subtidal zone of the Sheepscot estuary (Larsen and Doggett 1978b). 

 Commercially important worm flats are illustrated in atlas map 4. 



Life history . Despite in-depth studies of the reproductive cycle of the 

 sandworm by Bass and Brafield (1972) in Great Britain, Rasmussen (1973) in 

 Denmark, and Snow and Marsden (1974) in New Brunswick, Canada, knowledge of 

 its development remains incomplete. Sexual maturation is reached in 2 to 3 

 years. Most data (e.g., Bass and Brafield 1972) indicate that only males 

 undergo epitoky (significant body tissue modification) before spawning and 

 only males swarm. 



In coastal Maine spawning occurs from mid-March to late June and peaks in late 

 April and May. Laboratory culture experiments indicate that temperature 

 affects the rate of sexual maturation but does not appear to trigger 

 successful spawning (Bass and Brafield 1972). Raising the temperature of the 

 water in cultures causes worms to develop and release gametes more quickly but 

 the gametes usually are not viable. Tidal fluctuation and subsequent changes 

 in hydrostatic pressure are considered influential in the timing of spawning. 

 Hormonal and physiological factors are probably significant also (Bass and 

 Brafield 1972). 



At the time of swarming, males swim to the surface where they release sperm, 

 and then die. Individual females release from 100,000 to 17 million eggs 

 depending on the size of the female within the burrow (TRIGOM 1974), and may 

 subsequently die. 



Most sandworms live to be about 3 years old but Dean (1978a) found a few worms 

 up to 5 years old, plus one individual which may have been older. 



Fertilized eggs sink to the bottom and the larvae develop in the burrow for 5 

 to 6 days after which they become pelagic for a short time. Growth of larvae 

 is initially achieved by increasing the number of segments followed by 

 enlargement of the segments (Bass and Brafield 1972). 



Larvae then resume a benthic existence, probably subtidally, and attach to the 

 sediment surface. After 12 days the organism may form shallow burrows and 

 after 4 months it either establishes a subtidal burrow or migrates to the 

 intertidal zone. Migration to the intertidal zone also may occur after a year 

 (Bass and Brafield 1972). 



Adult sandworms feed on various types of invertebrates, both in the water 

 column and on the bottom. They also feed on algae, Ulva (Pettibone 1963) and 

 detritus (personal communication from K. Fauchald, University of Southern 

 California, Los Angeles, CA; April, 1979). 



Habitat preferences . Sandworms live in the intertidal and subtidal zone 

 of both the marine and estuarine systems. This species is found in estuarine 

 areas where the salinity of the water column is <0.5 ppt for over 8 hours of 

 the tidal cycle (Larsen and Doggett 1978b). The greatest subtidal abundances 

 (637 worms/m ) in the Sheepscot estuary occurred in an area where salinity 

 varied from 0.5 to 19 ppt (Larsen and Doggett 1978b). 



The adult life of the sandworm is spent on subtidal unconsolidated sediments, 

 flats, or beach/bar habitats (Larsen and Doggett 1978a). This species is 



12-27 



10-80 



