6. Species composition shifts Y Y 



7. "Distinctiveness" of canyon 



species Y ? 



"Distinctiveness" was expressed in a number of different forms: "canyon 

 indicator" species and communities, "unique" species and communities, and 

 commercially important species "typically" found in canyons. Although it was 

 agreed that no species is unique to canyons, a number are particularly 

 diagnostic of canyon environments. These include the white hake, tilefish, 

 lobster, and various corals and sponges. Further discussion dealt with 

 various aspects of canyon populations including: migratory species vs. 

 permanent residents; mobile vs. attached (sessile) forms; and juvenile forms 

 that use canyons as nursery sites. Cooper stated that canyons are unique for 

 lobsters in that they serve as a major nursery site as well as home grounds. 

 Valentine said distinctive bottom communities such as the "pueblo villages" 

 (burrowed outcrops of Pleistocene silt that harbor a diverse fauna of fish and 

 crustaceans) are found in some larger canyons but not in small, shallow 

 canyons or gullies such as Heeltapper, Filebottom, and Dogbody. It is 

 difficult to agree on a generic "canyon" classification when present data 

 suggest there are at least three types of canyons along the Georges Bank 

 shelf. Butman suggested that the biological characteristics could be applied 

 on a canyon-by-canyon basis. Teal pointed out that the people presently 

 discussing the issues were best qualified to do that. 



POSSIBLE BIOLOGICAL IMPACTS 



Hecker continued with a series of questions on possible impacts of 

 drilling on canyon communities. 



■ What are the "stock" populations in canyons and how are they 

 influenced? 



90 



