Geir Johnsen – författare

Pigments act as tracers to elucidate the fate of phytoplankton in the world's oceans and are often associated with important biogeochemical cycles related to carbon dynamics in the oceans. They are increasingly used in in situ and remote-sensing applications, detecting algal biomass and major taxa through changes in water colour. This book is a follow-up to the 1997 volume Phytoplankton Pigments in Oceanography (UNESCO Press). Since then, there have been many advances concerning phytoplankton pigments. This book includes recent discoveries on several new algal classes particularly for the picoplankton, and on new pigments. It also includes many advances in methodologies, including liquid chromatography-mass spectrometry (LC-MS) and developments and updates on the mathematical methods used to exploit pigment information and extract the composition of phytoplankton communities. The book is invaluable primarily as a reference for students, researchers and professionals in aquatic science, biogeochemistry and remote sensing.

Until recently, the prevailing view of marine life at high latitudes has been that organisms enter a general resting state during the dark Polar Night and that the system only awakens with the return of the sun. Recent research, however, with coordinated, multidisciplinary field campaigns based on the high Arctic Archipelago of Svalbard, have provided a radical new perspective. Instead of a system in dormancy, a new perspective of a system in full operation and with high levels of activity across all major phyla is emerging. Examples of such activities and processes include: Active marine organisms at sea surface, water column and the sea-floor. At surface we find active foraging in seabirds and fish, in the water column we find a high biodiversity and activity of zooplankton and larvae such as active light induced synchronized diurnal vertical migration, and at seafloor there is a high biodiversity in benthic animals and macroalgae. The Polar Night is a period for reproductionin many benthic and pelagic taxa, mass occurrence of ghost shrimps (Caprellides), high abundance of Ctenophores, physiological evidence of micro- and macroalgal cells that are ready to utilize the first rays of light when they appear, deep water fishes found at water surface in the Polar night, and continuous growth of bivalves throughout the winter.These findings not only begin to shape a new paradigm for marine winter ecology in the high Arctic, but also provide conclusive evidence for a top-down controlled system in which primary production levels are close to zero. In an era of environmental change that is accelerated at high latitudes, we believe that this new insight is likely to strongly impact how the scientific community views the high latitude marine ecosystem. Despite the overwhelming darkness, the main environmental variable affecting marine organisms in the Polar Night is in fact light. The light regime during the Polar Night is unique with respect to lightintensity, spectral composition of light and photoperiod.