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Archival records of the Antarctic clam shells from Marian Cove, King George Island suggest a protective mechanism against ocean acidification

Published 21 February 2024 Science Closed
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Abstract

Continuous emissions of anthropogenic CO2 are changing the atmospheric and oceanic environment. Although some species may have compensatory mechanisms to acclimatize or adapt to the changing environment, most marine organisms are negatively influenced by climate change. In this study, we aimed to understand the compensatory mechanisms of the Antarctic clam, Laternula elliptica, to climate-related stressors by using archived shells from 1995 to 2018. Principal component analysis revealed that seawater pCO2 and salinity in the Antarctic Ocean, which have increased since the 2000’s, are the most influential factors on the characteristics of the shell. The periostracum thickness ratio and nitrogen on the outermost surface have increased, and the dissolution area (%) has decreased. Furthermore, the calcium content and mechanical properties of the shells have not changed. The results suggest that L. elliptica retains the mechanism of protecting the shell from high pCO2 by thickening the periostracum as a phenotype plasticity.

Highlights

  • We analyzed archival shells of the Antarctic clams in response to climate change.
  • Seawater pCO2 and salinity in the Antarctic Ocean have increased since the 2000’s.
  • Shell dissolution decreased over time while total shell thickness remained constant.
  • The calcium content and mechanical properties of the shell remained unchanged.
  • Shell integrity was retained by thickening the organic layer enriched with nitrogen.
Continue reading ‘Archival records of the Antarctic clam shells from Marian Cove, King George Island suggest a protective mechanism against ocean acidification’

Turf algae drives coral bioerosion under high CO2

Published 20 February 2024 Science Closed
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Turf algal prevalence will increase in coral ecosystems under ocean acidification yet their contribution towards the ongoing and projected degradation of reefs is often overlooked. Turf algal settlement was induced on exposed coral skeleton adjacent to live coral tissue to investigate coral-turf algal interactions through a combination of laboratory and field transplantation (shallow volcanic CO2 seep) experiments across two temperature regimes. Here, we show that turf algae are competitively favored over corals under high pCO2 conditions. Turf algae-associated biological activity locally acidified the microenvironment overlying the exposed coral skeleton, leading to its bioerosion. Increases in coral-turf algal interactions could shift coral ecosystems towards net dissolution and should be integrated into global accretion models when considering future carbonate budgets under climate change.

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A decade of marine inorganic carbon chemistry observations in the northern Gulf of Alaska – insights into an environment in transition (update)

Published 19 February 2024 Science Closed
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As elsewhere in the global ocean, the Gulf of Alaska is experiencing the rapid onset of ocean acidification (OA) driven by oceanic absorption of anthropogenic emissions of carbon dioxide from the atmosphere. In support of OA research and monitoring, we present here a data product of marine inorganic carbon chemistry parameters measured from seawater samples taken during biannual cruises between 2008 and 2017 in the northern Gulf of Alaska. Samples were collected each May and September over the 10 year period using a conductivity, temperature, depth (CTD) profiler coupled with a Niskin bottle rosette at stations including a long-term hydrographic survey transect known as the Gulf of Alaska (GAK) Line. This dataset includes discrete seawater measurements such as dissolved inorganic carbon and total alkalinity, which allows the calculation of other marine carbon parameters, including carbonate mineral saturation states, carbon dioxide (CO2), and pH. Cumulative daily Bakun upwelling indices illustrate the pattern of downwelling in the northern Gulf of Alaska, with a period of relaxation spanning between the May and September cruises. The observed time and space variability impart challenges for disentangling the OA signal despite this dataset spanning a decade. However, this data product greatly enhances our understanding of seasonal and interannual variability in the marine inorganic carbon system parameters. The product can also aid in the ground truthing of biogeochemical models, refining estimates of sea–air CO2 exchange, and determining appropriate CO2 parameter ranges for experiments targeting potentially vulnerable species. Data are available at https://doi.org/10.25921/x9sg-9b08 (Monacci et al., 2023).

