Ocean acidification poses multiple challenges for coral reefs on molecular to ecological scales, yet previous experimental studies of the impact of projected CO2 concentrations have mostly been done in aquarium systems with corals removed from their natural ecosystem and placed under artificial light and seawater conditions. The Coral-Proto Free Ocean Carbon Enrichment System (CP-FOCE) uses a network of sensors to monitor conditions within each flume and maintain experimental pH as an offset from environmental pH using feedback control on the injection of low pH seawater. Carbonate chemistry conditions maintained in the -0.06 and -0.22 pH offset treatments were significantly different than environmental conditions. The results from this short-term experiment suggest that the CP-FOCE is an important new experimental system to study in situ impacts of ocean acidification on coral reef ecosystems.

Coral cores collected nearby the Atlantic Ocean Acidification Test-bed (AOAT) at La Parguera, Puerto Rico were used to characterize the relationship between paleo-variations in coral growth and calcification and seawater pH via the boron isotope proxy. This study addressed impacts of ocean acidification in a geological context to quantify baseline variability in growth and pH and assess the historical response of coral ecosystems to increased atmospheric CO2 and enhance on-going AOAT observations.

High-precision measurements of changes in oxygen and various parameters of the CO2 system in sea water were used to monitor community metabolism in four Pacific coral reef systems. The reefs studied were One Tree Island and Lizard Island on the Great Barrier Reef, Kaneohe Bay, Oahu Island, Hawaii and Johnston Island in the central Pacific Ocean. This research was undertaken to gain further understanding of carbon fluxes through coral reef systems at an operational level. Data was collected during November 1961 at Heron Island, and during September- November, 1967 at One Tree Island.

This dataset includes lab-based measurements of ocean acidification on Caribbean bioeroders (endolithic algae and reef-excavating sponges) collected on Cheeca Rocks Reef, Florida Keys, Northwest Atlantic Ocean, from 2018-06-11 to 2018-07-12. Caribbean coral reef ecosystems have entered a state of net erosion in response to ocean acidification (OA) due to a combination of reduced carbonate production and enhanced bioerosion. The negative response of coral reef calcifiers to OA has been well-established, whereas OA-enhanced bioerosion is relatively poorly understood. Microboring algae and macroboring sponges are both major contributors to coral reef carbonate budgets (Perry et al., 2012). Microboring algae use exclusively chemical (extracellular ion transport) means (Garcia-Pichel, 2006) to break down carbonate framework, whereas macroboring sponges use a combination of both chemical (enzymatic dissolution) and mechanical (substrate dislodgment) methods (Rutzler and Rieger, 1973) to erode reef framework. Prior studies have found that both microboring algae and macroboring sponges appear to benefit from OA through both enhanced bioerosion and physiological fitness, but have disproportionally focused on the responses of Pacific Ocean species. Here, we independently evaluated the OA-response of two Caribbean bioeroders to quantify the impact of OA on their physiology and bioerosion rates.

The study is based on field investigations of clear-water coral reefs and seagrass communities around three cool volcanic seeps of ~99% CO2 gas, and at three adjacent control sites with similar geomorphology, seawater temperature and salinity, that fringe the D'Entrecastraux Islands, Milne Bay Province, Papua New Guinea. Co2 has been streaming from the seabed for over 70 years (likely much longer), resulting in localised acidified conditions: seeps (pCO2 ,500 to 900 ppm, pHTotal 7.8 – 7.9) adjacent control areas (pCO2 ,390 ppm,pHTotal ,8.0 – 8.05) Field surveys were conducted from 2010 to characterise seawater chemistry and ecological and physiological conditions in coral reefs control sites and seeps. See Fabricius et al. (2011) for further details. Environmental parameters (measured: pH, dissolved inorganic carbon, total alkalinity, salinity, and temperature; calculated with CO2SYS software: pCO2 and aragonite saturation state) were obtained across a 4-year period (2010–2013) at 1–5 m depth in both control and seep sites. A total of 433 colonies were sampled from six species of scleractinian coral: Acropora millepora, Pocillopora damicornis, Seriatopora hystrix, Poritescylindrica, massive Porites sp. and Galaxea fascicularis. Favites pentagona was the only species that occurred in moderate abundance at the extreme seep site and 10 colonies were sampled from the Upa-Upasina seep. DNA sequencing and statistical analysis was conducted, see Noonan et al. (2013) Samples of A. millepora, G. fasciularis, P.damicornis, and massive Porites. Analysis were analyised for skeletal porosity, bulk density and micro-density as described in the paper Prada et.al (2021), led by the team at the University of Bologna, Italy.

