The German researcher Victor Hanson is associated with:

deep sea cores
plankton
sea anemones
sub-surface currents

Unfortunately, as an AI language model, I am unable to determine the specific field of research of a person named Victor Hanson without further context. There could be multiple researchers with the same name, and it is unclear which one you are referring to. Please provide more information or context so that I could provide a more accurate answer.

The German researcher Victor Hanson is primarily associated with studying deep sea cores.