Copepod groups distribution in a cyclonic eddy in Bay of La Paz, Gulf of California, Mexico, during summer 2009

This study assessed the effects of a cyclonic eddy on copepod groups in the Bay of La Paz, Gulf of California, Mexico, during summertime.We collected high-resolution hydrographic records for conductivity, temperature and depth and performed oblique zooplankton hauls during a research cruise performed in August 2009.The results showed the presence of a cyclonic eddy with a diameter of ~30 km and velocities reaching 50 cm s -1 .Copepod abundances showed differences for each group.Calanoid abundances ranged from 95 to 1019 ind 100 m -3 , cyclopoids ranged from 208 to 1082 ind 100 m -3 and abundance of all copepodite stages ranged from 420 to 11800 ind 100 m -3 .Their horizontal distributions showed interesting patterns of variability into the eddy field.The calanoids showed high relative abundances at stations close to the center of the eddy.The cyclopoids had maximum abundances at peripheral stations, while all copepodite stages had maximum abundances at stations close to Boca Grande.A canonical correspondence analysis confirmed dependence with environmental variables.We found that copepod groups showed a clear relationship with the presence of the cyclonic eddy through and its effects on hydrographic conditions; possibly, as result of several additional processes, such as ecological interactions, population dynamics as well as feeding habits were also impacted.