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Effects of year-long exposure to elevated pCO2 on the metabolism of back reef and fore reef communities

Published 16 February 2024 Science Closed
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The implications of ocean acidification are acute for calcifying organisms, notably tropical reef corals, for which accretion generally is depressed and dissolution enhanced at reduced seawater pH. We describe year-long experiments in which back reef and fore reef (17-m depth) communities from Moorea, French Polynesia, were incubated outdoors under pCO2 regimes reflecting endpoints of representative concentration pathways (RCPs) expected by the end the century. Incubations were completed in three to four flumes (5.0 × 0.3 m, 500 L) in which seawater was refreshed and circulated at 0.1 m s−1, and the response of the communities was evaluated monthly by measurements of net community calcification (NCC) and net community productivity (NCP). For both communities, NCC (but not NCP) was affected by treatments and time, with NCC declining with increasing pCO2, and for the fore reef, becoming negative (i.e., dissolution was occurring) at the highest pCO2 (1067–1433 μatm, RCP8.5). There was scant evidence of community adjustment to reduce the negative effects of ocean acidification, and inhibition of NCC intensified in the back reef as the abundance of massive Porites spp. declined. These results highlight the risks of dissolution under ocean acidification for coral reefs and suggest these effects will be most acute in fore reef habitats. Without signs of amelioration of the negative effects of ocean acidification during year-long experiments, it is reasonable to expect that the future of coral reefs in acidic seas can be predicted from their current known susceptibility to ocean acidification.

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Spatial variability of aragonite saturation state (Ωarag) in Indonesian coastal waters

Published 15 February 2024 Science Closed
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Highlights

  • Regional disparities reveal lower Ωarag in Pari, Lombok; higher levels in Selayar, Flores.
  • Salinity impact ranges 24.13%–52.92%, showing a negative sea surface temperature-Ωarag correlation.
  • Climate change projections for 2100 predict substantial Ωarag reduction in Indonesian coastal waters.
  • The susceptibility to ocean acidification suggests coral reefs deteriorate by 2100, except for those in the coastal waters of Selayar Island.

Abstract

The effects of Ocean acidification (OA) on the coastal waters of small islands in Indonesia have yet to be extensively studied. This research aims to investigate the process of OA in the coastal waters of small Indonesian islands and examine how land-sea interactions impact carbonate mineral saturation. We collected seawater samples from seven locations on small islands in Indonesia between 2015 and 2021 to analyze the aragonite saturation state. The result shows that most of Indonesia’s coastal waters are accompanied by supersaturation of aragonite saturation state (Ωarag>1). Selayar Island’s waters had the highest aragonite saturation, averaging 4.96 ± 0.48, while Pari Island’s coastal waters had the lowest, averaging 2.49 ± 0.50. Salinity had the greatest effect on Ωarag in all of the sampling sites, ranging from 24.13% to 52.92%, except Aceh Island, where temperature had a greater impact (34.35%) than salinity (26.99%). By the end of this century, Ωarag is predicted to decline based on projections related to climate change. Small island coastal waters are expected to experience a more substantial decline compared to those near the mainland, ranging from 4.71% to 79.58%. The coastal waters of Weh and Selayar Island are probably going to decline the greatest, while the coastal waters of Sorong (mainland) are probably going to decline the least. All seven sampling locations are expected to observe the decrease. This decline will be observed at all seven sampling locations, with Ωarag values ranging from 1.91 to 3.35.

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Divergent morphological and microbiome strategies of two neighbor sponges to cope with low pH in Mediterranean CO2 vents

Published 14 February 2024 Science Closed
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Highlights

  • Sponges are seen as winner taxa of future OA, yet not all species respond equally.
  • Neighbor sponges had different morphology and microbiome patterns in CO2 vents.
  • Vent S. cunctatrix displayed morphology changes and incipient microbial dysbiosis.
  • C. reniformis microbiomes were normobiotic, diverse and functionally flexible.
  • Symbioses supplying C–N–S cycles, vitamins and probiotics uphold resilience to OA.

