LANGTON and UZMANN: GULF OF MAINE MEGAFAUNA 



saster, and Solaster) occurred over viilually all 

 substrate types but were more prevalent on 

 coarser sediments, reaching a maximum density 

 of 0.17 m~" in a bouldery area. In contrast, 

 Ophiuroidea did not occur on gravel substrates 

 in significant numbers but did occur on slightly 

 gravelly sand at high density (1.23 m"") as 

 well as on the finer sands and muds. Only two 

 fish species occuiTed in sufficient density to de- 

 monstrate any substrate specificity. The silver 

 hake, Merluccius bilinearis, was observed rest- 

 ing on the bottom on fine mud sediments, while 

 the snake blenny, Lnmpenus lumpretaefoi'mis, 

 was observed on sandy silt. 



DISCUSSION 



This study is the first, broad scale, mega- 

 faunal survey in the Gulf of Maine using man- 

 ned submersibles. Previous submersible work 

 was limited to four DSRV Alvin dives in Wil- 

 kinson and Murray Basins in 1971 and 1972, 

 described by Rowe et al. (1975). The study by 

 Rowe et al. reported that pandalid shrimp and 

 ophiuroids were the numerically dominant 

 megafaunal animals observed along several 

 transects in these basins. From the present 

 work, it is cleai* that ophiuroids are numerically 

 dominant throughout the central and eastern 

 Gulf on the finer sediments (Figs. 2, 3). Pan- 

 dalid shrimp, on the other hand, ranked only 

 seventh in abundance in the present work (Fig. 

 2). Perhaps the abundance of shrimp observed 

 by Rowe et al. (1975) reflected the high popula- 

 tion levels, and correspondingly high catches, of 

 Pandalus borealis that occurred in the Gulf of 

 Maine in the late 1960s and early 1970s (Shum- 

 way et al. 1985). 



The description of the megafauna in the Gulf 

 of Maine that emerges from this study is not 

 complex. Relatively few taxa, or taxonomic 

 gi'oups, from two phyla dominated the mega- 

 benthos on a numerical basis (Fig. 2; App. 

 Table 1). These two phyla (Echinodermata and 

 Cnidaria) are different from the dominants iden- 

 tified from macrobenthic sui-veys in the Gulf, as 

 might be expected, owing to the methodological 

 differences and scales of resolution. Theroux 

 and Wigley (fn. 1), for example, reported mol- 

 luscs, annelids, and crustaceans to be the nu- 

 merical dominants, based on a more extensive 

 and geographically restricted analysis of the 

 Emery et al. (1965) survey, using surface de- 

 ployed sampling gear. Watling et al. (1988) 

 identified annelids, crustaceans, and echino- 



derms as the numerically dominant groups 

 based primarily on surface deployed box core 

 samples. Neither ceriantharians nor penna- 

 tulids, the numerical dominants in this study, 

 are adequately sampled with a 0.1 m" box core 

 (Watling^). Rowe et al. (1975) also noted signifi- 

 cant differences between core samples and vis- 

 ual counts, while other studies specifically com- 

 paring submersibles and photographic transects 

 with other sampling gear have shown substan- 

 tial differences when conducting a faunal census 

 (Wigley and Theroux 1970; Uzmann et al. 1977; 

 Theroux 1984). 



The distribution of megafaunal animals is re- 

 lated to sediment type in the Gulf of Maine (see 

 Figure 3 and Appendix Table 1). Watling et al. 

 (1988) also identified substrate, together with 

 the temperature range of the overlying water 

 mass, as major factors resulting in seven dis- 

 crete macrobenthic species assemblages in the 

 Gulf of Maine. Their analysis is based on both 

 box core and submersible sampling. Zoogeo- 

 graphic studies on specific megafaunal com- 

 ponents in the Gulf of Maine are rare, only 

 three taxonomic gi'oups occurring in this geo- 

 gi'aphic region have been investigated (Wigley 

 1960; Haynes and Wigley 1969; Franz et al. 

 1981; Shepard et al. 1986). In these three in- 

 stances the various environmental factors, in- 

 cluding sediment type, that potentially control 

 the animals distributional patterns have been 

 examined. Shepard et al. (1986), for example, 

 completed an extensive study of Ceriantharia 

 off the northeast coast of the United States. 

 Geographic and bathymetric zonation was at- 

 tributed primarily to temperature and sec- 

 ondarily to food supply and sediment type. 

 They found Cerianthus to be tolerant of a wide 

 range of temperature (8°-16°C) and to occur on 

 most substrates except gi-avel and coarse shift- 

 ing sand. In the present study cerianthai'ians 

 were also found to have httle substrate fidehty 

 although there was a noticeable absence from 

 areas of boulders and gravel (Fig. 3). Pandalid 

 shrimp, on the other hand, have been shown to 

 have a stronger affinity for sediment type 

 (Wigley 1960). Unfortunately the species of 

 shrimp could not be identified in the photo- 

 graphs we examined so a detailed comparison 

 with Wigley's results on the four species of 

 PandaHdae occurring in the Gulf of Maine is not 

 possible. Nevertheless, Haynes and Wigley 



-L. Watling, Darling Marine Center, University of Maine, 

 Walpole, ME 04573, pers. commun. 1988. 



949 



