Calcification Rates Research Articles

Seasonal Upwelling Conditions Modulate the Calcification Response of a Tropical Scleractinian Coral

Natural processes such as upwelling of deeper-water masses change the physical-chemical conditions of the water column creating localized ocean acidification events that can have an impact on the natural communities. This study was performed in a coral reef system of an archetypical bay within the Tayrona National Natural Park (PNNT) (Colombia), and aimed to quantify net calcification rates of a foundational coral species within a temporal context (6 months) taking into account the dynamics of seasonal upwelling that influence the study area. Net calcification rates of coral fragments were obtained in situ by the alkalinity anomaly technique in short-term incubations (~2.5 h). We found a significant effect of the upwelling on net calcification rates (Gnet) (p < 0.05) with an 42% increase in CaCO3 accretion compared to non-upwelling season. We found an increase in total alkalinity (AT) and dissolved inorganic carbon (DIC) with decreased aragonite saturation (Ωara) for the upwelling months, indicating an influence of the Subtropical Under Water mass (SAW) in the PNNT coral community. Significant negative correlations between net calcification with temperature and Ωara, which indicates a positive response of M. auretenra with the upwelling conditions, thus, acting as “enhancer” of resilience for coral calcification.

Preoperative strain ultrasound elastography can predict occult central cervical lymph node metastasis in papillary thyroid cancer: a single-center retrospective study.

To determine whether preoperative ultrasound elastography can predict occult central cervical lymph node metastasis (CCLNM) in patients with papillary thyroid cancer. This retrospective study included 541 papillary thyroid cancer patients with clinically negative lymph nodes prior to surgery between July 2019 and December 2021. Based on whether CCLNM was present on postoperative pathology, patients were categorized as CCLNM (+) or CCLNM (-). Preoperative clinical data, conventional ultrasound features, and ultrasound elastography indices were compared between the groups. Univariate and multivariate logistic regression analysis were performed to identify the independent predictors of occult CCLNM. A total of 36.60% (198/541) patients had confirmed CCLNM, while 63.40% (343/541) did not. Tumor location, bilaterality, multifocality, echogenicity, margin, shape, vascularity, capsule contact, extrathyroidal extension, aspect ratio, and shear wave elasticity parameters were comparable between the groups (all P > 0.05). Univariate analysis showed statistically significant differences between the two groups in age, sex, tumor size, calcification, capsule invasion, and strain rates ratio in strain ultrasound elastography (all P < 0.05). In multivariate logistic regression analysis, the independent predictors of occult CCLNM were age (OR = 0.975, 95% CI = 0.959-0.991, P = 0.002), sex (OR = 1.886, 95% CI = 1.220-2.915, P = 0.004), tumor size (OR = 1.054, 95% CI = 1.014-1.097, P = 0.008), and strain rates ratio (OR = 1.178, 95% CI = 1.065-1.304, P = 0.002). Preoperative strain ultrasound elastography can predict presence of occult CCLNM in papillary thyroid cancer patients and help clinicians select the appropriate treatment strategy.

Tracing timing of growth in cultured molluscs using strontium spiking

IntroductionGrowth experiments present a powerful tool for determining the effect of environmental parameters on growth and carbonate composition in biogenic calcifiers. For successful proxy calibration and biomineralization studies, it is vital to identify volumes of carbonate precipitated by these organisms at precise intervals during the experiment. Here, we investigate the use of strontium labelling in mollusc growth experiments.MethodsThree bivalve species (Cerastoderma edule, Mytilus edulis and Ostrea edulis) were grown under monitored field conditions. The bivalves were regularly exposed to seawater with elevated concentrations of dissolved strontium chloride (SrCl2). In addition, the size of their shells was determined at various stages during the experiment using calliper measurements and digital photography. Trace element profiles were measured in cross sections through the shells of these molluscs using laser ablation ICPMS and XRF techniques.ResultsOur results show that doses of dissolved strontium equivalent to 7-8 times the background marine value (~0.6 mmol/L) are sufficient to cause reproducible peaks in shell-incorporated strontium in C. edule and M. edulis shells. No negative effects were observed on shell calcification rates. Lower doses (3-5 times background values) resulted in less clearly identifiable peaks, especially in M. edulis. Strontium spiking labels in shells of O. edulis are more difficult to detect, likely due to their irregular growth.DiscussionStrontium spiking is a useful technique for creating time marks in cultured shells and a reproducible way to monitor shell size during the growing season while limiting physical disturbance of the animals. However, accurate reconstructions of growth rates at high temporal resolution require frequent spiking with high doses of strontium.

