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Smoke and acid: where wildfires meet the ocean

Published 18 September 2020 Web sites and blogs Closed
Buildings in West Vancouver are obscured by heavy smoke on Sept. 14 as wildfires burn across the U.S. border. Photo: The Canadian Press / Jonathan Hayward

As forest fires burn uncontrollably south of the U.S. border, the smokey skies over B.C. hint at the suffocating life in an ocean growing increasingly acidic

By Fiona Beaty, PhD candidate at the University of British Columbia studying the impacts of ocean warming and acidification on B.C.’s coastal ecosystems and communities

Yesterday I realized what it might feel like to live in an acidifying ocean. After waking up to red hazy light filtering through my blinds, I prepared to take my daily coffee walk — one of my COVID-19 rituals to break up the monotony of working from home in my small bedroom. Upon stepping outside, my first inhalation brought acrid smoke and ash from 4.7 million acres of land burning in another country into my lungs.

The air we breathe in Vancouver right now is unhealthy. It is filled with toxins that compromise our respiratory systems. It brings sadness and fatigue into our minds and bodies, and most importantly, it does not affect us equally. Portions of our population — the elderly, the young and the immunocompromised — are at a significantly higher risk of acute health impacts caused by the smoke, which further increases their vulnerability to COVID-19.

This experience is exactly what is happening to our ocean and the millions of sea creatures who are trying to breathe, grow and survive in increasingly corrosive and acidic seawater

Continue reading ‘Smoke and acid: where wildfires meet the ocean’

Two Texas students begin NOAA Ocean Acidification Graduate Research Fellowship

Published 18 September 2020 Web sites and blogs Closed

The fellowship program was created to develop ocean acidification researchers in the Gulf of Mexico, a region expected to experience increased ocean acidification in the future.

Larissa Dias and Richard Rosas, both nominated by Texas Sea Grant, are beginning their Ocean Acidification Graduate Research Fellowships, a joint effort between Texas Sea Grant, Louisiana Sea Grant, and the NOAA Ocean Acidification Program (OAP). They are among five students selected for the fellowship, which began in Sept. 2020.

The fellowship program was created to develop ocean acidification researchers in the Gulf of Mexico, a region expected to experience increased ocean acidification in the future. Fellows will address issues relevant to coastal ecosystems and communities related to ocean, coastal and estuarine acidification. The goal is to improve the understanding of the potential ecological consequences of increasing carbon dioxide concentration, which causes ocean acidification, in regional ocean, coastal and estuarine waters.

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pH variability off Goa (eastern Arabian Sea) and the response of sea urchin to ocean acidification scenarios

Published 18 September 2020 Science Closed
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The increasing atmospheric CO2 concentration in the last few decades has resulted in a decrease in oceanic pH. In this study, we assessed the natural variability of pH in coastal waters off Goa, eastern Arabian Sea. pHT showed large variability (7.6–8.1) with low pH conditions during south‐west monsoon (SWM), and the variability is found to be associated with upwelling rather than freshwater runoff. Considering that marine biota inhabiting dynamic coastal waters off Goa are exposed to such wide range of natural fluctuations of pH, an acidification experiment was carried out. We studied the impact of low pH on the local population of sea urchin Stomopneustes variolaris (Lamarck, 1816). Sea urchins were exposed for 210 days to three treatments of pHT: 7.96, 7.76 and 7.46. Our results showed that S. variolaris at pHT 7.96 and 7.76 were not affected, whereas the ones at pHT 7.46 showed adverse effects after 120 days and 50% mortality by 210 days. However, even after exposure to low pH for 210 days, 50% organisms survived. Under low pH conditions (pHT 7.46), the elemental composition of sea urchin spines exhibited deposition of excess Sr2+ as compared to Mg2+ ions. We conclude that although the sea urchins would be affected in future high CO2 waters, at present they are not at risk even during the south‐west monsoon when low pH waters reside on the shelf.

