Local-scale faunal turnover on the deep Pacific seafloor

The high biodiversity of the deep-sea floor is often attributed to high local coexistence of species achieved through microhabitat variation.Grassle & Sanders (1973; Deep-Sea Res 34: 313-341) proposed that deep-sea species were differentially adapted to multiple and small-scale successional patches that varied across the landscape and through time.However, results from both manipulative experiments and precision sampling to test the patch-mosaic model of Grassle & Sanders (1973) have varied, leading some authors to suggest that patch dynamics may be unimportant in explaining deep-sea biodiversity.We utilized a remotely operated vehicle and a rigid spatial sampling protocol to document macrofaunal turnover and individual species spatial dispersion at a 3203 m deep site in the Pacific Ocean over scales of 1 to 350 m.We found high variability in assemblage composition and, in contrast to most previous work, we also found that intraspecific species aggregation was common.These findings suggest that patch dynamics and microhabitat variation are important in promoting local species coexistence in the deep-sea benthos.