Constant shell density of hyaline large benthic foraminifers under thermal stress

Recently, increased concentrations of anthropogenic atmospheric CO2 have caused ocean warming and acidification, leading to swift environmental alterations. In coral reef regions, bleaching and death of symbiotic calcifying organisms have been distressing. Generally, large benthic foraminifers (LBF), a principal symbiotic calcifying organisms in coral reefs, have gained popularity because thermal stress impedes their growth and ecological functions. Nevertheless, due to the complex nature of the shell structure, it is unclear whether indicators (shell volume, density, and size) influence the calcification rate. Micro X-ray computed tomography (MicroCT) has been efficiently used to study these parameters on porcelaneous LBF; however, hyaline LBF remained largely unexplored. In this research, reproducing populations of LBF Calcarina gaudichaudii were grown asexually under six varying temperatures (19 °C–29 °C). They were then determined using MicroCT. Shell weight and volume is reduced under high and low thermal stress with an optimal water temperature of 26 °C. However, the density of the shell was sustained at a continual level. These outcomes indicate that C. gaudichaudii can sustain a continual shell density given circumstances of growth inhibition due to thermal stress.

Production and accumulation of reef framework by calcifying corals and macroalgae on a remote Indian Ocean cay

Abstract. Coral reefs face increasing pressures in response to unprecedented rates of environmental change at present. The coral reef physical framework is formed through the production of calcium carbonate (CaCO3) and maintained by marine organisms, primarily hermatypic corals, and calcifying algae. The northern part of Western Australia, known as the Kimberley, has largely escaped land-based anthropogenic impacts and this study provides important metabolic data on reef-building organisms from an undisturbed set of marine habitats. From the reef platform of Browse Island, located on the mid-shelf just inside the 200 m isobath off the Kimberley coast, specimens of the dominant coral (six species) and algal (five species) taxa were collected and incubated ex situ in light and dark shipboard experimental mesocosms for 4 h to measure rates of calcification and production patterns of oxygen. During experimental light and dark incubations, all algae were net autotrophic producing 6 to 111 mmolO2m-2d-1. In contrast, most corals were net consumers of O2 with average net fluxes ranging from −42 to 47 mmolO2m-2d-1. The net change in pH was generally negative for corals and calcifying algae (−0.01 to −0.08 h−1). Resulting net calcification rates (1.9 to 9.9 gCaCO3m-2d-1) for corals and calcifying algae (Halimeda and Galaxura) were all positive and were strongly correlated with net O2 production. In intertidal habitats around Browse Island, estimated relative contributions of coral and Halimeda to the reef production of CaCO3 were similar at around 600 to 840 gm-2yr-1. The low reef platform had very low coral cover of &lt; 3 % which made a smaller contribution to calcification of ∼ 240 gCaCO3m-2yr-1. Calcification on the subtidal reef slope was predominantly from corals, producing ∼ 1540 gCaCO3m-2yr-1, twice that of Halimeda. These data provide the first measures of community metabolism from the offshore reef systems of the Kimberley. The relative contributions of the main reef builders, in these undisturbed areas, to net community metabolism and CaCO3 production is important to understand exclusively climate-driven negative effects on tropical reefs.

Coronary calcifications as a new prognostic marker in COVID-19 patients: role of CT.

