Fig. 4. The correlation between dimethyl sulfide in the air (DMSg) and seawater (DMSaq) and acoustic estimates (Nautical Area Scattering Coefficient (NASC)) of zooplankton and fish off the coast of Cape Cod, MA, USA.
The relationships varied between a zooplankton biomass and DMS in seawater, b zooplankton biomass and DMS in air, c fish biomass and DMS in seawater and d fish biomass and DMS in air. The panels (e–h) use the same data (n = 173 for e, f and n = 185 for g, h) as above and show the same relationships as the panels (a–d) but are split at the midpoint of the DMS range to highlight differences (or lack thereof) in zooplankton (or fish) biomass between low- and high-DMS values. Since zooplankton and fish NASC values are from different acoustic frequencies (710 and 38 kHz, respectively), the NASC values for the fish and zooplankton cannot be directly compared with each other.