WIGLEY and STINTON: REMAINS FROM MARINE SEDIMENTS 



Figure 25. — Bathymetric distribution of skeletal re- 

 mains of crustaceans and coelenterates. 



COMPARATIVE DISTRIBUTION OF 

 ALL TAXONOMIC GROUPS 



groups whose centers of concentration were in- 

 shore in relatively shallow waters were cirri- 

 pedes and Echinarachnius parma. The dominant 

 midshelf and outer-shelf components were gas- 

 tropods, pelecypods, and decapods. Pelecypods, 

 scaphopods, Brisaster, and Flabelhim were com- 

 mon along the outer portion of the continental 

 shelf and upper portion of the continental slope. 

 The chief components in deeper sections of the 

 continental slope were fish otoliths and cephalo- 

 pod mandibles. 



The distribution of the principal animal re- 

 mains in relation to each other, sediment type, 

 and water depth, and, to a limited extent, their 

 north-south geographical position on the conti- 

 nental shelf and slope are illustrated in Figure 

 26. This chart is a generalized profile of the 

 study area with the inshore (north) section on 

 the lefthand side and the oflFshore (south) sec- 

 tion on the righthand side. Broad, diagonally 

 striped bands indicate relatively high density, 

 and narrow lines indicate low density. Animal 



SEDIMENT 

 TYPE 



in 



0. 



lij 

 o 



a: 



i 



m 





" / Sri 



i 



-4 





IHIGH DENSITY 



I 



LOW DENSITY 



_ SILTY SAND 



SAND 



SANDY SILT 



SILTY SAND 



SAND 



Figure 26. — Schematic diagram of the density distribu- 

 tion of macroscopic remains of the major animal groups 

 represented in bottom sediments arranged according to 

 water depth and sediment type (see text for details). 



SUMMARY 



Skeletal remains of deceased animals were 

 common seabed components on the southern New 

 England continental shelf and the upper part 

 of the continental slope. In some sections, par- 

 ticularly in shallow water, skeletal remains con- 

 stituted a substantial portion of the substrate 

 volume — up to nearly 30 9f in the vicinity of 

 Nantucket Shoals. Offshore, near the margin 

 of the continental shelf and in the upper portion 

 of the continental slope, macroscopic animal re- 

 mains generally constituted less than 1 9f of the 

 substrate. 



Remains of benthic, pelagic, and nektonic or- 

 ganisms were present; benthic forms were dom- 

 inant. Planktonic animals (represented only by 

 pteropods) were sparse. Fish and cephalopods 

 were the principal nektonic forms. They were 

 rather abundant in the deeper waters, particu- 

 larly on the outer portion of the continental 

 shelf and on the continental slope. 



The two animal groups that contributed the 

 largest quantities of material to the substrate 

 were echinoid echinoderms and pelecypod mol- 

 lusks. Although remains of a wide variety of 

 fish species were present, the quantity was mod- 

 erate and the sizes small; consequently the vol- 

 ume of fish remains was rather small. 



ECHINODERMS 



The exceedingly abundant remains of echino- 

 derms consisted exclusively of echinoids. Onlj'- 

 one species — Echinarachnius panna — occurred 

 in high densities and was the most abundant 

 and widely distributed component of organic 



37 



