scholarly journals Skeletal mineralogy of coral recruits under high temperature and <i>p</i>CO<sub>2</sub>

2016 ◽  
Vol 13 (5) ◽  
pp. 1717-1722 ◽  
Author(s):  
T. Foster ◽  
P. L. Clode
Keyword(s):  
High Temperature ◽  
Ocean Acidification ◽  
High Pco2 ◽  
X Ray Diffraction ◽  
Calcite Precipitation ◽  
Ambient Seawater ◽  
The Past ◽  
Coral Reef Ecosystems ◽  
Combined Impact ◽  
The Impact

Abstract. Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility may leave animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg ∕ Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ∼ 540 Ma. Experimentally reduced Mg ∕ Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals; however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of 1-month-old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (∼ 900 µatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be the investigation of the combined impact of high pCO2 and reduced Mg ∕ Ca ratio on coral skeletal mineralogy.

scholarly journals Skeletal mineralogy of coral recruits under high temperature and <i>p</i>CO<sub>2</sub>

2015 ◽  
Vol 12 (15) ◽  
pp. 12485-12500 ◽  
Author(s):  
T. Foster ◽  
P. L. Clode
Keyword(s):  
High Temperature ◽  
Ocean Acidification ◽  
High Pco2 ◽  
X Ray Diffraction ◽  
Calcite Precipitation ◽  
Ambient Seawater ◽  
The Past ◽  
Coral Reef Ecosystems ◽  
Combined Impact ◽  
The Impact

Abstract. Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility leaves animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore, important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg / Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ∼540 myr. Experimentally reduced Mg / Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals, however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of one-month old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (∼900 μatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be to investigate the combined impact of high pCO2 and reduced Mg / Ca ratio on coral skeletal mineralogy.

scholarly journals High tolerance of microzooplankton to ocean acidification in an Arctic coastal plankton community

2013 ◽  
Vol 10 (3) ◽  
pp. 1471-1481 ◽  
Author(s):  
N. Aberle ◽  
K. G. Schulz ◽  
A. Stuhr ◽  
A. M. Malzahn ◽  
A. Ludwig ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Indirect Effects ◽  
High Arctic ◽  
Taxonomic Composition ◽  
High Pco2 ◽  
Marine Biota ◽  
High Tolerance ◽  
Wide Range ◽  
Low Sensitivity ◽  
The Impact

Abstract. Impacts of ocean acidification (OA) on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal microzooplankton community during the post-bloom period in Kongsfjorden (Svalbard) to direct and indirect effects of high pCO2/low pH. We found almost no direct effects of OA on microzooplankton composition and diversity. Both the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of microzooplankton remained unaffected by changes in pCO2/pH. Although the different pCO2 treatments affected food availability and phytoplankton composition, no indirect effects (e.g. on the total carrying capacity and phenology of microzooplankton) could be observed. Our data point to a high tolerance of this Arctic microzooplankton community to changes in pCO2/pH. Future studies on the impact of OA on plankton communities should include microzooplankton in order to test whether the observed low sensitivity to OA is typical for coastal communities where changes in seawater pH occur frequently.

scholarly journals High tolerance of protozooplankton to ocean acidification in an Arctic coastal plankton community

2012 ◽  
Vol 9 (9) ◽  
pp. 13031-13051 ◽  
Author(s):  
N. Aberle ◽  
K. G. Schulz ◽  
A. Stuhr ◽  
A. Ludwig ◽  
U. Riebesell
Keyword(s):  
Ocean Acidification ◽  
Indirect Effects ◽  
High Arctic ◽  
Taxonomic Composition ◽  
High Pco2 ◽  
Marine Biota ◽  
High Tolerance ◽  
Wide Range ◽  
Low Sensitivity ◽  
The Impact

Abstract. Impacts of ocean acidification (OA) on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal protozooplankton (PZP in the following) community during the post-bloom period in the Kongsfjorden (Svalbard) to direct and indirect effects of high pCO2/low pH. We found almost no direct effects of OA on PZP composition and diversity. Both, the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of protozoans remained unaffected by changes in pCO2/pH. The different pCO2 treatments did not have any effect on food availability and phytoplankton composition and thus no indirect effects e.g. on the total carrying capacity and phenology of PZP could be observed. Our data points at a high tolerance of this Arctic PZP community to changes in pCO2/pH. Future studies on the impact of OA on plankton communities should include PZP in order to test whether the observed low sensitivity of protozoans to OA is typical for coastal communities where changes in seawater pH occur frequently.

