2,100-Meter Stations 



We sampled three stations at 2,100 m: one in the canyon and two on the 

 adjacent slope. At this depth, the story was very different from that at 150 

 or 550 m. At 2,100 m, the fauna at all three stations was very similar. The 

 top dominant species at all three stations was the polychaete Aurospio 

 dibranchiata, the dominant infaunal species at 2,100 m along the east coast of 

 the United States at least as far south as Cape Hatteras. This species 

 accounted for 8 to 11 percent of all individuals at each station. At 

 shallower stations, the percentage contribution of the top dominant species to 

 each community was very different. 



Of the top 20 dominants at the 2,100-m stations, 11 or 12 were shared 

 between the slope and canyon stations, compared to 4 or 6 species shared 

 between canyon and slope stations at the shallower depths. Total densities 

 were similar at all three 2,100-m stations. 



Diversity 



Also in contrast to the situation at the shallower stations, diversity 

 was higher at the canyon station than at either of the 2,100-m slope stations, 

 whether measured by Shannon-Wiener or Hurlbert rarefaction. 



Similarity 



At 150 and 550 m, the canyon stations were clearly different from the 

 adjacent slope stations. At 2,100 m, the canyon station was highly similar to 

 the slope stations. 



SUMMARY 



In conclusion, we see that major differences in community structure occur 

 between canyon and slope stations at 150 and 550-m depth, but differences at 

 2,100 m are minor. Most interestingly, it appears that although subtle 



71 



