Sustainable oceans series: using data to save our oceans

World Ocean Day, celebrated every year on 8 June, is an opportunity to reflect on the importance of oceans to our lives and livelihoods, and the environmental impact of human activity on oceans.

The University of Bergen (Norway), United Nations Academic Impact (UNAI) SDG Hub for Goal 14: Life below water, is a center of scholarship, research and innovation for the preservation of oceans for the future of mankind.

In this series commemorating World Oceans Day, the University of Bergen explores various aspects of sustainable oceans and how universities can contribute to the stewardship of this natural resource. In this article, the university explores the use of data management to combat ocean acidification.

Continue reading ‘Sustainable oceans series: using data to save our oceans’

Ocean acidification threatens bivalve industry

Worldwide, ocean levels are rising at an accelerated pace. Cape May County is feeling the effects of exacerbated weather events, as a result.

Yet, there is another drastic change affecting the oceans – a decrease in the water’s pH levels. This is a change that industry leaders and scientists fear will drastically affect the county, namely its bivalve (aquatic invertebrates with a hinged shell) industry that is, as marine and coastal sustainability expert Dr. Daphne Munroe said, “At the heart of the economy in this region.”

As carbon is released into the atmosphere, it was once speculated that the ocean’s tendency to absorb emissions would be a net positive, as it spared the Earth’s atmosphere from the worst of the emissions. Dr. Feely, senior scientist at National Oceanic and Atmospheric Administration (NOAA), said, “[It’s] a huge service the oceans are doing that significantly reduces global temperature.”

Continue reading ‘Ocean acidification threatens bivalve industry’

Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections

Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation, reductions in near-surface nutrients, and changes to primary production, all of which are expected to affect marine ecosystems. Here we assess projections of these drivers of environmental change over the twenty-first century from Earth system models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) that were forced under the CMIP6 Shared Socioeconomic Pathways (SSPs). Projections are compared to those from the previous generation (CMIP5) forced under the Representative Concentration Pathways (RCPs). A total of 10 CMIP5 and 13 CMIP6 models are used in the two multi-model ensembles. Under the high-emission scenario SSP5-8.5, the multi-model global mean change (2080–2099 mean values relative to 1870–1899) ± the inter-model SD in sea surface temperature, surface pH, subsurface (100–600 m) oxygen concentration, euphotic (0–100 m) nitrate concentration, and depth-integrated primary production is +3.47±0.78 ∘C, −0.44±0.005, −13.27±5.28, −1.06±0.45 mmol m−3 and −2.99±9.11 %, respectively. Under the low-emission, high-mitigation scenario SSP1-2.6, the corresponding global changes are +1.42±0.32 ∘C, −0.16±0.002, −6.36±2.92, −0.52±0.23 mmol m−3, and −0.56±4.12 %. Projected exposure of the marine ecosystem to these drivers of ocean change depends largely on the extent of future emissions, consistent with previous studies. The ESMs in CMIP6 generally project greater warming, acidification, deoxygenation, and nitrate reductions but lesser primary production declines than those from CMIP5 under comparable radiative forcing. The increased projected ocean warming results from a general increase in the climate sensitivity of CMIP6 models relative to those of CMIP5. This enhanced warming increases upper-ocean stratification in CMIP6 projections, which contributes to greater reductions in upper-ocean nitrate and subsurface oxygen ventilation. The greater surface acidification in CMIP6 is primarily a consequence of the SSPs having higher associated atmospheric CO2 concentrations than their RCP analogues for the same radiative forcing. We find no consistent reduction in inter-model uncertainties, and even an increase in net primary production inter-model uncertainties in CMIP6, as compared to CMIP5.

Continue reading ‘Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections’

Video: What is the global community doing to address ocean acidification?

Continue reading ‘Video: What is the global community doing to address ocean acidification?’