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A sea of change is coming

Published 18 September 2020 Web sites and blogs Closed
Dr. Tessa Hill (left) with colleagues in Tomales Bay, CA (Credit: A. Ninokawa)

Professor partners with community to better understand our oceans

A team of UC Davis faculty and students, community partners, local businesses, and policy makers are working together to turn the tide on a problematic change facing our waters — ocean acidification. Ocean acidification is the change in the pH of water due to the absorption of carbon dioxide, and it’s posing a significant problem for ocean animals and ecosystems.

“The ocean is a tremendous sponge for carbon dioxide. It actually soaks it up,” said UC Davis marine geochemist and oceanographer Tessa Hill. “About 30 percent of what we put in the atmosphere goes straight into the ocean.”

According to Hill, if you look at the earth’s geological records, ocean acidification is rising at an unprecedented rate. She and her colleagues at the Ocean Climate Lab @ UC Davis and the UC Davis Bodega Marine Laboratory are focused on answering broad questions about how climate change is impacting marine ecosystems.
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Job opportunity: OA-ICC Associate Project Officer

Published 17 September 2020 Jobs Closed

Organization: NAEL-Radioecology Laboratory

Primary Location: Monaco-IAEA Environment Laboratories in Monaco

Application Deadline: 14 October 2020

Main Purpose: As a member of a team reporting to the Laboratory Head and Project Manager of the Peaceful Uses Initiative (PUI) project “Ocean Acidification International Coordination Center (OA-ICC)”, the Associate Project Officer (Radioecology Laboratory) provides assistance in project management, reporting and analytical support within the different working areas, with the objective of effective, efficient, and timely implementation of the project.

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Acclimatization drives differences in reef-building coral calcification rates

Published 17 September 2020 Science Closed
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Coral reefs are susceptible to climate change, anthropogenic influence, and environmental stressors. However, corals in Kāneʻohe Bay, Hawaiʻi have repeatedly shown resilience and acclimatization to anthropogenically-induced rising temperatures and increased frequencies of bleaching events. Variations in coral and algae cover at two sites—just 600 m apart—at Malaukaʻa fringing reef suggest genetic or environmental differences in coral resilience between sites. A reciprocal transplant experiment was conducted to determine if calcification (linear extension and dry skeletal weight) for dominant reef-building species, Montipora capitata and Porites compressa, varied between the two sites and whether or not parent colony or environmental factors were responsible for the differences. Despite the two sites representing distinct environmental conditions with significant differences between temperature, salinity, and aragonite saturation, M. capitata growth rates remained the same between sites and treatments. However, dry skeletal weight increases in P. compressa were significantly different between sites, but not across treatments, with linear mixed effects model results suggesting heterogeneity driven by environmental differences between sites and the parent colonies. These results provide evidence of resilience and acclimatization for M. capitata and P. compressa. Variability of resilience may be driven by local adaptations at a small, reef-level scale for P. compressa in Kāneʻohe Bay.

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Incorporation of minor and trace elements into cultured brachiopods: implications for proxy application with new insights from a biomineralisation model

