Larval fish habitats in a mesoscale dipole eddy in the gulf of California

The three-dimensional distribution of larval fish habitats in a mesoscale dipole eddy was analyzed in the Southern Gulf of California in July 2010. Detection of the characteristic mushroom-shape using chlorophyll and sea surface temperature satellite images was used to direct sampling of two transects across the structure with conductivity, temperature, depth casts and stratified oblique zooplankton hauls with opening-closing net. The latter sampled every 17m layer down to the thermocline and every 50m layer from the thermocline down to 200m depth. Lowered Acoustic Doppler Current Profiler velocities revealed that the dipole structure persisted down to 800m depth. The “cap” showed two opposite poles: one cyclonic with diameter ~50km, and the other anticyclonic with diameter~80km. It had a vigorous central jet with speeds>25cm/s. The Θ-SA properties were consistent with formation of the structure outside the Gulf of California in Tropical Surface and Subtropical Subsurface water masses. In this context, three larval fish habitats were statistically defined (P