// 20 / . v,_ 

 S' ,' \'- 40°30' 



.■/ 



C\ ---''7 / 290 / I 

 ^ K/ fir' '- v ' 1 ■' I \ 



A < ,\ \ 



V \ 



M / 



-■'I / 



I 



l \ I 





40 20' 



~J 1-99 m' 

 3 100-299/n 



40°10 



7350' 



73°40' 



Figure 14.— Distribution and abundance of Phoronis architecta in the \e» 

 York Bight apex. 



FEEDING ECOLOGY: Phoronids. like other lophophorates. are 

 ciliary mucous suspension feeders, subsisting on plankters or detri- 

 tus fragments (Gosner 1971). 



REPRODUCTION AND GROWTH: P. architecta has been 

 regarded as a protandric hermaphrodite, but Hyman ( 1959) has 

 questioned this view. Fertilization is external. No brooding occurs, 

 with eggs hatching as an actinotroch larva (Gosner 1971). Typical 

 actinotroch larvae were taken in plankton tows in Florida waters by 

 Paine ( 1961) in December and February-August when towing was 

 discontinuous. Adults reared in November had ova floating in their 

 coelomic spaces, indicating a long, if not continuous, breeding sea- 

 son. Davis (1950) also collected actinotrochs in Florida in Decem- 

 ber and September and Hedgpeth (1954) recorded their presence 

 during winter months in Louisiana and Texas. 



After several weeks of a free-swimming planktonic existence. 

 the actinotroch undergoes a rapid metamorphosis and sinks to the 

 bottom, where it secretes a tube and begins its adult existence 

 (Barnes 1963). 



Phylum Mollusc. i 



Class Gastropoda 



Nassarius trivittatus (Say, 1822) 



DESCRIPTION: 1.9 cm in length: rather light shelled. 8-9 

 whorls, nuclear whorls smooth. Whorls in spire with 4-5 rows of 



strong, distinct beads. Color light ash to yellowish gray (Abbott 

 1974). The Nassariidae are gregarious, often occurring in great 

 numbers (Abbott 1968). 



DISTRIBUTION: 



(Abbott 1974). 



Newfoundland to off northeast Florida 



HABITAT: Common from shallow water to about 82 m (Abbott 

 1974). Franz (1976) stated that Nassarius trivittatus is characteris- 

 tic of the medium sand community in Long Island Sound. How- 

 ever, N. trivittatus has also been recorded in muddy sediments in 

 Delaware Bay (Kinneret al. 1974) and in high silt-clay sediments in 

 northwestern Buzzards Bay (Driscoll and Brandon 1973). 



Nassarius trivittatus was the only abundant gastropod, occurring 

 in numbers up to 20/m-\ collected in the New York Bight apex. It 

 was found in depths of 1 1-27 m and was most characteristic of low 

 organic fine sands (Fig. 15; Table 1). 



FEEDING ECOLOGY: N. trivittatus, as all nassa snails (Nassa- 

 riidae), is one of the most active and responsive scavengers among 

 marine invertebrates. It has a keen ability to detect the products of 

 chemical decomposition of dead flesh. Within a few seconds of 

 sensing such a stimulus, the snail heads directly for its source. Nas- 

 sas eat decaying fish and invertebrates; polychaete egg masses; 

 eggs of the moon snail, Lunalia hews; benthic diatoms; and detri- 

 tus on the sediment surface (Clarke 1956; Scheltema 1964; Abbott 

 1968). They, in turn, are preyed upon by fish such as haddock, 

 Melanogrammus aeglefinus (Wigley 1956). 



7340' 



I 



Figure 15.— Distribution and abundance of Nassarius trivittatus in the Nev* 

 York Bight apex. 



10 



