Impact of large-scale natural physical disturbance on the diversity of deep-sea North Atlantic nematodes

Nematode alpha diversity from 3 physically disturbed sites in the deep Nort h Atlantic was compared with reference sites. Nematode diversity at the HEB BLE benthic storm site was statistically, and significantly, lower than at reference sites. Nematode diversity at the Madeira Abyssal Plain site, whic h was subject to a turbidite dated at 930 BP, also showed a significantly l ower diversity than reference sites. However, limited data suggest that div ersity was not low at a Venezuela Basin turbidite site. The difference in n ematode diversity between the 2 turbidite sites is ascribed to a long term change in sediment conditions at the Madeira site. The Venezuela Basin turb idite site has a sedimentation rate greater than the Maderia site by 1 to 2 orders of magnitude, and this was reflected in the sediment profiles. Anot her possibility is that the Venezuela Basin turbidite is considerably older , by at least 1000 yr, than the Madeira turbidite, allowing more time for r ecolonisation. The data suggest that deep-sea nematode diversity may be aff ected by physical disturbance but that deep-sea nematodes, like their shall ow counterparts, are more robust than macrofauna such as polychaetes to suc h impacts.