Forms of nitrogen found experimentally in salt marshes include nitrate, 

 ammonia, and nitrite. Nitrate concentrations are high in winter and low or 

 undetectable in summer. Ammonia is the dominant form of nitrogen in tidal 

 creeks in summer. Nitrite concentrations rarely exceed 1.5 '■ g-atoms/1 and 

 showed no discernible seasonable patterns in a Delaware salt marsh (Aurand and 

 Daiber 1973). 



The import of nutrients from other systems fertilizes wetlands. Sewage and 

 fertilizer from terrestrial sources, transported to the wetland via the 

 riverine system or by direct runoff into the intertidal wetland, may increase 

 production greatly. There is a limit, however, to the amount of nutrient 

 loading and physical alteration that these wetlands can handle and still 

 maintain their critical functions. 



The role that tides play in transporting vital nutrients to intertidal salt 

 marshes generally is known. Some researchers have suggested that the action 

 of the tides 'subsidizes' the intertidal marsh (Odum and Riedenburg 1976). 

 Increased nutrient loads, aeration, and other environmental factors controlled 

 by the tides are cited as giving creek bank cordgrass (which grows more 

 vigorously than cordgrass in other physiographic locations) a greater growth 

 potential. Odum (1971) stated "...the higher the tidal amplitude the greater 

 the production potential..." In Maine, the high tidal amplitude and twice- 

 daily tides could play a critical role in expanding the hypothetical role of 

 'tidal subsidy' in supplying nutrients needed for growth and carrying away 

 waste products. 



RESEARCH NEEDS 



In comparison with other estuaries on the east coast of the United States, 

 such as Chesapeake Bay, Long Island Sound, and the New York Bight, estuaries 

 in coastal Maine are poorly studied. Major data gaps exist in virtually every 

 scientific discipline. Knowledge of estuarine hydrography is embryonic. Data 

 are needed on coastal currents and circulation, both tidal and nontidal. 

 Upwelling and frontal processes need to be investigated, especially in eastern 

 Maine (region 6) where such processes may be responsible for maintaining high 

 biological productivity. Information on circulation in estuaries and water 

 exchanges between estuaries and coastal marine waters of the Gulf of Maine is 

 lacking almost completely. Annual and interannual trends in water temperature 

 and salinity need investigation, as does spatial and seasonal variability in 

 water masses, in order to facilitate more accurate delineation of estuarine 

 habitats . 



Present data on nutrients are random and patchy. Monitoring of nutrient 

 distributions spatially and temporally is a high priority. The nutrients in 

 estuaries need to be sampled at fixed stations at frequent time intervals, 

 monthly or more often. A combined study of hydrography, nutrient 

 distribution, and primary productivity in both coastal and estuarine waters is 

 the most efficient way of filling the data gaps in these areas. Pollution 

 levels in Maine coastal waters, especially estuaries, are little known. 



Surveys of heavy metals, hydrocarbons, and pesticides, in water, sediments, 

 and organisms would provide a baseline against which future improvements or 

 declines in environmental quality could be measured. Presently, the amount of 

 these substances entering the environment and the location of their 



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