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  • Springer  (4)
  • ASLO (Association for the Sciences of Limnology and Oceanography)  (2)
  • 2015-2019  (6)
  • 1
    Publication Date: 2020-02-06
    Description: Ocean acidification can impair an animal’s physiological performance and energetically demanding activities such as swimming. Behavioural abnormalities and changed activity in response to ocean acidification are reported in fish and crustacean species. We studied swimming activity in the calanoid copepod Pseudocalanus acuspes in response to near-future ocean acidification. Water and copepods were sampled from ten mesocosms deployed on the Swedish west coast. The experiments were conducted on animals reared in the mesocosms for 2 months during spring. Copepods were filmed after long-term (chronic) high-CO2, and after 20 h acute exposure to CO2. There was no significant effect of CO2 on copepods in chronic high-CO2, nor significant effect after the 20 h acute exposure. In addition, we measured prosome length from a large number of adult copepods, but no effect of acidification on body size was found. In this study, P. acuspes did not show sensitivity to near-future pCO2 levels. Even if a number of papers suggest that copepods seem robust to future ocean acidification, interaction between multiple stress factors, such as elevated temperature, hypoxia and salinity changes may impair a copepod’s ability to resist lowered pH.
    Type: Article , PeerReviewed
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  • 2
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    ASLO (Association for the Sciences of Limnology and Oceanography)
    In:  Limnology and Oceanography, 60 (6). pp. 2145-2157.
    Publication Date: 2018-10-01
    Description: Global change leads to a multitude of simultaneous modifications in the marine realm among which shoaling of the upper mixed layer, leading to enhanced surface layer light intensities, as well as increased carbon dioxide (CO2) concentration are some of the most critical environmental alterations for phytoplankton. In this study, we investigated the responses of growth, photosynthetic carbon fixation and calcification of the coccolithophore Gephyrocapsa oceanica to elevated inline image (51 Pa, 105 Pa, and 152 Pa) (1 Pa ≈ 10 μatm) at a variety of light intensities (50–800 μmol photons m−2 s−1). By fitting the light response curve, our results showed that rising inline image reduced the maximum rates for growth, photosynthetic carbon fixation and calcification. Increasing light intensity enhanced the sensitivity of these rate responses to inline image, and shifted the inline image optima toward lower levels. Combining the results of this and a previous study (Sett et al. 2014) on the same strain indicates that both limiting low inline image and inhibiting high inline image levels (this study) induce similar responses, reducing growth, carbon fixation and calcification rates of G. oceanica. At limiting low light intensities the inline image optima for maximum growth, carbon fixation and calcification are shifted toward higher levels. Interacting effects of simultaneously occurring environmental changes, such as increasing light intensity and ocean acidification, need to be considered when trying to assess metabolic rates of marine phytoplankton under future ocean scenarios.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2020-02-06
    Description: Thecosome pteropods are considered highly sensitive to ocean acidification. During the Arctic winter, increased solubility of CO2 in cold waters intensifies ocean acidification and food sources are limited. Ocean warming is also particularly pronounced in the Arctic. Here, we present the first data on metabolic rates of two pteropod species (Limacina helicina, Limacina retroversa) during the Arctic winter at 79°N (polar night/twilight phase). Routine oxygen consumption rates and the metabolic response [oxygen consumption (MO2), ammonia excretion (NH3), overall metabolic balance (O:N)] to elevated levels of pCO2 and temperature were examined. Our results suggest lower routine MO2 rates for both Limacina species in winter than in summer. In an 18-h experiment, both pCO2 and temperature affected MO2 of L. helicina and L. retroversa. After a 9-day experiment with L. helicina all three metabolic response variables were affected by the two factors with interactive effects in case of NH3 and O:N. The response resembled a “hormesis-type” pattern with up-regulation at intermediate pCO2 and the highest temperature level. For L. retroversa, NH3 excretion was affected by both factors and O:N only by temperature. No significant effects of pCO2 or temperature on MO2 were detected. Metabolic up-regulation will entail higher energetic costs that may not be covered during periods of food limitation such as the Arctic winter and compel pteropods to utilize storage compounds to a greater extent than usual. This may reduce the fitness and survival of overwintering pteropods and negatively impact their reproductive success in the following summer.
    Type: Article , PeerReviewed
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  • 4
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    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, The Netherlands, Chapter 37, 1-2. ISBN 978-94-007-6644-0
    Publication Date: 2018-01-19
    Description: Definition Ocean acidification refers to the process of increasing seawater acidity by dissolving additional carbon dioxide (CO2) from the atmosphere. As CO2 dissolves in seawater, it forms carbonic acid (H2CO3), which readily dissociates into bicarbonate (HCO3−) and hydrogen (H+) ions. The hydrogen ion concentration determines the acidity of seawater, expressed by the pH scale. Part of the hydrogen ions released in this process is buffered by the seawater carbonate system by consuming carbonate ions (CO32−) and forming additional bicarbonate. As pH is defined as the negative logarithm of the hydrogen ion concentration, pH decreases as the acidity increases (Fig. 1). Fig. 1 The process of ocean acidification: (1) atmospheric carbon dioxide (CO2) dissolving in seawater; (2) dissolved CO2 reacting with water to form carbonic acid (H2CO3); (3) carbonic acid dissociating to bicarbonate (HCO3−) and hydrogen ion (H+); and (4) hydrogen ion reacting with carbonate (CO3 ... This is an excerpt from the content
    Type: Book chapter , NonPeerReviewed
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  • 5
    Publication Date: 2018-06-01
    Description: Carbon uptake and partitioning of two globally abundant diatom species, Thalassiosira weissflogii and Dactyliosolen fragilissimus, was investigated in batch culture experiments under four conditions: ambient (15 degrees C, 400 atm), high CO2 (15 degrees C, 1000 atm), high temperature (20 degrees C, 400 atm), and combined (20 degrees C, 1000 atm). The experiments were run from exponential growth into the stationary phase (six days after nitrogen depletion), allowing us to track biogeochemical dynamics analogous to bloom situations in the ocean. Elevated CO2 had a fertilizing effect and enhanced uptake of dissolved inorganic carbon (DIC) by about 8% for T. weissflogii and by up to 39% for D. fragilissimus. This was also reflected in higher cell numbers, build-up of particulate and dissolved organic matter, and transparent exopolymer particles. The CO2 effects were most prominent in the stationary phase when nitrogen was depleted and CO2(aq) concentrations were low. This indicates that diatoms in the high CO2 treatments could take up more DIC until CO2 concentrations in seawater became so low that carbon limitation occurs. These results suggest that, contrary to common assumptions, diatoms could be highly sensitive to ongoing changes in oceanic carbonate chemistry, particularly under nutrient limitation. Warming from 15 to 20 degrees C had a stimulating effect on one species but acted as a stressor on the other species, highlighting the importance of species-specific physiological optima and temperature ranges in the response to ocean warming. Overall, these sensitivities to CO2 and temperature could have profound impacts on diatoms blooms and the biological pump.
    Type: Article , PeerReviewed
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  • 6
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    Springer
    In:  In: Faszination Meeresforschung : ein ökologisches Lesebuch. , ed. by Hempel, G., Bischof, K. and Hagen, W. Springer, Heidelberg, Germany, pp. 357-364. 2. Aufl. ISBN 978-3-662-49713-5
    Publication Date: 2017-05-22
    Type: Book chapter , NonPeerReviewed
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