scholarly journals Seagrass beds as ocean acidification refuges for mussels? High resolution measurements of <i>p</i>CO<sub>2</sub> and O<sub>2</sub> in a <i>Zostera marina</i> and <i>Mytilus edulis</i> mosaic habitat

2015 ◽  
Vol 12 (14) ◽  
pp. 11423-11461 ◽  
Author(s):  
V. Saderne ◽  
P. Fietzek ◽  
S. Aßmann ◽  
A. Körtzinger ◽  
C. Hiebenthal
Keyword(s):  
High Resolution ◽  
Ocean Acidification ◽  
High Pco2 ◽  
Seagrass Beds ◽  
Carbonate Chemistry ◽  
Calcium Carbonates ◽  
Positive Side ◽  
Chemical Conditions ◽  
Technological Limitations ◽  
The Impact

Abstract. It has been speculated that macrophytes beds might act as a refuge for calcifiers from ocean acidification. In the shallow nearshores of the western Kiel Bay (Baltic Sea), mussel and seagrass beds are interlacing, forming a mosaic habitat. Naturally, the diverse physiological activities of seagrasses and mussels are affected by seawater carbonate chemistry and they locally modify it in return. Calcification by shellfishes is sensitive to seawater acidity; therefore the photosynthetic activity of seagrasses in confined shallow waters creates favorable chemical conditions to calcification at daytime but turn the habitat less favorable or even corrosive to shells at night. In contrast, mussel respiration releases CO2, turning the environment more favorable for photosynthesis by adjacent seagrasses. At the end of summer, these dynamics are altered by the invasion of high pCO2/low O2 coming from the deep water of the Bay. However, it is in summer that mussel spats settle on the leaves of seagrasses until migrating to the permanent habitat where they will grow adult. These early life phases (larvae/spats) are considered as most sensitive with regard to seawater acidity. So far, the dynamics of CO2 have never been continuously measured during this key period of the year, mostly due to the technological limitations. In this project we used a combination of state-of-the-art technologies and discrete sampling to obtain high-resolution time-series of pCO2 and O2 at the interface between a seagrass and a mussel patch in Kiel Bay in August and September 2013. From these, we derive the entire carbonate chemistry using statistical models. We found the monthly average pCO2 more than 50 % (approx. 640 μatm for August and September) above atmospheric equilibrium right above the mussel patch together with large diel variations of pCO2 within 24 h: 887 ± 331 μatm in August and 742 ± 281 μatm in September (mean ± SD). We observed important daily corrosiveness for calcium carbonates (Ωarag and Ωcalc < 1) centered on sunrise. On the positive side, the investigated habitat never suffered from hypoxia during the study period. We emphasize the need for more experiments on the impact of these acidic conditions on (juvenile) mussels with a focus on the distinct day-night variations observed.

scholarly journals Species interactions can shift the response of a maerl bed community to ocean acidification and warming

2017 ◽  
Vol 14 (23) ◽  
pp. 5359-5376 ◽  
Author(s):  
Erwann Legrand ◽  
Pascal Riera ◽  
Mathieu Lutier ◽  
Jérôme Coudret ◽  
Jacques Grall ◽  
...  
Keyword(s):  
Primary Production ◽  
Ocean Acidification ◽  
Species Interactions ◽  
Gross Primary Production ◽  
Benthic Communities ◽  
Community Response ◽  
High Pco2 ◽  
Effects Of Temperature ◽  
The Impact ◽  
Positive Effect

