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Vol. 54, 2015
Spatial changes in the vertical distribution of calanoid copepods down to great depths in the North Pacific
Atsushi Yamaguchi1,*, Kohei Matsuno2,
and Tomoe Homma1
1Laboratory
of Marine Biology, Graduate School of Fisheries Science, Hokkaido
University, 3-1-1 Minatomachi, Hakodate, Hokkaido 041-8611, Japan
2Arctic Environmental Research Centre, National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan
Abstract
Background: Despite
its ecological importance, little information is available regarding
the spatial and vertical changes in the calanoid copepod community over
large geographical regions. This study investigated the spatial and
vertical patterns in calanoid copepod abundance and community structure
using zooplankton samples collected between depths of 0 and 2,615 m
across the North Pacific from 0° to 56°N.
Results: A
total of 211 calanoid copepod species belonging to 66 genera and 24
families were identified. Calanoid copepod abundance decreased with
increasing depth, and few latitudinal differences were detected. Across
the entire region, species diversity peaked near 500 to 2,000 m in
depth. The calanoid copepod community was separated into seven groups
with distinct spatial and vertical distributions. For all groups, the
number of species was low (28 to 37 species) in the subarctic region
(north of 40°N) and high (116 to 121 species) in the
subtropical-tropical region. The deepest group in the
subtropical-tropical region was composed of cosmopolitan species, and
this group was also observed in deep water in the subarctic region.
Conclusions: In
deep water, most of the calanoid copepod community consisted of
cosmopolitan species, while an endemic community was observed in the
subarctic region. Because the food of deep-sea calanoid copepods
originates from the surface layer, sufficient and excess flux in the
eutrophic subarctic region may be responsible for maintaining the
endemic species in the region.
Key words: Zooplankton; Calanoid copepods; Community structure; Diversity; Deep-sea; North Pacific.
*Correspondence: E-mail: a-yama@fish.hokudai.ac.jp
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