scholarly journals Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers

2015 ◽  
Vol 12 (1) ◽  
pp. 93-133 ◽  
Author(s):  
C. J. Daniels ◽  
A. J. Poulton ◽  
M. Esposito ◽  
M. L. Paulsen ◽  
R. Bellerby ◽  
...  
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
North Atlantic ◽  
Phytoplankton Community ◽  
Spring Bloom ◽  
Early Stage ◽  
Biological Factors ◽  
Phytoplankton Composition ◽  
Bloom Formation ◽  
Phytoplankton Communities

Abstract. The 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 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 nanno-sized (< 5 μm) diatoms present (101–600 cells mL–1). We suggest micro-zooplankton 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.

scholarly journals Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers

2015 ◽  
Vol 12 (8) ◽  
pp. 2395-2409 ◽  
Author(s):  
C. J. Daniels ◽  
A. J. Poulton ◽  
M. Esposito ◽  
M. L. Paulsen ◽  
R. Bellerby ◽  
...  
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
North Atlantic ◽  
Phytoplankton Community ◽  
Spring Bloom ◽  
Early Stage ◽  
Biological Factors ◽  
Phytoplankton Composition ◽  
Bloom Formation ◽  
Phytoplankton Communities

Abstract. The 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.

scholarly journals ECOSMO II(CHL): a marine biogeochemical model for the North Atlantic and the Arctic

2021 ◽  
Author(s):  
Veli Çağlar Yumruktepe ◽  
Annette Samuelsen ◽  
Ute Daewel
Keyword(s):  
Primary Production ◽  
Baltic Sea ◽  
Chlorophyll A ◽  
North Sea ◽  
North Atlantic ◽  
Spring Bloom ◽  
The Arctic ◽  
The North ◽  
The North Sea ◽  
The North Atlantic

Abstract. ECOSMO II is a fully coupled bio-physical model of 3d-hydrodynamics with an intermediate complexity N(utrient) P(hytoplankton) Z(ooplankton) D(etritus) type biology including sediment-water column exchange processes originally formulated for the North Sea and Baltic Sea. Here we present an updated version of the model incorporating chlorophyll a as a prognostic state variable: ECOSMO II(CHL). The version presented here is online coupled to the HYCOM ocean model. The model is intended to be used for regional configurations for the North Atlantic and the Arctic incorporating coarse to high spatial resolutions for hind-casting and operational purposes. We provide the full descriptions of the changes in ECOSMO II(CHL) from ECOSMO II and provide the evaluation for the inorganic nutrients and chlorophyll variables, present the modeled biogeochemistry of the Nordic Seas and the Artic and experiments on various parameterization sets as use cases targeting chlorophyll a dynamics. The model evaluations demonstrated that the simulations are consistent with the large-scale climatological nutrient settings, and are capable of representing regional and seasonal changes. The Norwegian and Barents Seas primary production show distinct seasonal patterns with a pronounced spring bloom dominated by diatoms and low biomass during winter months. The Norwegian Sea annual primary production is around double that of the Barents Sea while also having an earlier spring bloom. The parameterization experiments showed that the representation of open ocean chlorophyll a benefits from using higher phytoplankton growth and zooplankton grazing rates with less photosynthesis efficiency compared to the original implementation of ECOSMO II, which was valid for the North Sea and the Baltic Sea representing coastal domains. Thus, for open ocean modeling studies, we suggest the use of the parameterization sets presented in this study.

Differences between Nearshore and Offshore Phytoplankton Communities in Lake Ontario

1987 ◽  
Vol 44 (12) ◽  
pp. 2155-2163 ◽  
Author(s):  
I. M. Gray
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Algal Biomass ◽  
Phytoplankton Community ◽  
Seasonal Pattern ◽  
Principal Component ◽  
Lake Ontario ◽  
Dominant Group ◽  
Phytoplankton Communities ◽  
Eutrophic Species