Abstract. Predicted ocean acidification and warming are likely to have major implications for marine organisms, especially marine calcifiers. However, little information is available on the response of marine benthic communities as a whole to predicted changes. Here, we experimentally examined the combined effects of temperature and partial pressure of carbon dioxide (pCO2) increases on the response of maerl bed assemblages, composed of living and dead thalli of the free-living coralline alga Lithothamnion corallioides, epiphytic fleshy algae, and grazer species. Two 3-month experiments were performed in the winter and summer seasons in mesocosms with four different combinations of pCO2 (ambient and high pCO2) and temperature (ambient and +3 °C). The response of maerl assemblages was assessed using metabolic measurements at the species and assemblage scales. This study suggests that seasonal variability represents an important driver influencing the magnitude and the direction of species and community response to climate change. Gross primary production and respiration of assemblages was enhanced by high pCO2 conditions in the summer. This positive effect was attributed to the increase in epiphyte biomass, which benefited from higher CO2 concentrations for growth and primary production. Conversely, high pCO2 drastically decreased the calcification rates in assemblages. This response can be attributed to the decline in calcification rates of living L. corallioides due to acidification and increased dissolution of dead L. corallioides. Future changes in pCO2 and temperature are likely to promote the development of non-calcifying algae to the detriment of the engineer species L. corallioides. The development of fleshy algae may be modulated by the ability of grazers to regulate epiphyte growth. However, our results suggest that predicted changes will negatively affect the metabolism of grazers and potentially their ability to control epiphyte abundance. We show here that the effects of pCO2 and temperature on maerl bed communities were weakened when these factors were combined. This underlines the importance of examining multi-factorial approaches and community-level processes, which integrate species interactions, to better understand the impact of global change on marine ecosystems.

scholarly journals Ocean acidification affects coral growth by reducing skeletal density

2018 ◽  
Vol 115 (8) ◽  
pp. 1754-1759 ◽  
Author(s):  
Nathaniel R. Mollica ◽  
Weifu Guo ◽  
Anne L. Cohen ◽  
Kuo-Fang Huang ◽  
Gavin L. Foster ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Skeletal Growth ◽  
Ion Concentration ◽  
Skeletal Density ◽  
Carbonate Ion ◽  
Carbonate Ions ◽  
Coral Reef Ecosystems ◽  
Upward Growth ◽  
Seawater Environment ◽  
The Impact

Ocean acidification (OA) is considered an important threat to coral reef ecosystems, because it reduces the availability of carbonate ions that reef-building corals need to produce their skeletons. However, while theory predicts that coral calcification rates decline as carbonate ion concentrations decrease, this prediction is not consistently borne out in laboratory manipulation experiments or in studies of corals inhabiting naturally low-pH reefs today. The skeletal growth of corals consists of two distinct processes: extension (upward growth) and densification (lateral thickening). Here, we show that skeletal density is directly sensitive to changes in seawater carbonate ion concentration and thus, to OA, whereas extension is not. We present a numerical model of Porites skeletal growth that links skeletal density with the external seawater environment via its influence on the chemistry of coral calcifying fluid. We validate the model using existing coral skeletal datasets from six Porites species collected across five reef sites and use this framework to project the impact of 21st century OA on Porites skeletal density across the global tropics. Our model predicts that OA alone will drive up to 20.3 ± 5.4% decline in the skeletal density of reef-building Porites corals.

The Rapid Simultaneous Measurement of Thermal and Structural Data by a Novel DSC/XRD Instrument

1984 ◽  
Vol 28 ◽  
pp. 227-232
Author(s):  
T. G. Fawcett ◽  
C. E. Crowder ◽  
L. F. Whiting ◽  
J. C. Tou ◽  
W. F. Scott ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
High Temperature ◽  
Solid State ◽  
Structural Data ◽  
State Transitions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Precise Control ◽  
The Past

Over the past 25 years, numerous studies utilizing both X-ray diffraction (XRE) and differential scanning calorimetry (DSC) have been reported In the literature. Generally, conventional high-temperature X-ray data identifies solid-state transitions, then attempts to correlate them with thermal events observed by the calorimeter. Since changes occur in the sample during studies such as these, separate portions of the sample must be used for XRD and DSC experiments. When comparing results of the two experiments, questions arise concerning sample homogeniety as well as temperature and environmental differences. In fact, no conventional high-temperature X-ray diffraction instrument can give the precise control over temperature and heating rate available with a DSC, The problems of sample inhomogeneltles and Instrumental differences could be avoided if X-ray diffraction and DSC could be performed simultaneously on one sample.

