Le rôle de la prospection sous-marine autonome dans les recherches de biologie marine et d'océanographie biologique

Abstract

At the present time the autonomous exploration of the sea may be divided into three main fields: airScuba down to 60 m; diving saucers down to 1200 m; bathyscaph down to the greatest depths of the ocean. In the near future, theScuba with special gas mixtures, excluding nitrogen, and the underwater permanent laboratories, will open a new field for biological investigations; progress in metallurgy may also allow diving with engines, without a floating tank, down to 2000 m. The ability of the deep-sea vehicles to stop and remain at a definite depth below the surface needs further research. TheScuba is interesting for investigating the biotopes where the usual devices cannot be used from a surface vessel, for instance in submarine caves. Very special biocoenoses have been found in the totally dark parts of these caves with impoverished stocks and sometimes relict species; the sampling may be perfect both on soft and hard bottoms. With the deep-sea vehicles, investigations may be carried out on the behaviour and distribution of the bottom epifauna. The bathyscaph also allows a general view of the vertical distribution of plankton much better than using plankton samplers, because the plankton nets or pumps are always working on a discontinuous scale. Unfortunately the sampling is much more difficult, especially as far as the plankton is concerned. It is necessary that the engineers pay more attention to the biological devices; very good data have been obtained for temperature, pressure, sound-velocity, etc., but in many instances the biologist diving with a deep-sea vehicle cannot do more than look at the animals and take photographs.