13 were also dominant at the slope station. Of the top 20 dominants at the 

 fine-sediment canyon station, only 4 were also dominant at the slope station. 

 Density was highest at the fine-sediment canyon station, followed by the 

 coarse-sediment canyon and slope stations. 



Diversity 



We measured diversity using both the Shannon-Wiener information index and 

 the Hurlbert rarefaction method. The coarse-sediment canyon station had the 

 highest Shannon-Wiener diversity (5.41), followed by the fine-sediment canyon 

 station (4.72). The slope station had the lowest diversity (4.25). 



For the rarefaction method, we calculated the number of species expected 

 for a given number of individuals. This method allows us to compare samples 

 of unequal sizes by reducing them to a common sample size. According to this 

 measure, the two canyon stations were less diverse than the slope station. 



Similarity 



Based on this analysis, we found that none of the three 150-m stations 

 were really very similar to each other. The canyon station with fine 

 sediments was seen to be most similar to a station in the "mud patch" located 

 far to the west (on the shelf south of Martha's Vineyard). The coarse- 

 sediment station was similar to a station near the head of Oceanographer 

 Canyon, and the slope station was most similar to other slope stations near 

 the drill site in Block 410, several kilometers away. Despite the dominance 

 of Ampelisca at both the slope and fine-sediment canyon stations, the 

 remaining faunal composition at the two stations was very different. 



550-Meter Stations 



There were two stations at 550 m, one inside the canyon and one on the 

 adjacent slope. Sediment texture--a muddy sand--was very similar at the two 

 stations. 



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