Published 17 September 2020 Science Closed
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Brachiopods present a key fossil group for Phanerozoic palaeo-environmental and palaeo-oceanographical reconstructions, owing to their good preservation and abundance in the geological record. Yet to date, hardly any geochemical proxies have been calibrated in cultured brachiopods and only little is known on the mechanisms that control the incorporation of various key elements into brachiopod calcite. To evaluate the feasibility and robustness of multiple Element/Ca ratios as proxies in brachiopods, specifically Li/Ca, B/Ca, Na/Ca, Mg/Ca, Sr/Ca, Ba/Ca, as well as Li/Mg, we cultured Magellania venosa, Terebratella dorsata and Pajaudina atlantica under controlled experimental settings over a period of more than two years with closely monitored ambient conditions, carbonate system parameters and elemental composition of the culture medium. The experimental setup comprised of two control aquariums (pH0 = 8.0 and 8.15, T = 10 °C) and treatments where pCO2 − pH (pH1 = 7.6 and pH2 = 7.35), temperature (T = 16 °C) and chemical composition of the culture medium were manipulated. Our results indicate that the incorporation of Li and Mg is strongly influenced by temperature, growth effects as well as carbonate chemistry, complicating the use of Li/Ca, Mg/Ca and Li/Mg ratios as straightforward reliable proxies. Boron partitioning varied greatly between the treatments, however without a clear link to carbonate system parameters or other environmental factors. The partitioning of both Ba and Na varied between individuals, but was not systematically affected by changes in the ambient conditions. We highlight Sr as a potential proxy for DIC, based on a positive trend between Sr partitioning and carbonate chemistry in the culture medium. To explain the observed dependency and provide a quantitative framework for exploring elemental variations, we devise the first biomineralisation model for brachiopods, which results in a close agreement between modelled and measured Sr distribution coefficients. We propose that in order to sustain shell growth under increased DIC, a decreased influx of Ca2+ to the calcifying fluid is necessary, driving the preferential substitution of Sr2+ for Ca2+ in the crystal lattice. Finally, we conducted micro-computed tomography analyses of the shells grown in the different experimental treatments. We present pore space – punctae – content quantification that indicates that shells built under increased environmental stress, and in particular elevated temperature, contain relatively more pore space than calcite, suggesting this parameter as a potential novel proxy for physiological stress and even environmental conditions.

Continue reading ‘Incorporation of minor and trace elements into cultured brachiopods: implications for proxy application with new insights from a biomineralisation model’

Effects of temperature and food concentration on pteropod metabolism along the Western Antarctic Peninsula

Published 17 September 2020 Science Closed
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Highlights

  • Measured respiration and excretion of the Antarctic pteropod Limacina.
  • Analyzed effects of future temperature and food conditions on pteropod metabolism.
  • Highest metabolism occurred under higher temperatures with less response to food.
  • Metabolic ratios of C, N, and P were all below the canonical Redfield ratio.
  • Pteropod metabolism responsive to ocean change, affecting biogeochemical cycles.

Abstract

Pteropods (pelagic snails) are abundant zooplankton in the Southern Ocean where they are important grazers of phytoplankton, prey for higher trophic levels, and sensitive to environmental change. The Western Antarctic Peninsula (WAP) is a highly dynamic and productive region that has undergone rapid warming, but little is known about how environmental changes there will affect pteropod physiology. In this study, the effects of warming seawater temperatures and shifting food availability on Limacina helicina antarctica metabolism (respiration and excretion) were determined by conducting shipboard experiments that exposed pteropods to a range of temperatures and phytoplankton (food) concentrations. Highest respiration (up to 69 μmol O2 gDW−1 h−1) and usually highest excretion rates occurred under higher temperature with more limited metabolic response to food concentration, indicating these factors do not always have an additive effect on pteropod metabolism. The proportion of dissolved organic matter (DOM) to total organic and inorganic dissolved constituents was high and was also significantly affected by shifts in temperature and food. Dissolved organic carbon, nitrogen, and phosphorus (DOC, DON, and DOP) were on average 27, 51, and 11.5% of the total C, N, and P metabolized, respectively. The proportion of total N excreted as DON and the proportion of total P excreted as DOP were significantly affected by a combination of shifting temperature and food concentrations. There were no effects of temperature or food on DOC excretion (mean 8.79 μmol C gDW−1 h−1; range 0.44 to 44) as a proportion of total C metabolized. Metabolic O2:N ratio ranged from 2 to 9 and decreased significantly with increasing temperature and food, indicating a shift toward increased protein catabolism. Metabolic ratios of C, N, and P were all below the canonical Redfield ratio, which has implications for phytoplankton nutrient uptake and bacterial production. Respiration rates at ambient conditions of other WAP pteropods, and excretion rates for Clio pyramidata, were also measured, with respiration rates ranging from 24.39 (Spongiobranchaea australis) to 28.86 (L. h. antarctica) μmol O2 gDW−1 h−1. Finally, a CO2 perturbation experiment measuring L. h. antarctica metabolism under pre-industrial and elevated dissolved pCO2 conditions showed no significant change in mean L. h. antarctica respiration or excretion rates with higher pCO2. These insights into the metabolic response of pteropods to ocean variability increase our understanding of the role of zooplankton in biogeochemical cycles and help predict future responses to climate change.

