scholarly journals Mineralogical response of the Mediterranean crustose coralline alga <i>Lithophyllum cabiochae</i> to near-future ocean acidification and warming

2016 ◽  
Author(s):  
Merinda C. Nash ◽  
Sophie Martin ◽  
Jean-Pierre Gattuso
Keyword(s):  
Ocean Acidification ◽  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
Coralline Alga ◽  
Magnesium Calcite ◽  
The Mediterranean ◽  
One Year ◽  
The Stability ◽  
Strong Control ◽  
Near Future

Abstract. Red calcareous coralline algae are thought to be among organisms the most vulnerable to ocean acidification due to the high solubility of their magnesium calcite skeleton. Although, skeletal mineralogy is proposed to change as CO2 and temperature continues rising, there is currently very little information available on the response of coralline algal carbonate mineralogy to near-future changes in pCO2 and temperature. Here we present results from a one-year controlled laboratory experiment to test mineralogical responses to pCO2 and temperature in the Mediterranean crustose coralline alga (CCA) Lithophyllum cabiochae. Our results show that Mg incorporation is mainly constrained by temperature (+1 mol% MgCO3 for an increase of 3 °C) and there was no response to pCO2. This suggests that L. cabiochae thalli have the ability to buffer calcifying medium against ocean acidification, enabling them to continue to deposit Mg-calcite with a significant mol% MgCO3 under elevated pCO2. Analyses of CCA dissolution chips showed a decrease in Mg content after 1 year for all treatments but this was not affected by pCO2 nor by temperature. Our findings suggest that biological processes exert a strong control on calcification on Mg-calcite and that CCA may be more resilient under rising CO2 than previously thought. However, previously demonstrated increased skeletal dissolution with ocean acidification will still have major consequences for the stability and maintenance of Mediterranean coralligenous habitats.

scholarly journals Mineralogical response of the Mediterranean crustose coralline alga <i>Lithophyllum cabiochae</i> to near-future ocean acidification and warming

2016 ◽  
Vol 13 (21) ◽  
pp. 5937-5945 ◽  
Author(s):  
Merinda C. Nash ◽  
Sophie Martin ◽  
Jean-Pierre Gattuso
Keyword(s):  
Ocean Acidification ◽  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
Coralline Alga ◽  
Magnesium Calcite ◽  
The Mediterranean ◽  
The Stability ◽  
Strong Control ◽  
Mg Content ◽  
Near Future

Abstract. Red calcareous coralline algae are thought to be among the organisms most vulnerable to ocean acidification due to the high solubility of their magnesium calcite skeleton. Although skeletal mineralogy is proposed to change as CO2 and temperature continue to rise, there is currently very little information available on the response of coralline algal carbonate mineralogy to near-future changes in pCO2 and temperature. Here we present results from a 1-year controlled laboratory experiment to test mineralogical responses to pCO2 and temperature in the Mediterranean crustose coralline alga (CCA) Lithophyllum cabiochae. Our results show that Mg incorporation is mainly constrained by temperature (+1 mol % MgCO3 for an increase of 3 °C), and there was no response to pCO2. This suggests that L. cabiochae thalli have the ability to buffer their calcifying medium against ocean acidification, thereby enabling them to continue to deposit magnesium calcite with a significant mol % MgCO3 under elevated pCO2. Analyses of CCA dissolution chips showed a decrease in Mg content after 1 year for all treatments, but this was affected neither by pCO2 nor by temperature. Our findings suggest that biological processes exert a strong control on calcification on magnesium calcite and that CCA may be more resilient under rising CO2 than previously thought. However, previously demonstrated increased skeletal dissolution with ocean acidification will still have major consequences for the stability and maintenance of Mediterranean coralligenous habitats.

scholarly journals Nitrogen enrichment offsets direct negative effects of ocean acidification on a reef-building crustose coralline alga

2018 ◽  
Vol 14 (7) ◽  
pp. 20180371 ◽  
Author(s):  
Maggie D. Johnson ◽  
Robert C. Carpenter
Keyword(s):  
Ocean Acidification ◽  
Nutrient Enrichment ◽  
Multiple Stressors ◽  
Crustose Coralline Alga ◽  
Nitrogen Enrichment ◽  
Coralline Alga ◽  
Ambient Conditions ◽  
Negative Effects ◽  
Near Shore ◽  
Near Future

