108 



NOAA Technical Report NMFS 140 



Frequency of occurrence of sipunculids in the samples 

 paralleled the trends established by density and bio- 

 mass. Range of occurrence was from 2 to 31% (Table 30). 



Echiura 



Echiurid worms, like sipunculids and priapulids to which 

 they are taxonomically allied and which they resemble 

 somewhat in terms of size and habits, form a rather 

 obscure and small group and are not very well known in 

 this region. They are not especially abundant in the 

 New England region, accounting for only 0.2% of total 

 biomass and >0.1% of total density (Table 3). 



Echiurids are round, unsegmented worms that typi- 

 cally burrow into sand and mud. Others are found 

 among rocks and on coral reefs; one southern species 

 uses the tests of sand dollars as a habitat. 



Their size varies greatly, ranging from tiny 3-mm 

 males to large females over 300 mm in length. Speci- 

 mens in our samples were in the 2 to 8 cm size range. 



They are reported to prefer shallow waters; however, 

 the majority of our specimens were collected from deep 

 water. Depth range of our samples was from 20 to 3,975 

 m, but only 5 of the samples were in water depths of less 

 than 1.000m. 



Color of specimens ranges from drab grays and brown 

 to green, red, and rose colored, and some were transparent. 



Echiurids occurred in 17 samples (1.6% of total). Den- 

 sity averaged 0.1 /m 2 and biomass 0.30 g/m 2 (Table 5). 



Geographic Distribution 



Echiurids were almost exclusively restricted in their 

 geographic distribution to the lower continental shelf 

 and upper continental slope and were found in rather 

 small, discrete patches (Fig. 87). The onlv exceptions 

 were two small areas inshore, one at the mouth of Long 

 Island Sound and the other near Mt. Desert Island in 

 the Gulf of Maine. Densities averaged between 1 and 9 

 individuals/m 2 , whereas average biomass ranged from 

 <0. 1 to a high of 12.5 g/m 2 . 



Echiurids were absent from Nova Scotia and Georges 

 Bank and were present in generally equitable densities 

 in the other standard geographic areas. Highest aver- 

 age densities occurred in the two slope areas (Table 6; 

 Fig. 88). Biomass was also highest in the slope area; 

 significantly lower values were observed in the other 

 areas in which they were found (Table 8; Fig. 88). 

 Frequency of occurrence of echiurids in samples ranged 

 from <1% to 15%. Lowest occurrence was in Gulf of 

 Maine and highest on Georges Slope (Table 10). 



Bathymetric Distribution 



Echiurids were found at depths ranging from 20 to 



3,975 m. Their numerical abundance was greatest, al- 



beit low (0.5 to 0.6/m 2 ), in water depths greater than 

 1,000 m and even lower (0.02-0.3/m 2 ) at shelf and 

 inshore depths (Table 1 1, Fig. 89). 



The relation of biomass to water depth was similar to 

 that of numerical density. Continental slope depths ( 1 ,000 

 to nearly 4,000 m) provided highest mean biomass of this 

 small group ranging from 3.5 to 5 g/m 2 . Significantly 

 lower (0.22 to 0.01 g/m 2 ) biomasses occurred in inshore 

 and midshelf depths, respectively (Table 13; Fig. 89). 



Echiurids were found in 19 to 21% of the samples in 

 the two depth range classes below 1,000 m, but in only 

 <1% of the samples in the 100-199 m range and 2% in 

 the 0-24 m range class (Table 15). 



Relation to Sediments 



Echiurids in our samples were rather restrictive in their 

 choice of sediment, preferring to inhabit only the two 

 finest-grained types. Both mean density (0.2 and 0.3/ 

 m 2 ) and biomass (0.79 and 0.69 g/m 2 ) were quite evenly 

 apportioned between sand-silt and silt-clay, respectively 

 (Tables 16, 18; Fig. 90). Three percent of the samples 

 in sand-silt and 5% in silt-clay contained specimens 

 (Table 20) 



Relation to Water Temperature 



Considering the deep water and fine sediment prefer- 

 ences of echiurids, it is not surprising to find that they 

 also had restricted temperature preferences. They oc- 

 cupied only three temperature ranges; areas with the 

 most stable annual range (0-3. 9°C) contained the low- 

 est density (0.1/m 2 ) but the highest biomass (0.9 g/m 2 ); 

 areas with an annual range of 16-19. 9°C had the high- 

 est density (0.4/m 2 ) and also contained the second 

 highest biomass; and areas where the temperature range 

 was between 4° and 7.9°C had moderate density and 

 low biomass (Tables 21, 23; Fig. 91). 



Frequency of occurrence ranged from 1 to 4% (Table 

 25), being highest in the narrowest temperature range. 



Relation to Sediment Organic Carbon 



Echiurids were also restrictive in relation to organic 

 carbon content of sediments, occurring only where 

 amounts ranged from 0.01 to 1.49% (Fig. 92). Density- 

 was greatest in carbon contents 0.50 to 0.99%, falling to 

 lower levels in areas of both lesser and greater content 

 (Table 26); conversely, biomass showed an increasing 

 trend with organic carbon content (Table 28). Fre- 

 quency of occurrence in samples reflected the trend 

 for density (Table 30). 



Priapulida 



Among the invertebrate fauna of the New England 

 region priapulid worms make up perhaps the rarest 



