FN Archimer Export Format
PT J
TI Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers
BT 
AF DANIELS, C. J.
   POULTON, A. J.
   ESPOSITO, M.
   PAULSEN, M. L.
   BELLERBY, R.
   ST JOHN, M.
   MARTIN, AAdrian P.
AS 1:1;2:2;3:2;4:3;5:4,5,6;6:7;7:2;
FF 1:;2:;3:;4:;5:;6:;7:;
C1 Univ Southampton, Natl Oceanog Ctr Southampton, Ocean & Earth Sci, Southampton, Hants, England.
   Univ Southampton, Natl Oceanog Ctr, Ocean Biogeochem & Ecosyst, Southampton, Hants, England.
   Univ Bergen, Dept Biol, Marine Microbiol Dept, Bergen, Norway.
   Norwegian Inst Water Res NIVA, Bergen, Norway.
   Uni Bjerknes Ctr, Bergen, Norway.
   E China Normal Univ, State Key Lab Estuarine & Coastal Res, Shanghai 200062, Peoples R China.
   Tech Univ Denmark, Natl Inst Aquat Resources, Charlottenlund, Denmark.
C2 UNIV SOUTHAMPTON, UK
   NOC, UK
   UNIV BERGEN, NORWAY
   NIVA, NORWAY
   UNI BJERKNES, NORWAY
   UNIV E CHINA NORMAL, CHINA
   UNIV TECH DENMARK (DTU AQUA), DENMARK
IN DOAJ
IF 3.7
TC 38
UR https://archimer.ifremer.fr/doc/00309/42025/41324.pdf
LA English
DT Article
AB he spring bloom is a key annual event in the phenology of pelagic ecosystems, making a major contribution to the oceanic biological carbon pump through the production and export of organic carbon. However, there is little consensus as to the main drivers of spring bloom formation, exacerbated by a lack of in situ observations of the phytoplankton community composition and its evolution during this critical period.  We investigated the dynamics of the phytoplankton community structure at two contrasting sites in the Iceland and Norwegian basins during the early stage (25 March–25 April) of the 2012 North Atlantic spring bloom. The plankton composition and characteristics of the initial stages of the bloom were markedly different between the two basins. The Iceland Basin (ICB) appeared well mixed down to >400 m, yet surface chlorophyll a (0.27–2.2 mg m−3) and primary production (0.06–0.66 mmol C m−3 d−1) were elevated in the upper 100 m. Although the Norwegian Basin (NWB) had a persistently shallower mixed layer (<100 m), chlorophyll a (0.58–0.93 mg m−3) and primary production (0.08–0.15 mmol C m−3 d−1) remained lower than in the ICB, with picoplankton (<2 μm) dominating chlorophyll a biomass. The ICB phytoplankton composition appeared primarily driven by the physicochemical environment, with periodic events of increased mixing restricting further increases in biomass. In contrast, the NWB phytoplankton community was potentially limited by physicochemical and/or biological factors such as grazing.  Diatoms dominated the ICB, with the genus Chaetoceros (1–166 cells mL−1) being succeeded by Pseudo-nitzschia (0.2–210 cells mL−1). However, large diatoms (>10 μm) were virtually absent (<0.5 cells mL−1) from the NWB, with only small nano-sized (<5 μm) diatoms (i.e. Minidiscus spp.) present (101–600 cells mL−1). We suggest microzooplankton grazing, potentially coupled with the lack of a seed population of bloom-forming diatoms, was restricting diatom growth in the NWB, and that large diatoms may be absent in NWB spring blooms. Despite both phytoplankton communities being in the early stages of bloom formation, different physicochemical and biological factors controlled bloom formation at the two sites. If these differences in phytoplankton composition persist, the subsequent spring blooms are likely to be significantly different in terms of biogeochemistry and trophic interactions throughout the growth season, with important implications for carbon cycling and organic matter export.
PY 2015
SO Biogeosciences
SN 1726-4170
PU Copernicus Gesellschaft Mbh
VL 12
IS 8
UT 000353840500009
BP 2395
EP 2409
DI 10.5194/bg-12-2395-2015
ID 42025
ER

EF