Effects of ocean acidification and phosphate limitation on physiology and toxicity of the dinoflagellate Karenia mikimotoi

Abstract. The ongoing rise in atmospheric pCO2 and the consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton which potentially translates into altered carbon export. To date it remains unclear first, how nutrient ratio, in particular from coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation. Second, how direct physiological responses on the cellular level translate into a net population response. In this study cultures of Emiliania huxleyi were full-factorially exposed to two different N:P ratios (Redfield and high N:P) and three different pCO2 levels. Effects on net population particulate inorganic and organic carbon (PIC, POC) were measured after E. huxleyi cultures reached stationary phase. Thereby cell sizes and total cell abundance were taken into account. Corresponding to literature results show a significant negative cellular PIC and POC response which, however, was strongest under high N:P ratio. In contrast, net population PIC and POC accumulation was significantly attenuated under high N:P ratio. We suggest that less cellular nutrient accumulation allowed for higher cell abundances which compensated for the strong negative cellular PIC and POC response to pCO2 on the population level. Moreover, the design of this study also allowed following natural alteration of carbon chemistry through changing DIC and alkalinity. Our results suggest that at high initial pCO2 natural alteration of pCO2 during the experimental runtime was regulated by algal biomass. In contrast, at low initial pCO2 the PIC/POC ratio was responsible for changes in pCO2. Our results point to the fact that the physiological (i.e. cellular) PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore recommended to consider effects of nutrient limitation on cell physiology and translate these to net population carbon accumulation when predicting the influence of coccolithophores on both, the atmospheric pCO2 feedback and their function in carbon export mechanisms.

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The responses of harmful dinoflagellate Karenia mikimotoi to simulated ocean acidification at the transcriptional level

Harmful Algae ◽

10.1016/j.hal.2021.102167 ◽

2022 ◽

Vol 111 ◽

pp. 102167

Author(s):

Jiazhu Zhang ◽

Qiongying Yang ◽

Qianlou Liu ◽

Shuqi Liu ◽

Yue Zhu ◽

...

Keyword(s):

Ocean Acidification ◽

Transcriptional Level ◽

Karenia Mikimotoi ◽

Harmful Dinoflagellate

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Effect of ocean acidification on the structure and fatty acid composition of a natural plankton community in the Baltic Sea

10.5194/bg-2015-669 ◽

2016 ◽

Cited By ~ 3

Author(s):

J. R Bermúdez ◽

M. Winder ◽

A. Stuhr ◽

A. K. Almén ◽

J. Engström-Öst ◽

...

Keyword(s):

Fatty Acid ◽

Ocean Acidification ◽

Baltic Sea ◽

Community Composition ◽

Brackish Water ◽

Plankton Community ◽

Phosphate Limitation ◽

High Pco2 ◽

Co2 Uptake ◽

Fa Composition

Abstract. Increasing atmospheric carbon dioxide (CO2) is changing seawater chemistry towards reduced pH, which consequently affects various properties of marine organisms. Coastal and brackish water communities are expected to be less affected by ocean acidification (OA) as these communities are typically adapted to high fluctuations in CO2 and pH. Here we investigate the response of a coastal brackish water plankton community to increasing CO2 levels as projected for the coming decades and the end of this century in terms of community and biochemical fatty acid (FA) composition. A Baltic Sea plankton community was enclosed in a set of off-shore mesocosms and subjected to a CO2 gradient ranging from natural concentrations (~347 μatm pCO2) up to values projected for the year 2100 (~1333 μatm pCO2). We show that the phytoplankton community composition was resilient to CO2 and did not diverge between the treatments. Seston FA composition was influenced by community composition, which in turn was driven by silicate and phosphate limitation in the mesocosms, and showed no difference between the CO2 treatments. These results suggest that CO2 effects are dampened in coastal communities that already experience high natural fluctuations in pCO2. Although this coastal plankton community was tolerant to high pCO2 levels, hypoxia and CO2 uptake by the sea can aggravate acidification and may lead to pH changes outside the currently experienced range for coastal organisms.