COVID-19 pneumonia, caused by the virus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), was declared a pandemic by the WHO on 11th March 2020. While Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) represents the diagnostic gold standard of infection, computed tomography (CT) has been shown to have an important role in supporting the diagnosis, quantifying the severity, and assessing the efficacy of treatment and its response. Coronary artery calcification (CAC) is a CT finding that estimates atherosclerosis and can be quantified using the coronary artery calcium score (CACS). The purpose of this study is to demonstrate the correlation between coronary artery calcification and mortality rate in COVID-19 patients. Three hundred seventeen (317) hospitalized patients with SARS-CoV-2 infection were ruled in this retrospective study. All patients underwent a non-ECG-gated chest CT to evaluate lung parenchymal involvement. In the same cohort, we observed the two main coronary arteries (common trunk, circumflex, anterior interventricular and right coronary heart) using a visual score, so patients were divided into four groups based on Ordinal CAC Score (OCS) levels. The multivariate analysis proved that the OCS value was statistically correlated with the mortality rate (p < 0.001). In fact, in the group of patients with an OCS value of 0, the mortality rate was 10.1% (10/99 patients), in the group with OCS between 1 and 4 was 18.9% (21/111), in the OCS group of patients ranged from 5 to 8 was 30.4% (24/79) and in the OCS group between 9 and 12 was 46.4% (13/28). We suggest that calcific atheromasia of the coronary arteries in patients with COVID-19 can be considered a prognostic marker of clinical outcome.

Inside a sediment‐stressed Middle Devonian carpet reef: Cave exposes details of three‐dimensional facies architecture and palaeoecology

ABSTRACTDuring the Middle Devonian, reef growth reached an acme, and corals and stromatoporoids colonized depositional niches commonly considered unfavourable for reefal organisms. This paper documents the detailed facies architecture and palaeoecology of a stratigraphically thin (ca12 m, ‘carpet reef’), lower Givetian reefal body exposed along the walls and ceilings of the labyrinthine passages in the Klutert Cave in western Germany. The cave exposures (ca26 000 m2of rock surface) and data from short cores, neighbouring caves and outcrops document the growth and demise of an autoparabiostrome. The reef forms part of a parasequence with a lower carbonate and an upper clastic unit, bounded by flooding surfaces. Despite the comparatively small study area (ca1 km2), the exceptional exposure quality reveals facies changes over relatively short distances both vertical and lateral. The sedimentary matrix of the reefal build‐up contains between 20 to 95 wt.‐% of clay and quartz of silt to sand fraction. Based on this observation, the corals and stromatoporoids thrived in murky waters and under sediment‐stressed conditions. Stromatoporoids, for example, display irregular ragged flanks, a feature that is in agreement with a sediment‐stressed environment. No evidence of reduced growth rates, decreased calcification rates, or lower numbers of species is found. In fact, coral diversity and density are highest within one of the two biostromal units that show peak clastic matrix values, indicating a remarkable adaptation of reef builders to sediment‐stressed conditions. The initial settlement of rugose phaceloid corals took place on a mixed clastic–carbonate substrate (the basal flooding surface). Up‐section, a succession of coral–stromatoporoids is present that is here described in great detail. Reef collapse occurred when much of the accommodation space was filled, and argillaceous sediments suffocated stromatoporoids and corals in a protected, low‐energy environment.

The association of epicardial adipose tissue volume and density with coronary calcium in HIV-positive and HIV-negative patients