Abstract

Ocean Acidification (OA) profoundly impacts marine biochemistry, resulting in a net loss of biodiversity. Porifera are often forecasted as winner taxa, yet the strategies to cope with OA can vary and may generate diverse fitness status. In this study, microbial shifts based on the V3–V4 16S rRNA gene marker were compared across neighboring Chondrosia reniformis sponges with high microbial abundance (HMA), and Spirastrella cunctatrix with low microbial abundance (LMA) microbiomes. Sponge holobionts co-occurred in a CO2 vent system with low pH (pHT ~ 7.65), and a control site with Ambient pH (pHT ~ 8.05) off Ischia Island, representing natural analogues to study future OA, and species’ responses in the face of global environmental change. Microbial diversity and composition varied in both species across sites, yet at different levels. Increased numbers of core taxa were detected in S. cunctatrix, and a more diverse and flexible core microbiome was reported in C. reniformis under OA. Vent S. cunctatrix showed morphological impairment, along with signs of putative stress-induced dysbiosis, manifested by: 1) increases in alpha diversity, 2) shifts from sponge related microbes towards seawater microbes, and 3) high dysbiosis scores. Chondrosia reniformis in lieu, showed no morphological variation, low dysbiosis scores, and experienced a reduction in alpha diversity and less number of core taxa in vent specimens. Therefore, C. reniformis is hypothesized to maintain an state of normobiosis and acclimatize to OA, thanks to a more diverse, and likely metabolically versatile microbiome. A consortium of differentially abundant microbes was identified associated to either vent or control sponges, and chiefly related to carbon, nitrogen and sulfur-metabolisms for nutrient cycling and vitamin production, as well as probiotic symbionts in C. reniformis. Diversified symbiont associates supporting functional convergence could be the key behind resilience towards OA, yet specific acclimatization traits should be further investigated.

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Effects of acidification on the biogeochemistry of unvegetated and seagrass marine sediments

Published 14 February 2024 Science Closed
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Highlights

  • A −0.3 pH units difference causes minor effects on unvegetated sediments organic matter
  • Acidification slows down organic C degradation in unvegetated sediments
  • Acidification stimulates organic C in seagrass sediments
  • Acidification will affect benthic trophic webs under worsening ocean scenarios

Abstract

Many studies addressed ocean acidification (OA) effects on marine life, whereas its effects on sedimentary organic matter (OM) have received less attention. We investigated differences in OM features in sediments from unvegetated and seagrass (Posidonia oceanica) beds in a shallow hydrothermal area (Aeolian Archipelago, Mediterranean Sea), under natural (8.1–8.0) and acidified (7.8–7.9) conditions. We show that a pH difference of −0.3 units have minor effects on OM features in unvegetated sediments, but relevant consequences within acidified seagrass meadows, where OM quantity and nutritional quality are lower than those under natural pH conditions. Effects of acidified conditions on OM biogeochemistry vary between unvegetated and seagrass sediments, with lower C degradation rates and longer C turnover time in the former than in the latter. We conclude that OA, although with effects not consistent between unvegetated and vegetated sediments, can affect OM quantity, composition, and degradation, thus having possible far-reaching consequences for benthic trophic webs.

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Nutrient and carbonate chemistry patterns associated with Karenia brevis blooms in three West Florida Shelf estuaries 2020-2023

Published 13 February 2024 Science Closed
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Ocean acidification (OA) driven by eutrophication, riverine discharge, and other threats from local population growth that affect the inorganic carbonate system is already affecting the eastern Gulf of Mexico. Long-term declines in pH of ~ -0.001 pH units yr-1 have been observed in many southwest Florida estuaries over the past few decades. Coastal and estuarine waters of southwest Florida experience high biomass harmful algal blooms (HABs) of the dinoflagellate Karenia brevis nearly every year; and these blooms have the potential to impact and be impacted by seasonal to interannual patterns of carbonate chemistry. Sampling was conducted seasonally along three estuarine transects (Tampa Bay, Charlotte Harbor, Caloosahatchee River) between May 2020 and May 2023 to obtain baseline measurements of carbonate chemistry prior to, during, and following K. brevis blooms. Conductivity, temperature and depth data and discrete water samples for K. brevis cell abundance, nutrients, and carbonate chemistry (total alkalinity, dissolved inorganic carbonate (DIC), pCO2, and pHT were evaluated to identify seasonal patterns and linkages among carbonate system variables, nutrients, and K. brevis blooms. Karenia brevis blooms were observed during six samplings, and highest pCO2 and lowest pHT was observed either during or after blooms in all three estuaries. Highest average pH and lowest pCO2 were observed in Tampa Bay. In all three estuaries, average DIC and pHT were higher and pCO2 was lower during dry seasons than wet seasons. There was strong influence of net community calcification (NCC) and net community production (NCP) on the carbonate system; and NCC : NCP ratios in Tampa Bay, Charlotte Harbor, and the Caloosahatchee River were 0.83, 0.93, and 1.02, respectively. Linear relationships between salinity and dissolved ammonium, phosphate, and nitrate indicate strong influence of freshwater inflow from river input and discharge events on nutrient concentrations. This study is a first step towards connecting observations of high biomass blooms like those caused by K. brevis and alterations of carbonate chemistry in Southwest Florida. Our study demonstrates the need for integrated monitoring to improve understanding of interactions among the carbonate system, HABs, water quality, and acidification over local to regional spatial scales and event to decadal time scales.