Impacts of Multiple Stressors on a Benthic Foraminiferal Community: A Long-Term Experiment Assessing Response to Ocean Acidification, Hypoxia and Warming

2021 ◽  
Vol 8 ◽  
Author(s):  
Joan M. Bernhard ◽  
Johannes C. Wit ◽  
Victoria R. Starczak ◽  
David J. Beaudoin ◽  
William G. Phalen ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Atmospheric Carbon Dioxide ◽  
Environmental Changes ◽  
Multiple Stressors ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Species Responses ◽  
Combined Impact ◽  
The Impact

Ocean chemistry is changing as a result of human activities. Atmospheric carbon dioxide (CO2) concentrations are increasing, causing an increase in oceanic pCO2 that drives a decrease in oceanic pH, a process called ocean acidification (OA). Higher CO2 concentrations are also linked to rising global temperatures that can result in more stratified surface waters, reducing the exchange between surface and deep waters; this stronger stratification, along with nutrient pollution, contributes to an expansion of oxygen-depleted zones (so called hypoxia or deoxygenation). Determining the response of marine organisms to environmental changes is important for assessments of future ecosystem functioning. While many studies have assessed the impact of individual or paired stressors, fewer studies have assessed the combined impact of pCO2, O2, and temperature. A long-term experiment (∼10 months) with different treatments of these three stressors was conducted to determine their sole or combined impact on the abundance and survival of a benthic foraminiferal community collected from a continental-shelf site. Foraminifera are well suited to such study because of their small size, relatively rapid growth, varied mineralogies and physiologies. Inoculation materials were collected from a ∼77-m deep site south of Woods Hole, MA. Very fine sediments (&lt;53 μm) were used as inoculum, to allow the entire community to respond. Thirty-eight morphologically identified taxa grew during the experiment. Multivariate statistical analysis indicates that hypoxia was the major driving factor distinguishing the yields, while warming was secondary. Species responses were not consistent, with different species being most abundant in different treatments. Some taxa grew in all of the triple-stressor samples. Results from the experiment suggest that foraminiferal species’ responses will vary considerably, with some being negatively impacted by predicted environmental changes, while other taxa will tolerate, and perhaps even benefit, from deoxygenation, warming and OA.

scholarly journals Species interactions can shift the response of a maerl bed community to ocean acidification and warming

2017 ◽  
Author(s):  
Erwann Legrand ◽  
Pascal Riera ◽  
Mathieu Lutier ◽  
Jérôme Coudret ◽  
Jacques Grall ◽  
...  
Keyword(s):  
Primary Production ◽  
Ocean Acidification ◽  
Species Interactions ◽  
Gross Primary Production ◽  
High Pco2 ◽  
Marine Communities ◽  
Effects Of Temperature ◽  
The Impact ◽  
Positive Effect ◽  
Grazer Species

Abstract. Predicted ocean acidification and warming are likely to have major implications for marine organisms, especially marine calcifiers. However, little information is available on the response of marine communities as a whole to predicted changes. Here, we experimentally examined the combined effects of temperature and partial pressure of carbon dioxide (pCO2) increases on the response of maerl bed assemblages, composed of living and dead thalli of the free-living coralline alga Lithothamnion corallioides, epiphytic fleshy algae, and grazer species. Two three-month experiments were performed in the winter and summer seasons in mesocosms with four different combinations of pCO2 (ambient and high pCO2) and temperature (ambient and +3 °C). The response of maerl assemblages was assessed using metabolic measurements at the species and assemblage scales. Gross primary production and respiration of assemblages were enhanced by high pCO2 conditions in the summer. This positive effect was attributed to the increase in epiphyte biomass, which benefited from higher CO2 concentrations for growth and primary production. Conversely, high pCO2 drastically decreased the calcification rates in assemblages. This response can be attributed to the decline in calcification rates of living L. corallioides due to acidification as well as increased dissolution of dead L. corallioides. Future changes in pCO2 and temperature are likely to promote the development of non-calcifying algae to the detriment of the engineer species L. corallioides. The development of fleshy algae may be modulated by the ability of grazers to regulate epiphyte growth. However, our results suggest that predicted changes will negatively affect the metabolism of grazers and potentially their ability to control epiphyte abundance. Here, we demonstrate that the response of marine communities to climate change will depend on the direct effects on species physiology and the indirect effects due to shifts in species interactions. This double, interdependent response underlines the importance of examining community-level processes, which integrate species interactions, to better understand the impact of global change on marine ecosystems.

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