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JOURNAL OF PLANKTON RESEARCH

j

VOLUME 32 j

NUMBER 4 j

PAGES 441456 j 2010

Light-dependent behavior of abundant zooplankton species in the White Sea

12 DARIA M. MARTYNOVA * AND ANNAV. GORDEEVA

1WHITE SEA BIOLOGICAL STATION, ZOOLOGICAL INSTITUTE OF RUSSIAN ACADEMY OF SCIENCES, UNIVERSITETSKAYA NAB., 1, 199034 SAINT-PETERSBURG,

RUSSIA AND 2A.N. BACH INSTITUTE OF BIOCHEMISTR , RUSSIAN ACADEMY OF SCIENCES, LENINSKY PROSPECT 33, BUILDING 2, MOSCOW 119071, RUSSIA

*CORRESPONDING AUTHOR: daria.martynova@gmail.com

Received March 27, 2009; accepted in principle December 18, 2009; accepted for publication December 19, 2009

Corresponding editor: Roger Harris

Light-dependent behavior of the abundant zooplankton species inhabiting the White Sea were studied experimentally during: (i) the spring equinox (March); (ii) the polar day (late May to June), (iii) August, 17/7 h day–night light cycle, (iv) the fall equinox (October). Behavioral patterns were investigated for eight species of Copepoda (Metridia longa, Calanus glacialis, Pseudocalanus minutus, Oithona similis, Oncaea

borealis,

emora longicornis, Centropages hamatus, Acartia spp.), one Cladocera species

(Evadne nordmanni) and Polychaeta larvae. The hypothesis was tested that attraction to (or repulsion from) light is the primary mechanism involved in the vertical migration of zooplankton with different trophic characteristics in relation to phyto- plankton-rich upper water layer. The impact of red (680 nm), yellow (560 nm) and UV (280 nm) light was tested. The animals were acclimated to two food con- ditions: natural seawater (satiated) and filtered (1 mm) seawater (hungry). The posi- tive light response of predominantly herbivorous and omnivorous copepods and cladocerans inhabiting the photic water layer corresponds with their distribution and their food vertical distribution. Hungry animals display the strongest responses to light. Light effects on behavior were weak in deep-dwelling O. borealis. We suggest that red and yellow light is an indicator of the photic layer (high food con- centration) to zooplankton groups that feed on phytoplankton. In contrast, dia- pausing (e.g. non-feeding) copepods totally avoid light, especially when they hibernate in the aphotic layer. We hypothesize that there is a relationship between

the light response of the zooplankton, their trophic characteristics, havior (diel and ontogenetic) and the water layer occupied.

migration

be-

KEYWORDS: Copepods; UVB; Visible light; Life cycle; Feeding

I N T RO D U C T I O N

It is widely accepted that light plays an important role in the behavior of pelagic animals (Forward, 1988). Numerous plankton species, particularly copepods and cladocerans, have both diel and ontogenetic vertical migrations (Leech and Johnsen, 2003). Diel vertical migrations involve daily changes in vertical distribution of plankton. Ontogenetic vertical migrations involve seasonal and life history specific changes in their

distribution. The latter are characteristic of many high- latitude species, especially the genus Calanus. These animals actively feed and reproduce in the surface water layers in spring but move down to deeper layers to hibernate during the long winter period (Conover and Huntle , 1991). Ontogenetic migrations are thought to be governed by factors other than light. However, light is a major trigger of diel vertical migrations.

doi:10.1093/plankt/fbp144, available online at www.plankt.oxfordjournals.org. Advance Access publication January 21, 2010

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    The Author 2010. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org

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