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 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 European sea bass show behavioural resilience to near-future ocean acidification

2016 ◽  
Vol 3 (11) ◽  
pp. 160656 ◽  
Author(s):  
M. Duteil ◽  
E. C. Pope ◽  
A. Pérez-Escudero ◽  
G. G. de Polavieja ◽  
I. Fürtbauer ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Ambient Conditions ◽  
European Sea Bass ◽  
Agent Based ◽  
Automated Tracking ◽  
Individual Fitness ◽  
Commercially Important ◽  
Near Future

Ocean acidification (OA)—caused by rising concentrations of carbon dioxide (CO 2 )—is thought to be a major threat to marine ecosystems and has been shown to induce behavioural alterations in fish. Here we show behavioural resilience to near-future OA in a commercially important and migratory marine finfish, the Sea bass ( Dicentrarchus labrax ). Sea bass were raised from eggs at 19°C in ambient or near-future OA (1000 µatm p CO 2 ) conditions and n  = 270 fish were observed 59–68 days post-hatch using automated tracking from video. Fish reared under ambient conditions, OA conditions, and fish reared in ambient conditions but tested in OA water showed statistically similar movement patterns, and reacted to their environment and interacted with each other in comparable ways. Thus our findings indicate behavioural resilience to near-future OA in juvenile sea bass. Moreover, simulated agent-based models indicate that our analysis methods are sensitive to subtle changes in fish behaviour. It is now important to determine whether the absences of any differences persist under more ecologically relevant circumstances and in contexts which have a more direct bearing on individual fitness.

scholarly journals pH Variability Exacerbates Effects of Ocean Acidification on a Caribbean Crustose Coralline Alga

2019 ◽  
Vol 6 ◽  
Author(s):  
Maggie D. Johnson ◽  
Lucia M. Rodriguez Bravo ◽  
Shevonne E. O’Connor ◽  
Nicholas F. Varley ◽  
Andrew H. Altieri
Keyword(s):  
Ocean Acidification ◽  
Crustose Coralline Alga ◽  
Coralline Alga
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