210 



NOAA Technical Report NMFS 140 



and mean biomass between <0.01 and 0.03 

 g/m 2 (Tables 26, 28; Fig. 236). Only 1% 

 of the samples in the three carbon con- 

 tent classes contained specimens of acorn 

 worms (Table 30). 



Chordata 



Ascidiacea — Ascidians were moderately 

 common in the New England benthos and 

 constituted 1.1% of the total number of 

 specimens and 2.2% of the total biomass 

 (Table 3). 



The size of solitary tunicates in our col- 

 lections ranged from 4 mm to more than 

 20 cm. Although colonial forms are known 

 to attain lengths greater than 50 cm in 

 this region, the specimens in our samples 

 were smaller (12 cm or less in length) 

 than the largest solitary forms. 



Interspecific variation in color of New 

 England tunicates was rather broad, and 

 in some groups the intraspecific varia- 

 tion was also considerable. The majority 

 of species were dull olive, tan, or brown. 

 A rather large number covered their tests 

 with sand grains or silt that very effec- 

 tively camouflaged them. A few groups 

 contained beautifully colored species. 

 Their coloration consisted of a blend- 

 ing of cream and light yellow with vari- 

 ous shades of orange and red. 



In order to control their rapid coloni- 

 zation on hard substrates and fouling of 

 man-made structures, such as ship bot- 

 toms, pipes, buoys, and similar structures, 

 the maritime industry incurs high eco- 

 nomic costs. Ascidians occurred in 181 

 samples (17% of the total). Their density 

 averaged 16.3/m- and their biomass aver- 

 aged 4.1 g/m 2 (Table 5). 



Geographic Distribution 

 Ascidians were distributed over large por- 

 tions of the study area (Fig. 237), but 

 their occurrence was patchy, with density 

 changing abruptly from one locality to 

 another. They were most common in the 

 coastal areas and on the offshore banks 

 and were sparse or absent from the fol- 

 lowing areas: the deeper part of the west- 

 ern Gulf of Maine, north-central Georges 

 Bank, and parts of the continental shelf 

 off Connecticut, New York, and Newjer- 



