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Distribution and vertical fluxes of silicoflagellates, ebridians, and the endoskeletal dinoflagellate Actiniscus in the western Arctic Ocean

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Spatial and temporal variations in major phytoplankton populations such as diatoms in the changing Arctic Ocean have been well studied, whereas only a few monitoring studies have been conducted on minor siliceous flagellates. To discern the relationship between hydrographic conditions and the spatio-temporal distribution of silicoflagellates, ebridians, and the endoskeletal dinoflagellate Actiniscus pentasterias, we analyzed seawater and bottom-tethered sediment-trap samples from the western Arctic Ocean. Silicoflagellates and ebridians were commonly observed in shelf waters around the southern Chukchi Sea in September–October during 2010 and 2013. However, one mesoscale patch with abundant silicoflagellates and ebridians was observed in the southwestern Canada Basin during September–October 2010. This offshore patch reflected an unusual occurrence of a mesoscale eddy deriving from the Alaskan Coastal Water. The active lateral transport of shelf materials by eddies was also evident in high silicoflagellate and ebridian fluxes at station Northwind Abyssal Plain (NAP) (75°N, 162°W, 1975-m water depth) in November–December during 2010 and 2011. The summer silicoflagellate flux at station NAP was mainly composed of Distephanus speculum. During the sea-ice cover period, except for July, silicoflagellates D. medianoctisol and D. octonarius were relatively abundant in the assemblage. The spike in D. speculum flux during July 2011 was observed with fecal pellets containing abundant silicoflagellates, suggesting a temporal silicoflagellate contribution to some kinds of zooplankton. The common occurrence of A. pentasterias in settling particles at station NAP during the winter may indicate their tolerance to cold water under sea ice.
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ORIGINAL PAPER
Distribution and vertical fluxes of silicoflagellates, ebridians,
and the endoskeletal dinoflagellate Actiniscus in the western Arctic
Ocean
Jonaotaro Onodera
1,2
Eiji Watanabe
2
Shigeto Nishino
2
Naomi Harada
1,2
Received: 16 December 2014 / Revised: 29 June 2015 / Accepted: 22 August 2015 / Published online: 14 October 2015
ÓSpringer-Verlag Berlin Heidelberg 2015
Abstract Spatial and temporal variations in major phy-
toplankton populations such as diatoms in the changing
Arctic Ocean have been well studied, whereas only a few
monitoring studies have been conducted on minor siliceous
flagellates. To discern the relationship between hydro-
graphic conditions and the spatio-temporal distribution of
silicoflagellates, ebridians, and the endoskeletal dinoflag-
ellate Actiniscus pentasterias, we analyzed seawater and
bottom-tethered sediment-trap samples from the western
Arctic Ocean. Silicoflagellates and ebridians were com-
monly observed in shelf waters around the southern
Chukchi Sea in September–October during 2010 and 2013.
However, one mesoscale patch with abundant silicoflag-
ellates and ebridians was observed in the southwestern
Canada Basin during September–October 2010. This off-
shore patch reflected an unusual occurrence of a mesoscale
eddy deriving from the Alaskan Coastal Water. The active
lateral transport of shelf materials by eddies was also evi-
dent in high silicoflagellate and ebridian fluxes at station
Northwind Abyssal Plain (NAP) (75°N, 162°W, 1975-m
water depth) in November–December during 2010 and
2011. The summer silicoflagellate flux at station NAP was
mainly composed of Distephanus speculum. During the
sea-ice cover period, except for July, silicoflagellates D.
medianoctisol and D. octonarius were relatively abundant
in the assemblage. The spike in D. speculum flux during
July 2011 was observed with fecal pellets containing
abundant silicoflagellates, suggesting a temporal sili-
coflagellate contribution to some kinds of zooplankton. The
common occurrence of A. pentasterias in settling particles
at station NAP during the winter may indicate their toler-
ance to cold water under sea ice.
Keywords Silicoflagellate Ebridian Actiniscus
pentasterias Sinking particles Sediment trap Northwind
Abyssal Plain Chukchi Sea Arctic Ocean
Introduction
Silicoflagellates and other siliceous flagellates in sinking
particles have been studied in both low- and high-latitude
oceans (Takahashi 1987; Lange et al. 2000; Romero et al.
2002,2009; Rigual-Herna
´ndez et al. 2010; Onodera and
Takahashi 2012); however, few studies are reported from
the Arctic Ocean (Zernova et al. 2000). In the Arctic Ocean
there are snapshot records of silicoflagellate occurrences in
seawater and sea ice (Melnikov 1997; Takahashi et al.
2009). Zernova et al. (2000) reported sporadic silicoflag-
ellate occurrences in a 1-year record (from September 1995
to August 1996) of settling particle flux at station LOMO2
on the basin side of the Laptev Sea. Onodera and Taka-
hashi (2012) considered that the relative abundance of the
silicoflagellate Distephanus medianoctisol may increase in
colder waters covered with sea ice in the Arctic Ocean
compared to the subarctic North Pacific Ocean and the
Bering Sea. Matsuno et al. (2014a) showed a marked
relationship between the horizontal distribution of major
Electronic supplementary material The online version of this
article (doi:10.1007/s00300-015-1784-y) contains supplementary
material, which is available to authorized users.
&Jonaotaro Onodera
onoderaj@jamstec.go.jp
1
Research and Development Center for Global Change, Japan
Agency for Marine Earth Science and Technology,
Natsushima-cho 2-15, Yokosuka 237-0061, Japan
2
Institute of Arctic Climate and Environment Research, Japan
Agency for Marine Earth Science and Technology,
Natsushima-cho 2-15, Yokosuka 237-0061, Japan
123
Polar Biol (2016) 39:327–341
DOI 10.1007/s00300-015-1784-y
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

Supplementary resource (1)

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