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Assessing the magnitude of anthropogenic ocean warming and ocean acidification using the novel Li/Mg-SST and δ11B-pH proxies in the Caribbean coral Siderastrea siderea

Published 21 November 2017 Science Closed
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Coral reefs are highly sensitive ecosystems becoming increasingly damaged by anthropogenic climate change and pollution, particularly in the form of ocean warming, ocean acidification, and chronic sedimentation. In order for us to project how coral reefs will respond to future climate change, it is imperative to determine how they have responded to anthropogenic changes to date. This is a difficult task given that in situ observations of sea surface temperature (SST) and pH (-log10[H]+) are short and sparse prior to recent decades. However, coral skeletons are archives of historic climate and environmental conditions, storing over century-long records at sub-annual resolutions. These archives can be unlocked by calibrating geochemical proxies against modern in situ observations. For instance, the Sr/Ca ratios of tropical coral skeletons are traditionally used to reconstruct historic SST changes, yet the accuracy of this proxy is debated, leading to recent investigations into the Li/Mg-SST proxy which has produced promising results. However, by investigating this proxy for the first time in the Caribbean reef-building coral Siderastrea siderea, it has been found that the Li/Mg ratio of colonies from the forereef zone are three times more sensitive to changes in SST than their backreef coral counterparts. This resulted in accurate reconstructions of SST in the forereef, but unfeasible SSTs in the backreef, suggesting a secondary influence on both the Li/Mg- and Sr/Ca-SST proxies. A combined field and laboratory study confirmed that these ratios are also sensitive to pH change, but the full variability in Li/Mg and Sr/Ca is not described by pH and SST change combined.

Long-term records of seawater pH in Belize reconstructed from the boron isotopic composition (δ11B) of S. siderea showed that forereef corals, which have declining skeletal extension rates, have not been exposed to significant long-term ocean acidification. This contrasts with the ~0.15 pH unit decrease observed in the backreef since the 1920s, despite a lack of evidence of declining extension in this reef zone. Sub-annual δ11B records revealed that seasonal pH cycles in these two reef zones are controlled by two different parameters.

Chronic and increasing sedimentation in the forereef from terrestrial sources implies that nutrification in this region is stimulating macroalgae production, and thus buffering against ocean acidification.

Corals are therefore suitable archives of historic climate that can be used to reconstruct multiple environmental parameters such as sea surface temperature and pH. The structure and longevity of coral skeletons allows changes in these environmental parameters to be assessed at monthly to century-long scales. However, although it is possible to use geochemical proxies from coral, the full extent of additional influences on such proxies are not yet fully quantified and therefore may not be suitable to use in all coral reefs.

Continue reading ‘Assessing the magnitude of anthropogenic ocean warming and ocean acidification using the novel Li/Mg-SST and δ11B-pH proxies in the Caribbean coral Siderastrea siderea’

The future of oysters (audio)

Published 21 November 2017 Media coverage 1 Comment

Increasing levels of acidity in our oceans could have a serious impact on the oyster industry.

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Assessing the consequences of environmental impacts: variation in species responses has unpredictable functional effects

Published 21 November 2017 Science Closed
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Many biological processes underpin ecosystem functioning and health. Determining changes in these processes following disturbance is crucial in assessing the wider impacts on ecosystem function and ultimately ecosystem services. Whilst the focus is often on whether disturbance drives changes in ecosystem function through mortality, sub-lethal effects on the physiology and behaviour of organisms may also have cascading effects on ecosystem processes, functions and services. In this mesocosm study, we investigated the effects of a severe short-term exposure (8 d) to a simulated environmental impact—a leak of a subsea geological CO2 capture and storage reservoir—on key biological processes (bioturbation), an ecosystem function (nutrient cycling) and on the functional group composition for 7 common benthic invertebrate species. We statistically allocated species to functional effect groups based on their measured functional effect relative to other species. Following exposure, we observed behavioural responses driving changes in bioturbation for several species and altered nutrient cycling. Responses were species specific and resulted in shifts in functional effect group composition for some key nutrients (nitrate and silicate). We show that the allocation of species to functional groups by measuring specified ecosystem processes and functions can change following environmental perturbations. This implies that whilst biodiversity and ecosystem functioning are intricately linked, maintaining species identities and abundances after environmental perturbation is no guarantee to maintaining ecosystem functions, as species alter their rate and mode of activity following an environmental stress.