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Acidification and hypoxia in seawater, and pollutant enrichment in the sediments of Qi’ao Island mangrove wetlands, Pearl River Estuary, China

Published 9 February 2024 Science Closed
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Highlights

  • Nutrient absorption and consumption in the mangrove forest exhibited a significantly higher nitrogen-to-phosphorus ratio compared to utilized nutrients.
  • The mangrove forest demonstrated a concerning trend of hypoxia and acidification, with dissolved oxygen saturation reaching a mere 57.0% and pH measuring 7.58 during ebb tides.
  • The enrichment factors of oils, organic carbon, and sulfide were 4.37, 2.04, and 2.06, respectively, fostering the accumulation of total Hg, Zn, and Cu in the sediments of the mangrove forest.

Abstract

Mangrove forests are crucial in absorbing, storing, and purifying pollutants while maintaining ecological balance. A study was conducted in 2020 to investigate the biogeochemical processes of seawater and sedimentary environmental factors in the Qi’ao Island mangrove wetland. The study comprised two survey sections and ten survey stations within the mangrove forest and 16 large-scale survey stations in the adjacent sea area. During ebb tides, the mean concentrations of inorganic nitrogen and phosphate in Section D1 of the mangrove forest were 0.63 mg/L and 0.003 mg/L, respectively. These levels were significantly lower than the results observed in the adjacent sea area and Section D2 of the mangrove forest during flood tides. The mangrove forest efficiently absorbed and consumed nutrients, with the nitrogen-to-phosphorus ratio of consumed nutrients being notably higher than that typically utilized by plants during growth. We identified various biogeochemical processes, including nitrogen fixation, mineralization, nitrification, and denitrification, occurring within the mangrove forest. Seawater measurements in Section D1 during ebb tides showed the mean pH of 7.58 and dissolved oxygen levels of 4.52 mg/L, resulting in a dissolved oxygen saturation level of only 57.0 %. The low dissolved oxygen levels were attributed to organic matter degradation in the forest. Consequently, the longer the water retention time, the more obvious the trend of hypoxia and acidification was observed. In the adjacent sea area, the sedimentary environment was deemed healthy, with pollutants primarily originating from runoff and ship discharge from waterways and ports. However, within the mangrove forest, the sediments exhibited higher enrichment factors for organic carbon and sulfide, indicating significant pollution compared to the adjacent sea area. The sediments were conducive to the accumulation and burial of total Hg, Zn, and Cu, while other heavy metals did not show prominent deposition and enrichment. Notably, the enrichment factor of oils was as high as 4.37, leading to the formation of an oil pollution zone at the forest edge, and the enrichment of pollutants in sediment may inhibit the growth and expansion of mangroves. Overall, this study shed light on the occurrence of seawater acidification, hypoxia, and the behavior of sediment pollutants within the mangrove forest. The findings provide valuable insights to support efforts aimed at promoting and maintaining the ecosystem health of mangrove forests.

