This chapter describes the general physical and biological features of the 

 estuarine system in coastal Maine and details the characteristics of the 

 subsystems and classes that comprise the system. Abiotic physical factors 

 addressed are geology, hydrography, and climate. The biological features are 

 introduced in the estuarine system level discussion and a general description 

 of biotic roles in the ecosystem is included. The biota are described further 

 in the specific subsystem (e.g., subtidal and intertidal) and class level 

 (e.g., flat, rocky shore, and emergent wetland) discussions. Biological 

 features described include the producers (phytoplankton, macroalgae, rooted 

 aquatics, benthic diatoms, and microbes), consumers (zooplankton, benthic 

 invertebrates, and fish and birds) and decomposers (bacteria and fungi). 



The interactions of characteristic components of the different trophic levels 

 are described under "Food Webs." The interactions of the biota with physical 

 factors are discussed under "Energy Flow." Primary production is examined 

 under "Primary Productivity." Biogeochemical cycling is illustrated in a 

 description of the role of nitrogen and the organic matter cycle in Maine 

 estuaries. Following the system level discussions, the subsystems and classes 

 comprising the estuarine system are described. Detailed descriptions of the 

 physical features and communities found in the varied estuarine habitats 

 identified in coastal Maine are described at this level. 



The descriptions of estuarine systems, subsystems, and classes presented in 

 this chapter apply generically to the various individual estuarine systems 

 (e.g., Machias River estuary and Penobscot River estuary) in coastal Maine 

 unless a specific estuary is cited. 



Many components (e.g., phytoplankton, zooplankton, invertebrates, fish, birds, 

 and marine mammals) of the estuarine system are similar to those of the marine 

 system. All aspects of the estuarine system are discussed in this chapter on 

 the general level but, for the sake of brevity, all habitats except those that 

 are unique to the marine system are discussed later on the class level. 

 Habitats discussed in the estuarine intertidal subsystem include protected 

 rocky shores, streambeds, gravel and cobble beaches, and sand and mud flats. 

 Habitats with characteristics unique to the estuarine subtidal subsystem 

 include unconsolidated bottoms, rock bottoms, and aquatic beds. The remaining 

 classes are discussed in chapter 4, "Marine System." 



Common names of species are used here except where accepted common names do 

 not exist. Taxonomic names of all species mentioned are given in the appendix 

 to chapter 1. 



DATA SOURCES AND COMPILATION OF DATA 



This chapter synthesizes the existing environmental information on Maine's 

 estuarine system. It draws on published and unpublished literature, 

 preliminary results of the National Wetlands Inventory (NWI) of the U.S. Fish 

 and Wildlife Service, personal communication with persons active in research 

 or management of the system, and the experience of the authors. 



Sufficiently reliable data are not available to characterize many of the 

 components of the estuarine system or to understand fully interactions 

 between the components. To some extent, this shortcoming has been overcome by 

 using data generated in other similar areas, such as Nova Scotia or 



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