and Johnson 1937). The life cycle of various species is controlled by food 

 supply (quantity and quality) and physical factors (see below). 



Only a few species of zooplankton are either dominant or abundant in the 

 coastal waters of Maine. The seasonal abundance and time of reproduction of 

 11 species of copepods and seven groups of meroplanktonic species are 

 discussed in appendix F of chapter 4. The zooplankton Calanus f inmarchicus is 

 not dominant in the estuaries of Maine; however, it is abundant in coastal 

 waters of Maine. Meroplanktonic zooplankton, which are addressed in appendix 

 F of chapter 4, are characterized as being (1) dominant (i.e., abundant); (2) 

 important to the benthic population (e.g., barnacles, molluscs, or 

 polychaetes) ; (3) important as predators (i.e., coelenterates or Sagitta 

 elegans ) ; or (4) dominant in marine populations and included for comparison 

 (i.e., Cladocerans) . 



Data on zooplankton species composition come from studies reported by McAlice 

 (1970 to 1977) on the Montsweag Bay area of the Sheepscot River estuary and by 

 Lee (1974) on the Damariscotta River estuary. Gross estimates of the relative 

 abundance of zooplankton in 1975 to 1976 are given for the Montsweag Bay area 

 in the Sheepscot River estuary (McAlice et al. 1978; table 5-5). Copepods and 

 tintinnids dominate zooplankton populations in the upper Sheepscot estuary. 



Fishes are found primarily in the subtidal zone. Demersal fishes are more 

 closely associated with specific bottom types (classes) than pelagic fishes. 

 The majority of pelagic and some semidemersal fishes range freely throughout 

 the water column and are dependent on estuarine open water habitat for at 

 least part of their life cycle. These fishes include the rainbow smelt, 

 striped bass, spiny dogfish, bluefish, Atlantic mackerel, the herrings 

 (Atlantic herring, blueback herring, alewife, American shad, and Atlantic 

 menhaden), and some trout (Atlantic salmon, brook trout, and brown trout). 

 Fishes are discussed in detail in chapter 11, "Fishes." 



A number of bird species use estuarine open water for feeding and resting. 

 Large concentrations of waterfowl inhabit estuarine open water. The most 

 abundant species are eiders, scoters, oldsquaw, scaup, mergansers, goldeneyes, 

 and bufflehead. They are primarily migrants and wintering species. They may 

 feed on a variety of substrates. Dabbling ducks and the above mentioned bay 

 ducks and sea ducks often rest on open water. Large numbers of gulls use 

 estuarine open water both for feeding and resting. Cormorants feed in large 

 numbers on benthic and pelagic estuarine fish. Ospreys, bald eagles, and 

 kingfishers also feed in estuarine open water. Chapter 14, "Waterbirds ," 

 chapter 15, "Waterfowl," and chapter 16, "Terrestrial Birds," contain more 

 detailed information on these birds. 



Subtidal unconsolidated bottom . In Maine estuaries, unconsolidated 

 bottoms are the predominant habitat type. The preliminary data from NWI 

 indicate that only 5% of the identified estuarine subtidal subsystem consists 

 of unconsolidated bottom. However, the vast majority of the estuarine areas 

 underlying estuarine open water in coastal Maine (subtidal open water 

 comprises more than 90% of the identified subtidal area) is actually 

 unconsolidated bottoms. This habitat probably comprises most of the estuarine 

 floor along with a relatively small area of aquatic beds. 



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