Distribution of siphonophores in the upwelling area off NW Africa

Using a Bongo-Net equipped with a multiple coded 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). This 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 comparision with the warmer oceanic water offshore: (1) a lower diversity, (2) a shallower distribution of some of the deep living species die to the lower temperature in the upper 300 m an a lower transparency, (3) no contribution to acoustic scattering by physonect siphonophores.

Mean cover and frequencies of vascular plant species during three decades around Abisko Scientific Research Station

Plant species distributions are expected to shift and diversity is expected to decline as a result of global climate change, particularly in the Arctic where climate warming is amplified. We have recorded the changes in richness and abundance of vascular plants at Abisko, sub-Arctic Sweden, by re-sampling five studies consisting of seven datasets; one in the mountain birch forest and six at open sites. The oldest study was initiated in 1977-1979 and the latest in 1992. Total species number increased at all sites except for the birch forest site where richness decreased. We found no general pattern in how composition of vascular plants has changed over time. Three species, Calamagrostis lapponica, Carex vaginata and Salix reticulata, showed an overall increase in cover/frequency, while two Equisetum taxa decreased. Instead, we showed that the magnitude and direction of changes in species richness and composition differ among sites.