A 7-year time-series study of a
benthic boundary layer community
in the abyssal N.E. Pacific

Ken Smith, Ph.D.
Scripps Institution of Oceanography

Wednesday, September 16, 1998
3:00 p.m.—Pacific Forum

Temporal variability of plankton production in the upper ocean is well documented. That fraction of this production which escapes the upper 1,000 m of the water column into the deep sea also exhibits temporal variability, reflecting the changes in surface water production. However, the cycling of organic matter in the deep ocean has been difficult to evaluate because synoptic measurements on sufficiently long time scales are rare. The lack of long time-series measurements to examine concurrently the input of a pelagically-derived food supply and its impact on benthic boundary layer (BBL) processes prompted us to establish a long-term, abyssal study site in the N.E. Pacific (4,100 m water depth) in June 1989, with continuing measurements through October 1996. Over this 7-year period we monitored continuously the flux of sinking particulate matter through the BBL and employed time-lapse photography to record dynamic benthic processes. During this same time period, in situ seasonal measurements of sediment community oxygen consumption were conducted using free-vehicle and Alvin-manipulated respirometers to estimate food demand.

Our results show considerable intra- and inter-annual variation in BBL processes during this long-term study, reflecting hydrographic variations in the upper water column. Long time-series studies are essential for resolving biological and chemical processes in the deep ocean, given the high variability encountered on time scales of hours to years.

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