5-33 



Potydora ligni 



Polydora lignl is a small, tube-dwelling spionid polychaete 

 commonly found on oyster and mussel beds. It was extremely abundant 

 from July 1976 through 1977 on panels maintained at Long Wharf and 

 occurred in lower numbers throughout New Haven Harbor. 



Work on pollution-indicator species revealed this opportun- 

 istic (Grassle and Grassle, 1974) mudworm to be an indicator of organic 

 pollution (Anger, 1977; Leppakoski, 1975). It is restricted to estu- 

 aries (Blake, 1969) where it builds tubes of silt from suspended sedi- 

 ments (TRIGOM, 1973) . Reproduction occurs early in the spring (TRIGOM, 

 1973) , after which adults brood their eggs in tiibes and the larvae are 

 released to the water column from April through July (Blake, 1969) . P. 



ligni are gregarious with larvae tending to settle near other mudworm 



2 

 tubes. Larsen (in TRIGOM, 1973) reported peak densities of 10,721/m as 



a normal post-reproductive level. These high densities can cause exten- 

 sive silt build-up resulting in oyster mortality (Daro and Polk, 1973; 

 Galtsoff , 1964) . 



Distribution of Polydora ligni in New Haven Harbor and other 

 Long Island Sound estuaries has been sporadic. Unusually high numbers 

 recorded in New Haven Harbor at Long Wharf in 1976 and 1977 may have 

 been the result of a successful population set (Figure 5-11) ; alterna- 

 tively, previous years' samplings may have underestimated this species, 

 when it was recorded in lower niambers as mudworm tubes. The generally 

 higher abundance at Long Wharf is probably related to the higher silt 

 content of the inner harbor. Seasonal peak abundances were reported in 

 July at Long Wharf in 1976 and all stations in 1977. Mudworm tubes at 

 Millstone were recorded in August and September 1973 on short-term 

 panels. 