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A regional neural network approach to estimate water-column nutrient concentrations and carbonate system variables in the Mediterranean Sea: CANYON-MED

Published 16 September 2020 Science Closed
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A regional neural network-based method, “CANYON-MED” is developed to estimate nutrients and carbonate system variables specifically in the Mediterranean Sea over the water column from pressure, temperature, salinity, and oxygen together with geolocation and date of sampling. Six neural network ensembles were developed, one for each variable (i.e., three macronutrients: nitrates (NO−33-), phosphates (PO3−443-) and silicates (SiOH4), and three carbonate system variables: pH on the total scale (pHT), total alkalinity (AT), and dissolved inorganic carbon or total carbon (CT), trained using a specific quality-controlled dataset of reference “bottle” data in the Mediterranean Sea. This dataset is representative of the peculiar conditions of this semi-enclosed sea, as opposed to the global ocean. For each variable, the neural networks were trained on 80% of the data chosen randomly and validated using the remaining 20%. CANYON-MED retrieved the variables with good accuracies (Root Mean Squared Error): 0.73 μmol.kg–1 for NO−33-, 0.045 μmol.kg–1 for PO3−443- and 0.70 μmol.kg–1 for Si(OH)4, 0.016 units for pHT, 11 μmol.kg–1 for AT and 10 μmol.kg–1 for CT. A second validation on the ANTARES independent time series confirmed the method’s applicability in the Mediterranean Sea. After comparison to other existing methods to estimate nutrients and carbonate system variables, CANYON-MED stood out as the most robust, using the aforementioned inputs. The application of CANYON-MED on the Mediterranean Sea data from autonomous observing systems (integrated network of Biogeochemical-Argo floats, Eulerian moorings and ocean gliders measuring hydrological properties together with oxygen concentration) could have a wide range of applications. These include data quality control or filling gaps in time series, as well as biogeochemical data assimilation and/or the initialization and validation of regional biogeochemical models still lacking crucial reference data. Matlab and R code are available at https:// github.com/MarineFou/CANYON-MED/.

Continue reading ‘A regional neural network approach to estimate water-column nutrient concentrations and carbonate system variables in the Mediterranean Sea: CANYON-MED’

Physiological resilience of pink salmon to naturally occurring ocean acidification

Published 16 September 2020 Science Closed
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Pacific salmon stocks are in decline with climate change named as a contributing factor. The North Pacific coast of British Columbia is characterized by strong temporal and spatial heterogeneity in ocean conditions with upwelling events elevating CO2 levels up to 10-fold those of pre-industrial global averages. Early life stages of pink salmon have been shown to be affected by these CO2 levels, and juveniles naturally migrate through regions of high CO2 during the energetically costly phase of smoltification. To investigate the physiological response of out-migrating wild juvenile pink salmon to these naturally occurring elevated CO2 levels, we captured fish in Georgia Strait, British Columbia and transported them to a marine lab (Hakai Institute, Quadra Island) where fish were exposed to one of three CO2 levels (850, 1500 and 2000 μatm CO2) for 2 weeks. At ½, 1 and 2 weeks of exposure, we measured their weight and length to calculate condition factor (Fulton’s K), as well as haematocrit and plasma [Cl−]. At each of these times, two additional stressors were imposed (hypoxia and temperature) to provide further insight into their physiological condition. Juvenile pink salmon were largely robust to elevated CO2 concentrations up to 2000 μatm CO2, with no mortality or change in condition factor over the 2-week exposure duration. After 1 week of exposure, temperature and hypoxia tolerance were significantly reduced in high CO2, an effect that did not persist to 2 weeks of exposure. Haematocrit was increased by 20% after 2 weeks in the CO2 treatments relative to the initial measurements, while plasma [Cl−] was not significantly different. Taken together, these data indicate that juvenile pink salmon are quite resilient to naturally occurring high CO2 levels during their ocean outmigration.

