Acoustic measurements at 25 kHz show that a well-defined sound-scattering layer in the Cariaco Trench migrates down in the early morning to the oxic-anoxic interface and splits into two components: one remains in oxygen-deficient water above the interface; the other penetrates several hundred meters into the anoxic hydrogen sulfide- and methane-containing region of the water column....
Wilson, Donald F.. 1972. "Diel migration of sound scatterers into, and out of, the Cariaco Trench anoxic water." Journal of Marine Research 30, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1237