Faunal Composition 



As at the 150-ni stations, faunal composition was very different between 

 canyon and slope stations at 550 m. The same small polychaete, Tharyx 

 baptisteae, was the top dominant at both stations, but it accounted for 32 

 percent of total individuals at the canyon station and only about 6 percent at 

 the slope station. In all, of the top 20 dominant species, only 6 were 

 dominant at both stations. 



Many species occurred at both stations but in significantly different 

 densities. We used analysis of variance to test for significant differences 

 in mean densities of individual species found at both stations: in almost all 

 cases, differences between stations were highly significant. For example, 

 abundance of the bivalve Nucula subovatdi was significantly higher at the slope 

 station, whereas the polychaete Cossura longocirrata was significantly more 

 abundant at the canyon station. As at 150 m, total densities were much higher 

 in the canyon than on the slope. 



Diversity 



Using either the Shannon index or Hurlbert rarefaction, the canyon 

 station had lower diversity than the slope station. The Shannon H' values 

 were 4.66 in the canyon and 6.00 on the slope. 



Similarity 



We compared the 550-m stations among themselves and with all other 

 stations sampled in the program. Cluster analysis of the 550-m stations 

 showed the slope station near the canyon to be more similar to another 550-m 

 slope station several kilometers distant than it was to the nearby canyon 

 station. The same pattern was seen when all stations were analyzed together. 



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