We sought to assess and compare the association of epicardial adipose tissue (EAT) with cardiovascular disease (CVD) in HIV-positive and HIV-negative groups METHODS AND RESULTS: Using existing clinical databases we analysed 700 patients (195 HIV-positive, 505 HIV-negative). CVD was quantified by the presence of coronary calcification from both dedicated cardiac computed tomography (CT) and non-dedicated CT of the thorax. Epicardial adipose tissue (EAT) was quantified using dedicated software. The HIV-positive group had lower mean age (49.2 versus 57.8, p<0.005), higher proportion of male sex (75.9% versus 48.1%, p<0.005) and lower rates of coronary calcification (29.2% versus 58.2%, p<0.005). Mean EAT volume was also lower in the HIV-positive group (68mm3 versus 118.3mm3, p<0.005). Multiple linear regression demonstrated EAT volume was associated hepatosteatosis (HS) in the HIV-positive group but no the HIV-negative group after adjustment for BMI (p<0.005 versus p=0.066). In the multivariate analysis, after adjustment for CVD risk factors, age, sex, statin use and body mass index (BMI), EAT volume and hepatosteatosis were significantly associated with coronary calcification (odds ratio [OR] 1.14, p<0.005 and OR 3.17, p<0.005 respectively). In the HIV-negative group the only significant association with EAT volume after adjustment was total cholesterol (OR 0.75, p=0.012). We demonstrated a strong and significant independent association of EAT volume and coronary calcium, after adjustment, in HIV-positive group but not in the HIV-negative group. This result hints at differences in the mechanistic drivers of atherosclerosis between HIV-positive and HIV-negative groups.

INTERACTION OF CO2 AND LIGHT AVAILABILITY ON PHOTOPHYSIOLOGY OF TROPICAL COCCOLITOPHORIDS (EMILIANIA HUXLEYI, GEPHYROCAPSA OCEANICA, AND OCHOSPHAERA SP.)

The study to examine the calcification rate, adaptation, and the biotic response of three tropical coccolithophorids (Emiliania huxleyi, Gephyrocapsa oceanica, and Ochosphaera sp) to changes in CO2 concentration. Three selected calcifying coccolitophorids were grown at batch culture with CO2 system at two levels of CO2 (385 and 1000 ppm) and two light dark periods. The parameters measured and calculation including growth rate, particulate organic carbon content, particulate inorganic carbon content, chlorophyll a, cell size, photosynthetic, organic, inorganic carbon production, photosynthesis, and calcification rate. The results showed that there was a different response to carbonate chemistry changes and dark and light periods in any of the analyzed parameters. The growth rate of three selected calcifying microalgae tested was decreasing significantly at high concentrations of CO2 (1000 ppm) treatment on 14:10 hour light: dark periods. However, there was no significant difference between the two CO2 concentrations where they were illuminated by 24 hours light in growth rate. The increasing CO2 concentration and light-dark periods were species-specific responses to photosynthesis and calcification rate for three selected calcifying microalgae.

Surgical outcomes of the Frey procedure for chronic pancreatitis: correlation between preoperative characteristics and the histological severity of pancreatic fibrosis.

To evaluate the efficacy of the Frey procedure and clarify the relationship between preoperative characteristics and thehistological severity of chronic pancreatitis (CP). Thirty patients who underwent the Frey procedure for CP between January, 2002 and December, 2020, at our hospital, were enrolled in this study. The specimen cored out of the pancreatic head was assessed for CP severity. We evaluated preoperative status and surgical outcomes according to CP severity. Long-term pain relief was achieved in all 26 patients with sustained long-term follow-up, with complete pain relief attained in 19 (63%). Albumin levels were significantly higher 1year postoperatively than preoperatively (p = 0.038). Histological fibrosis was assessed in the 26 patients as follows: normal (n = 4; 15%), mild (n = 8; 31%), moderate (n = 2; 8%), and severe (n = 12; 46%). These patients were divided into two groups according to the severity of fibrosis: normal/mild (n = 12) and moderate/severe (n = 14). The rates of diffuse calcification on preoperative computed tomography (CT) (71% vs. 17%, p = 0.008) and islet atrophy on insulin immunohistochemistry (100% vs. 33%, p < 0.001) were significantly higher in the moderate/severe group than in the normal/mild group. The Frey procedure can achieve good pain relief and improve nutritional status. The severity of fibrosis can be predicted based on the extent of calcification on preoperative imaging studies.