These data are from the article “Seasonal carbonate chemistry dynamics on southeast Florida coral reefs: localized acidification hotspots from navigational inlets” published in Frontiers in Marine Science. The data in this package were collected from inlets and reefs along the coast of Southeast Florida. Water was collected bi-monthly from four reefs (Oakland Ridge, Barracuda, Pillars, and Emerald) and three closely-associated inlets (Port Everglades, Bakers Haulover, and Port of Miami). Water samples were collected at these locations either at the surface (~1m depth) or immediately above the benthos measured using a rosette sampler (ECO 55, Seabird). Temperature was recorded at each depth using a CTD (SBE 19V2, Seabird). Turbidity (NTU) was measured at time of water collection. Once collected, water samples were transferred to borosilicate glass bottles, samples were fixed using 200 µL of HgCl2 and sealed using Apiezon grease and a glass stopper. Salinity was measured using a densitometer (DMA 5000M, Anton Paar), while total alkalinity (TA) and dissolved inorganic carbon (DIC) were determined using Apollo SciTech instruments (AS-ALK2 and AS-C3, respectively). All values were measured in duplicate and corrected using certified reference materials following recommendations in Dickson et al. (2007). Aragonite saturation state (ΩArag.), Calcite saturation state (ΩCa), pH (Total scale), and the partial pressure of CO2 (pCO2) were calculated with CO2SYS (Lewis and Wallace, 1998) using the dissociation constants of Mehrbach et al. (1973) as refit by Dickson and Millero (1987) and Dickson (1990). Water samples were reserved for nutrient analyzed at time of collection to determine Total Kjeldahl Nitrogen, Total Phosphorus, and fluorescence of Chlorophyll-a. This research was supported through NOAA’s Coral Reef Conservation Program.

This data package contains a hybrid surface OA data product that is produced based on three recent observational data products: (a) the Surface Ocean CO2 Atlas (SOCAT, version 2022), (b) the Global Ocean Data Analysis Product version 2 (GLODAPv2, version 2022), and (c) the Coastal Ocean Data Analysis Product in North America (CODAP-NA, version 2021), and 14 Earth System Models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The trajectories of ten OA indicators, including fugacity of carbon dioxide, pH on Total Scale, total hydrogen ion content, free hydrogen ion content, carbonate ion content, aragonite saturation state, calcite saturation state, Revelle Factor, total dissolved inorganic carbon content, and total alkalinity content are provided under preindustrial conditions, historical conditions, and future Shared Socioeconomic Pathways: SSP1-19, SSP1-26, SSP2-45, SSP3-70, and SSP5-85 from 1750 to 2100 on a global surface ocean grid. These OA trajectories are improved relative to previous OA data products with respect to data quantity, spatial and temporal coverage, diversity of the underlying data and model simulations, and the provided SSPs over the 21st century.

This dataset contains potential effects of ocean acidification on Alaskan corals based on calcium carbonate mineralogy composition analysis. Effects of ocean acidification (OA) on deep-sea coral habitats in Alaska could be pronounced given the particularly shallow and rapidly shoaling calcite and aragonite saturation horizons in the region. The magnitude of potential effects could partially depend on the corals' calcium carbonate mineralogy. We used X-ray diffraction and powerful full-pattern Rietveld data refinement to precisely determine the skeletal composition of 62 species of Alaskan corals-the most comprehensive cold-water coral dataset for any region of the world. Alaskan corals have complex mineralogy, including a high percentage of slightly polymorphic taxa. Scleractinians and octocorals were principally aragonite and calcite, respectively. A few octocorals were composed of the most soluble form of calcium carbonate (high-Mg calcite). Hydrocorals have the most complex mineralogy with many polymorphic taxa, and some genera have both aragonite and calcite species. Most coral taxa live at least partially below the current saturation horizons so may be physiologically compensating for the effects of OA via important life-history trade-offs. We found evidence of mineral-switching related to depth distribution or broad-scale biogeography. All Alaskan corals are protected by organic tissue and may have the ability to up-regulate the pH of internal calcifying fluid relative to ambient seawater. No Alaskan corals are at risk for skeletal dissolution based on present-day carbonate chemistry conditions in the North Pacific Ocean although the carbonate mineralogy of a few taxa may approach estimated dissolution points. Alaska's ecologically most important corals (Primnoa pacifica and Stylaster spp.) are most at risk to potential effects of OA given their highly soluble skeletons, depth distribution, and observed propensity for tissue loss from contact with fishing gear and predation. Laboratory experiments are currently underway to determine if Primnoa pacifica can tolerate carbonate chemistry conditions predicted for year 2100 and maintain important life-history functions.