Publication Date:
2015-02-10
Description:
Pteropods are important organisms in highlatitude
ecosystems, and they are expected to severely
suffer from climate change in the near future. In this study,
sedimentation patterns of two pteropod species, the polar
Limacina helicina and the subarctic boreal L. retroversa,
are presented. Time series data received by moored sediment
traps at the Long-Term Ecological Research (LTER)
Observatory HAUSGARTEN in eastern Fram Strait were
analyzed during the years 2008 to 2012. Results were
derived from four different deployment depths (200,
1,250, 2,400, and 2,550 m) at two different sites (79°N
04'200E; 79°430N 04'300E). A species-specific sedimentation
pattern was present at all depths and at both sites
showing maximal flux rates during September/October for
L. helicina and in November/December for L. retroversa.
The polar L. helicina was outnumbered by L. retroversa
(55–99 %) at both positions and at all depths supporting
the recently observed trend toward the dominance of the
subarctic boreal species. The largest decrease in pteropod
abundance occurred within the mesopelagic zone
(*200–1,250 m), indicating loss via microbial degradation
and grazing. Pteropod carbonate (aragonite) amounted up
to *75 % of the total carbonate flux at 200 m and 2–13 %
of the aragonite found in the shallow traps arrived at the
deep sediment traps (*160 m above the seafloor),
revealing the significance of pteropods in carbonate export
at Fram Strait. Our results emphasize the relevance and the
need for continuation of long-term studies to detect and
trace changes in pteropod abundances and community
composition and thus in the vertical transport of aragonite.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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