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Quantifying the combined impacts of anthropogenic CO2 emissions and watershed alteration on estuary acidification at biologically-relevant time scales: a case study from Tillamook Bay, OR, USA

Published 7 February 2024 Science Closed
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The impacts of ocean acidification (OA) on coastal water quality have been subject to intensive research in the past decade, but how emissions-driven OA combines with human modifications of coastal river inputs to affect estuarine acidification dynamics is less well understood. This study presents a methodology for quantifying the synergistic water quality impacts of OA and riverine acidification on biologically-relevant timescales through a case study from a small, temperate estuary influenced by coastal upwelling and watershed development. We characterized the dynamics and drivers of carbonate chemistry in Tillamook Bay, OR (USA), along with its coastal ocean and riverine end-members, through a series of synoptic samplings and continuous water quality monitoring from July 2017 to July 2018. Synoptic river sampling showed acidification and increased CO2 content in areas with higher proportions of watershed anthropogenic land use. We propagated the impacts of 1). the observed riverine acidification, and 2). modeled OA changes to incoming coastal ocean waters across the full estuarine salinity spectrum and quantified changes in estuarine carbonate chemistry at a 15-minute temporal resolution. The largest magnitude of acidification (-1.4 pHT units) was found in oligo- and mesohaline portions of the estuary due to the poor buffering characteristics of these waters, and was primarily driven by acidified riverine inputs. Despite this, emissions-driven OA is responsible for over 94% of anthropogenic carbon loading to Tillamook Bay and the dominant driver of acidification across most of the estuary due to its large tidal prism and relatively small river discharges. This dominance of ocean-sourced anthropogenic carbon challenges the efficacy of local management actions to ameliorate estuarine acidification impacts. Despite the relatively large acidification effects experienced in Tillamook Bay (-0.16 to -0.23 pHT units) as compared with typical open ocean change (approximately -0.1 pHT units), observations of estuarine pHT would meet existing state standards for pHT. Our analytical framework addresses pressing needs for water quality assessment and coastal resilience strategies to differentiate the impacts of anthropogenic acidification from natural variability in dynamic estuarine systems.

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Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings

Published 7 February 2024 Science Closed
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The pH of coastal seawater varies based on several local forcings, such as water circulation, terrestrial inputs, and biological processes, and these forcings are changing along with global climate change. Understanding the mechanism of pH variation in each coastal area is thus important for a realistic future projection that considers changes in these forcings. From 2020 to 2021, we performed parallel year-round observations of pH and related ocean parameters at five stations around the Japanese coast (Miyako Bay, Shizugawa Bay, Kashiwazaki Coast, Hinase Archipelago, and Ohno Strait) to understand the characteristics of short-term pH variations and their forcings. Annual variability (∼ 1 standard deviation) of pH and aragonite saturation state (Ωar) were 0.05–0.09 and 0.25–0.29, respectively, for three areas with low anthropogenic pressures (Miyako Bay, Kashiwazaki Coast, and Shizugawa Bay), while it increased to 0.16–0.21 and 0.52–0.58, respectively, in two areas with medium anthropogenic pressures (Hinase Archipelago and Ohno Strait in Seto Inland Sea). Statistical assessment of temporal variability at various timescales revealed that most of the annual variabilities in both pH and Ωar were derived by short-term variation at a timescale of <10 d, rather than seasonal-scale variation. Our analyses further illustrated that most of the short-term pH variation was caused by biological processes, while both thermodynamic and biological processes equally contributed to the temporal variation in Ωar. The observed results showed that short-term acidification with Ωar < 1.5 occurred occasionally in Miyako and Shizugawa bays, while it occurred frequently in the Hinase Archipelago and Ohno Strait. Most of such short-term acidified events were related to short-term low-salinity events. Our analyses showed that the amplitude of short-term pH variation was linearly correlated with that of short-term salinity variation, and its regression coefficient at the time of high freshwater input was positively correlated with the nutrient concentration of the main river that flows into the coastal area.

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Habitat sensitivity in the West African coastal area: inferences and implications for regional adaptations to climate change and ocean acidification

