The role of in hospite zooxanthellae photophysiology and reef chemistry on elevated pCO2 effects in two branching Caribbean corals: Acropora cervicornis and Porites divaricata

2016 ◽  
Vol 74 (4) ◽  
pp. 1103-1112 ◽  
Author(s):  
Hayley E. Bedwell-Ivers ◽  
Marguerite S. Koch ◽  
Katherine E. Peach ◽  
Luke Joles ◽  
Elizabeth Dutra ◽  
...  
Keyword(s):  
Linear Extension ◽  
Dissolved Inorganic Carbon ◽  
Elevated Pco2 ◽  
Acropora Cervicornis ◽  
Cayman Island ◽  
Co2 Partial Pressure ◽  
Coral Calcification ◽  
Algal Symbiont ◽  
Porites Divaricata

Previous studies suggest uniform reductions in coral calcification under ocean acidification (OA); however, greater tolerance has been observed under natural diel metabolic signals present on reefs. In addition, few studies have examined the role of in hospite zooxanthellae energetics on coral OA tolerance. In this study, we examined zooxanthellae photosynthesis and coral calcification responses using seawater with natural metabolic dissolved inorganic carbon (DIC) dynamics from a fringing back reef on Little Cayman Island, Caribbean. The experimental design included Acropora cervicornis and Porites divaricata microcolonies grown in continuously flowing seawater with (∼1000 μatm) and without (∼500 μatm) CO2 enrichment to year 2100 predicted levels. Calcification rates were measured weekly, while linear extension and zooxanthellae photosynthesis were determined at the termination of the 28 d experiment. Results showed A. cervicornis microcolonies maintained both photosynthesis and calcification under elevated CO2 partial pressure (pCO2) relative to controls. However, photosynthesis and calcification rates of P. divaricata microcolonies were reduced by ∼80 and 20%, respectively, under relatively high [DIC]:[H+] ratios and aragonite saturation states (Ωarag). Porites divaricata calcification response to elevated pCO2 was linked to photophysiological dysfunction of the algal symbiont, an indicator that this species was metabolically depressed under elevated pCO2. In contrast to calcification, linear extension rates were unaffected by pCO2 in both species. Future studies should investigate how elevated pCO2 may compromise zooxanthellae–coral interactions with an emphasis on DIC uptake pathways.

scholarly journals Ion transporter gene expression is linked to the thermal sensitivity of calcification in the reef coral Stylophora pistillata

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
C. Bernardet ◽  
E. Tambutté ◽  
N. Techer ◽  
S. Tambutté ◽  
A. A. Venn
Keyword(s):  
Gene Expression ◽  
Dissolved Inorganic Carbon ◽  
Thermal Sensitivity ◽  
Expression Patterns ◽  
Transport Processes ◽  
Gene Expression Response ◽  
Stylophora Pistillata ◽  
Coral Calcification ◽  
Spread Model

AbstractCoral calcification underpins biodiverse reef ecosystems, but the physiology underlying the thermal sensitivity of corals to changing seawater temperatures remains unclear. Furthermore, light is also a key factor in modulating calcification rates, but a mechanistic understanding of how light interacts with temperature to affect coral calcification is lacking. Here, we characterized the thermal performance curve (TPC) of calcification of the wide-spread, model coral species Stylophora pistillata, and used gene expression analysis to investigate the role of ion transport mechanisms in thermally-driven declines in day and nighttime calcification. Focusing on genes linked to transport of dissolved inorganic carbon (DIC), calcium and H+, our study reveals a high degree of coherence between physiological responses (e.g. calcification and respiration) with distinct gene expression patterns to the different temperatures in day and night conditions. At low temperatures, calcification and gene expression linked to DIC transport processes were downregulated, but showed little response to light. By contrast, at elevated temperature, light had a positive effect on calcification and stimulated a more functionally diverse gene expression response of ion transporters. Overall, our findings highlight the role of mechanisms linked to DIC, calcium and H+ transport in the thermal sensitivity of coral calcification and how this sensitivity is influenced by light.

scholarly journals Response of the temperate coral <i>Cladocora caespitosa</i> to mid- and long-term exposure to <i>p</i>CO<sub>2</sub> and temperature levels projected for the year 2100 AD

