Hydrology 



Hydrological factors affecting palustrine areas include: 



1. Water chemistry; 



2. Water flow and its characteristics of import, export, and reten- 

 tion time; 



3. Water temperature; 



4. Water level and its fluctuation extremes. 



Water flow transports animals, organic matter, nutrients, and other chemical 

 compounds through palustrine wetlands. Inflowing water can provide nutrients 

 to organisms in palustrine areas and outflowing water exports food to organ- 

 isms downstream. Where blocked drainage occurs in combination with other abi- 

 otic factors, organic matter may accumulate, resulting in the formation of 

 peat, a characteristic of bogs in coastal Maine. Drainage is further 

 congested by the growth of bogs. 



As mentioned above, the low water temperature characteristic of coastal Maine 

 contributes to the formation of bogs. Water levels vary in palustrine 

 wetlands. The relationship of the water table to the wetland surface is one 

 factor contributing to the type of wetland a basin develops (table 8-4). 



Palustrine species are very vulnerable to fluctuations in water levels. In 

 spring, for example, fluctuating water levels may affect the use of wetlands 

 by waterfowl. Water that is too high at critical periods during the breeding 

 season can result in lower waterfowl populations and lower production: (1) 

 through direct losses when nests are flooded; and (2) indirectly, by making 

 the environment less attractive to waterfowl (flooding food supplies and 

 nests) and therefore less extensively used (Mendall 1958). When water levels 

 decrease during the breeding season, terrestrial predators on waterfowl nests 

 may gain access to nesting areas that would otherwise have been inaccessible. 



Geology 



Deglaciation 12,000 years ago modified the topography of the Maine coast and 

 thereby altered drainage patterns, mainly through the deposition of glacial or 

 glacially-derived sediments. In many areas previously well-drained surfaces 

 were dammed by glacial deposits, or previously well-drained soils were 

 stripped and replaced by relatively impervious surficial materials (lodgment 

 till and marine silt-clay deposits). Palustrine wetlands developed behind 

 moraines, in blind valleys, and in kettle depressions (figure 8-5) where water 

 table levels were higher than the surrounding topography. Heeley and Motts 

 (1976) found that most wetlands in Massachusetts are underlain by stratified 

 drift, till, or bedrock. Similar substrates generally can be expected for 

 wetlands on the Maine coast although marine clays are also prevalent. 



The chemistry of runoff waters is dependent upon the character of bedrock and 

 surficial deposits. Variations in concentrations of nutrients (phosphate, 

 nitrates, potassium) in waters flowing into palustrine areas affect their pro- 

 ductivity and species composition. The scarcity of biogeochemicals in water- 

 sheds of siliceous bedrock may result in wetlands of low productivity. 



8-16 



