Physical reworking by near-bottom flow alters the metazoan meiofauna of Fieberling Guyot (northeast Pacific)

Although much of the deep sea is physically tranquil, some regions experien ce near-bottom flows that rework the surficial sediment. During periods of physical reworking, animals in the reworked layer risk being suspended, whi ch can have both positive and negative effects. Reworking can also change t he sediment in ecologically important ways, so the fauna of reworked sites should differ from that of quiescent locations. We combined data from two r eworked, bathyal sites on the summit of Fieberling Guyot (32 degrees 27.631 'N, 127 degrees 49.489'W; 32 degrees 27.581'N, 127 degrees 47.839'W) and co mpared the results with those of more tranquil sites. We tested for differe nces in the following parameters, which seemed likely to be sensitive to th e direct or indirect effects of reworking: (1) the vertical distribution of the meiofauna in the sea bed, (2) the relative abundance of surface-living harpacticoids, (3) the proportion of the fauna consisting of interstitial harpacticoids, (4) the ratio of harpacticoids to nematodes. We found that t he vertical distributions of harpacticoid copepods, ostracods, and kinorhyn chs were deeper on Fieberling. In addition, the relative abundance of surfa ce-living harpacticoids was less, the proportion of interstitial harpactico ids was greater, and the ratio of harpacticoids to nematodes was greater on Fieberling. These differences between Fieberling and the comparison sites suggest that physical reworking affects deep-sea meiofauna and indicate the nature of some of the effects. (C) 1999 Elsevier Science Ltd. AII rights r eserved.