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High nitrate to phosphorus regime attenuates negative effects of rising pCO2 on total population carbon accumulation

Biogeosciences ◽

10.5194/bg-9-1195-2012 ◽

2012 ◽

Vol 9 (3) ◽

pp. 1195-1203 ◽

Cited By ~ 17

Author(s):

B. Matthiessen ◽

S. L. Eggers ◽

S. A. Krug

Keyword(s):

Ocean Acidification ◽

Total Population ◽

Physiological Responses ◽

Carbon Accumulation ◽

Phosphate Limitation ◽

Cell Physiology ◽

Carbon Export ◽

Population Response ◽

Cell Abundance ◽

Atmospheric Pco2

Abstract. The ongoing rise in atmospheric pCO2 and consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton, which potentially alters carbon export. To date it remains unclear, firstly, how nutrient regime, in particular by coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation; secondly, how direct physiological responses on the cellular level translate into total population response. In this study, cultures of Emiliania huxleyi were full-factorially exposed to two different N:P regimes and three different pCO2 levels. Cellular biovolume and PIC and POC content significantly declined in response to pCO2 in both nutrient regimes. Cellular PON content significantly increased in the Redfield treatment and decreased in the high N:P regime. Cell abundance significantly declined in the Redfield and remained constant in the high N:P regime. We hypothesise that in the high N:P regime severe phosphorous limitation could be compensated either by reduced inorganic phosphorous demand and/or by enzymatic uptake of organic phosphorous. In the Redfield regime we suggest that enzymatic phosphorous uptake to supplement enhanced phosphorous demand with pCO2 was not possible and thus cell abundance declined. These hypothesised different physiological responses of E. huxleyi among the nutrient regimes significantly altered population carrying capacities along the pCO2 gradient. This ultimately led to the attenuated total population response in POC and PIC content and biovolume to increased pCO2 in the high N:P regime. Our results point to the fact that the physiological (i.e. cellular) PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore necessary to consider both effects of nutrient limitation on cell physiology and their consequences for population size when predicting the influence of coccolithophores on atmospheric pCO2 feedback and their function in carbon export mechanisms.

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Effect of ocean acidification on the structure and fatty acid composition of a natural plankton community in the Baltic Sea

Biogeosciences ◽

10.5194/bg-13-6625-2016 ◽

2016 ◽

Vol 13 (24) ◽

pp. 6625-6635 ◽

Cited By ~ 22

Author(s):

Rafael Bermúdez ◽

Monika Winder ◽

Annegret Stuhr ◽

Anna-Karin Almén ◽

Jonna Engström-Öst ◽

...

Keyword(s):

Fatty Acid ◽

Ocean Acidification ◽

Baltic Sea ◽

Community Composition ◽

Brackish Water ◽

Plankton Community ◽

Phosphate Limitation ◽

High Pco2 ◽

Co2 Uptake ◽

Fa Composition

Abstract. Increasing atmospheric carbon dioxide (CO2) is changing seawater chemistry towards reduced pH, which affects various properties of marine organisms. Coastal and brackish water communities are expected to be less affected by ocean acidification (OA) as these communities are typically adapted to high fluctuations in CO2 and pH. Here we investigate the response of a coastal brackish water plankton community to increasing CO2 levels as projected for the coming decades and the end of this century in terms of community and biochemical fatty acid (FA) composition. A Baltic Sea plankton community was enclosed in a set of offshore mesocosms and subjected to a CO2 gradient ranging from natural concentrations ( ∼  347 µatm fCO2) up to values projected for the year 2100 ( ∼  1333 µatm fCO2). We show that the phytoplankton community composition was resilient to CO2 and did not diverge between the treatments. Seston FA composition was influenced by community composition, which in turn was driven by silicate and phosphate limitation in the mesocosms and showed no difference between the CO2 treatments. These results suggest that CO2 effects are dampened in coastal communities that already experience high natural fluctuations in pCO2. Although this coastal plankton community was tolerant of high pCO2 levels, hypoxia and CO2 uptake by the sea can aggravate acidification and may lead to pH changes outside the currently experienced range for coastal organisms.

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