Strong Near-bottom Currents Research Articles

A deep-sea benthic community exposed to strong near-bottom currents on the Scotian Rise (western Atlantic) : Thistle, D., J.Y. Yingst and K. Fauchald, 1985. Mar. Geol., 66(1–4):91–112

A deep-sea benthic community exposed to strong near-bottom currents on the Scotian Rise (western Atlantic) : Thistle, D., J.Y. Yingst and K. Fauchald, 1985. Mar. Geol., 66(1–4):91–112

The nematode fauna of a deep-sea site exposed to strong near-bottom currents

Nematodes are the most abundant metazoans in marine soft-bottom habitats, yet little is known of their role in deep-sea communities. We describe the nematode fauna from 4626 m depth in the North Atlantic (40°24.0′N, 63°07.4′W) at the family and genus level and compare our findings to previous reports on deep-sea nematodes. The results of covariance studies between nematodes and environmental parameters are also given. At the species level, there is no evidence of association between small-scale variation in nematode abundance and variation in abundance of bacteria or several classes of biogenous structures, but there is evidence of an association with pebbles. At the functional-group level, feeding groups show no correlation with environmental variables, nor do groups based on tail morphology. However, four of the tail-morphology groups are significantly disproportionately abundant in either the 0 to 1 or the 1 to 2 cm sediment layer. Individuals of one group may use their long, retractable tails to escape into the sediment to avoid resuspension by noncatastrophic erosive flows, which are common at this hydrodynamically active deep-sea locality.

A deep-sea benthic community exposed to strong near-bottom currents on the Scotian Rise (western Atlantic)

This paper gives an overview of the structure of a benthic community at 4626 m depth on the Nova Scotian continental rise. Here, abundances of polychaetes, bivalves, isopods and tanaids are conspicuously high compared to those reported from comparable depths. Bacterial numbers and ATP concentrations are also high. We suspect that these anomalous abundances result from enhanced food availability caused by the strong near-bottom currents that flow through the area. The polychaete and bivalve faunas have few adults and high species dominance suggesting that currents create large-scale, sediment-transporting disturbances. The composition of the crustacean fauna supports this inference in that it is dominated by forms that can enter the seabed and thereby escape adverse conditions on the sediment surface.

Biological activity and associated sedimentary structures in HEBBLE-area deposits, western North Atlantic

Biological and sedimentologic samples along with X-radiographs of sediment slabs were taken from box cores in the HEBBLE area (4700 m) on the lower continental rise of Nova Scotia. These data suggest that this bottom region is influenced by periods of strong near-bottom currents which erode and physically transport sediments. These high periods alternate with periods of weaker flow. Biogenic reworking of sediments by an active benthic infauna dominates particle transport during low flow conditions.