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State largely ignores role as seas grow more acidic

Published 21 November 2017 Media coverage 1 Comment

Despite a bipartisan recognition of a threat to Maine’s shellfish industry, leadership on the issue has fallen to a group of concerned volunteers.

At last week’s United Nations Climate Change Conference in Germany, an issue of vital importance to Maine fishermen and shellfish growers took the international spotlight: the increasing acidity of the sea, which is making it harder for some shellfish to grow their shells.

The governors of Washington state and Oregon joined the fisheries minister of Fiji, the meeting’s official host nation, to announce the expansion of a year-old international alliance to combat the problem. It now includes four states, two Canadian provinces and nine national governments.

Maine isn’t one of them, nor was anyone from Maine state government at the conference.

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Interactive effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on the fitness and breeding of the amphipod Gammarus locusta

Published 20 November 2017 Science Closed
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Highlights

  • Combined effects of temperature, pCO2 and levonorgestrel on G. locusta were assessed.
  • G. locusta was strongly negatively affected under warming exposure (+4 °C).
  • Growth rates were significantly affected by the interactions of LNG with temperature and pCO2.
  • A negative effect of higher temperature and acidification on G. locusta fecundity was observed, contrarily to LNG.
  • Increased temperature and pCO2 were clearly more adverse for G. locusta than exposure to LNG.

Abstract

Given the lack of knowledge regarding climate change-chemical exposure interactions, it is vital to evaluate how these two drivers jointly impact aquatic species. Thus, for the first time, we aimed at investigating the combined effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on survival, growth, consumption rate and reproduction of the amphipod Gammarus locusta. For that, a full factorial design manipulating temperature [ambient temperature and warming (+4 °C)], pCO2 [normocapnia and hypercapnia (Δ pH 0.5 units)] and the progestin levonorgestrel (LNG: L1 – 10 ngLL−1 and L2 – 1000 ngLL−1, control – no progestin and solvent control – vehicle ethanol (0.01%)) was implemented for 21 days. G. locusta was strongly negatively affected by warming, experiencing higher mortality rates (50–80%) than in any other treatments. Instead, growth rates were significantly affected by interactions of LNG with temperature and pCO2. It was observed, in the short-term (7d) that under ambient temperature (18 °C) and hypercapnic conditions (pH 7.6), the LNG presence promoted the amphipod’s growth, while in the medium-term (21d) this response was not observed. Relative consumption rates (RCRs), during the first week were higher than in the third week. Furthermore, in the first week, RCRs were negatively affected by higher temperature while in the third week, RCRs were negatively affected by acidification. Furthermore, it was observed a negative effect of higher temperature and acidification on G. locusta fecundity, contrarily to LNG. Concluding, the impact of increased temperature and pCO2 was clearly more adverse for the species than exposure to the synthetic progestin, however, some interactions between the progestin and the climate factors were observed. Thus, in a future scenario of global change, the presence of LNG (and other progestins alike) may modulate to a certain level the effects of climate drivers (and vice-versa) on the gammarids fitness and reproduction.

Continue reading ‘Interactive effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on the fitness and breeding of the amphipod Gammarus locusta’

Turning the tides: Santa Monica Bay ocean acidification project

Published 20 November 2017 Projects Closed

When picturing Santa Monica, what comes to mind first and foremost is the ocean – shops, the ferris wheel, the pier – but mostly the ocean. However, what doesn’t usually come to mind is the toll ocean acidification is taking on the marine life and biodiversity just off our shores. The ocean acts as a carbon sink, absorbing a quarter to a third of carbon dioxide emissions in the atmosphere. As humans continue to emit increasing amounts of carbon dioxide, more and more is absorbed into the ocean. Absorbing this carbon dioxide lowers the seawater’s pH and increases the ocean’s acidity. These seemingly slight changes to the chemistry of our oceans threaten to disrupt the delicate balance of ocean life, resulting in habitat destruction and marine life loss. Ocean acidification is a silent, destructive force and eye grabbing headlines about its impacts usually come too late. One of the most tragic examples of this is the death of large sections of Australia’s Great Barrier Reef, which is largely due to warming temperatures and increasing acidity. Unfortunately though, ocean acidification affects us here at home as well. We hope to gather data to curb acidification before it becomes too late.

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Ocean acidification: CO2 robs the Great Barrier Reef’s ability of self-recovery (video)

Published 20 November 2017 Media coverage Closed

Scientists in Australia are already seeing some of the immediate impacts from climate change on the world’s oceans, and especially on coral reefs. But they warn that the long term impacts are what may cause the greatest devastation. CGTN’s Greg Navarro has more.