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New edition of the “Ocean Acidification Report” by Global Ocean Health

Published 16 September 2020 Newsletters and reports Closed

The “Ocean Acidification Report” is a timely compilation of news from the front lines of ocean acidification research, legislation, resources, and profiles from the waterfront.

The September 2020 edition covers topic such as Climate Change Effects on Aquaculture, Changes in Fish Communities under OA, 10-year OA Roadmap Released, Coral Reefs, Carbon Myths & Realities and more.

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Reversing ocean acidification is doable, if we have the political will | Opinion

Published 15 September 2020 Web sites and blogs Closed

A new study has found that ocean acidification is damaging the shells of young Dungeness crab off the Oregon coast. TNS

Ocean acidification, one of many devastating effects of the warming earth, has been well-documented. It’s no longer up for debate. We now know that this process is adversely affecting many of the species that are the cornerstone of major oceanic ecosystems.

The public has been focusing on recent hurricanes in the Gulf of Mexico, along with massive wildfires and record heat waves in the West, as dangers of global warming. However, what has been ignored is the other danger, the increasing atmospheric carbon dioxide concentrations — the increasing acidification of our oceans!

Continue reading ‘Reversing ocean acidification is doable, if we have the political will | Opinion’

An extreme decline effect in ocean acidification ecology

Published 15 September 2020 Science Closed
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Ocean acidification – deceasing oceanic pH resulting from the uptake of excess atmospheric CO2 – is expected to affect marine life in the future. Among the possible consequences, a series of studies on coral reef fishes suggested that the direct effects of acidification on fish behaviour will be the most catastrophic. Recent studies documenting a lack of effect of experimental ocean acidification on fish behaviour, however, call this dire prediction into question. Here, we critically assess the past decade of ocean acidification research regarding direct effects on fish behaviour. Using a meta-analysis, we provide quantitative evidence that the research to date on this topic is strongly characterized by a phenomenon known as the “decline effect”, where large effects have all but disappeared over a decade. The decline effect in this field cannot be explained biologically, but is strongly associated with well-known biases to which the process of science is generally prone. We contend that ocean acidification does not have as much of a direct impact on fish behaviour as previously thought, and we advocate for improved approaches to minimize the potential for a decline effect in future avenues of research.

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Ervilia castanea (Mollusca, Bivalvia) populations adversely affected at CO2 seeps in the North Atlantic

Published 15 September 2020 Science Closed
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Highlights

  • The bivalve Ervilia castanea was studied at volcanic CO2 seeps and reference sites.
  • Abundance, size and net-calcification were inversely related to CO2 levels.
  • Large individuals were scarce or absent at high CO2 sites.
  • Recruitment of this bivalve was highest at the CO2 seeps.
  • Abundance and size of E. castanea were positively correlated with Chl-a in sediment.

Abstract

Sites with naturally high CO2 conditions provide unique opportunities to forecast the vulnerability of coastal ecosystems to ocean acidification, by studying the biological responses and potential adaptations to this increased environmental variability. In this study, we investigated the bivalve Ervilia castanea in coastal sandy sediments at reference sites and at volcanic CO2 seeps off the Azores, where the pH of bottom waters ranged from average oceanic levels of 8.2, along gradients, down to 6.81, in carbonated seawater at the seeps. The bivalve population structure changed markedly at the seeps. Large individuals became less abundant as seawater CO2 levels rose and were completely absent from the most acidified sites. In contrast, small bivalves were most abundant at the CO2 seeps. We propose that larvae can settle and initially live in high abundances under elevated CO2 levels, but that high rates of post-settlement dispersal and/or mortality occur. Ervilia castanea were susceptible to elevated CO2 levels and these effects were consistently associated with lower food supplies. This raises concerns about the effects of ocean acidification on the brood stock of this species and other bivalve molluscs with similar life history traits.