Evaluation of the correlation between multiple organ calcification on CT and disease severity in patients with TAFRO syndrome

PurposeThe purpose of this study was to investigate the incidence of multiple organ calcification and the correlation between multiple organ calcification and clinical severity in patients with thrombocytopenia, anasarca, fever, reticulin fibrosis, renal dysfunction, and organomegaly (TAFRO) syndrome.MethodsWe retrospectively identified 13 patients with TAFRO syndrome who were treated at our hospital between February 2019 and March 2021. Computed tomography (CT) images of TAFRO patients, which were acquired at admission and one month after admission, were evaluated. Additionally, clinical and laboratory data related to organ calcification and severity classification of TAFRO syndrome were investigated. The correlation between the presence of organ calcification on CT and TAFRO syndrome-severity classification was evaluated.ResultsOne month after admission, calcification of the myocardium, adrenal glands, gallbladder wall, pancreas, kidney, skeletal muscle, and skin were observed in 38%, 46%, 15%, 15%, 15%, 23%, and 15% of the thirteen patients, respectively. The occurrence rate of calcifications in the myocardium, adrenal glands, and skeletal muscle was significantly higher in patients with a grade 4 or higher clinical severity than in those with a level up to grade 3 (p = 0.001, p = 0.005, and p = 0.035, respectively).ConclusionsOur results suggest that the higher the clinical severity in patients with TAFRO syndrome, the higher is the frequency of calcification in the myocardium, adrenal glands, and skeletal muscle; therefore, the assessment of these organ calcifications on CT images may be useful in predicting the severity of TAFRO syndrome.

Seasonal drivers of productivity and calcification in the coral Platygyra carnosa in a subtropical reef

Scleractinian corals are increasingly subjected to local stressors combined with global changes. In subtropical areas, corals exhibit metabolic plasticity and resilience in response to variability and extremes in local temperature, salinity, and light; however, the physiological mechanisms by which corals acclimate or adapt to these changing conditions remain disputed. We assessed the physiological status of the coral Platygyra carnosa during a two-year in situ monitoring survey. To obtain metabolic rates (respiration and photosynthesis), photochemical efficiency (Fv / Fm), and biocalcification measurements, non-invasive techniques such as underwater respirometry, Pulse Amplitude Modulated (PAM) fluorometry, total alkalinity measurements, and digital photography were used. Our findings show clear seasonality in water quality parameters, which affected coral health. Elevated temperatures during the summer were below the maximum monthly mean &amp;lt; 31°C) but reduced the energetic productivity of corals (-44% relative to winter). Fluctuations in salinity (25–38 ppt) and pH (7.65–8.44) were linked to rainfall and reduced calcification rates. The conditions during the spring were favorable for coral metabolism and calcification (+20% relative to summer). Overall, our research demonstrates that the metabolic plasticity of P. carnosa in response to shifts in seawater quality allows this species to survive ongoing environmental change. Our in situ observations provide fundamental insights into coral response mechanisms under changing environmental conditions and contribute to projections of coral health under future scenarios of global change.

Co‐occurrence of herbivorous fish functional groups correlates with enhanced coral reef benthic state

AbstractAimBiodiversity loss is impacting essential ecosystem functions and services across the globe. Recently, our interest in the benefits of biodiversity for ecosystem function has shifted focus from measurements of species richness to functional diversity and composition. However, the additional importance of other community characteristics, such as species evenness and co‐occurrence, for diversity‐driven ecosystem function is less known. We used herbivorous coral reef fish as a model system to investigate how co‐occurrence of different functional groups, rather than purely functional diversity, within an assemblage might affect the coral reef benthic state.LocationWestern Atlantic.Time period2007–2017.Major taxa studiedHerbivorous reef fish.MethodsWe analysed benthic and fish assemblage data from 601 sites across 12 countries in the western Atlantic. Using diversity–interaction models, we investigated how the composition and relative abundances of reef fish functional groups were correlated with benthic cover and estimates of coral calcification rates. We used statistical interactions to explore the importance of co‐occurrence of herbivorous fish functional groups for the coral reef benthic state.ResultsWe found that co‐occurrence of herbivorous fish functional groups, in addition to functional diversity, was correlated with reduced algal cover and increased coral accretion. Moreover, pairwise statistical interactions between functional groups were significantly correlated with an improvement in the coral reef benthic state.Main conclusionsOur results support the idea that functional group co‐occurrence, in addition to functional diversity, within herbivorous fish offers additional benefits to the coral reef benthic state. We identify farming damselfish and excavating parrotfish as potential key determinants of the coral reef benthic state and highlight that co‐occurrence of cropping and scraping herbivores might promote coral accretion. Our findings support the argument that protecting herbivore abundance without regard to the species and functional groups present is not enough to preserve coral reef health and that fine‐scale community composition must be considered.