Neal Cantin peers through the glass of a giant aquarium at the Australian Institute of Marine Science in Northeast Queensland, like the father of a newborn.

“This tank here has the parent generation.”

Next to the parent corals, are their offspring. And the research scientist is purposely putting them under stress.

“To see if we can enhance the tolerance of future generations of corals.”

Continue reading ‘Ocean acidification: CO2 robs the Great Barrier Reef’s ability of self-recovery (video)’

Ocean acidification impacts olfactory functions of salmon

Published 20 November 2017 Media coverage Closed

Washington Sea Grant studies how acidity of ocean affects ability of cohos to find their way home

Researchers at the University of Washington are observing in laboratory studies that ocean acidification affects a fundamental sensory function of coho salmon, which may impact their ability to feed, avoid danger and find their way home.

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Salmon industry wants to prepare for more acidic oceans

Published 20 November 2017 Media coverage Closed

Carbon emissions are making the oceans more acidic. That’s long been known to harm shellfish, but new research shows more acidic water could take a toll on salmon as well.

“We want to have a future on the water, but we need our fish out there to do it,” says Amy Grondin, a commercial salmon fisher who trolls for chinook and coho off the coasts of Washington and southeast Alaska. That’s why Grondin is partnering with researchers to learn more about what more acidic oceans could mean for those species. “Fishermen really do know a lot,” she explains. “We’re on the water 24/7 observing.”

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CARIOCA project – coral reef acclimatization to ocean acidification (video; in French and in English)

Published 17 November 2017 Projects Closed

In the framework of the project CARIOCA (Coral reef acclimatization to ocean acidification at CO2 seeps) funded by the French National Agency ANR, Riccardo Rodolfo-Metalpa and the team IRD Entropie investigated a new promising CO2 vents system located in Papua New Guinea.

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Das andere CO2-Problem (video; in German)

Published 17 November 2017 Media coverage Closed

Wissenschaftler beenden achtjähriges Projekt zur Ozeanversauerung: Zuviel Kohlendioxid lässt weltweit die Ozeane versauern. Meeres-Forscher des Netzwerkes BIOACID warnen vor den dramatischen Auswirkungen.

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The future of seaweed aquaculture in a rapidly changing world

Published 17 November 2017 Science Closed
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Human activities are having increasingly negative impacts on the natural environment. The rapidly expanding human population has led to a shortage of resources and the ability to support the growing population sustainably is a major challenge for the future. Coastal environments, including natural seaweed communities, provide a range of important ecosystem services. Since seaweed aquaculture beds (SABs) provide many of the services associated with natural seaweed communities they have a potential role in providing solutions such as CO2 sequestration, provision of food and the supply of useful chemicals. However, the productivity of natural seaweed communities and SABs is under threat from the rapid changes in climate that the planet is experiencing. Here we examine the likely effects of global change, in particular elevated CO2 and ocean acidification, increased temperatures and elevated levels of UVB, on the performance of seaweeds. While it is clear that rising temperatures and elevated CO2 and their interactions with other environmental factors are likely to have profound effects on macroalgal production, such effects are likely to be species dependent. We also examine the fate of organic matter from seaweeds and the potential for using SAB productivity as a contributor to blue carbon as a strategy for amelioration of increases in anthropogenic CO2 emissions. There is considerable potential for increased drawdown of CO2 by SABs, though its effectiveness in amelioration of atmospheric CO2 increase will depend on the fate of the resulting biomass.

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Effects of high pCO2 on early life development of pelagic spawning marine fish

Published 17 November 2017 Science Closed
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The present study investigated the effect of elevated pCO2 on the development of early stages of the pelagic spawning marine fish Solea senegalensis, Diplodus sargus and Argyrosomus regius. Eggs and larvae were reared under control (pH 8.0, ~570 μatm) and two elevated pCO2 conditions (pH 7.8, ~1100 μatm; pH 7.6, ~1900 μatm) until mouth opening (3 days post-hatching). Egg size did not change with exposure to elevated pCO2, but hatching rate was significantly reduced under high pCO2 for all three species. Survival rate was not affected by exposure to increased pCO2, but growth rate was differently affected across species, with A. regius growing faster in the mid-level pCO2 treatment compared with control conditions. S. senegalensis and A. regius hatched with smaller yolk sacs under increased pCO2 but endogenous reserves of D. sargus were not affected. Otoliths were consistently larger under elevated pCO2 conditions for all the three species. Differences among egg batches and a significant interaction between batch and pCO2 suggest that other factors, such as egg quality, can influence the response to increased pCO2. Overall, the results support the occurrence of a species-specific response to pCO2, but highlight the need for cautious analysis of potential sensitivity of species from unreplicated observations.

