Shelled pteropods in peril: Assessing vulnerability in a high CO2 ocean

Manno, Clara; Bednaršek, Nina; Tarling, Geraint A.; Peck, Vicky L.; Comeau, Steeve; Adhikari, Deepak; Bakker, D. C. E.; Bauerfeind, Eduard; Bergan, Alexander J.; Berning, Maria I.; Buitenhuis, Erik T.; Burridge, Alice K.; Chierici, Melissa; Flöter, Sebastian; Fransson, Agneta; Gardner, Jessie; Howes, Ella L.; Keul, Nina; Kimoto, Katsunori; Kohnert, Peter; Lawson, Gareth L.; Lischka, Silke; Maas, Amy E.; Mekkes, Lisette; Oakes, Rosie L.; Pebody, Corinne; Peijnenburg, Katja T. C. A.; Seifert, Miriam; Skinner, Jennifer; Thibodeau, Patricia S.; Wall-Palmer, Deborah; Ziveri, Patrizia

doi:10.1016/j.earscirev.2017.04.005

Cited by 87 publications

(86 citation statements)

References 112 publications

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“…The CARIACO time series coupled sediment trap samples every 2 weeks with monthly oceanographic cruises to measure hydrography, nutrient concentrations, and biogeochemical parameters (see Muller-Karger et al, 2019). There have been numerous studies of planktic foraminifera from the CARIACO sediment trap samples, investigating their flux, the variability of assemblages both seasonally and interannually, and their ability to record changes in the oxygen isotopic composition and carbonate chemistry of seawater (e.g., Marshall et al, 2013Marshall et al, , 2015McConnell et al, 2009;Tedesco et al, 2007;Tedesco and Thunell, 2003). Despite this focus on calcareous plankton, there have not been any studies on pteropods from the CARIACO sediment trap records.…”

Section: The Cariaco Time Seriesmentioning

confidence: 99%

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Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin

Oakes

Sessa

2020

Biogeosciences

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Abstract. Pteropods have been nicknamed the “canary in the coal mine” for ocean acidification because they are predicted to be among the first organisms to be affected by changing ocean chemistry. This is due to their fragile, aragonitic shells and high abundances in polar and subpolar regions where the impacts of ocean acidification are most pronounced. For pteropods to be used most effectively as indicators of ocean acidification, the biotic and abiotic factors influencing their shell formation and dissolution in the modern ocean need to be quantified and understood. Here, we measured the shell condition (i.e., the degree to which a shell has dissolved) and shell characteristics, including size, number of whorls, shell thickness, and shell volume (i.e., amount of shell material) of nearly 50 specimens of the pteropod species Heliconoides inflatus sampled from a sediment trap in the Cariaco Basin, Venezuela, over an 11-month period. The shell condition of pteropods from sediment traps has the potential to be altered at three stages: (1) when the organisms are live in the water column associated with ocean acidification, (2) when organisms are dead in the water column associated with biotic decay of organic matter and/or abiotic dissolution associated with ocean acidification, and (3) when organisms are in the closed sediment trap cup associated with abiotic alteration by the preservation solution. Shell condition was assessed using two methods: the Limacina Dissolution Index (LDX) and the opacity method. The opacity method was found to capture changes in shell condition only in the early stages of dissolution, whereas the LDX recorded dissolution changes over a much larger range. Because the water in the Cariaco Basin is supersaturated with respect to aragonite year-round, we assume no dissolution occurred during life, and there is no evidence that shell condition deteriorated with the length of time in the sediment trap. Light microscope and scanning electron microscope (SEM) images show the majority of alteration happened to dead pteropods while in the water column associated with the decay of organic matter. The most altered shells occurred in samples collected in September and October when water temperatures were warmest and when the amount of organic matter degradation, both within the shells of dead specimens and in the water column, was likely to have been the greatest. The hydrographic and chemical properties of the Cariaco Basin vary seasonally due to the movement of the Intertropical Convergence Zone (ITCZ). Shells of H. inflatus varied in size, number of whorls, and thickness throughout the year. There was not a strong correlation between the number of whorls and the shell diameter, suggesting that shell growth is plastic. H. inflatus formed shells that were 40 % thicker and 20 % larger in diameter during nutrient-rich, upwelling times when food supply was abundant, indicating that shell growth in this aragonite-supersaturated basin is controlled by food availability. This study produces a baseline dataset of the variability in shell characteristics of H. inflatus pteropods in the Cariaco Basin and documents the controls on alteration of specimens captured via sediment traps. The methodology outlined for assessing shell parameters establishes a protocol for generating similar baseline records for pteropod populations globally.