Published 1 February 2024 Science Closed
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This study focuses on assessing coastal vulnerability and habitat sensitivity along the West African coast by delineating hotspots based on surface temperature, pH, chlorophyll-a, particulate organic carbon, and carbonate concentrations between 2018 and 2023 depending on data availability. Initial exploration of these variables revealed two distinct focal points i.e., the Togo-Nigerian coastal stretch and the stretch from Sierra Leone to Mauritania. Lower pH trends (acidification) in surface waters were observed off the West African coast, particularly in areas around the south-south Niger Delta in Nigeria and the coastal regions of Guinea and Guinea Bissau. Sea surface temperature analysis revealed highest temperatures (27–30°C) within Nigeria to Guinea coastal stretch, intermediate temperatures (24–27°C) within the Guinea Bissau and Senegal coastal stretch, and the lowest temperatures off the coast of Mauritania. Furthermore, correlation analysis between sea surface temperature and calcite concentration in the Mauritania-Senegal hotspot, as well as between overland runoff and particulate organic carbon in the Togo-Nigeria hotspot, revealed strong positive associations (r>0.60) and considerable predictive variability (R2 ≈ 0.40). From the habitat sensitivity analysis, certain regions, including Cape Verde, Côte d’Ivoire, Nigeria, Senegal, and Sierra Leone, exhibited high sensitivity due to environmental challenges and strong human dependence on coastal resources. Conversely, Gambia, Guinea, Guinea-Bissau, Liberia, and Togo displayed lower sensitivity, influenced by geographical-related factors (e.g. coastal layout, topography, etc.) and current levels of economic development (relatively lower industrialization levels). Regional pH variations in West African coastal waters have profound implications for ecosystems, fisheries, and communities. Addressing these challenges requires collaborative regional policies to safeguard shared marine resources. These findings underscore the link between ecosystem health, socioeconomics, and the need for integrated coastal management and ongoing research to support effective conservation.

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A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset (update)

Published 31 January 2024 Science Closed
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Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties with respect to understanding the ocean carbon cycle and its link to global change (ocean carbon sinks and sources, ocean acidification) and ultimately finding carbon-based solutions or mitigation procedures (marine carbon removal). We present a database of more than 44 400 AT and CT observations along with basic ancillary data (spatiotemporal location, depth, temperature and salinity) from various ocean regions obtained, mainly in the framework of French projects, since 1993. This includes both surface and water column data acquired in the open ocean, coastal zones and in the Mediterranean Sea and either from time series or dedicated one-off cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ±4 µmol kg−1 for both AT and CT. The data are provided in two separate datasets – for the Global Ocean and the Mediterranean Sea (https://doi.org/10.17882/95414, Metzl et al., 2023), respectively – that offer a direct use for regional or global purposes, e.g., AT–salinity relationships, long-term CT estimates, and constraint and validation of diagnostic CT and AT reconstructed fields or ocean carbon and coupled climate–carbon models simulations as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. When associated with other properties, these data can also be used to calculate pH, the fugacity of CO2 (fCO2) and other carbon system properties to derive ocean acidification rates or air–sea CO2 fluxes.

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Hydrographical studies in the nearshore seawaters of the Red Sea coast of Al-Hodeida city, Yemen

Published 30 January 2024 Science Closed
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Hydrographic studies of nearshore seawaters are important because they are sensitive to both natural and human influences. The hydrographic study is very important for nearshore waters because it is very sensitive to natural and human influences. In this research, an attempt was made to study the hydrographic properties of the nearshore waters of the Red Sea coast of Hodeida city, Yemen. During the period from December 2021 to June 2022, to represent the two seasons of winter and summer. The water temperatures ranged from 30 to 34.5 °C, salinity fluctuated from 39.3 to 42.4 psu, pH varied from 7.9 to 8.2 and dissolved oxygen ranged from 4.88 to 8.54 mg/l. The higher values of temperature and salinity were recorded during summer season. In contrast, an increase in pH and dissolved oxygen were observed during winter season. The present study confirmed that salinity has a negative correlation with pH and dissolved oxygen although it was not significant and also it showed significant positive correlation between pH and dissolved oxygen (0.828). The hydrographical parameters showed significant spatial and temporal variations. The present baseline information is useful for the further ecological monitoring and assessment along the coastal beaches.

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The interplay of freshwater inputs and catchment geology in regulating seawater chemistry in Irish coastal areas

Published 30 January 2024 Science Closed
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Highlights

  • Coastal carbonate chemistry depends on land-ocean interactions.
  • Multiple drivers should be considered: bedrock geology, freshwater inputs typology.
  • Human activities and SGD might affect coastal buffering capacity and TA:DIC ratio.
  • TA and DIC should be included in all coastal monitoring programs.