Differences between nearshore and offshore phytoplankton biomass and composition were evident in Lake Ontario in 1982. Phytoplankton biomass was characterized by multiple peaks which ranged over three orders of magnitude. Perhaps as a consequence of the three times higher current velocities at the northshore station, phytoplankton biomass ranged from 0.09 to 9.00 g∙m−3 compared with 0.10 to 2.40 g∙m−3 for the midlake station. Bacillariophyceae was the dominant group at the northshore station until September when Cyanophyta contributed most to the biomass (83%). Although Bacillariophyceae was the principal component of the spring phytoplankton community at the midlake station, phytoflagellates (49%) and Chlorophyceae (25%) were responsible for summer biomass, with the Chlorophyceae expanding to 80% in the fall. The seasonal pattern of epilimnetic chlorophyll a correlated with temperature. While chlorophyll a concentrations were similar to values from 1970 and 1972, algal biomass had declined and a number of eutrophic species (Melosira binderana, Stephanodiscus tenuis, S. hantzschii var. pusilla, and S. alpinus) previously found were absent in 1982.

scholarly journals Summer aspect of phytoplankton communities in some Montenegrin lakes: Are there changes after more than two decades?

2012 ◽  
Vol 64 (2) ◽  
pp. 745-755
Author(s):  
Jelena Rakocevic
Keyword(s):  
Water Quality ◽  
Sustainable Management ◽  
Aquatic Ecosystems ◽  
Phytoplankton Community ◽  
Management Plan ◽  
Phytoplankton Composition ◽  
Qualitative And Quantitative ◽  
Environmental Monitoring System ◽  
Phytoplankton Communities ◽  
Second Period

Qualitative and quantitative phytoplankton compositions of 10 Montenegrin lakes were investigated in the summer of 2007. The obtained results were compared with a previous study-period that was undertaken two decades ago. In the first period, diatoms numerically dominated the phytoplankton community in all studied lakes, while in the second period, the same was observed only in three of the ten lakes; in other studied lakes the relative contributions of green algae, dinoflagellates and/or cyanobacteria increased, while the contribution of diatoms decreased. The shift observed in phytoplankton composition and diversity in some of the studied lakes indicates an increase in the trophic level over the two decades. The sustainable management plan of the aquatic ecosystems in Montenegro should include the establishment of an environmental monitoring system in order to record any alterations that may take place in water quality.

Effects of zooplankton grazing on phytoplankton communities in Mt Bold Reservoir, South Australia, using enclosures

1988 ◽  
Vol 39 (4) ◽  
pp. 503 ◽  
Author(s):  
CJ Merrick ◽  
GG Ganf
Keyword(s):  
Chlorophyll A ◽  
Selection Criteria ◽  
Phytoplankton Community ◽  
Food Selection ◽  
South Australia ◽  
Zooplankton Grazing ◽  
Multivariate Statistical ◽  
Phytoplankton Communities ◽  
Phytoplankton Size ◽  
Temporal Path

Enclosure experiments demonstrated that zooplankton grazing changed the composition of the phytoplankton community in Mt Bold Reservoir. Phytoplankton biomass as measured by chlorophyll a did not change within the enclosures but changed across the experiments in response to zooplankton grazing. The chlorophyll a : phaeophytin a ratio did not reflect zooplankton grazing activity. Phytoplankton species richness and diversity did not change but the frequencies of many individual phytoplankton taxa differed in response to zooplankton grazing. Neither taxonomic identity nor phytoplankton size as measured by greatest axial linear dimension and volume determined the susceptibility of a taxon to grazing. This suggests that other criteria are important in food selection, criteria which vary between experiments. Multivariate statistical techniques successfully differentiated the grazed and the ungrazed phytoplankton communities based on the different frequencies of the component taxa. There was an indication that, within the enclosures, zooplankton grazing advanced the phytoplankton community along a temporal path. Microzooplankton grazing was not examined in these experiments but there was evidence that it was significant.

scholarly journals Declining silica availability – a challenge in the North Atlantic region?

2020 ◽  
Author(s):  
Kriste Makareviciute-Fichtner ◽  
Birte Matthiessen ◽  
Heike K. Lotze ◽  
Ulrich Sommer
Keyword(s):  
Primary Production ◽  
Food Webs ◽  
Silicic Acid ◽  
North Atlantic ◽  
North Atlantic Region ◽  
Atlantic Region ◽  
The North ◽  
Phytoplankton Communities ◽  
Limiting Nutrient ◽  
The North Atlantic

