scholarly journals The onset of the spring phytoplankton bloom in the coastal North Sea supports the Disturbance Recovery Hypothesis

2021 ◽  
Author(s):  
Ricardo González-Gil ◽  
Neil S. Banas ◽  
Eileen Bresnan ◽  
Michael R. Heath
Keyword(s):  
North Sea ◽  
Phytoplankton Biomass ◽  
Spring Bloom ◽  
Phytoplankton Bloom ◽  
Biomass Accumulation ◽  
Coastal Areas ◽  
Rate Of Change ◽  
Winter Solstice ◽  
Spring Phytoplankton Bloom ◽  
Disturbance Recovery

Abstract. The spring phytoplankton bloom is a key event in temperate and polar seas, yet the mechanisms that trigger it remain under debate. Some hypotheses claim that the spring bloom onset occurs when light is no longer limiting, allowing phytoplankton division rates to surpass a critical threshold. In contrast, the Disturbance Recovery Hypothesis (DRH) proposes that the onset responds to an imbalance between phytoplankton growth and loss processes, allowing phytoplankton biomass to start accumulating, and this can occur even when light is still limiting. Although many studies have shown that the DRH explains the spring bloom onset in oceanic waters, it is less certain whether and how it also applies to coastal areas. To address this question at a coastal location in the Scottish North Sea, we combined 21 years (1997–2017) of weekly in situ data with meteorological information. The onset of phytoplankton biomass accumulation occurred around the same date each year, 16 ± 11 days (mean ± SD) after the winter solstice, when light limitation for growth was strongest. Also, negative and positive biomass accumulation rates (r) occurred respectively before and after the winter solstice at similar light levels. The seasonal change from negative to positive r was mainly driven by the rate of change in light availability rather than light itself. Our results support the validity of the DRH for the studied coastal region and suggest its applicability to other coastal areas.

scholarly journals Seasonal changes in the D  /  H ratio of fatty acids of pelagic microorganisms in the coastal North Sea

2016 ◽  
Vol 13 (19) ◽  
pp. 5527-5539 ◽  
Author(s):  
Sandra Mariam Heinzelmann ◽  
Nicole Jane Bale ◽  
Laura Villanueva ◽  
Danielle Sinke-Schoen ◽  
Catharina Johanna Maria Philippart ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Isotopic Composition ◽  
North Sea ◽  
Phytoplankton Bloom ◽  
Isotopic Fractionation ◽  
Spring Phytoplankton Bloom ◽  
Fractionation Factor ◽  
Culture Studies ◽  
Hydrogen Isotopic Composition

Abstract. Culture studies of microorganisms have shown that the hydrogen isotopic composition of fatty acids depends on their metabolism, but there are only few environmental studies available to confirm this observation. Here we studied the seasonal variability of the deuterium-to-hydrogen (D / H) ratio of fatty acids in the coastal Dutch North Sea and compared this with the diversity of the phyto- and bacterioplankton. Over the year, the stable hydrogen isotopic fractionation factor ε between fatty acids and water (εlipid/water) ranged between −172 and −237 ‰, the algal-derived polyunsaturated fatty acid nC20:5 generally being the most D-depleted (−177 to −235 ‰) and nC18:0 the least D-depleted fatty acid (−172 to −210 ‰). The in general highly D-depleted nC20:5 is in agreement with culture studies, which indicates that photoautotrophic microorganisms produce fatty acids which are significantly depleted in D relative to water. The εlipid/water of all fatty acids showed a transient shift towards increased fractionation during the spring phytoplankton bloom, indicated by increasing chlorophyll a concentrations and relative abundance of the nC20:5 polyunsaturated fatty acids, suggesting increased contributions of photoautotrophy. Time periods with decreased fractionation (less negative εlipid/water values) can potentially be explained by an increased contribution of heterotrophy to the fatty acid pool. Our results show that the hydrogen isotopic composition of fatty acids is a promising tool to assess the community metabolism of coastal plankton potentially in combination with the isotopic analysis of more specific biomarker lipids.

scholarly journals Grazing behavior and winter phytoplankton accumulation

2021 ◽  
Vol 18 (20) ◽  
pp. 5595-5607
Author(s):  
Mara Freilich ◽  
Alexandre Mignot ◽  
Glenn Flierl ◽  
Raffaele Ferrari
Keyword(s):  
North Atlantic ◽  
Phytoplankton Biomass ◽  
Phytoplankton Bloom ◽  
Biomass Accumulation ◽  
Grazing Pressure ◽  
Mathematical Framework ◽  
Grazing Behavior ◽  
Phytoplankton Concentration ◽  
The North ◽  
The North Atlantic

