Samples of deep-ocean water(3170m)taken from the Rockall Trough(North-EastAtlantic)were
incubated for one-monthat atmospheric and in-situ pressure(31MPa),at4 1C and in the absence and
presence of added nutrients. Prokaryotic abundance(directcellcounts) in creased by atleast28-fold in enrichments without added nutrients. However,the magnitude of increase in abundance was less for incubations carried out at in-situ pressure(131–181-fold) than those incubations at surface pressure (163–1714-fold in crease in abundance).