Spring coccolithophore production and dispersion in the temperate eastern North Atlantic Ocean

Production and dispersion of coccolithophores are assessed within their ecologic and hydrographic context across enhanced spring chlorophyll production in the surface eastern North Atlantic. Within a 4 day period from 12 to 16 March 2004, a N-S transect from 47 degrees N to 33 degrees N was sampled along 20 degrees W. Water samples from defined depths down to 200 m were analyzed for coccolithophores from 0.45 mu m polycarbonate filters by scanning electron microscopy. At 47 degrees N coccolithophores flourished when euphotic conditions allowed new production at deep mixing, low temperatures, and high nutrient concentrations. Emiliania huxleyi flourished at high turbulence during an early stage of the phytoplankton succession and contributed half of the total coccolithophore assemblage, with up to 150 x 10(3) cells L(-1) and up to 12 x 10(9) cells m(-2) when integrated over the upper 200 m of the water column. Maximum chlorophyll concentrations occurred just north of the Azores Front, at 37 degrees N-39 degrees N, at comparatively low numbers of coccolithophores. To the south, at 35 degrees N-33 degrees N, coccolithophores were abundant within calm and stratified Subtropical Mode Waters, and E. huxleyi was the dominant species again. Although the cell densities of coccolithophores observed here remained below those typical of plankton blooms visible from satellite images, the depth-integrated total mass makes them significant producers of calcite and contributors to the total carbon sedimentation at a much wider range of ecological conditions during late winter and early spring than hitherto assumed

Calcareous nannoplankton of DSDP Leg 43 holes

During Leg 43, six holes (Sites 382-387) were drilled in the western part of the North Atlantic Ocean; locations of sites are shown in Figure 1. Lower Cretaceous to Quaternary calcareous nannofossils were found in 127 of 189 cores recovered during the leg. The ages and zonal assignments of these fossiliferous cores based upon light-microscopical observation are given in Table 1. An almost continuous succession of nannofossil assemblages of the lower Maestrichtian to upper Paleocene is present at Site 384. A detailed investigation was conducted on samples at this site, and the evolution of approximately 50 species is documented through almost the entire Paleocene epoch