Ocean acidification (OA) and nutrient enrichment threaten the persistence of near shore ecosystems, yet little is known about their combined effects on marine organisms. Here, we show that a threefold increase in nitrogen concentrations, simulating enrichment due to coastal eutrophication or consumer excretions, offset the direct negative effects of near-future OA on calcification and photophysiology of the reef-building crustose coralline alga, Porolithon onkodes . Projected near-future pCO 2 levels (approx. 850 µatm) decreased calcification by 30% relative to ambient conditions. Conversely, nitrogen enrichment (nitrate + nitrite and ammonium) increased calcification by 90–130% in ambient and high pCO 2 treatments, respectively. pCO 2 and nitrogen enrichment interactively affected instantaneous photophysiology, with highest relative electron transport rates under high pCO 2 and high nitrogen. Nitrogen enrichment alone increased concentrations of the photosynthetic pigments chlorophyll a , phycocyanin and phycoerythrin by approximately 80–450%, regardless of pCO 2 . These results demonstrate that nutrient enrichment can mediate direct organismal responses to OA. In natural systems, however, such direct benefits may be counteracted by simultaneous increases in negative indirect effects, such as heightened competition. Experiments exploring the effects of multiple stressors are increasingly becoming important for improving our ability to understand the ramifications of local and global change stressors in near shore ecosystems.

scholarly journals One-year experiment on the physiological response of the Mediterranean crustose coralline alga,Lithophyllum cabiochae, to elevatedpCO2and temperature

2013 ◽  
Vol 3 (3) ◽  
pp. 676-693 ◽  
Author(s):  
Sophie Martin ◽  
Stéphanie Cohu ◽  
Céline Vignot ◽  
Guillaume Zimmerman ◽  
Jean-Pierre Gattuso
Keyword(s):  
Physiological Response ◽  
Crustose Coralline Alga ◽  
Coralline Alga ◽  
The Mediterranean ◽  
One Year

Rapid dissolution of shells of weakly calcified Antarctic benthic macroorganisms indicates high vulnerability to ocean acidification

2009 ◽  
Vol 21 (5) ◽  
pp. 449-456 ◽  
Author(s):  
James B. McClintock ◽  
Robert A. Angus ◽  
Michelle R. Mcdonald ◽  
Charles D. Amsler ◽  
Shane A. Catledge ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Marine Invertebrates ◽  
Experimental Studies ◽  
Coralline Algae ◽  
Coralline Alga ◽  
Compensatory Mechanisms ◽  
Dissolution Rates ◽  
Rapid Dissolution ◽  
Definition Of ◽  
Macroinvertebrate Species

AbstractAntarctic calcified macroorganisms are particularly vulnerable to ocean acidification because many are weakly calcified, the dissolution rates of calcium carbonate are inversely related to temperature, and high latitude seas are predicted to become undersaturated in aragonite by the year 2100. We examined the post-mortem dissolution rates of aragonitic and calcitic shells from four species of Antarctic benthic marine invertebrates (two bivalves, one limpet, one brachiopod) and the thallus of a limpet shell-encrusting coralline alga exposed to acidified pH (7.4) or non-acidified pH (8.2) seawater at a constant temperature of 4°C. Within a period of only 14–35 days, shells of all four species held in pH 7.4 seawater had suffered significant dissolution. Despite calcite being 35% less soluble in seawater than aragonite, there was surprisingly, no consistent pattern of calcitic shells having slower dissolution rates than aragonitic shells. Outer surfaces of shells held in pH 7.4 seawater exhibited deterioration by day 35, and by day 56 there was exposure of aragonitic or calcitic prisms within the shell architecture of three of the macroinvertebrate species. Dissolution of coralline algae was confirmed by differences in weight loss in limpet shells with and without coralline algae. By day 56, thalli of the coralline alga held in pH 7.4 displayed a loss of definition of the conceptacle pores and cracking was evident at the zone of interface with limpet shells. Experimental studies are needed to evaluate whether there are adequate compensatory mechanisms in these and other calcified Antarctic benthic macroorganisms to cope with anticipated ocean acidification. In their absence, these organisms, and the communities they comprise, are likely to be among the first to experience the cascading impacts of ocean acidification.

scholarly journals Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, <i>Porolithon onkodes</i> in an experimental system

2015 ◽  
Vol 12 (2) ◽  
pp. 1373-1404 ◽  
Author(s):  
M. C. Nash ◽  
S. Uthicke ◽  
A. P. Negri ◽  
N. E. Cantin
Keyword(s):  
Ocean Acidification ◽  
Experimental System ◽  
Coralline Algae ◽  
Crustose Coralline Algae ◽  
Experimental Conditions ◽  
Pco2 Treatment ◽  
Wide Range ◽  
Dolomite Formation ◽  
Time Frames ◽  
Near Future