Testing hypotheses on the calcification in scleractinian corals using a spatio-temporal model that shows a high degree of robustness

Calcification in photosynthetic scleractinian corals is a complicated process that involves many different biological, chemical, and physical sub-processes that happen within and around the coral tissue. Identifying and quantifying the role of separate processes in vivo or in vitro is difficult or not possible. A computational model can facilitate this research by simulating the sub-processes independently. This study presents a spatio-temporal model of the calcification physiology, which is based on processes that are considered essential for calcification: respiration, photosynthesis, Ca2＋-ATPase, carbonic anhydrase. The model is used to test different hypotheses considering ion transport across the calicoblastic cells and Light Enhanced Calcification (LEC). It is also used to quantify the effect of ocean acidification (OA) on the Extracellular Calcifying Medium (ECM) and ATP-consumption of Ca2＋-ATPase. It was able to reproduce the experimental data of three separate studies and finds that paracellular transport plays a minor role compared to transcellular transport. In the model, LEC results from increased Ca2＋-ATPase activity in combination with increased metabolism. Implementing OA increases the concentration of CO2 throughout the entire tissue, thereby increasing the availability of CO3− in the ECM. As a result, the model finds that calcification becomes more energy-demanding and the calcification rate increases.

Clinical and radiologic outcomes of pleomorphic adenoma and adenoid cystic carcinoma of the lacrimal gland.

To compare the radiologic and clinical features of primary lacrimal gland pleomorphic adenoma and adenoid cystic carcinoma. This study retrospectively reviewed imaging findings and medical records of lacrimal gland pleomorphic adenoma and adenoid cystic carcinoma. Eleven patients with pleomorphic adenoma and 16 patients with adenoid cystic carcinoma were evaluated. There were no statistically significant differences between groups regarding age or sex. Proptosis was the most common presenting symptom in both groups. Adenoid cystic carcinomas were more likely to present with a palpable mass, diplopia, pain, and sensory loss than pleomorphic adenomas, although the differences were not statistically significant between groups. Furthermore, there were no significant differences in terms of homogeneity and globe indentation between lacrimal gland pleomorphic adenoma and adenoid cystic carcinoma on computed tomography (CT)(all p>0.05). The rates of bone invasion, tumor calcification, and wedge sign were significantly higher in adenoid cystic carcinomas, and bone remodeling was statistically significantly higher in pleomorphic adenomas, on CT(all p<0.05). Pleomorphic adenomas were significantly more likely to show well-defined margins, lobulated contours, heterogeneous contrast enhancement, and hyperintensity on T2-weighted magnetic resonance images (all p<0.05). When differentiating between lacrimal gland pleomorphic adenoma and adenoid cystic carcinoma, evaluation of radiologic features along with clinical features is of great importance. Lobulated contours may be a significant distinguishing radiologic feature suggesting pleomorphic adenoma.

