surveying microbes at seaCourtesy C-MOREDr. Dan Repeta from the Woods Hole Oceanographic Institution (WHOI) is C-MORE’s Chief Scientist on the BiG RAPA expedition, which is conducting research off the coast of Chile. Dr. Repeta and his team of scientists are sampling the underwater microbial environment using a variety of instruments, including a water collector called a CTD (see educational resource below). Two interesting results have turned up in the CTD data:
- chlorophyll -- The greatest amount of the green pigment, representing floating microscopic plants in the sea known as phytoplankton, was found about 30 meters below the sea surface. (That's where oceanographers expect the most chlorophyll. Perhaps phytoplankton living at that depth must produce more chlorophyll in order to capture the lower light intensities, just like leaves are usually darker green if they're growing on a land plant in the shade). However, a surprise awaited oceanographers at 60 meters. At that depth, they discovered an unusual “secondary, deeper chlorophyll max," something not seen many other places in the world.
- Oxygen -- This gas enters the ocean primarily at the surface, from the air and also from phytoplankton photosynthesis. Bacteria and other heterotrophs consume the O2 as they metabolize. Therefore, oxygen is expected to decrease with depth. At BiG RAPA's Station 1 oxygen not only fell; it fell all the way to near zero.
Dr. Angel White and the CTDCourtesy Eric Grabowski, C-MORE"Sea It Live" in some BiG RAPA videos. Join Dr. Angel White from Oregon State University as she demonstrates the CTD rosette. Then join Dr. Repeta for his Chief Scientist Station 1 Update .
*Educational resource = C-MORE Science Kit Ocean Conveyor Belt's Powerpoint, "Lesson 3: Using Data to Explore Ocean Processes "