Abstract. There are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification. Due to the higher solubility of Mg-calcite, it has been hypothesized that magnesium concentrations in CCA Mg-calcite will decrease as the ocean acidifies, and that this decrease will make their skeletons more chemically stable. In addition to Mg-calcite, CCA Porolithon onkodes the predominant encrusting species on tropical reefs, can have dolomite (Ca0.5Mg0.5CO3) infilling cell spaces which increases their stability. However, nothing is known about how bio-mineralised dolomite formation responds to higher pCO2. Using P. onkodes grown for 3 and 6 months in tank experiments, we aimed to determine (1) if mol % MgCO3 in new crust and new settlement affected by increasing pCO2 levels (365, 444, 676 and 904 ppm), (2) whether bio-mineralised dolomite formed within these time frames, and (3) if so, whether this was effected by pCO2. Our results show there was no significant effect of pCO2 on mol % MgCO3 in any sample set, indicating an absence of a plastic response under a wide range of experimental conditions. Dolomite within the CCA cells formed within 3 months and dolomite abundance did not vary significantly with pCO2 treatment. While evidence mounts that climate change will impact many sensitive coral and CCA species, the results from this study indicate that reef-building P. onkodes will continue to form stabilising dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution.

scholarly journals First discovery of dolomite and magnesite in living coralline algae and its geobiological implications

2011 ◽  
Vol 8 (11) ◽  
pp. 3331-3340 ◽  
Author(s):  
M. C. Nash ◽  
U. Troitzsch ◽  
B. N. Opdyke ◽  
J. M. Trafford ◽  
B. D. Russell ◽  
...  
Keyword(s):  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
X Ray Diffraction ◽  
Sedimentary Environments ◽  
Mineral Phases ◽  
Magnesium Calcite ◽  
Tropical Reef ◽  
Dolomite Problem ◽  
Diffraction Patterns ◽  
Micro Analysis

Abstract. Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the "Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes, a prolific global tropical reef species. Chemical micro-analysis of the coralline skeleton reveals that not only are the cell walls calcitised, but that cell spaces are typically filled with magnesite, rimmed by dolomite, or both. Mineralogy was confirmed by X-ray Diffraction. Thus there are at least three mineral phases present (magnesium calcite, dolomite and magnesite) rather than one or two (magnesium calcite and brucite) as previously thought. Our results are consistent with dolomite occurrences in coralline algae rich environments in fossil reefs of the last 60 million years. We reveal that the standard method of removing organic material prior to Xray Diffraction analysis can result in a decrease in the most obvious dolomite and magnesite diffraction patterns and this may explain why the abundant protodolomite and magnesite discovered in this study has not previously been recognized. This discovery of dolomite in living coralline algae extends the range of palaeo-environments for which biologically initiated dolomite can be considered a possible source of primary dolomite.

scholarly journals Biomineralization of dolomite and magnesite discovered in tropical coralline algae: a biological solution to the geological dolomite problem

2011 ◽  
Vol 8 (3) ◽  
pp. 5881-5906 ◽  
Author(s):  
M. C. Nash ◽  
U. Troitzsch ◽  
B. N. Opdyke ◽  
J. M. Trafford ◽  
B. D. Russell ◽  
...  
Keyword(s):  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
X Ray Diffraction ◽  
Sedimentary Environments ◽  
Mineral Phases ◽  
Magnesium Calcite ◽  
Tropical Reef ◽  
Dolomite Problem ◽  
Geologic Record ◽  
Micro Analysis

Abstract. Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the ''Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes, a prolific global tropical reef species. Chemical micro-analysis of the coralline skeleton reveals that not only are the cell walls calcitised, but that cell spaces are typically filled with magnesite, rimmed by dolomite, or both. Mineralogy was confirmed by X-ray diffraction. Thus there are at least three mineral phases present (magnesium calcite, dolomite and magnesite) rather than one or two (magnesium calcite and brucite) as previously thought. Our results are consistent with dolomite occurrences in coralline algae rich environments in fossil reefs. Instead of a theory of post-depositional dolomitisation, we present evidence revealing biomineralization that can account for the massive formations seen in the geologic record. Additionally, our findings imply that previously unrecognized dolomite and magnesite have formed throughout the Holocene. This discovery together with the scale of coralline algae dominance in past shallow carbonate environments raises the possibility that environmental factors driving this biological dolomitisation process have influenced the global marine magnesium/calcium cycle. Perhaps, most importantly, we reveal that what has been considered a geological process can be a biological process, having many implications for both disciplines.

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