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Environmentally-induced parental or developmental conditioning influences coral offspring ecological performance

Published 14 September 2020 Science Closed
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The persistence of reef building corals is threatened by human-induced environmental change. Maintaining coral reefs into the future requires not only the survival of adults, but also the influx of recruits to promote genetic diversity and retain cover following adult mortality. Few studies examine the linkages among multiple life stages of corals, despite a growing knowledge of carryover effects in other systems. We provide a novel test of coral parental conditioning to ocean acidification (OA) and tracking of offspring for 6 months post-release to better understand parental or developmental priming impacts on the processes of offspring recruitment and growth. Coral planulation was tracked for 3 months following adult exposure to high pCO2 and offspring from the second month were reciprocally exposed to ambient and high pCO2 for an additional 6 months. Offspring of parents exposed to high pCO2 had greater settlement and survivorship immediately following release, retained survivorship benefits during 1 and 6 months of continued exposure, and further displayed growth benefits to at least 1 month post release. Enhanced performance of offspring from parents exposed to high conditions was maintained despite the survivorship in both treatments declining in continued exposure to OA. Conditioning of the adults while they brood their larvae, or developmental acclimation of the larvae inside the adult polyps, may provide a form of hormetic conditioning, or environmental priming that elicits stimulatory effects. Defining mechanisms of positive acclimatization, with potential implications for carry over effects, cross-generational plasticity, and multi-generational plasticity, is critical to better understanding ecological and evolutionary dynamics of corals under regimes of increasing environmental disturbance. Considering environmentally-induced parental or developmental legacies in ecological and evolutionary projections may better account for coral reef response to the chronic stress regimes characteristic of climate change.

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Keystone predators govern the pathway and pace of climate impacts in a subarctic marine ecosystem

Published 14 September 2020 Science Closed
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Predator loss and climate change are hallmarks of the Anthropocene yet their interactive effects are largely unknown. Here, we show that massive calcareous reefs, built slowly by the alga Clathromorphum nereostratum over centuries to millennia, are now declining because of the emerging interplay between these two processes. Such reefs, the structural base of Aleutian kelp forests, are rapidly eroding because of overgrazing by herbivores. Historical reconstructions and experiments reveal that overgrazing was initiated by the loss of sea otters, Enhydra lutris (which gave rise to herbivores capable of causing bioerosion), and then accelerated with ocean warming and acidification (which increased per capita lethal grazing by 34 to 60% compared with preindustrial times). Thus, keystone predators can mediate the ways in which climate effects emerge in nature and the pace with which they alter ecosystems.

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Comparing subsurface seasonal deoxygenation and acidification in the Yellow Sea and Northern East China Sea along the North-to-South latitude gradient

