52, 



occurrences are very limited in Baltimore Canyon. In both 

 of these northern canyons the coral populations exhibit very 

 little cohesive structure. Only 39% of the data variance 

 in Lydonia Canyon was explained by eleven species, nine mono- 

 specific and one dispecific end-members. In Oceanographer 

 Canyon 63% of the data variance was explained by ten mono- 

 specific end-members. The coral fauna in most of the areas 

 surveyed tends to be dominated by one of these end-members. 

 This means that the distributions of most of the coral species 

 are controlled by different factors. However, this phenomenon 

 may also be an artifact of a problem encountered during the 

 survey, namely the disjointed photographic coverage in many 

 of the areas having rough terrain. Thus, some of these corals 

 may consistently co-occur in many of the areas, but spotty 

 coverage in these areas would not necessarily reflect this. 



Faunal associations 



Basically two patterns of symbiosis exist between animals, 

 facultative and obligatory. In facultative associations the 

 organisms have the "faculty" to enter into a symbiotic relation- 

 ship but need not do so to survive. In obligatory associations 

 one of the organisms needs to enter into a symbiotic relation- 

 ship in order to survive. There are also three major types 

 of interactions between symbionts. Mutualism means that 

 both animals derive benefit from the association. Commensalism 



