Deep-SeaResearch 1, Vol 40 No 4 pp 643-652 1993 0967~637/93$6 00 + 0 00 Printed m GreatBritain (~) i993PergamonPressLtd Maintenance of abyssal benthic foraminifera under high pressure and low temperature: some preliminary results C. M. TURLEY,* A. J. GOODAYt and J. C. GREEN* (Received 7 February 1992, in revised form 27 May 1992, accepted 11 June 1992) Abstract--Abyssal benthic foraminifera have been maintained ahve for periods of several weeks under laboratory simulated deep-sea condmons of high pressure and low temperature. In separate experiments, bacterial-sized fluorescent microspheres and three species of microalgae were supplied as food particles Subsequent hght and electron microscopy showed that the algae had been ingested by several foramimferal speoes. Furthermore, the fine structure of the forammlferal cytoplasm was well-preserved which m&cates, along with the ingestion of algal food, that they had remained in a viable condiuon during the incubation. Other observations m&cate that abyssal benthic foramlmfera ingest naturally occumng photosynthetic cells carried to the deep-sea bed by rapidly sedlmenting aggregates The ability to keep foraminifera originating from depths exceed- mg 4000 m alive In the laboratory paves the way for the experimental investigation of some important issues in deep-sea biology and palaeoceanography INTRODUCTION FORAMINIFERA are among the most abundant marine eukaryotic organisms and many of the species which live in shallow water are often relatively easy to culture in aquaria (ARNOLD, 1974; LEE, 1974). Recently, the feasibility of maintaining bathyal species alive at surface pressure, providing that they are maintained at their original ambient tempera- ture, has been demonstrated. For example, KITAZATO (1989) made ecological observations on several foraminiferal species, collected at depths down to 1452 m off Japan and kept alive in unpressurized aquaria. LINKE (1989, 1992) undertook short term (23 days) physiological experiments on foraminifera recovered in core samples from 1245 m depth in the Norwegian-Greenland Sea and HEEGER (1990) conducted feeding experiments on specimens from the same area. Several specimens of the foraminifer Laticarinina pauper- ata, collected by WEINBERG(1990, 1991) from 773 m depth off New England, remained alive and active after 772 days at 3°C and 1 atm. However, foraminifera and many other organisms originating from greater depths (>2000-3000 m) do not survive for any length of time following depressurization to I atm. For many years microbiologists have used pressure vessels to maintain bacteria (ZOBEL and MORITA, 1957) and flagellates (TURLEY et al., 1988) alive under laboratory simulated deep-sea conditions of high pressure and low temperature. *Plymouth Marine Laboratory, Citadel Hill, Plymouth PL1 2PB, U K tlnstltute of Oceanographic Science Deacon Laboratory, Brook Road, Wormley, Godalmlng, Surrey GU8 5UB, U K 643