&lt;p&gt;Understanding how changes in limiting nutrient availability affect life in the oceans requires interdisciplinary efforts. Here we illustrate this with an example of silicon, one of the most common elements on land which bioavailable form, silicic acid (Si(OH)&lt;sub&gt;4&lt;/sub&gt;), is a limiting nutrient for silicifying primary producers, such as diatoms.&lt;/p&gt;&lt;p&gt;&amp;#160;Silicic acid concentrations in the pelagic polar and subpolar North Atlantic have declined by 1-2 &amp;#956;M during spring pre-bloom conditions over the past 25 years. Many coastal areas of the North Atlantic region also face decreased relative availability of silicon due to increased riverine supply of nitrogen and phosphorus and stable or declining loads of silicon. Both declining silicic acid concentrations and declining silicon to nitrogen (Si:N) ratios limit the growth of diatoms, which are major primary producers contributing up to a quarter of global primary production.&lt;/p&gt;&lt;p&gt;To assess the effects of declining silicon availability on phytoplankton communities we conducted a mesocosm experiment manipulating Si:N ratios and copepod grazing pressure on phytoplankton communities from the Baltic Sea. Declining Si:N ratio affected not only diatom abundance and relative biomass but also their species composition and overall plankton diversity. Our results illustrate the importance of silicon in structuring community composition at the base of temperate marine food webs. Changes in silicic acid concentrations and Si:N ratios, therefore, may have far-reaching consequences on oceanic primary production and planktonic food webs.&lt;/p&gt;&lt;p&gt;The decline in silicon concentrations in polar and subpolar North Atlantic waters is attributed to natural multi-decadal variability but is likely amplified by reduced ocean mixing due to increased water temperatures, illustrating the need of international efforts to curb global climate change. The decline in Si:N ratios in coastal oceans also highlights the need for further reduction of nutrient pollution and improved river basin management. This may require interdisciplinary and international approaches to manage anthropogenic perturbations of the silicon cycle.&lt;/p&gt;

scholarly journals Sargasso Sea phosphorus biogeochemistry: an important role for dissolved organic phosphorus (DOP)

2010 ◽  
Vol 7 (2) ◽  
pp. 695-710 ◽  
Author(s):  
M. W. Lomas ◽  
A. L. Burke ◽  
D. A. Lomas ◽  
D. W. Bell ◽  
C. Shen ◽  
...  
Keyword(s):  
Time Series ◽  
Primary Production ◽  
North Atlantic ◽  
Spring Bloom ◽  
Organic Phosphorus ◽  
Seasonal Pattern ◽  
Euphotic Zone ◽  
Inorganic Phosphorus ◽  
Dissolved Organic Phosphorus ◽  
Phosphorus Export

Abstract. Inorganic phosphorus (SRP) concentrations in the subtropical North Atlantic are some of the lowest in the global ocean and have been hypothesized to constrain primary production. Based upon data from several transect cruises in this region, it has been hypothesized that dissolved organic phosphorus (DOP) supports a significant fraction of primary production in the subtropical North Atlantic. In this study, a time-series of phosphorus biogeochemistry is presented for the Bermuda Atlantic Time-series Study site, including rates of phosphorus export. Most parameters have a seasonal pattern, although year-over-year variability in the seasonal pattern is substantial, likely due to differences in external forcing. Suspended particulate phosphorus exhibits a seasonal maximum during the spring bloom, despite the absence of a seasonal peak in SRP. However, DOP concentrations are at an annual maximum prior to the winter/spring bloom and decline over the course of the spring bloom while whole community alkaline phosphatase activities are highest. As a result of DOP bioavailability, the growth of particles during the spring bloom occurs in Redfield proportions, though particles exported from the euphotic zone show rapid and significant remineralization of phosphorus within the first 50 m below the euphotic zone. Based upon DOP data from transect cruises in this region, the southward cross gyral flux of DOP is estimated to support ~25% of annual primary production and ~100% of phosphorus export. These estimates are consistent with other research in the subtropical North Atlantic and reinforce the hypothesis that while the subtropics may be phosphorus stressed (a physiological response to low inorganic phosphorus), utilization of the DOP pool allows production and accumulation of microbial biomass at Redfield proportions.

scholarly journals Chlorophyll-a transformations associated with sinking diatoms during termination of a North Atlantic spring bloom

2015 ◽  
Vol 172 ◽  
pp. 23-33 ◽  
Author(s):  
Nicole J. Bale ◽  
Ruth L. Airs ◽  
Patrick Martin ◽  
Richard S. Lampitt ◽  
Carole A. Llewellyn
Keyword(s):  
Chlorophyll A ◽  
North Atlantic ◽  
Spring Bloom
Sign in / Sign up

Export Citation Format

Share Document