Research Task 1 Development of a Hyperspectral Imaging system for in situ benthic studies.

PhD position. Supervisors: Dr Lubos Polerecky and Dr Dirk De Beer. Host: MPI

Hyperspectral Imaging is a well-established method to study the distribution of oxygenic phototrophic communities, and their physiological status. At the moment it is used in remote sensing of chlorophyll, by satellites and airplanes, of landmasses, oceans, intertidal flats and transparent coastal seas. MPI introduced this method to study the distribution of phototrophs in complex benthic communities, including anoxygenic phototrophs. By a sophisticated illumination protocol, using defined wavelengths for excitation, MPI can distinguish with large precision the distribution of various functional groups, such as diatoms, green algae, flagellates, cyanobacteria and various anoxygenic phototrophs. The system can be operated on the scale of microns to decimeters. It has equal species resolution as extractive pigment analyses, but is much faster and has unsurpassed spatial and temporal resolution. A portable prototype that can be used in the laboratory and in the field is operating highly reliably. We propose to include this technology in a submersible unit, that will allow us to map the sediment surfaces, and by using an invasive prism as used for planar optode imaging ^(1,2) the vertical distribution and dynamics of phototrophs inside sediments. The deployment is envisioned by a remotely operated underwater vehicle (ROV) and by divers. The studies will be accompanied by measurements with planar optodes, benthic chambers and microsensors to determine the net and gross oxygen conversion rates of coastal areas, including subtidal and intertidal flats.

Planar optode: the actual sensor is on the prism that is entering the sediment, the camera is in the housing focusing on the planar optode via a mirror.					Microsensor profiler: needle shaped microsensors are visible under the titanium cylinder.
Both sensors are measuring at 2700m depth in the Mediterranean, on a mud volcano. The instruments were deployed on the ROV Quest and the photos were also taken by the ROV Quest. Images courtesy of, and copyright Marum, University of Bremen

⁽¹⁾ Glud, R. N., et al., 2001. L&O. 46:2073-2080. ⁽²⁾ Wenzhöfer F., & Glud R.N., 2004. L&O. 49 (5) 1471-1481.