Multiple excitation fluorometer for in situ oceanographic applications.

A new in situ fluorometer for the detection of oceanic photosynthetic pigment fluorescence is described. Emission spectra from 546 to 733 nm are recorded for each of three different visible excitation bands ten times a second. A Spectralon cell is used to improve the excitation coupling to and the collection efficiency from the sample volume. Laboratory tests demonstrated that the fluorescence emission spectra from the violet, blue, and green excitation can be used to discriminate among various algal species. The instrument was used at sea in extended in situ deployments on an undulating vehicle (SeaSoar).