Investigation of the biological carbon pump in two Norwegian fjords, and sampling of mass jellyfish blooms.

HE570 will conduct a process study of the biological carbon pump (the cycling of carbon through the natural ecosystem) in two Norwegian Fjords that are located close together and are of similar size and structure, but have fundamentally different pelagic ecosystem structures. This makes them ideal environments to use as natural laboratories. One fjord – Masfjorden – sustains populations of mesopelagic fishes (those that live in the middle of the water column, about 200-1000 m water depth) and has negligible populations of jellyfish; the other fjord – Lurefjorden – is characterised by a year-round mass abundance of the deep-sea jellyfish Periphylla periphylla.

The scientists aim to quantify the respective contributions that the different components of the ecosystem (zooplankton and fishes) make to the mass flux of carbon in the natural system. To do this, they will deploy a suite of different state-of-the-art in situ imaging systems, hydroacoustic instruments, sediment traps, and vertically stratified nets. They will also try to collect specimens of the Periphylla jellyfish to measure their response to different temperatures and amounts of sediment in the water, as part of iAtlantic’s work on understanding the effects of multiple stressors on deep-sea ecosystems.