HEINCKE HE570

During the Heincke expedition HE570, we will conduct a process study of the Biological Carbon Pump in two Norwegian Fjords that are close to each other and feature similar dimensions and little advection, but a fundamentally differing structure of the pelagic ecosystem and are thus ideal environments as Natural Mesocosms. While Masfjorden sustains populations of mesopelagic fishes and has negligible populations of jellyfish, Lurefjorden is characterized by year-round mass abundance of the deep sea jellyfish Periphylla periphylla. We aim to quantify the respective contribution to export flux by different zooplankton (in particular Periphylla and copepods of the genus Calanus) by respiration, fecal pellet production and subsiding of individuals as well as characterizing particle-zooplankton interactions. The variability of these processes – spatially and temporally – has only been captured and understood in parts and even less well quantified. To this end, we will deploy a suite of different state-of-the-art in situ imaging systems to cross-calibrate and harmonize output data, to resolve a broad size spectrum, and to ensure intercomparison between instruments. We combine this high-resolution in situ imaging approach with complementary methods, such as vertical net hauls, hydroacoustics, sediment traps, and shipboard experiments. We will here i) investigate and quantify the underlying mechanisms of the Biological Carbon Pump in two contrasting Fjord ecosystems on unprecedented temporal and spatial scales and ii) will conduct crucial harmonisation approaches between different underwater imaging systems to allow an intercomparison of the datasets obtained. This is the first concerted action of the newly formed Pelagic Imaging Consortium (PIC), a collaborative effort of HZG, AWI and GEOMAR within HGFs Earth and Environment.