Table 1. — Residues of Polyslream in oysters and clams on 

 a 0.4-hectare bed in New Haven Harbor, Conn., after it 

 was treated with Poly stream-sand, June S7-S9, 1966 



Table 2. — Residues of Polyslream in oysters collected at 

 various distances from lot 42, Norwalk, Conn. Lot was 

 treated on August 24, 1966 



were at similar levels and were lost at similar rates 

 (table 1). 



Oysters removed from a treated bed and re- 

 jjlanted on an untreated area lost any residue of 

 Polystream within a Aveek. Nevertheless, the first 

 few times oysters that had once grown on a treated 

 bed were to be harvested, they were analyzed for 

 any possible residue of Polystream before clear- 

 ance for marketing. None of these oysters had 

 residues. 



In 1966, 1 determined the rates of loss of Poly- 

 stream in oysters at several distances from lot 42, 

 Norwalk, which was treated on August 24, 1966, 

 and where strong currents had washed many gran- 

 ules off the lot. After 8 days, residues were as high 

 as 0.3 p.p.m. in oysters 150 m. from the lot and 

 were higher in oysters closer to the lot. On October 

 13, however, only those oysters 15 m. or closer to 

 the lot showed any residue. At this distance the 

 level had dropped from 1.7 p.p.m. in September 

 to 0.2 p.p.m. On December 8, 106 days after the 

 treatment, no residues were detected in any oysters 

 outside the treated lot (table 2) . 



To determine the quantity of Polystream in tis- 

 sues of other organisms inhabiting an oyster bed, 



I made periodic collections from treated beds. All 

 species of animals or plants collected within a year 

 had accumulated a small quantity of Polystream. 

 Residues of Polystream eventually diminished in 

 those species, namely, the bay scallop, Pecten irra- 

 (liaTis, hermit crab, and sea lettuce, Ulva sp., where 

 comparisons between time intervals were made 

 (tables). 



By holding northern lobsters in a cage for a 

 week in the center of a bed 45 days after it was 

 treated, I found that they do accumulate a small 

 residue of Polystream (1.4 p.p.m.) when retained 

 in a treated area. A group of lobsters held on the 

 treated lot for a week and then held on an un- 

 treated area for another week did not have any 

 residue. Thus, lobsters may accumulate a small 

 quantity of Polystream while they inhabit a 

 treated bed, but they lose it soon after they leave 

 the bed. 



To determine mortality rates of oysters because 

 of possible predation by oyster drills on treated 

 beds, divere collected oysters periodically on sev- 

 eral beds. The divers either swam across the center 

 of beds for a distance of perhaps 150 m., gathering 

 about 30 clusters of oysters randomly, or they col- 

 lected oysters and all other material from within 

 a metal ring enclosing either 1 or 1.5 m.= of bottom 

 from 10 different sections. 



Table 3. — Residues of Polystream in animals and plants inhabiting oyster beds in Conn, and N.Y. treated with Polystream 



Animal or plant 



Location 



Time art«r Residue 

 treatment 



Northern puffer {SphatToides maculaius) New Haven (State spawning bed). 



Sea robin {Prionotua carolinus) New Haven (State spawning bed). 



Sand shark (.Carcharias taurue) _ _. New Haven (lot 152) 



Starflsh (Asteri<u forbesi) New Haven (lot 16) 



Bay scallop {PecUn irradiant) Sag Harbor (lot S) 



Bay scallop Sag Harbor (lot S) 



Northern moon shells iPolinictB sp.) Northport Got 1) , 



Hermit crab (Pojurus sp.) New Haven Oot 162) 



Hermit crab. 



Mud crab (Neopanope teiana) __ New Haven (lot 152). 



Red sponge (Microciona proliftrd) New Haven (lot 13).. 



Spaghetti grass (Codium fragile) Sag Harbor (lot S)... 



Sea lettuce (Wcasp.).. New Haven (lot 162). 



Sea lettuce. Sag Harbor OotS)... 



288 



U.S. FISH AND WILDLIFE SERVICE 



