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Response of foraminifera Ammonia confertitesta (T6) to ocean acidification, warming, and deoxygenation - An experimental approach

Muller, Elsa LU (2023) In Dissertations in Geology at Lund University GEOR02 20231
Department of Geology
Abstract (Swedish)
Ocean acidification, warmer temperatures, and the expansion of hypoxic zones in coastal areas are direct
consequences of the increase in anthropogenic activities. However, so far, the combined effects of these stressors
on calcium carbonate-secreting marine microorganisms - foraminifera are complex and poorly understood. This
study reports the foraminiferal survival behavior, and geochemical trace elements incorporation measured from the
shells of living cultured benthic foraminifera from the Gullmar fjord (Sweden) after exposure to warming,
acidification, and hypoxic conditions. An experimental set-up was designed with two different temperatures (fjord’s
in-situ 9 ˚C and 14 ˚C), two different oxygen concentrations (oxic versus... (More)
Ocean acidification, warmer temperatures, and the expansion of hypoxic zones in coastal areas are direct
consequences of the increase in anthropogenic activities. However, so far, the combined effects of these stressors
on calcium carbonate-secreting marine microorganisms - foraminifera are complex and poorly understood. This
study reports the foraminiferal survival behavior, and geochemical trace elements incorporation measured from the
shells of living cultured benthic foraminifera from the Gullmar fjord (Sweden) after exposure to warming,
acidification, and hypoxic conditions. An experimental set-up was designed with two different temperatures (fjord’s
in-situ 9 ˚C and 14 ˚C), two different oxygen concentrations (oxic versus hypoxic), and three different pH (control,
medium, and low pH based on the IPCC scenario for the year 2100). Duplicate aquariums, meaning aquariums
displaying the same conditions and same number of species, were employed for the controls and the two lower pH
conditions at both temperatures. The stability of the aquariums was ensured by regular measurement of the water
parameters and confirmed by statistical analysis. The species Ammonia confertitesta’s (T6) survival (CTB-labeled),
shell calcification (calcein-labeled), and geochemical analyses (laser-ablation ICP-MS) were investigated at the end
of the experimental period (48 days). Investigated trace elements (TE) ratios were Mg/Ca, Mn/Ca, Ba/Ca, and Sr/
Ca. Results show that A. confertitesta (T6) calcified chambers in all the experimental conditions except for the most
severe combination of stressors (i.e., warm, hypoxic, low pH). Survival rates varied by up to a factor of two
between duplicates for all conditions suggesting that foraminiferal response may not solely be driven by
environmental conditions but also by internal or confounding factors (e.g., physiological stress). A large variability
of all the TE/Ca values of foraminifera growing at low pH is observed suggesting that A. confertitesta (T6) may
struggle to calcify in these conditions. Thus, this study demonstrates the vulnerability of a resilient species to the
triple-stressor scenario in terms of survival, calcification, and trace element incorporation. Overall, the experimental
set-up yielded coherent results compared to previous studies in terms of ontogeny, trace elements ratios, and
partition coefficient making it advantageous for environmental reconstructions. (Less)
Please use this url to cite or link to this publication:
author
Muller, Elsa LU
supervisor
organization
course
GEOR02 20231
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Acidification, Warming, Deoxygenation, Foraminifera, Ammonia confertitesta (T6), Culture Experiment, Trace elements
publication/series
Dissertations in Geology at Lund University
report number
667
language
English
id
9135664
date added to LUP
2023-08-30 15:51:24
date last changed
2023-08-30 15:51:24
@misc{9135664,
  abstract     = {{Ocean acidification, warmer temperatures, and the expansion of hypoxic zones in coastal areas are direct 
consequences of the increase in anthropogenic activities. However, so far, the combined effects of these stressors 
on calcium carbonate-secreting marine microorganisms - foraminifera are complex and poorly understood. This 
study reports the foraminiferal survival behavior, and geochemical trace elements incorporation measured from the 
shells of living cultured benthic foraminifera from the Gullmar fjord (Sweden) after exposure to warming, 
acidification, and hypoxic conditions. An experimental set-up was designed with two different temperatures (fjord’s 
in-situ 9 ˚C and 14 ˚C), two different oxygen concentrations (oxic versus hypoxic), and three different pH (control, 
medium, and low pH based on the IPCC scenario for the year 2100). Duplicate aquariums, meaning aquariums 
displaying the same conditions and same number of species, were employed for the controls and the two lower pH 
conditions at both temperatures. The stability of the aquariums was ensured by regular measurement of the water 
parameters and confirmed by statistical analysis. The species Ammonia confertitesta’s (T6) survival (CTB-labeled), 
shell calcification (calcein-labeled), and geochemical analyses (laser-ablation ICP-MS) were investigated at the end 
of the experimental period (48 days). Investigated trace elements (TE) ratios were Mg/Ca, Mn/Ca, Ba/Ca, and Sr/
Ca. Results show that A. confertitesta (T6) calcified chambers in all the experimental conditions except for the most 
severe combination of stressors (i.e., warm, hypoxic, low pH). Survival rates varied by up to a factor of two 
between duplicates for all conditions suggesting that foraminiferal response may not solely be driven by 
environmental conditions but also by internal or confounding factors (e.g., physiological stress). A large variability 
of all the TE/Ca values of foraminifera growing at low pH is observed suggesting that A. confertitesta (T6) may 
struggle to calcify in these conditions. Thus, this study demonstrates the vulnerability of a resilient species to the 
triple-stressor scenario in terms of survival, calcification, and trace element incorporation. Overall, the experimental 
set-up yielded coherent results compared to previous studies in terms of ontogeny, trace elements ratios, and 
partition coefficient making it advantageous for environmental reconstructions.}},
  author       = {{Muller, Elsa}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Dissertations in Geology at Lund University}},
  title        = {{Response of foraminifera Ammonia confertitesta (T6) to ocean acidification, warming, and deoxygenation - An experimental approach}},
  year         = {{2023}},
}