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Diversity and stability of coral endolithic microbial communities at a naturally high pCO2 reef

Published 17 November 2017 Science Closed
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The health and functioning of reef-building corals is dependent on a balanced association with prokaryotic and eukaryotic microbes. The coral skeleton harbours numerous endolithic microbes, but their diversity, ecological roles and responses to environmental stress, including ocean acidification (OA), are not well characterized. This study tests whether pH affects the diversity and structure of prokaryotic and eukaryotic algal communities associated with skeletons of Porites spp. using targeted amplicon (16S rRNA gene, UPA and tufA) sequencing. We found that the composition of endolithic communities in the massive coral Porites spp. inhabiting a naturally high pCO2 reef (avg. pCO2 811 μatm) is not significantly different from corals inhabiting reference sites (avg. pCO2 357 μatm), suggesting that these microbiomes are less disturbed by OA than previously thought. Possible explanations may be that the endolithic microhabitat is highly homeostatic or that the endolithic micro-organisms are well adapted to a wide pH range. Some of the microbial taxa identified include nitrogen-fixing bacteria (Rhizobiales and cyanobacteria), algicidal bacteria in the phylum Bacteroidetes, symbiotic bacteria in the family Endozoicomoniaceae, and endolithic green algae, considered the major microbial agent of reef bioerosion. Additionally, we test whether host species has an effect on the endolithic community structure. We show that the endolithic community of massive Porites spp. is substantially different and more diverse than that found in skeletons of the branching species Seriatopora hystrix and Pocillopora damicornis. This study reveals highly diverse and structured microbial communities in Porites spp. skeletons that are possibly resilient to OA.

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Aragonite saturation state in a tropical coastal embayment dominated by phytoplankton blooms (Guanabara Bay – Brazil)

Published 16 November 2017 Science Closed
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Highlights

  • The spatio-temporal variations of Ωarag were studied in a highly polluted coastal embayment.
  • High values of Ωarag were prevalent in surface waters dominated by phytoplankton blooms.
  • Lowest values of Ωarag were restricted to poorly buffered waters that receive direct effluent discharges.
  • Variations of Ωarag related to biological processes override those related to the atmospheric CO2.

Abstract

The dynamics of the aragonite saturation state (Ωarag) were investigated in the eutrophic coastal waters of Guanabara Bay (RJ-Brazil). Large phytoplankton blooms stimulated by a high nutrient enrichment promoted the production of organic matter with strong uptake of dissolved inorganic carbon (DIC) in surface waters, lowering the concentrations of dissolved carbon dioxide (CO2aq), and increasing the pH, Ωarag and carbonate ion (CO32 −), especially during summer. The increase of Ωarag related to biological activity was also evident comparing the negative relationship between the Ωarag and the apparent utilization of oxygen (AOU), with a very close behavior between the slopes of the linear regression and the Redfield ratio. The lowest values of Ωarag were found at low-buffered waters in regions that receive direct discharges from domestic effluents and polluted rivers, with episodic evidences of corrosive waters (Ωarag < 1). This study showed that the eutrophication controlled the variations of Ωarag in Guanabara Bay.

Continue reading ‘Aragonite saturation state in a tropical coastal embayment dominated by phytoplankton blooms (Guanabara Bay – Brazil)’

Study urges global-change researchers to embrace variability

Published 16 November 2017 Press releases Closed

Scientists typically make every effort to keep all factors but one constant when doing an experiment. Global-change scientists might move a coral from a reef to an aquarium whose water is held 1°C higher to test the effects of the ocean warming predicted for the end of the century. Or they might decrease the water’s pH by 0.4 units to study the effects of ocean acidification.

But a new review article presents evidence that argues for a more nuanced approach to the design of these experiments—one that acknowledges and purposefully incorporates the variability inherent in nature.

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The role of natural variability in shaping the response of coral reef organisms to climate change

Published 16 November 2017 Science Closed
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Purpose of Review

We investigate whether regimes of greater daily variability in temperature or pH result in greater tolerance to ocean warming and acidification in key reef-building taxa (corals, coralline algae).