2010 ◽  
Vol 7 (1) ◽  
pp. 289-300 ◽  
Author(s):  
R. Rodolfo-Metalpa ◽  
S. Martin ◽  
C. Ferrier-Pagès ◽  
J.-P. Gattuso
Keyword(s):  
Slow Growth ◽  
Elevated Pco2 ◽  
Saturation State ◽  
Co2 Partial Pressure ◽  
Cladocora Caespitosa ◽  
Temperate Coral ◽  
Predominant Factor ◽  
Zooxanthellate Coral ◽  
Temperature Levels

Abstract. Atmospheric CO2 partial pressure (pCO2) is expected to increase to 700 μatm or more by the end of the present century. Anthropogenic CO2 is absorbed by the oceans, leading to decreases in pH and the CaCO3 saturation state (Ω) of the seawater. Elevated pCO2 was shown to drastically decrease calcification rates in tropical zooxanthellate corals. Here we show, using the Mediterranean zooxanthellate coral Cladocora caespitosa, that an increase in pCO2, in the range predicted for 2100, does not reduce its calcification rate. Therefore, the conventional belief that calcification rates will be affected by ocean acidification may not be widespread in temperate corals. Seasonal change in temperature is the predominant factor controlling photosynthesis, respiration, calcification and symbiont density. An increase in pCO2, alone or in combination with elevated temperature, had no significant effect on photosynthesis, photosynthetic efficiency and calcification. The lack of sensitivity C. caespitosa to elevated pCO2 might be due to its slow growth rates, which seem to be more dependent on temperature than on the saturation state of calcium carbonate in the range projected for the end of the century.

scholarly journals Diagnosis of CO2 dynamics and fluxes in global coastal oceans

2019 ◽  
Vol 7 (4) ◽  
pp. 786-797 ◽  
Author(s):  
Zhimian Cao ◽  
Wei Yang ◽  
Yangyang Zhao ◽  
Xianghui Guo ◽  
Zhiqiang Yin ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Analytical Framework ◽  
Coastal System ◽  
Coastal Oceans ◽  
Co2 Dynamics ◽  
Earth System Models

Abstract Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO2, we show that the latitudinal distribution of global coastal surface pCO2 does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO2 source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle.

scholarly journals Variation in susceptibility among three Caribbean coral species and their algal symbionts indicates the threatened staghorn coral, Acropora cervicornis, is particularly susceptible to elevated nutrients and heat stress

2021 ◽  
Author(s):  
Ana M. Palacio-Castro ◽  
Caroline E. Dennison ◽  
Stephanie M. Rosales ◽  
Andrew C. Baker
Keyword(s):  
Heat Stress ◽  
Coral Species ◽  
Coral Cover ◽  
Photochemical Efficiency ◽  
Acropora Cervicornis ◽  
Nutrient Inputs ◽  
Algal Symbionts ◽  
Algal Symbiont ◽  
Orbicella Faveolata ◽  
Significant Mortality

Coral cover is declining worldwide due to multiple interacting threats. We compared the effects of elevated nutrients and temperature on three Caribbean corals: Acropora cervicornis, Orbicella faveolata, and Siderastrea siderea. Colonies hosting different algal types were exposed to either ambient nutrients (A), elevated NH4 (N), or elevated NH4 + PO4 (N+P) at control temperatures (26 °C) for > 2 months, followed by a 3-week thermal challenge (31.5 °C). A. cervicornis hosted Symbiodinium (S. fitti) and was highly susceptible to the combination of elevated nutrients and temperature. During heat stress, A. cervicornis pre-exposed to elevated nutrients experienced 84%-100% mortality and photochemical efficiency (Fv/Fm) declines of 41-50%. In comparison, no mortality and lower Fv/Fm declines (11-20%) occurred in A. cervicornis that were heat-stressed but not pre-exposed to nutrients. O. faveolata and S. siderea response to heat stress was determined by their algal symbiont community and was not affected by nutrients. O. faveolata predominantly hosted Durusdinium trenchii or Breviolum, but only corals hosting Breviolum were susceptible to heat, experiencing 100% mortality, regardless of nutrient treatment. S. siderea colonies predominantly hosted Cladocopium C1 (C. goreaui), Cladocopium C3, D. trenchii, or variable proportions of Cladocopium C1 and D. trenchii. This species was resilient to elevated nutrients and temperature, with no significant mortality in any of the treatments. However, during heat stress, S. siderea hosting Cladocopium C3 suffered higher reductions in Fv/Fm (41-56%) compared to S. siderea hosting Cladocopium C1 and D. trenchii (17-26% and 10-16%, respectively). These differences in holobiont susceptibility to elevated nutrients and heat may help explain historical declines in A. cervicornis starting decades earlier than other Caribbean corals. Our results suggest that tackling only warming temperatures may be insufficient to ensure the continued persistence of Caribbean corals, especially A. cervicornis. Reducing nutrient inputs to reefs may also be necessary for these iconic coral species to survive.

