On the vertical distribution of siphonophores in the upwelling area off NW Africa (Auftriebs-Expedition R.V. "Meteor", cruise 26, 1972)

Using a Bongo-Net equipped with a multiple codend closing device, the vertical distribution of siphonophores has been observed in 100 m depth intervals at 13 stations off Cap Mirik (19° N) (from 0-500 m depth). The distributional pattern of the 15 siphonophores species found is discussed in relationship to the hydrography of this upwelling region. The following main features have been observed in comparison with the warmer oceanic water offshore: (1) a lower diversity, (2) a shallower distribution of some of the deep living species due to the lower temperature in the upper 300 m and a lower transparency, (3) no contribution to acoustic scattering by physonect siphonophores