Gene expression patterns of Red Sea urchins (Mesocentrotus Franciscanus) exposed to different combinations of temperature and pCO2 during early development

Red sea urchins were collected and spawned as described in [31]. Briefly, adults were collected from Ellwood Mesa, Goleta, California, USA (34° 25.065’N, 119° 54.092’W) at 14-m depth via SCUBA on February 21, 2018 under California Scientific Collecting Permit SC-1223 and transported to the Marine Science Institute at the University of California Santa Barbara (UCSB). Spawning was induced by injecting 0.53 M KCl into the coelom through the perioral membrane [145]. Eggs from five individual females and sperm from a single male were collected. A subsample of eggs from each female was fertilized with sperm from the male and high fertilization success was examined for each cross (i.e., visually confirming the formation of fertilization envelopes). These subsamples were only used to verify suitable male-female compatibility and were discarded prior to the experiment. An approximately equal number of eggs from each of the five females were gently pooled together. The pool of eggs was fertilized by slowly adding dilute, activated sperm from the male until approximately 98% fertilization success was reached. Performing crosses with a single male ensured that all cultures were composed of full- or half-sibling embryos. This approach was selected in an effort to limit paternal genetic variability and differences in male-female interactions that could otherwise impact the results of the study.

Continue reading ‘Gene expression patterns of Red Sea urchins (Mesocentrotus Franciscanus) exposed to different combinations of temperature and pCO2 during early development’

Responses of a coral reef shark acutely exposed to ocean acidification conditions

Anthropogenic ocean acidification (OA) is a threat to coral reef fishes, but few studies have investigated responses of high-trophic-level predators, including sharks. We tested the effects of 72-hr exposure to OA-relevant elevated partial pressures of carbon dioxide (pCO2) on oxygen uptake rates, acid–base status, and haematology of newborn tropical blacktip reef sharks (Carcharhinus melanopterus). Acute exposure to end-of-century pCO2 levels resulted in elevated haematocrit (i.e. stress or compensation of oxygen uptake rates) and blood lactate concentrations (i.e. prolonged recovery) in the newborns. Conversely, whole blood and mean corpuscular haemoglobin concentrations, blood pH, estimates of standard and maximum metabolic rates, and aerobic scope remained unaffected. Taken together, newborn blacktip reef sharks appear physiologically robust to end-of-century pCO2 levels, but less so than other, previously investigated, tropical carpet sharks. Our results suggest peak fluctuating pCO2 levels in coral reef lagoons could still physiologically affect newborn reef sharks, but studies assessing the effects of long-term exposure and in combination with other anthropogenic stressors are needed.

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Call for manuscripts: Special issue “Effects of ocean acidification on marine ecosystems”

Deadline for manuscript submissions: 15 October 2020

Special Issue information: The expected impact of climate change on ecosystems and the service they provide to human populations is one of the most urgent research topics of our times. Among the various consequences of global climate change, ocean acidification is one subtle effect that is raising serious concerns in the scientific community due to the expected impacts on calcifying organisms, the biomineralized structures they produce, and associated communities. In recent decades, research on ocean acidification impacts has provided support for these concerns, as several negative impacts of this process have been observed in a variety of taxa in aquarium, mesocosm, and natural laboratory studies (e.g., carbon dioxide volcanic vents).

This Special Issue provides a framework to highlight new research contributing to our understanding of the impact of ocean acidification at all latitudes (polar to tropical), on all ecosystems, and through all scientific approaches (from observations in the field to laboratory-controlled experiments). Even if the session does not preclude other topics, studies focusing on the process of biomineralization and on the alteration of ecosystem services provided by systems impacted by ocean acidification are encouraged.

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Biogenic carbonate dissolution in shallow marine environments

Ocean acidification (OA), the decrease in surface ocean pH and seawater saturation state with respect to carbonate minerals (Ω), is expected to increase carbonate mineral dissolution. However, the influence of OA on carbonate dissolution has been largely neglected despite evidence that it is more sensitive to OA than calcification. Increases in the rate of carbonate dissolution could have severe impacts for ecosystems such as coral reefs, which rely on the accumulation of carbonate structures and substrates to exist. At present, dissolution rates of bulk shallow biogenic carbonate sediments are largely unknown and laboratory dissolution rates exceed in situ rates by orders of magnitude. The goal of this study was to develop a better understanding of the drivers and controls of bulk carbonate sediment dissolution in coral reef environments. Based on results from in situ benthic chambers and laboratory free-drift experiments of bulk biogenic carbonate sediments from global locations, dissolution rates were found to be primarily controlled by organic matter decomposition, but significantly influenced by the overlying seawater carbonate chemistry and the solubility of the most soluble mineral phase in the sediments. Shallow carbonate dissolution will therefore be enhanced via ocean acidification, increased respiration, or a combination of these processes. The sensitivity of bulk sediment dissolution rates to changes in Ω was not related to median grain size or mineralogy, but may be attributed to organic coatings on sediment grains. Dissolution rates in bulk sediments increased ~2-3-fold when these coatings were removed, suggesting that they act as a protective barrier that limits direct interaction of seawater with the mineral surface, thus inhibiting dissolution. On the ecosystem scale, carbonate dissolution was inferred from calcium anomalies measured using a novel spectrophotometric titration system and confirms seasonal and inter-annual trends in reef biogeochemical processes based on parallel alkalinity measurements. However, calcium measurements may be best employed in environments where multiple processes significantly influence alkalinity or Mg-calcites are precipitating and dissolving. Although many questions remain, this work has elucidated certain key drivers and controls of shallow carbonate sediment dissolution and how they may respond to a rapidly changing ocean.

