SHEPARD ET AL.: ECOLOGY OF CERIANTHARIA 



Hecker et al. (1980) also reported seeing small 

 unidentified Ceriantharia at about 1,300 and 1,000 

 m, respectively. We saw (from submersibles) no 

 Ceriantharia from 1,000 to 1,600 m for comparison. 

 In addition to the six documented species above, 

 other Ceriantharia sighted in or near the region in- 

 clude two possible species photographed by Hecker 9 : 

 one at depths of 1,800 to 2,800 m (from Lydonia 

 Canyon to Cape Lookout, NC), which resembles a 

 stout black Cerianthid B, and another resembling 

 Cerianthid A (except its tube extends above the 

 seafloor) at depths of 500 to 1,000 m off Cape Hat- 

 teras. Rowe and Menzies (1969) photographed 

 Ceriantharia on the continental slope (at depths of 

 400 to 3,000 m) south of Cape Hatteras (about lat. 

 34 °N) which they guessed to be Ceriantheomorphe 

 brasiliensis Carlgren. However, they presented no 

 photographs for comparison and collected no 

 voucher specimens. The C. brasiliensis specimens 

 identified by Carlgren (1931) were from Brazil, 

 South America, and its resemblance to other slope 

 species is uncertain. Submersible dive time devoted 

 to in situ documentation and collection of specimens 

 is obviously needed in order to identify the deep- 

 water species 10 . 



Relation to Latitude 



North of Cape Cod and Georges Bank (lat. 42° to 

 44 °N) the continental shelf is dominated by the Gulf 

 of Maine, a feature unlike the rest of the shelf in 

 the region because of its topographic irregularity 

 and because it reaches depths of more than 100 m 

 closer to shore. The lack of tidal mixing below 100 

 m over much of the gulf, and the fact that the prin- 

 cipal source of its bottom water is thermally stable 

 continental slope water introduced through the 

 Northeast Channel, results in water temperature 

 stratification which keeps the gulf bottom water 

 temperatures virtually constant throughout the year 

 (TRIGOM-PARC 1974; Rowe et al. 1975; Ingham et 

 al. 1982, p. 43). The narrow extreme range of bot- 

 tom water temperature (A T) dominant from lat. 42° 

 to 43°N (Fig. 5) may account for low Ceriantharia 

 occurrence at grab sample stations there (Fig. 4), 

 while peaks in occurrence are evident at lat. 40° to 

 41 °N (shelf just south of Cape Cod, including south- 

 ern Georges Bank), and from 44° to 45°N (shelf off 



9 B. Hecker, Lamont-Doherty Geological Observatory, Columbia 

 University, Palisades, NY 10964, pers. commun. October 1984. 



10 For all photographed, but unidentified slope species, we know 

 of only one voucher specimen (of Unidentified Species I), present- 

 ly located at the Harvard Museum of Comparative Zoology, Cam- 

 bridge, MA. 



Nova Scotia) may be associated with more favorable 

 intermediate temperature ranges which prevail 

 there (8° to 15.9°C). High Ceriantharia occurrence 

 at grab sample stations between 37° to 38 °N is in 

 part due to high occurrence at stations in the lower 

 half of Chesapeake Bay; occurrence was 56% at nine 

 Bay Stations and 23% at 52 shelf/slope stations. 

 However, our data is too sparse and inconclusive to 

 make a bay versus non-bay comparison, or explain 

 the high occurrence at shelf stations in this area. 



According to Gosner (1971), the continental 

 margin from Cape Hatteras to Nova Scotia is 

 divided into two faunal provinces with respect to 

 benthic invertebrates: a Boreal (cold-temperate) 

 province north of Cape Cod, and a Virginian (warm- 

 temperate) province of Cape Cod, MA. Theroux (in 

 press) considers the situation to be more complex 

 and to depend on the species considered, but agrees 

 that Cape Cod and Georges Bank are the beginning 

 of a rapid transition from cold to warm temperate 

 fauna, and suggests that the transition is associated 

 with Georges Bank and Nantucket Shoals thermal 

 fronts (Fig. 5; Ingham et al. 1982, p. 40-41). 



Using Gosner's (1971) faunal province descrip- 

 tions, our submersible data indicate that, in addi- 

 tion to C. americanus, at least two other warm- 

 temperate species inhabit the northwest Atlantic 

 continental shelf (Cerianthids C and D). The only 

 cold-temperate shelf species, Cerianthid B (probably 

 C. borealis) ranges south to Cape Hatteras (Tables 

 1, 3). The last species we saw (Cerianthid A) is 

 bathyal. 



Relation to Bathymetry 



Bathymetric zonation of benthic fauna has been 

 previously described for the continental shelf-slope 

 region of the northwest Atlantic (Wigley and Emery 

 1967; Rowe and Menzies 1969; Sanders and Hessler 

 1969; Rowe 1972; Grassle et al. 1975; Haedrich et 

 al. 1975, 1980; Hecker et al. 1980; Valentine et al. 

 1980; Wigley and Theroux 1981). Rowe et al. (1982) 

 cautioned, "'zones' that previous investigations 

 have described apparently are a function both of the 

 animal groups studied and distribution of samples 

 with depth". Thus, our discussion of Ceriantharia 

 zonation is limited to depths <2,000 m, since below 

 that depth there were no submersible data to sup- 

 port the grab sample data. 



Ceriantharia distribution, as determined from the 

 grab sample data (Fig. 4), our submersible obser- 

 vations (Table 3), and data from other investigations 

 (Table 1) imply boundaries (defined here as depths 

 characterized by distinct changes in the benthic com- 



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