Proof of concept for measuring growth of shelf marine calcifiers: ‘a Bryozoan odyssey’

Context The variation observed in growth rate estimates of bryozoans raise questions regarding the validity of the methods used to measure growth in these animals. Naturally, the best way for measuring growth rate is to understand the growth in situ, but access is not always straightforward. Aims This study assesses a field experiment for measuring in situ growth of heavily calcified bryozoans in the open ocean at 56 m, the deepest such deployment attempted for bryozoans. Methods Cellaria immersa colonies were collected by dredge from the continental shelf off Otago, marked using calcein, mounted on a purpose-built frame, called ‘Odyssey’, and returned to the shelf for 3 months in the Austral summer (November–February). Key results Data from 10 internodes indicated that growth was, on average, 0.97 ± 0.84 mm year−1 and showed some interesting intracolonial growth patterns. Conclusions and implications The data obtained from this study are only indicative at this stage, but we have succeeded in developing a reproducible experimental set-up for in situ growth experiments of shelf bryozoans, enabling us to record growth, lifespan, and calcification rates of heavily calcified and ecologically important species. Understanding such key species is critical to identifying their role in the ecosystem and providing valuable information for future conservation initiatives.

The DIC carbon isotope evolutions during CO2 bubbling: Implications for ocean acidification laboratory culture

Ocean acidification increases pCO2 and decreases pH of seawater and its impact on marine organisms has emerged as a key research focus. In addition to directly measured variables such as growth or calcification rate, stable isotopic tracers such as carbon isotopes have also been used to more completely understand the physiological processes contributing to the response of organisms to ocean acidification. To simulate ocean acidification in laboratory cultures, direct bubbling of seawater with CO2 has been a preferred method because it adjusts pCO2 and pH without altering total alkalinity. Unfortunately, the carbon isotope equilibrium between seawater and CO2 gas has been largely ignored so far. Frequently, the dissolved inorganic carbon (DIC) in the initial seawater culture has a distinct 13C/12C ratio which is far from the equilibrium expected with the isotopic composition of the bubbled CO2. To evaluate the consequences of this type of experiment for isotopic work, we measured the carbon isotope evolutions in two chemostats during CO2 bubbling and composed a numerical model to simulate this process. The isotopic model can predict well the carbon isotope ratio of dissolved inorganic carbon evolutions during bubbling. With help of this model, the carbon isotope evolution during a batch and continuous culture can be traced dynamically improving the accuracy of fractionation results from laboratory culture. Our simulations show that, if not properly accounted for in experimental or sampling design, many typical culture configurations involving CO2 bubbling can lead to large errors in estimated carbon isotope fractionation between seawater and biomass or biominerals, consequently affecting interpretations and hampering comparisons among different experiments. Therefore, we describe the best practices on future studies working with isotope fingerprinting in the ocean acidification background.

Size matters: Physiological sensitivity of the scallop Argopecten purpuratus to seasonal cooling and deoxygenation upwelling-driven events

Environment imposes physiological constraints which are life-stage specific as growth-maintenance and/or growth-reproduction energetic requirements are size and volume-dependent. The scallop Argopecten purpuratus, one of the most important bivalve species subjected to fishery and aquaculture along the Humboldt Current System, inhabits spaces affected by continuous changes in temperature, pH, oxygen, and food availability driven by remote and local oceanographic processes. Specifically, in Chile, this species is mainly cultured in central-north Chile where is permanently affected by upwelling events of dissimilar intensity and duration which generate local conditions of acidification, deoxygenation, and cooling with different magnitudes. However, to date, it remains unknown how this economic valuable resource is physiologically affected throughout its life cycle by the continuous environmental changes driven by upwelling events of different intensities and duration along the year. Here, for the first time, A. purpuratus life-stage physiological sensitivity was assessed at a seasonal scale through a year-field experiment where growth, calcification, and survivorship were evaluated. Our study shows how seasonal differences in the upwelling phenology (here measured as changes in temperature, dissolved oxygen, pH, and primary productivity, but also as the number, duration, and intensity of cooling and de-oxygenation events) notably impacted the A. purpuratus physiological performance from juvenile to adult life-stages. This was especially noticeable during the spring season which showed the most intense cooling and deoxygenation events driven by stronger favorable-upwelling winds and the lowest growth and gross calcification rates (the highest decalcification rates) where adult stages showed the lowest performance. On the other hand, A. purpuratus survivorship was not significantly affected by upwelling intensity which would be providing evidence of the high physiological flexibility and well-locally adapted is this species to fluctuating and occasional stressful environmental conditions. Our results are significantly relevant in the climate change context as some upwelling systems are at risk to change shortly (i.e., an upwelling intensification in frequency and intensity) as a consequence of changes in the atmospheric pressures that modulate favourable-upwelling winds. These changes may certainly increase the climate related-risks of the entire socio-ecological systems related to the fishery and aquaculture of A. purpuratus along the Humboldt Current System.

