economically important species by cooperating Temperature and salinity characteristics 



Federal and State agencies . vary throughout the year and with locality and 



tidal stage so that a simple summary statement 



The estuary is large relative to the size cannot be made with respect to these variables, 



of the river, but its greatest area was found to However graphs are presented that summarize 



be not estuarine ecologically or hydrographically. this information reasonably well. 

 It can be conveniently divided into two parts: an 



upper, or interior part, and a lower . The upper Animal and plant life in the lower estuary 



section, within about six nautical miles of the are characteristically neritlc or coastal marine . 



river mouth, is characteristically estuarine. There is a much greater number of phyla and 



with marked dilution by the river and subject to species represented there than in the upper 



strong seasonal and tidal variations in salinity. estuary. The populations of the upper estuary 



The lower section, extending about 14 nautical are either isolated oligohaline species or mes- 



miles further to the Gulf of Maine, is actually a ohaline species with some extension of euryhaline 



ria or long, narrow bay with typical neritic populations from the lower estuary. A few 



marine conditions . It is a complex system with species appear to be isolated in the upper estuary 



many islands and interconnecting channels, one by a temperature barrier as well, 

 of which connects it with the estuary of the 

 Kennebec River. This has the effect of produc- 

 ing a local lowering of salinity in the surface 

 water toward the seaward end. 



Table 1. List of the more common aquatic animals collected or 



recorded from the Sheepscot estuary arranged according to habitat. 



I. High salinity (28-30 o/oo) intertidal sediments 

 Polychaete worms: 



Nereis virens Sars sand worm 



Nephtys caeca Fabricius 



Polydora ligni Webster 



Streblospio benedictr Webster 



Heteromastus filiformisClaparede 



Arenicola marina Linnaeus lug worm 



Clymenella torquata Leidy bamboo worm 



Pectinaria hyperborea Malmgren trumpet worm 



Amphitrite sp. 

 Molluscs: 



Mya arenaria Linnaeus soft-shell clam 



Macoma balthica Linnaeus 



Ensis directus Conrad razor clam 



Gemma gemma Totten 



_/ This list contains but a small fraction of the aquatic organisms in the estuary. The most 



interesting, conspicuous, or abundant species of fish and invertebrates are listed according to the 

 habitat in which they are most likely to be found. It does not follow, however, that every situation 

 where these various conditions prevail will be inhabited by every species listed for that habitat, nor 

 that many species so Listed will not be found elsewhere . 



Most of these animals have no common names, but where such a name is in general usage it 

 is included in the righthand column of the table as an aid to those not familiar with the Latin names. 

 As a further aid, the species are arranged in groups of more or less related members . 



14 



