Chapter III — S3 — Collecting Samples at Sea 



On the contrary, as many viable bacteria have been found in water sam- 

 ples collected with an evacuated glass bottle as in the J-Z collapsible rub- 

 ber bottle in which the pressure inside and outside is virtually the same 

 at all times. Experimental evidence that hydrostatic pressures consid- 

 erably higher than any that occur in the sea are not inimical to microbial 

 life is summarized on page 69. 



The alleged injurious effects of releasing the pressure can be largely 

 discounted because it requires an hour or two to haul a sample from the 

 deep sea to the surface. This would be regarded as a gradual decrease in 

 pressure to which the microorganisms in the sample are subjected. In the 

 experiments of Larsen et al. (1918), bacteria subjected to pressures of 

 6000 atmospheres were not injured when decompressed in five or ten min- 

 utes, although decompressing the bacteria within a few seconds killed 

 some of them. 



Krogh (1934) points out that only marine animals with swim bladders 

 are injured by sudden changes of pressure because they consist largely of 

 water. According to Sverdrup et al. (1942), ''pressure in itself does not 

 exclude life from the abyssal regions of the sea, for water is but little com- 

 pressed and equilibrium exists between the inner and outer pressure affect- 

 ing body tissue." Some marine animals are known to migrate daily 400 

 meters vertically, corresponding to a pressure change of 40 atmospheres. 



The collection of mud samples : — Samples of bottom deposits are 

 collected by various kinds of buckets, spuds, grabs, snappers, dredges, 

 and coring devices, several types of which are described by NAUikLA.NN 

 (1930) and Trask (1939). With the exception of the Renn sampler, none 

 of them makes provisions for aseptic technic. The Renn sampler, which 

 uses the evacuated glass tube principle, is suitable for collecting only the 

 uppermost layer of poorly compacted, fine-grained sediments in relatively 

 shallow water. 



The Renn sampler consists of an evacuated bottle with a projecting glass 

 tube about one inch in diameter mounted in a metal frame. The latter is 

 attached to the dredging or hydrographic wire by which it is lowered to 

 the sea floor. The end of the glass tube is broken off" by a mechanism 

 activated by a spring, which is released when a trigger makes contact with 

 the bottom. A sample of the bottom material is sucked into the pievi- 

 ously sterilized glass tube. 



While a sampler which reaches the bottom in a sterile condition may 

 be desirable for the collection of mud samples, for bacteriological analysis, 

 such a sampler is not prerequisite. There is Httle likelihood that either 

 quantitative or qualitative results will be influenced by contaminating 

 organisms from the overlying water, because wherever samples have been 

 carefully examined, hundreds to thousands of times as many bacteria have 

 been found per unit volume of bottom deposits as in the overlying water, 

 and any bacterial species found in the water may be carried to the bottom 

 by the processes of sedimentation or otherwise. By taking certain pre- 

 cautions to minimize the possibilities of contamination, samples of bottom 

 deposits, which are satisfactory for bacteriological analysis, can be col- 

 lected with coring tubes which of necessity go down open. 



A coring tube is a thin-walled pipe which can be driven into the mud 

 in such a way that a core of mud enters the tube or pipe and remains there 

 when the apparatus is pulled to the surface. Mechanisms have been 

 described for driving the core barrel into the bottom deposits mechan- 