Abstract

Open ocean carbonate chemistry is altered by the dissolution of atmospheric CO2 in seawater. Up to 40% of anthropogenic CO2 emissions have dissolved in the surface ocean since the pre-industrial era, driving changes in marine carbonate pools and promoting ocean acidification. Under open ocean conditions, Total Alkalinity (TA) generally relates with salinity and temperature due to the conservative nature of its constituents. In coastal areas, however, land-ocean interactions may greatly contribute to making TA far less predictable, since freshwater inputs can affect the chemistry of coastal water masses by increasing TA and Dissolved Inorganic Carbon (DIC) or, alternatively, lowering them through dilution. Here we analysed and compared coastal carbonate chemistry dynamics in selected coastal areas of Ireland, in order to assess whether rivers and their catchment geology can influence coastal water chemistry and to verify the occurrence of local ocean acidification processes. Data on TA, DIC, salinity, temperature, and nutrients (total nitrogen, phosphate, and silicate) collected during several surveys along the Irish coastline by The Marine Institute Foras Na Mara (MIFNM) from 2009 to 2018 were analysed against those available on the main watercourses feeding the selected coastal areas. The relationships among the different variables were scrutinized, also considering the geological characteristics of river catchments. Results showed a clear linkage between coastal water chemistry and local freshwater inputs, whereas changes in the geology of catchment areas exerted only a secondary influence. An in-depth scrutiny of the Galway Bay sector performed by comparing MIFNM data with those collected during an oceanographic cruise carried out in October 2017 further indicated remarkable effects of the interaction between river inputs and submarine groundwater discharges on seasonal variations in the water chemistry of the area. Future studies, integrating chemical data across the land-ocean boundary, may provide additional, useful information on the factors actually affecting the variation in water carbonates in coastal areas. Elucidating how land-ocean interactions influence the coastal carbonate system may ultimately provide a key for a more advanced understanding of the resilience of coastal areas to ocean acidification.

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The annual update GLODAPv2.2023: the global interior ocean biogeochemical data product

Published 29 January 2024 Science Closed
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The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2023 is an update of the previous version, GLODAPv2.2022 (Lauvset et al., 2022). The major changes are as follows: data from 23 new cruises were added. In addition, a number of changes were made to data included in GLODAPv2.2022. GLODAPv2.2023 includes measurements from more than 1.4 million water samples from the global oceans collected on 1108 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, chlorofluorocarbon-11 (CFC-11), CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 23 new cruises were derived by comparing those data with the data from the 1085 quality-controlled cruises in the GLODAPv2.2022 data product using crossover analysis. SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO2) chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 μmol kg-1 in dissolved inorganic carbon, 4 μmol kg-1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments.

The original data, their documentation and DOI codes are available at the Ocean Carbon and Acidification Data System of NOAA NCEI, which also provides access to the merged data product. This is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/zyrq-ht66 (Lauvset et al., 2023). These bias-adjusted product files also include significant ancillary and approximated data, which were obtained by interpolation of, or calculation from, measured data. This living data update documents the GLODAPv2.2023 methods and provides a broad overview of the secondary quality control procedures and results.

Continue reading ‘The annual update GLODAPv2.2023: the global interior ocean biogeochemical data product’

Building unique collaborative global marine CO2 observatories

Published 25 January 2024 Science Closed
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The NOAA Pacific Marine Environmental Laboratory (PMEL) carbon program has made sustained investments over the last two decades in equipment development, autonomous sampling, and virtual support that undergird the global carbon observing infrastructure. As a result, the program plays an integral role in supporting ocean carbon research with collaborating institutions worldwide (Sutton and Sabine, 2023, in this issue).

Here, we discuss the field support and data product strategies we developed to build a successful moored autonomous air-sea CO2 and ocean acidification program that relies on moored buoys maintained by other collaborators. The most critical component of our program is partnering with other agencies, universities, and oceanographic institutions. Sharing resources and results allows scientists to collaborate on global climate issues at an international level. We provide instrument refurbishments, real-time (remote) troubleshooting, data handling and dissemination, and centralized coordination. Our partners provide ship and personnel-based resources for deployment/recovery of moorings as well as in-person troubleshooting. No one institution can provide all the physical support necessary for a global array of buoys, but many hands make light work when the effort is dispersed among multiple partnerships. To date, we have partnered with over 100 individuals from more than 20 US and global institutions (Figure 1) in support of nearly 50 autonomous air-sea CO2 and ocean acidification sites since 2003.