Recent Findings

Temperature and pH histories will likely influence responses to future warming and acidification. Past exposure of corals to increased temperature variability generally leads to greater thermotolerance. However, the effects of past pH variability are unclear. Variability in pH or temperature will likely modify responses during exposure to stressors, independent of environmental history. In the laboratory, pH variability often limited the effects of ocean acidification, but the effects of temperature variability on responses to warming were equivocal.

Summary

Environmental variability could alter responses of coral reef organisms to climate change. Determining how both environmental history as well as the direct impacts of environmental variability will interact with the effects of anthropogenic climate change should now be high priority.

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Local habitat influences on feeding and respiration of the intertidal mussels Perumytilus purpuratus exposed to increased pCO2 levels

Published 16 November 2017 Science Closed
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Coastal ecosystems are exposed to changes in physical-chemical properties, such as those occurring in upwelling and freshwater-influenced areas. In these areas, inorganic carbon can influence seawater properties that may affect organisms and populations inhabiting benthic habitats such as the intertidal mussel Perumytilus purpuratus. Feeding and metabolic responses were measured in adult mussels from two geographic regions (central and southern Chile) and two local habitats (river-influenced and non-river-influenced) and three pCO2 levels (380, 750, and 1200 μatm pCO2 in seawater). The feeding rates of mussels tend to increase at high pCO2 levels in seawater; however this response was variable across regions and local habitats. In contrast, there was no difference in the respiratory rate of mussels between geographic areas, but there was a significant reduction of oxygen consumption at intermediate and high levels of pCO2. The results indicate that river-influenced organisms compensate for reductions in metabolic cost at elevated pCO2 levels by having their energy demands met, in contrast with non-river-influenced organisms. The lack of regional-scale variability in the physiological performance of mussels may indicate physiological homogeneity across populations and thus potential for local adaptation. However, the local-scale influences of river- and non-river-influenced habitats may counterbalance this regional response promoting intra-population variability and phenotypic plasticity in P. purpuratus. The plasticity may be an important mechanism that allows mussels to confront the challenges of projected ocean acidification scenarios.

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Multidecadal fCO2 increase along the United States southeast coastal margin

Published 16 November 2017 Science Closed
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Coastal margins could be hotspots for acidification due to terrestrial-influenced CO2 sources. Currently there are no long-term (>20 years) records from biologically important coastal environments that could demonstrate sea surface CO2 fugacity (fCO2) and pH trends. Here, multi-decadal fCO2 trends are calculated from underway and moored time series observations along the United States southeast coastal margin, also referred to as the South Atlantic Bight (SAB). fCO2 trends across the SAB, derived from ∼26 years of cruises and ∼9.5 years from a moored time series, range from 3.0 to 4.5 µatm y−1, and are greater than the open ocean increases. The pH decline related to the fCO2 increases could be as much as -0.004 y−1; a rate greater than that expected from atmospheric-influenced pH alone. We provide evidence that fCO2 increases and pH decreases on an ocean margin can be faster than those predicted for the open ocean from atmospheric influence alone. We conclude that a substantial fCO2 increase across the marginal SAB is due to both increasing temperature on the middle and outer shelves, but to lateral land-ocean interactions in the coastal zone and on inner shelf.

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Associate Research Scientist, GOA-ON support – IAEA Environment Laboratories (NAEL), Monaco

Published 15 November 2017 Jobs Closed

Closing date: 3 December 2017. Position open for US citizens.

Note: This position is part of an IOC-UNESCO/IAEA- collaboration to support GOA-ON.

Organizational Setting

The Department of Nuclear Sciences and Applications implements the IAEA’s Major Programme 2, “Nuclear Techniques for Development and Environmental Protection”. This Major Programme comprises individual programmes on food and agriculture, human health, water resources, environment and radiation technologies. These programmes are supported by laboratories in Seibersdorf, Monaco and Vienna. The Major Programme’s objective is to enhance the capacity of Member States to meet basic human needs and to assess and manage the marine and terrestrial environments through the use of nuclear and isotopic techniques in sustainable development programmes. The IAEA Environment Laboratories consists of four laboratories, three of which are located in Monaco and one in Seibersdorf. The Division implements the IAEA Environment Programme and operates in a complex matrix environment with inputs from many parts of the organization, such as the Department of Technical Cooperation for the implementation of projects, and collaborates with other Departments.

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