Zooplankton interactions with the oxygen minimum zone in the eastern south pacific
Zooplankton in the coastal upwelling zone off the eastern South Pacific must cope with a shallow oxygen minimum zone. In this work, I summarize available information on the zooplankton species that interact with the OMZ in the upwelling region off northern Chile. Data are available from the MinOx cruise carried out in March 2000 and the ZOMEI cruise perfomed in October 2005, both onboard the R/V Vidal Gormaz of the Chilean navy. Nineteen species of copepods and 10 of euphausiids were analyzed in their vertical distribution and migrating behavior. Several abundante species appeared constrained by the OMZ and restricted to the upper 50m layer. However, other abundant species inhabit temporarily or permanently the OMZ contributing substantially to the vertical flux of C produced in the photic zone through active vertical migration. Population dynamics and life cycle strategies, as well as metabolic adaptations of the species, may not only modulate their contributions to vertical fluxes of C, but also to the maintenance and persistence of the oxygen-depleted water mass.