SPATIOTEMPORAL PATTERNS IN THE DIEL VERTICAL MIGRATION OF THE COPEPODMETRIDIA-LUCENS IN THE NORTHEAST ATLANTIC DERIVED FROM THE CONTINUOUSPLANKTON RECORDER SURVEY

The archived data set collected over a 45-yr period (1948-1992) by Con tinuous Plankton Recorders (CPRs) towed in near-surface waters was use d to investigate the diel vertical migration of the copepod Metridia l ucens in the northeast Atlantic (47-63 degrees N and 10-30 degrees W). Although the CPR sampling intensity was uniform during the day and th e night, M. lucens was caught predominantly in samples collected at ni ght, consistent with a normal diel vertical migration pattern involvin g movement from greater depth during the day to shallower depths at ni ght. The length of time spent near the surface varied seasonally and w as closely correlated (r(2) = 0.80) with seasonal change in length of night. The residual variation in length of time spent at the surface w as nonrandom, with more time being spent at the surface in spring befo re the onset of the spring bloom, and less time being spent at the sur face in autumn, than that predicted from the length of night at these periods. The timing of this enhanced near-surface occupation in spring varied with latitude, occurring a mean of 3.4 d later per degree of l atitude.