Transcriptional responses indicate acclimation to prolonged deoxygenation in the coral Stylophora pistillata

The current decrease in oceanic dissolved oxygen is a widespread and pressing problem that raises concern as to how marine biota in general, and coral reefs in particular will be affected. However, the molecular response underlying tolerance of corals to prolonged severe deoxygenation where acclimation to hypoxia can accrue is not yet known. Here, we investigated the effect of two weeks of continuous exposure to conditions of extreme deoxygenation, not hitherto exerted under laboratory conditions (~ 0.35 mg L−1 dissolved oxygen), on the physiology and the diurnal gene expression of the coral, Stylophora pistillata. Deoxygenation had no physiologically significant effect on tissue loss, calcification rates, symbiont numbers, symbiont chlorophyll-a content and symbiont photosynthesis rate. However, deoxygenation evoked a significant transcriptional response that was much stronger at night, showing an acute early response followed by acclimation after two weeks. Acclimation included increased mitochondria DNA copy numbers, possibly increasing energy production. Gene expression indicated that the uptake of symbiosis-derived components was increased together with a decrease in nematocyst formation, suggesting that prolonged deoxygenation could enhance the corals’ need for symbiosis-derived components and reduces its predation abilities. Coral orthologs of the conserved hypoxia pathway, including oxygen sensors, hypoxia-inducible factor (HIF) and its target genes were differentially expressed in a similar temporal sequence as observed in other metazoans including other species of corals. Overall, our studies show that by utilizing highly conserved and coral–specific response mechanisms, S. pistillata can acclimate to deoxygenation and possibly survive under climate change-driven oceanic deoxygenation. On the other hand, the critical importance of algal symbionts in this acclimation suggests that any environmental perturbations that disrupt such symbiosis might negatively affect the ability of corals to withstand ocean oxygen depletion.

Structure-from-motion photogrammetry demonstrates variability in coral growth within colonies and across habitats.

Coral growth is an important metric of coral health and underpins reef-scale functional attributes such as structural complexity and calcium carbonate production. There persists, however, a paucity of growth data for most reef-building regions, especially for coral species whose skeletal architecture prevents the use of traditional methods such as coring and Alizarin staining. We used structure-from-motion photogrammetry to quantify a range of colony-scale growth metrics for six coral species in the Mexican Caribbean and present a newly developed workflow to measure colony volume change over time. Our results provide the first growth metrics for two species that are now major space occupiers on Caribbean reefs, Agaricia agaricites and Agaricia tenuifolia. We also document higher linear extension, volume increase and calcification rates within back reef compared to fore reef environments for four other common species: Orbicella faveolata, Porites astreoides, Siderastrea siderea and Pseudodiploria strigosa. Linear extension rates in our study were lower than those obtained via computed tomography (CT) scans of coral cores from the same sites, as the photogrammetry method averages growth in all dimensions, while the CT method depicts growth only along the main growth axis (upwards). The comparison of direct volume change versus potential volume increase calculated from linear extension emphasizes the importance of assessing whole colony growth to improve calcification estimates. The method presented here provides an approach that can generate accurate calcification estimates alongside a range of other whole-colony growth metrics in a non-invasive way.