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Section: The Cariaco Time Seriesmentioning

confidence: 99%

“…Bathymetric map of the Cariaco Basin. The location of the sediment trap (10 • 30.0 N, 64 • 38.5 W) is marked with a triangle (modified fromMarshall et al, 2013).…”

mentioning

confidence: 99%

Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin

Oakes

Sessa

2020

Biogeosciences

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“…Pteropods are found in the fossil record from the Early Eocene to the present, with possible specimens spanning back into the Cretaceous (Janssen, 2012;Janssen et al, 2011Janssen et al, , 2016Janssen & Peijnenburg, 2017). Because of their mineralogy, pteropod shells are often diagenetically altered, limiting their use in palaeoceanographic studies (Manno et al, 2017). Pteropod preservation in the fossil record is interpreted to be controlled by Ω arag in the surface ocean (Wall-Palmer et al, 2012) and at the sediment-water interface (Berger, 1978;Berner et al, 1976;Gerhardt et al, 2000;Gerhardt & Henrich, 2001).…”

Section: Fossil Recordmentioning

confidence: 99%

Degradation of Internal Organic Matter is the Main Control on Pteropod Shell Dissolution After Death

Oakes

Peck

Manno

et al. 2019

Global Biogeochemical Cycles

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The potential for preservation of thecosome pteropods is thought to be largely governed by the chemical stability of their delicate aragonitic shells in seawater. However, sediment trap studies have found that significant carbonate dissolution can occur above the carbonate saturation horizon. Here we present the results from experiments conducted on two cruises to the Scotia Sea to directly test whether the breakdown of the organic pteropod body influences shell dissolution. We find that on the timescales of 3 to 13 days, the oxidation of organic matter within the shells of dead pteropods is a stronger driver of shell dissolution than the aragonite saturation state of seawater. Three to four days after death, shells became milky white and nano scanning electron microscope images reveal smoothing of internal surface features and increased shell porosity, both indicative of aragonite dissolution. These findings have implications for the interpretation of the condition of pteropod shells from sediment traps and the fossil record, as well as for understanding the processes controlling particulate carbonate export from the surface ocean.

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“…Time series of atmospheric temperature anomaly and CO 2 concentration from Antarctic ice cores. Data from Parrenin et al, 2013;Snyder et al, 2016, andBereiter et al, 2015;plotted −9.4 GtC yr -1 Fossil + Industry the base of the food chain (Manno et al, 2017) to shellfish and coral reef systems. Reefs are also impacted by warming waters so may be doubly endangered (Hughes et al, 2017;Colin, 2018, in this issue).…”

Section: The Global Carbon Budgetmentioning

confidence: 99%

The Ocean’s Role in Climate

Schmitt¹

2018

Oceanog

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Shelled pteropods in peril: Assessing vulnerability in a high CO2 ocean

Cited by 87 publications

References 112 publications

Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin

Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin

Degradation of Internal Organic Matter is the Main Control on Pteropod Shell Dissolution After Death

The Ocean’s Role in Climate

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Shelled pteropods in peril: Assessing vulnerability in a high CO2 ocean

Cited by 87 publications

References 112 publications

Determining how biotic and abiotic variables affect the shell condition and parameters of &lt;i&gt;Heliconoides inflatus&lt;/i&gt; pteropods from a sediment trap in the Cariaco Basin

Determining how biotic and abiotic variables affect the shell condition and parameters of &lt;i&gt;Heliconoides inflatus&lt;/i&gt; pteropods from a sediment trap in the Cariaco Basin

Degradation of Internal Organic Matter is the Main Control on Pteropod Shell Dissolution After Death

The Ocean’s Role in Climate

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Product

Resources

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Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin

Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin