Abstract:

Coral disease has progressively become one of the most pressing issues affecting coral reef survival. In the last 50 years, several reefs throughout the Caribbean have been severely impacted by increased frequency and intensity of disease outbreaks leading to coral death. A recent example of this is stony coral tissue loss disease which has quickly spread throughout the Caribbean, devastating coral reef ecosystems. Emerging from these disease outbreaks has been a coordinated research response that often integrates ‘omics techniques to better understand the coral immune system. ‘Omics techniques encompass a wide range of technologies used to identify large scale gene, DNA, metabolite, and protein expression. In this review, we discuss what is known about coral immunity and coral disease from an ‘omics perspective. We reflect on the development of biomarkers and discuss ways in which coral disease experiments to test immunity can be improved. Lastly, we consider how existing data can be better leveraged to combat future coral disease outbreaks.

Abstract:

The fugacity or partial pressure of CO₂ in surface water (fCO_2w) is a key parameter to determine air-sea CO₂ fluxes and the evolution of ocean acidification. Despite its importance some key physical chemical characteristics are not fully resolved, notably its dependence on temperature. The fCO_2w is mostly measured by autonomous underway systems near in situ sea surface temperature (SST). Subsurface measurements are commonly carried out on individual (discrete) samples at a fixed temperature, normally 20 °C. Here, the underway system observations are compared with co-located discrete observations to determine the consistency of these types of measurements. The co-located discrete fCO_2w at 20 °C and underway fCO_2w measurements at SST are used to infer the temperature dependence of CO₂. In addition, calculated fCO_2w from total alkalinity (TA) and total dissolved inorganic carbon (DIC) are compared with the underway and discrete fCO_2w measurements. For 21 cruises spanning the major ocean basins from 1992 to 2020 a temperature dependence of 4.13 ± 0.01% °C⁻¹ is determined in close agreement with a widely used previous empirical estimate of 4.23 ± 0.02% °C⁻¹ for North Atlantic surface water. The temperature dependency of calculated fCO_2w from TA and DIC using recommended constants is 4.10% °C⁻¹ for 17 cruises where there are co-located measurements of fCO_2w, TA and DIC.

Abstract:

A high-quality dataset of surface water fugacity of CO₂ (fCO_2w), consisting of over a million observations, and derived products are presented for the northern Caribbean Sea, covering the time span from 2002 through 2018. Prior to installation of automated pCO₂ systems on cruise ships of Royal Caribbean International and subsidiaries, very limited surface water carbon data were available in this region. With this observational program, the northern Caribbean Sea has now become one of the best-sampled regions for pCO₂ of the world ocean. The dataset and derived quantities are binned and averaged on a 1° monthly grid and are available at http://accession.nodc.noaa.gov/0207749 (last access: 30 June 2020) (https://doi.org/10.25921/2swk-9w56; Wanninkhof et al., 2019a). The derived quantities include total alkalinity (TA), acidity (pH), aragonite saturation state (Ω_Ar), and air-sea CO₂ flux and cover the region from 15–28°N and 88–62°W. The gridded data and products are used for determination of status and trends of ocean acidification, for quantifying air-sea CO₂ fluxes, and for ground-truthing models. Methodologies to derive the TA, pH, and Ω_Ar and to calculate the fluxes from fCO_2w temperature and salinity are described.

Abstract:

This paper presents the SURATLANT data set (SURveillance ATLANTique). It consists of individual data of temperature, salinity, parameters of the carbonate system, nutrients, and water stable isotopes (δ¹⁸O and δD) collected mostly from ships of opportunity since 1993 along transects between Iceland and Newfoundland (https://doi.org/10.17882/54517). We discuss how the data are validated and qualified, their accuracy, and the overall characteristics of the data set. The data are used to reconstruct seasonal cycles and interannual anomalies, in particular of sea surface salinity (SSS); inorganic nutrients; dissolved inorganic carbon (DIC); and its isotopic composition δ¹³C_DIC, total alkalinity (A_t), and water isotope concentrations. Derived parameters such as fCO₂ and pH are also estimated. The relation between salinity and A_t is estimated from these data to investigate the possibility to replace missing A_t when estimating other parameters of the carbonate system. When examining the average seasonal cycle in the deep ocean, in both these data with other climatologies, we find a period of small seasonal change between January and late April. On the Newfoundland shelf and continental slope, changes related with spring stratification and blooms occur earlier. The data were collected in a period of multi-decennial variability associated with the Atlantic multi-decadal variability with warming between 1994 and 2004–2007, and with the recent cooling having peaked in 2014–2016. We also observe strong salinification in 2004–2009 and fresher waters in 1994–1995 as well as since 2010 south of 54°N and in 2016–2017 north of 54°N. Indication of multi-decadal variability is also suggested by other variables, such as phosphate or DIC, but cannot be well resolved seasonally with the discrete sampling and in the presence of interannual variability. As a whole, over the 24 years, the ocean fCO₂ trend (+1.9µatmyr⁻¹) is close to the atmospheric trend and associated with an increase in DIC (+0.77µmolkg⁻¹yr⁻¹). The data also revealed a canonical pH decrease of −0.0021yr⁻¹. There is also a decrease in δ¹³C_DIC between 2005 and 2017 (in winter, −0.014‰yr⁻¹, but larger in summer, −0.042‰yr⁻¹), suggesting a significant anthropogenic carbon signal at play together with other processes (mixing, biological activity).

Abstract:

The Surface Ocean CO₂ Atlas (SOCAT) is a synthesis of quality-controlled fCO₂ (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO₂ values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO₂ values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO₂ values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO₂ has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT_V3_GRID.

Abstract:

Ammonium is a nutrient frequently preferred by microorganisms that photosynthesizes at the base of the marine food web and removes atmospheric carbon dioxide via carbon fixation. Because their photosynthesis is concentrated in the ocean's thin euphotic zone, its nutrient concentrations are critical to oceanic carbon fixation. Identification of replacement processes for euphotic-zone ammonium thus becomes important. These processes were investigated in a two-experiment, Lagrangian field study that produced results consistent with an apparent inverse effect of wind forcing on upper-ocean ammonium concentrations. At low wind speeds (especially ≤ 4 ms^− 1), continuous seawater sampling, supported by sulfur-hexafluoride (SF6) water-mass tracing and meteorological measurements, detected 1.1–4.4-km-wide boluses of surface seawater exhibiting ammonium enrichments that were 5 - to-10-fold above background. In the first experiment, ammonium maxima comprising the enrichment event disappeared at higher wind speeds. In the second experiment, which had consistently higher wind speeds, an ammonium event composed of such maxima was never found. The apparent correlation between elevated ammonium concentrations and low wind stress could therefore be viewed as potentially important for understanding ammonium cycling and carbon fixation in the ocean.

Abstract:

The Surface Ocean CO₂ Atlas (SOCAT), an activity of the international marine carbon research community, provides access to synthesis and gridded fCO₂ (fugacity of carbon dioxide) products for the surface oceans. Version 2 of SOCAT is an update of the previous release (version 1) with more data (increased from 6.3 million to 10.1 million surface water fCO₂ values) and extended data coverage (from 1968–2007 to 1968–2011). The quality control criteria, while identical in both versions, have been applied more strictly in version 2 than in version 1. The SOCAT website (http://www.socat.info/) has links to quality control comments, metadata, individual data set files, and synthesis and gridded data products. Interactive online tools allow visitors to explore the richness of the data. Applications of SOCAT include process studies, quantification of the ocean carbon sink, and its spatial, seasonal, year-to-year and longer term variation, as well as initialization or validation of ocean carbon models and coupled climate-carbon models.

Abstract: In February, 2007, a tracer study was conducted on the Boynton Inlet, Florida, using sulfur hexafluoride (SF6) tracer. The objectives of this study were to determine if the data collected from the tracer study could be used to develop a farfield model of the plume exiting the Boynton Inlet using limited data to develop a useful predictive result. There are few studies of the farfield movement of inlet plumes in the coastal ocean. The plume was successfully modeled with a Gaussian plume model that appears to mimic the response. It was noted that the tracer concentrated in a series of boluses that migrated north of the inlet. Because the project injected the tracer for only 4 hours during the outgoing time, a long-term result that would hide the boluses was developed. The results showed velocities lower than predicted by the measured current data. The belief is that this is partially a result of tidal influences that affect outflow from the inlet.

Abstract:

Two ³He/SF₆ dual-gas tracer injections were conducted during the Southern Ocean Gas Exchange Experiment (SO GasEx) to determine gas transfer velocities. During the experiment, wind speeds of up to 16.4 m s^-1 were encountered. A total of 360 ³He and 598 SF₆ samples were collected at 40 conductivity-temperature-depth (CTD) rosette casts and two pumped stations. The gas transfer velocity k was calculated from the decrease in the observed ³He/SF₆ ratio using three different approaches. Discrete points of wind speed and corresponding k were obtained from the change in ³He/SF₆ ratio over three time intervals. The results were also evaluated using an analytical model and a 1-D numerical model. The results from the three approaches agreed within the error of the estimates of about ±13%±15% for Patch 1 and ±4% for Patch 2. Moreover, ³He/SF₆ dual-tracer results from SO GasEx are similar to those from other areas in both the coastal and open ocean and are in agreement with existing parameterizations between wind speed and gas exchange. This suggests that wind forcing is the major driver of gas exchange for slightly soluble gases in the ocean and that other known impacts are either intrinsically related to wind or have a small effect (<20% on average) on time scales of the order of days to weeks. The functionality of the wind speed dependence (quadratic or cubic) cannot be unequivocally determined from SO GasEx results.

Abstract: It has been predicted that the Arctic Ocean will sequester much greater amounts of carbon dioxide (CO₂) from the atmosphere as a result of sea ice melt and increasing primary productivity. However, this prediction was made on the basis of observations from either highly productive ocean margins or ice-covered basins before the recent major ice retreat. We report here a high-resolution survey of sea-surface CO₂ concentration across the Canada Basin, showing a great increase relative to earlier observations. Rapid CO₂ invasion from the atmosphere and low biological CO₂ drawdown are the main causes for the higher CO₂, which also acts as a barrier to further CO₂ invasion. Contrary to the current view, we predict that the Arctic Ocean basin will not become a large atmospheric CO₂ sink under ice-free conditions.

Abstract: The Florida Area Coastal Environment (FACE) research program gathers a variety of data related to water inputs into the coastal zone of southeast Florida. The water inputs studied include treated wastewater discharges, inlet flows, and upwelling events. Measurements include currents, nutrients, microbial contaminants, and stable isotopes. This report provides a glimpse of the data collected in this program. Data collected from the Boynton inlet point to the significance of this discharge as a source of nutrient and microbiological loads to coastal waters and demonstrate the importance of accounting for all major discharges in order to fully understand the impact of land use and water management decisions on coastal resources.

Abstract:

In order to facilitate the collection of high quality and uniform surface water pCO₂ data, an underway pCO₂ instrument has been designed based on community input and is now commercially available. Along with instrumentation, agreements were reached on data reduction and quality control that can be easily applied to data from these systems by using custom-made freeware. This new automated underway pCO₂ measuring system is designed to be accurate to within 0.1 μatm for atmospheric pCO₂ measurements and to within 2 µatm for seawater pCO₂, targeted by the scientific community to constrain the regional air-sea CO₂ fluxes to 0.2 Pg C year^-1. The procedure to properly reduce the underway pCO₂ data and perform the steps necessary for calculation of the fugacity of CO₂ from the measurements is described. This system is now widely used by the scientific community on many different types of ships. Combined with the recommended data-reduction procedures, it will facilitate producing data sets that will significantly decrease the uncertainty currently present in estimates of air-sea CO₂ fluxes.

Abstract: Acoustical methods play an important role in identifying sources of nutrient to coral reef ecosystems in the South Florida coastal waters. Nutrient fluxes into the coastal ocean are associated with distinct water masses such as inlet discharge plumes, wastewater outfall discharge plumes, and upwelling of deep oceanic water. Various nutrient-bearing water masses can be identified by water column acoustic backscatter profiles, obtained via either shipborne instrumentation or in-situ instrumentation. Such multidimensional images of water masses can be used to optimize the design of chemical and biological sampling efforts. Examples of water mass imaging will be presented, as well as the use of such images in the design of water quality sampling programs.

Abstract:

Pathways and dilution of a point source ocean discharge in the farfield (approximately equal to 10-66 km) were measured using the deliberate tracer sulfur hexafluoride (SF₆). The injection of SF₆ was performed by bubbling the gas over a period of 6 days into an ocean outfall pipe discharging into the southeast Florida coastal ocean. The surface SF₆ concentrations show that the discharged water flowed northward parallel to the coast with a broadening of the width of the plume to about 3 km at the farthest point sampled, 66 km from the outfall. The discharge was fully mixed throughout the water column within 13 km of the outfall terminus. In the first 20 km from the outfall, SF₆ surface concentrations were highly variable, while beyond this the SF₆ concentrations decreased monotonically going northward. The currents were measured during the study with a bottom-mounted acoustic Doppler current profiler (ADCP) located 5.5 km from the outfall. Velocities were variable in magnitude and direction but showed a net northward flow during the 6-day study. Maximum concentrations decreased by about 200-fold per kilometer from the outfall to the northern end of the study area. The study shows that SF₆ is an effective method to trace point source releases far from their origin.

Abstract:

The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.

Abstract:

Gas transfer velocities were determined in the Southern Ocean during the Southern Ocean Iron Fertilization experiment (SOFex) using the dual deliberate tracer technique. The decrease of the purposefully injected tracers, sulfur hexafluoride and helium-3, could be well described by gas exchange parameterizations with wind speed that satisfy global constraints based on bomb-¹⁴C uptake. The concentration decrease of tracers could be predicted slightly better with established relationships if gas transfer was modeled as a function of the cube rather than the square of the wind speed, particularly over a time interval with high and variable winds. However, both fits can model the concentration decrease within the uncertainty of the observations. This suggests that it will be singularly difficult to definitively determine if a quadratic or cubic dependence of gas exchange with wind is more appropriate based on deliberate tracer measurements. However, these results show that gas exchange rates in the Southern Ocean are not anomalous when compared with the rest of the ocean. Thus, this cannot account for discrepancy between observational and model-based estimates of uptake of CO₂ in the Southern Ocean. Using a high-quality wind speed field obtained from the QuikSCAT satellite Seawinds scatterometer and an established surface water pCO₂ climatology, the CO₂ uptake in the Southern Ocean (>34°S) is reassessed. The total uptake rates are similar to previous observation-based estimates, but the analysis shows that the uptake rate is sensitive to wind speed product used and the wind speed distribution.