scholarly journals The coral symbiont Candidatus Aquarickettsia is variably abundant in threatened Caribbean acroporids and transmitted horizontally

2021 ◽  
Author(s):  
Lydia J. Baker ◽  
Hannah G. Reich ◽  
Sheila A. Kitchen ◽  
J. Grace Klinges ◽  
Hanna R. Koch ◽  
...  
Keyword(s):  
Positive Selection ◽  
Horizontal Transmission ◽  
Sampling Location ◽  
Acropora Cervicornis ◽  
Single Nucleotide ◽  
Algal Symbiont ◽  
Genome Wide ◽  
The Us ◽  
Variant Analysis

AbstractThe aquatic symbiont “Candidatus Aquarickettsia rohweri” infects a diversity of non-bilaterian metazoan phyla. In the threatened coral Acropora cervicornis, Aquarickettsia proliferates in response to increased nutrient exposure, resulting in suppressed growth and increased disease susceptibility and mortality. This study evaluated the extent, as well as the ecology and evolution of Aquarickettsia infecting the Caribbean corals: Ac. cervicornis and Ac. palmata and their hybrid (‘Ac. prolifera’). The bacterial parasite Aquarickettsia was found in all acroporids, with host and sampling location impacting infection magnitude. Phylogenomic and genome-wide single nucleotide variant analysis found Aquarickettsia clustering by region, not by coral taxon. Fixation analysis suggested within coral colonies, Aquarickettsia are genetically isolated to the extent that reinfection is unlikely. Relative to other Rickettsiales, Aquarickettsia is undergoing positive selection, with Florida populations experiencing greater positive selection relative to the other Caribbean locations. This may be due to Aquarickettsia response to increased nutrient stress in Florida, as indicated by greater in situ replication rates in these corals. Aquarickettsia did not significantly codiversify with either coral animal nor algal symbiont, and qPCR analysis of gametes and juveniles from susceptible coral genotypes indicated absence in early life stages. Thus, despite being an obligate parasite, Aquarickettsia must be horizontally transmitted via coral mucocytes, an unidentified secondary host, or a yet unexplored environmentally mediated mechanism. Importantly, the prevalence of Aquarickettsia in Ac. cervicornis and high abundance in Florida populations suggests that disease mitigation efforts in the US and Caribbean should focus on preventing early infection via horizontal transmission.

scholarly journals Mineralization of organic matter in boreal lake sediments: rates, pathways, and nature of the fermenting substrates

2020 ◽  
Vol 17 (18) ◽  
pp. 4571-4589
Author(s):  
François Clayer ◽  
Yves Gélinas ◽  
André Tessier ◽  
Charles Gobeil
Keyword(s):  
Organic Matter ◽  
Lake Sediments ◽  
Dissolved Inorganic Carbon ◽  
Biogeochemical Models ◽  
Mineralization Of Organic Matter ◽  
Carbohydrate Fermentation ◽  
Mass Balancing ◽  
Reaction Transport ◽  
Lake Basins

Abstract. The complexity of organic matter (OM) degradation mechanisms represents a significant challenge for developing biogeochemical models to quantify the role of aquatic sediments in the climate system. The common representation of OM by carbohydrates formulated as CH2O in models comes with the assumption that its degradation by fermentation produces equimolar amounts of methane (CH4) and dissolved inorganic carbon (DIC). To test the validity of this assumption, we modelled using reaction-transport equation vertical profiles of the concentration and isotopic composition (δ13C) of CH4 and DIC in the top 25 cm of the sediment column from two lake basins, one whose hypolimnion is perennially oxygenated and one with seasonal anoxia. Furthermore, we modelled solute porewater profiles reported in the literature for four other seasonally anoxic lake basins. A total of 17 independent porewater datasets are analyzed. CH4 and DIC production rates associated with methanogenesis at the five seasonally anoxic sites collectively show that the fermenting OM has a mean (± SD) carbon oxidation state (COS) value of -1.4±0.3. This value is much lower than the value of zero expected from carbohydrate fermentation. We conclude that carbohydrates do not adequately represent the fermenting OM in hypolimnetic sediments and propose to include the COS in the formulation of OM fermentation in models applied to lake sediments to better quantify sediment CH4 outflux. This study highlights the potential of mass balancing the products of OM mineralization to characterize labile substrates undergoing fermentation in sediments.

