Marine Sciences

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Department News

Dead plankton cells

Department of Marine Science faculty, Dr. Jeffrey Krause, is part of ground-breaking research which challenges decades of science, led by Dr. Tristan Biard, postdoctoral scholar at Scripps Institution of Oceanography.

The biological pump, the process where plankton transport carbon from the surface ocean/atmosphere and lock it away in the deep ocean, plays a role in regulating earth's climate. When dead plankton cells sink, they carry organic matter, and silica (i.e. glass) shells makes cells sink faster.  Dr. Biard et al. estimate that one family of zooplankton, Phaeodaria, can do five to ten percent of all the silica sinking in the deep ocean.  Phaeodaria have a fragile shell made of silica fibers and reside just below the sunlit zone; while the existence of this group is not new, only recently have scientists understood how abundant they are in the ocean (a 2016 a study published by Dr. Biard).  In this sunlit zone, diatoms (which also have a glass shell) are at 100- to 1000-times more abundant than Phaeodaria.  The oceanographic field has typically assumed most of the sinking silica in the ocean is from diatoms, and it has provided a way to understand their relative importance in the biological pump.  The finding that Phaeodaria are important to silica sinking, turns this approach upside down, and makes scientists wonder what other groups have been missed.

“If these guys are the ones doing most of the sinking, then all those arguments we made on silica export, and inferences to diatom processes, require reassessment,” Dr. Krause said.  "This is an exciting finding, which opens up many new questions."