphologically with gradual desiccation 

 of the site. 



Oxygen Production and Nutrient Recycling 



Grant and Patrick ( 1970) found that the 512 acres of wetland in the 

 Tinicum Marshes produce a net increase of 20 tons of oxygen per day. 

 This is the product of photosynthesis. 



Modern man has drastically modified the nitrogen cycle. The annual 

 natural turnover of nitrogen compounds in the U.S. has been calcu- 

 lated to be about 7 or 8 million tons (Commoner 1970). Currently our 

 agricultural fertilizers add another estimated 7 million tons, and 

 nitrogen compounds produced as by-products from our power plants 

 and automobiles, another 2 to 3 million tons. More than doubling the 

 nitrogen input into the biosphere has resulted in a serious deterioration 

 of enviornmental quality in various parts of the country. Denitrifying 

 bacteria have the ability to take the deleterious nitrogen oxides that 

 are accumulating and convert them back into atmospheric nitrogen of 

 which most of the atmosphere is composed. Most wetlands support 

 vast numbers of these micro-organisms and thus serve to reduce the 

 load of dissolved nitrogen washed into them. 



Another role of aquatic ecosystems is the recycling of organic sulfur- 

 containing compounds by action of sulfate-reducing bacteria. As 