Permissive role of prostacyclin in cerebral vasodilation to hypercapnia in newborn pigs

1994 ◽  
Vol 267 (1) ◽  
pp. H285-H291 ◽  
Author(s):  
C. W. Leffler ◽  
R. Mirro ◽  
L. J. Pharris ◽  
M. Shibata
Keyword(s):  
Sodium Nitroprusside ◽  
Co2 Partial Pressure ◽  
Cranial Window ◽  
Prostacyclin Receptor ◽  
Artificial Cerebrospinal Fluid ◽  
Before And After ◽  
Newborn Pigs ◽  
Cerebral Vasodilation ◽  
Prostanoid Synthesis

Hypercapnic cerebral vasodilation in piglets is accompanied by increased cerebral prostanoid synthesis. Interventions that prevent the increased prostanoids also interfere with the vasodilation. However, the increased prostanoids may not produce vasodilation directly; instead, they may allow or enhance function of another mechanism. The present experiments examined the hypothesis that prostacyclin can allow, but may not directly produce, cerebral vasodilation to hypercapnia. Chloralose-anesthetized piglets were equipped with closed cranial windows for measurements of pial arteriolar diameters. Hypercapnia (arterial CO2 partial pressure approximately 70 mmHg) was administered before and after indomethacin (5 mg/kg iv) in all animals. Then artificial cerebrospinal fluid (aCSF) under the cranial window was replaced for the remainder of the experiment with aCSF containing vehicle, carbaprostacyclin (60 pM), iloprost (1 pM), prostaglandin E2 (PGE2; 1.7 and 3.3 nM), isoproterenol (10 and 100 nM), or sodium nitroprusside (1 microM), and hypercapnia was repeated. The two prostacyclin receptor agonists restored cerebral vasodilation to hypercapnia that had been blocked by indomethacin (to 92 +/- 31% and 76 +/- 11% of the before-indomethacin dilation for carbaprostacyclin and iloprost, respectively.) The highest dose of PGE2 partially restored the dilation (43 +/- 7% of the pre-indomethacin response). In contrast, neither isoproterenol nor sodium nitroprusside permitted significant dilation to hypercapnia following indomethacin treatment. These data indicate that prostacyclin can allow hypercapnic vasodilation to occur, but increasing levels do not appear to be necessary to cause the dilation directly. The short half-life of prostacyclin may explain why active prostanoid synthesis appears to be necessary for hypercapnia-induced cerebral vasodilation in newborn pigs.

scholarly journals Simulated CO2-induced ocean acidification for ocean in the East China: historical conditions since preindustrial time and future scenarios

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Han Zhang ◽  
Kuo Wang
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Reduction Rate ◽  
System Model ◽  
East China ◽  
Seawater Ph ◽  
The Individual ◽  
Induced Changes

AbstractSince preindustrial times, as atmospheric CO2 concentration increases, the ocean continuously absorbs anthropogenic CO2, reducing seawater pH and $$[{{\rm{C}}{\rm{O}}}_{3}^{2-}]$$[CO32−], which is termed ocean acidification. We perform Earth system model simulations to assess CO2-induced acidification for ocean in the East China, one of the most vulnerable areas to ocean acidification. By year 2017, ocean surface pH in the East China drops from the preindustrial level of 8.20 to 8.06, corresponding to a 35% rise in [H+], and reduction rate of pH becomes faster in the last two decades. Changes in surface seawater acidity largely result from CO2-induced changes in surface dissolved inorganic carbon (DIC), alkalinity (ALK), salinity and temperature, among which DIC plays the most important role. By year 2300, simulated reduction in sea surface $$[{{\rm{C}}{\rm{O}}}_{3}^{2-}]$$[CO32−] is 13% under RCP2.6, contrasted to 72% under RCP8.5. Furthermore, simulated results show that CO2-induced warming acts to mitigate reductions in $$[{{\rm{C}}{\rm{O}}}_{3}^{2-}]$$[CO32−], but the individual effect of oceanic CO2 uptake is much greater than the effect of CO2-induced warming on ocean acidification. Our study quantifies ocean acidification induced by anthropogenic CO2, and indicates the potentially important role of accelerated CO2 emissions in projections of future changes in biogeochemistry and ecosystem of ocean in the East China.

Sign in / Sign up

Export Citation Format

Share Document