Abstract. Recent observations have shown that phytoplankton biomass increases in the North Atlantic during winter, even when the mixed layer is deepening and light is limited. Current theories suggest that this is due to a release from grazing pressure. Here we demonstrate that the often-used grazing models that are linear at low phytoplankton concentration do not allow for a wintertime increase in phytoplankton biomass. However, mathematical formulations of grazing as a function of phytoplankton concentration that are quadratic at low concentrations (or more generally decrease faster than linearly as phytoplankton concentration decreases) can reproduce the fall to spring transition in phytoplankton, including wintertime biomass accumulation. We illustrate this point with a minimal model for the annual cycle of North Atlantic phytoplankton designed to simulate phytoplankton concentration as observed by BioGeoChemical-Argo (BGC-Argo) floats in the North Atlantic. This analysis provides a mathematical framework for assessing hypotheses of phytoplankton bloom formation.

scholarly journals An investigation of grazing behaviors that result in winter phytoplankton biomass accumulation

2020 ◽  
Author(s):  
Mara Freilich ◽  
Alexandre Mignot ◽  
Glenn Flierl ◽  
Raffaele Ferrari
Keyword(s):  
North Atlantic ◽  
Phytoplankton Biomass ◽  
Phytoplankton Bloom ◽  
Biomass Accumulation ◽  
Grazing Pressure ◽  
Mathematical Framework ◽  
Phytoplankton Concentration ◽  
The North ◽  
Bloom Formation ◽  
The North Atlantic

Abstract. Recent observations have shown that phytoplankton biomass increases in the North Atlantic during winter, even when the mixed layer is deepening and light is limited. Current theories suggest that this is due to a release from grazing pressure. Here we demonstrate that the often-used grazing models that are linear at low phytoplankton concentration do not allow for a wintertime increase in phytoplankton biomass. However, certain mathematical formulations of grazing that are quadratic (or more generally non-linear) in phytoplankton concentration at low concentrations can reproduce the fall to spring transition in phytoplankton, including wintertime biomass accumulation. We illustrate this point with a minimal model for the annual cycle of North Atlantic phytoplankton designed to simulate phytoplankton concentration as observed by BioGeoChemical-Argo (BGC-Argo) floats in the North Atlantic. This analysis provides a mathematical framework for assessing hypotheses of phytoplankton bloom formation.

scholarly journals Changes in structural and functional diversity of nematode communities during a spring phytoplankton bloom in the southern North Sea

2004 ◽  
Vol 52 (4) ◽  
pp. 281-292 ◽  
Author(s):  
Jan Vanaverbeke ◽  
Maaike Steyaert ◽  
Karline Soetaert ◽  
Véronique Rousseau ◽  
Dirk Van Gansbeke ◽  
...  
Keyword(s):  
Functional Diversity ◽  
North Sea ◽  
Phytoplankton Bloom ◽  
Spring Phytoplankton Bloom ◽  
Nematode Communities ◽  
Southern North Sea

scholarly journals A newly observed physical cause of the onset of the subsurface spring phytoplankton bloom in the southwestern East Sea/Sea of Japan

2014 ◽  
Vol 11 (5) ◽  
pp. 1319-1329 ◽  
Author(s):  
Y.-T. Son ◽  
K.-I. Chang ◽  
S.-T. Yoon ◽  
T. Rho ◽  
J. H. Kwak ◽  
...  
Keyword(s):  
Sea Of Japan ◽  
Mixed Layer ◽  
Spring Bloom ◽  
Phytoplankton Bloom ◽  
Mixed Layer Depth ◽  
East Sea ◽  
Ulleung Basin ◽  
Intermediate Water ◽  
Spring Phytoplankton Bloom ◽  
Bloom Period

Abstract. An ocean buoy, UBIM (Ulleung Basin Integrated Mooring), deployed during the spring transition from February to May 2010 reveals for the first time highly resolved temporal variation of biochemical properties of the upper layer of the Ulleung Basin in the southwestern East Sea/Sea of Japan. The time-series measurement captured the onset of subsurface spring bloom at 30 m, and collocated temperature and current data gives an insight into a mechanism that triggers the onset of the spring bloom not documented so far. Low-frequency modulation of the mixed layer depth ranging from 10 m to 53 m during the entire mooring period is mainly determined by shoaling and deepening of isothermal depths depending on the placement of UBIM on the cold or warm side of the frontal jet. The occurrence of the spring bloom at 30 m is concomitant with the appearance of colder East Sea Intermediate Water at buoy UBIM, which results in subsurface cooling and shoaling of isotherms to the shallower depth levels during the bloom period than those that occurred during the pre-bloom period. Isolines of temperature-based NO3 are also shown to be uplifted during the bloom period. It is suggested that the springtime spreading of the East Sea Intermediate Water is one of the important factors that triggers the subsurface spring bloom below the mixed layer.

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