Published 14 September 2020 Science Closed
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To better understand the relationship between subsurface seasonal deoxygenation and acidification in the Yellow Sea and northern East China Sea (ECS), we examined carbonate system parameters and dissolved oxygen (DO) of seven field surveys conducted in 2017–2018, spanning all four seasons. Low pHT values of 7.71–7.80 and critically low aragonite saturation state (Ωarag) values of 1.07–1.40 along with undersaturated DO of mostly higher than 150 μmol O2 kg–1 occurred in the Yellow Sea Cold Water Mass area in summer and autumn, while hypoxic DO values of 49–63 μmol O2 kg–1 and extremely low pHT values of 7.68–7.74 as well as critically low Ωarag values of 1.21–1.39 were observed in the northern ECS in July 2018. At the beginning of warm-season stratification formation, the cold Yellow Sea waters had much higher DO but lower Ωarag values than those in relatively warmer ECS waters, while yearly initial pHT values rarely exhibited differences between the two coastal seas. During warm seasons, the central Yellow Sea accumulated respiration products beneath the thermocline in summer and autumn, while the northern ECS bottom waters preserved them only in summer. This study highlights fundamental roles of wintertime carbon dioxide (CO2) solubility along a north-to-south latitude gradient in the coastal acidification development. In comparison with the relatively low-latitude northern ECS subject to seasonal hypoxia, relatively high-latitude Yellow Sea exhibits higher CO2 solubility in winter and longer respiration-product accumulations in warm seasons, leading to lower Ωarag in the central Yellow Sea than those in the northern ECS. However, the present-day central Yellow Sea is free from hypoxia.

Continue reading ‘Comparing subsurface seasonal deoxygenation and acidification in the Yellow Sea and Northern East China Sea along the North-to-South latitude gradient’

Monitoring ocean acidification from the sky

Published 11 September 2020 Web sites and blogs Closed

PML’s research into ocean acidification and its effects spans across scientific disciplines. One study from last year demonstrated how satellite technology can play a vital role in developing this understanding.

As the ocean absorbs carbon dioxide from Earth’s atmosphere, its pH levels are reducing, in a process known as ocean acidification. This is already putting stress on many marine organisms and will continue to do so as ocean acidification worsens. So it’s crucial for researchers to be able to monitor how the sea’s chemistry is changing, especially in regions that are particularly vulnerable and hard to access, such as the Arctic.

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Commission on Ocean Acidification

Published 11 September 2020 Events Closed

Date: Monday, September 14, 2020, 12:00 PM Eastern Time

Description: Meeting of the Special Legislative Commission on Ocean Acidification Scientific Literature Review working group

Agenda:
I. Welcome
II. Group discussion of preliminary recommendations for full commission meeting
III. Meeting Conclusion

Meeting location: Virtual via Zoom Public meeting link: https://harvard.zoom.us/j/98992932227

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Behavioural responses to predators in Mediterranean mussels (Mytilus galloprovincialis) are unaffected by elevated pCO2

Published 11 September 2020 Science Closed
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Highlights

  • Tested effects of elevated CO2 on valve gaping responses to predator alarm cues in Mediterranean mussels.
  • Mussels reduced valve gaping in response to predator alarm cues; no change in valve movement activity.
  • Elevated CO2 had no effect on baseline behaviour nor responses to predator cues.
  • Behavioural responses to predator cues in bivalves appear robust to high CO2.

Abstract

Ocean acidification is expected to affect marine organisms in the near future. Furthermore, abrupt short-term fluctuations in seawater pCO2 characteristic of near-short coastal regions and high-density aquaculture sites currently have the potential to influence organismal and community functioning by altering animal behaviour. While anti-predator responses in fishes exposed to elevated pCO2 are well documented, such responses in benthic marine invertebrates are poorly studied. We used high frequency, non-invasive biosensors to test whether or not short term (3-week) exposure to elevated pCO2 could impact behavioural responses to the threat of predation in adult Mediterranean mussels from Galicia on the northwestern coast of Spain. Predator alarm cues (crushed conspecifics) resulted in a prolonged (1 h) reduction in the degree of valve opening (−20%) but had no clear effect on overall valve movement activity, while elevated pCO2 did not affect either response. Our results add to the increasing body of evidence suggesting that the effects of end-of-century pCO2 levels on marine animal behaviour are likely weak. Nonetheless, longer-term exposures spanning multiple generations are needed to better understand how ocean acidification might impact behavioural responses to predation in marine bivalves.

Continue reading ‘Behavioural responses to predators in Mediterranean mussels (Mytilus galloprovincialis) are unaffected by elevated pCO2’

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