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Forecasting ocean acidification impacts on kelp forest ecosystems

Ocean acidification is one the biggest threats to marine ecosystems worldwide, but its ecosystem wide responses are still poorly understood. This study integrates field and experimental data into a mass balance food web model of a temperate coastal ecosystem to determine the impacts of specific OA forcing mechanisms as well as how they interact with one another. Specifically, we forced a food web model of a kelp forest ecosystem near its southern distribution limit in the California large marine ecosystem to a 0.5 pH drop over the course of 50 years. This study utilizes a modeling approach to determine the impacts of specific OA forcing mechanisms as well as how they interact. Isolating OA impacts on growth (Production), mortality (Other Mortality), and predation interactions (Vulnerability) or combining all three mechanisms together leads to a variety of ecosystem responses, with some taxa increasing in abundance and other decreasing. Results suggest that carbonate mineralizing groups such as coralline algae, abalone, snails, and lobsters display the largest decreases in biomass while macroalgae, urchins, and some larger fish species display the largest increases. Low trophic level groups such as giant kelp and brown algae increase in biomass by 16% and 71%, respectively. Due to the diverse way in which OA stress manifests at both individual and population levels, ecosystem-level effects can vary and display nonlinear patterns. Combined OA forcing leads to initial increases in ecosystem and commercial biomasses followed by a decrease in commercial biomass below initial values over time, while ecosystem biomass remains high. Both biodiversity and average trophic level decrease over time. These projections indicate that the kelp forest community would maintain high productivity with a 0.5 drop in pH, but with a substantially different community structure characterized by lower biodiversity and relatively greater dominance by lower trophic level organisms.

Continue reading ‘Forecasting ocean acidification impacts on kelp forest ecosystems’

Plastic response of the oyster Ostrea chilensis to temperature and pCO2 within the present natural range of variability

Estuaries are characterized by high fluctuation of their environmental conditions. Environmental parameters measured show that the seawater properties of the Quempillén estuary (i.e. temperature, salinity, pCO2, pH and ΩCaCO3) were highly fluctuating and related with season and tide. We test the effects of increasing temperature and pCO2 in the seawater on the physiological energetics of the bivalve Ostrea chilensis. Juvenile oysters were exposed to an orthogonal combination of three temperatures (10, 15, and 20°C) and two pCO2 levels (~400 and ~1000 μatm) for a period of 60 days to evaluate the temporal effect (i.e. 10, 20, 30, 60 days) on the physiological rates of the oysters. Results indicated a significant effect of temperature and time of exposure on the clearance rate, while pCO2 and the interaction between pCO2 and the other factors studied did not show significant effects. Significant effects of temperature and time of exposure were also observed on the absorption rate, but not the pCO2 nor its interaction with other factors studied. Oxygen consumption was significantly affected by pCO2, temperature and time. Scope for growth was only significantly affected by time; despite this, the highest values were observed for individuals subject to to 20°C and to ~1000 μatm pCO2. In this study, Ostrea chilensis showed high phenotypic plasticity to respond to the high levels of temperature and pCO2 experienced in its habitat as no negative physiological effects were observed. Thus, the highly variable conditions of this organism’s environment could select for individuals that are more resistant to future scenarios of climate change, mainly to warming and acidification.

Continue reading ‘Plastic response of the oyster Ostrea chilensis to temperature and pCO2 within the present natural range of variability’

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Ocean acidification in the IPCC AR5 WG II

OUP book