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Continue reading ‘Building unique collaborative global marine CO2 observatories’

Early stage ecological communities on artificial algae showed no difference in diversity and abundance under ocean acidification

Published 24 January 2024 Science Closed
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Marine habitat-forming species create structurally complex habitats that host macroinvertebrate communities characterized by remarkable abundance and species richness. These habitat-forming species also play a fundamental role in creating favourable environmental conditions that promote biodiversity. The deployment of artificial structures is becoming a common practice to help offset habitat loss although with mixed results. This study investigated the suitability of artificial flexible turfs mimicking the articulated coralline algae (mimics) as habitat providers and the effect of ocean acidification (OA) on early stage ecological communities associated to flexible mimics and with the mature community associated to Ellisolandia elongata natural turfs. The mimics proved to be a suitable habitat for early stage communities. During the OA mesocosms experiment, the two substrates have been treated and analysed separately due to the difference between the two communities. For early stage ecological communities associated with the mimics, the lack of a biologically active substrate does not exacerbate the effect of OA. In fact, no significant differences were found between treatments in crustaceans, molluscs and polychaetes diversity and abundance associated with the mimics. In mature communities associated with natural turfs, buffering capability of E. elongata is supporting different taxonomic groups, except for molluscs, greatly susceptible to OA.

Continue reading ‘Early stage ecological communities on artificial algae showed no difference in diversity and abundance under ocean acidification’

Local scale extreme low pH conditions and genetic differences shape phenotypic variation in a broad dispersal copepod species

Published 24 January 2024 Science Closed
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Extreme low pH events in estuaries and upwelling areas can modulate the phenotypic and genetic diversity of natural populations. To test this hypothesis, we explored the linkage between local scale extreme low pH events, genetic diversity, and variation in fecundity-related traits (body size, egg size, and egg production rate) in the broad-dispersal copepod Acartia tonsa. We assessed genetic and phenotypic characteristics of populations by contrasting extreme low pH environments (upwelling and temperate estuary) in the coastal Southeast Pacific, under natural and experimental conditions. These populations showed significant genetic differentiation with higher diversity in mitochondrial and nuclear loci (encoding mtCOI and 18S rRNA) in the estuarine population. Copepods from this population are exposed to more frequent extreme low pH events (< 7.7), and the adult females exhibit consistent phenotypic variation in body size, egg size, and egg production rate across different cohorts. Experimental acclimation to extreme low pH conditions revealed no significant differences in fecundity-related traits between A. tonsa populations. Although these results partially support our hypothesis, the experimental findings suggest other drivers might also influence phenotypic differences in the local environments.

Continue reading ‘Local scale extreme low pH conditions and genetic differences shape phenotypic variation in a broad dispersal copepod species’

The correlation between echinoderms diversity and physicochemical parameters in marine pollution: a case study of the Persian Gulf coastline

Published 24 January 2024 Science Closed
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This study was conducted with the aim of investigating the correlation between echinoderms diversity and physicochemical parameters in the Persian Gulf coastline in Bushehr province in 4 seasons from March to December 2017. The physicochemical parameters including water temperature, dissolved oxygen (DO), electrical conductivity (EC), salinity, pH and turbidity were measured at each sampling location. The results showed a significant correlation between echinoderms diversity and physicochemical parameters. The correlation coefficient of the Astropecten polyacanthus species with the parameters of temperature, DO, EC, salinity and turbidity was reported as -0.41, 0.64, -0.25, -0.44 and 0.60 respectively. This coefficient for the Ophiothrix fragilis species was reported as -0.68, 0.70, -0.21, -0.36 and -0.55 respectively. The results demonstrated that the most sensitive species were Astropecten polyacanthus and Ophiothrix fragilis respectively. The different species of echinoderms can be used as biological indicators of pollution in evaluating the physicochemical quality of marine environments.

Continue reading ‘The correlation between echinoderms diversity and physicochemical parameters in marine pollution: a case study of the Persian Gulf coastline’

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