Why do the two most abundant copepods in the North Atlantic differ so markedly in their die1 vertical migration behaviour?

• Main Authors: Sea Researce, G. C. Hays A, A. J. Warner B, P. Tranter B
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1997
• Subjects: North Atlantic; die1 vertical migration; copepod; Metridia; Calanus; CPR; Calanus finmarchicus; Copepods
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.527.8714; http://www.swan.ac.uk/bs/turtle/reprints/Hays_JSR_1997.pdf

A total of 55 113 plankton samples, collected between 1948 and 1992 in the North Atlantic by the Continuous Plankton Recorder (CPR) survey, were used to show that normal die1 vertical migration (NDVM) behaviour was far more marked in the copepod Metridia lucens than in the copepod Calanus finmarchicus. These two species are of similar size and pigmentation, but differ in morphology, with C. jinmarchicus being the more elongate. To examine whether this variation in morphology might be linked to the observed difference in NDVM behaviour, both body morphology and NDVM behaviour were quantified for a further five similar sized copepod species (Pleuromamma robusta, F! abdominalis, C. helgolandicus, C. glacialis and Neocalanus grucilis). NDVM behaviour was significantly less marked in the more elongate species. It is suggested that the more elongate species have a faster avoidance speed from predators, which leads to a lower susceptibility to predation and consequently these species do not need to exhibit marked NDVM behaviour.