3 research outputs found
Factors controlling the community structure of picoplankton in contrasting marine environments
The
effect of inorganic nutrients on planktonic assemblages has traditionally
relied on concentrations rather than estimates of nutrient supply. We
combined a novel dataset of hydrographic properties, turbulent mixing,
nutrient concentration, and picoplankton community composition with the aims
of (i)Â quantifying the role of temperature, light, and nitrate fluxes as
factors controlling the distribution of autotrophic and heterotrophic
picoplankton subgroups, as determined by flow cytometry, and (ii)Â describing
the ecological niches of the various components of the picoplankton
community. Data were collected at 97 stations in the Atlantic Ocean,
including tropical and subtropical open-ocean waters, the northwestern
Mediterranean Sea, and the Galician coastal upwelling system of the northwest
Iberian Peninsula. A generalized additive model (GAM) approach was used to
predict depth-integrated biomass of each picoplankton subgroup based on three
niche predictors: sea surface temperature, averaged daily surface irradiance,
and the transport of nitrate into the euphotic zone, through both diffusion
and advection. In addition, niche overlap among different picoplankton
subgroups was computed using nonparametric kernel density functions.
Temperature and nitrate supply were more relevant than light in predicting
the biomass of most picoplankton subgroups, except for
Prochlorococcus and low-nucleic-acid (LNA) prokaryotes, for which irradiance also played a
significant role. Nitrate supply was the only factor that allowed the
distinction among the ecological niches of all autotrophic and heterotrophic
picoplankton subgroups. Prochlorococcus and LNA prokaryotes were
more abundant in warmer waters (>20 ∘C) where the nitrate fluxes
were low, whereas Synechococcus and high-nucleic-acid (HNA)
prokaryotes prevailed mainly in cooler environments characterized by
intermediate or high levels of nitrate supply. Finally, the niche of
picoeukaryotes was defined by low temperatures and high nitrate supply. These
results support the key role of nitrate supply, as it not only promotes the
growth of large phytoplankton, but it also controls the structure of marine
picoplankton communities.Ministerio de EconomÃa y Competitividad | Ref. CTM2012-30680Ministerio de EconomÃa y Competitividad | Ref. CTM2008-0626I-C03-01Ministerio de EconomÃa y Competitividad | Ref. REN2003-09532-C03-01Ministerio de EconomÃa y Competitividad | Ref. CTM2004-05174 -C02Ministerio de EconomÃa y Competitividad | Ref. CTM2011-25035Xunta de Galicia | Ref. 09MMA027604PRXunta de Galicia | Ref. EM2013/021European Commission | Ref. FP7, n. 261860Ministerio de EconomÃa y Competitividad | Ref. FJCI-641 2015-2571
Factors controlling the community structure of picoplankton in contrasting marine environments
22 pages, 4 tables, 5 figuresThe effect of inorganic nutrients on planktonic assemblages
has traditionally relied on concentrations rather
than estimates of nutrient supply. We combined a novel
dataset of hydrographic properties, turbulent mixing, nutrient
concentration, and picoplankton community composition
with the aims of (i) quantifying the role of temperature, light,
and nitrate fluxes as factors controlling the distribution of autotrophic
and heterotrophic picoplankton subgroups, as determined
by flow cytometry, and (ii) describing the ecological
niches of the various components of the picoplankton
community. Data were collected at 97 stations in the Atlantic
Ocean, including tropical and subtropical open-ocean waters,
the northwestern Mediterranean Sea, and the Galician coastal
upwelling system of the northwest Iberian Peninsula. A generalized
additive model (GAM) approach was used to predict
depth-integrated biomass of each picoplankton subgroup
based on three niche predictors: sea surface temperature, averaged
daily surface irradiance, and the transport of nitrate
into the euphotic zone, through both diffusion and advection.
In addition, niche overlap among different picoplankton
subgroups was computed using nonparametric kernel density
functions. Temperature and nitrate supply were more
relevant than light in predicting the biomass of most picoplankton
subgroups, except for Prochlorococcus and lownucleic-
acid (LNA) prokaryotes, for which irradiance also
played a significant role. Nitrate supply was the only factor
that allowed the distinction among the ecological niches
of all autotrophic and heterotrophic picoplankton subgroups.
Prochlorococcus and LNA prokaryotes were more abundant
in warmer waters ( > 20 C) where the nitrate fluxes were
low, whereas Synechococcus and high-nucleic-acid (HNA)
prokaryotes prevailed mainly in cooler environments characterized
by intermediate or high levels of nitrate supply. Finally,
the niche of picoeukaryotes was defined by low temperatures
and high nitrate supply. These results support the
key role of nitrate supply, as it not only promotes the growth
of large phytoplankton, but it also controls the structure of
marine picoplankton communitiesThis research was supported by the Spanish Ministry of
Economy and Competitiveness (MINECO) through projects
CTM2012-30680 to Beatriz Mouriño, CTM2008-0626I-C03-01
to Mikel Latasa, REN2003-09532-C03-01 to Ramiro Varela Benvenuto,
CTM2004-05174-C02 to Emilio Marañón, and CTM2011-
25035 to Pedro Cermeño; by the Galician government through
grants 09MMA027604PR to Manuel Ruiz Villareal and
EM2013/021 to Beatriz Mouriño; by the Instituto Español de
Oceanografia (IEO) through the time series project RADIALES coordinated
by Antonio Bode and by the 7th Framework Programme
of the European Commission through grant FP7 SPACE.2010.1.1-
01 261860 to Manuel Ruiz Villareal. Jose Luis Otero Ferrer
acknowledges the receipt of a FPI contract from MINECO
(CTM2012-30680) and Bieito Fernádez Castro a Juan de La Cierva
Formación fellowship (FJCI-641 2015-25712, Ministerio de
EconomÃa y Competitividad, Spanish government)Peer reviewe