Sub-lethal predatory shell damage does not affect physiology under high CO2 in the intertidal gastropod Tritia reticulata

Ocean acidification (OA) poses a major threat to marine animals, especially marine shelled invertebrates such as molluscs. Although many organisms are capable of compensating for the effects of OA, this can impose physiological costs and impact performance (e.g. through increased metabolism and decreased growth). Sublethal injuries on shells may provoke changes in energy allocation. Under acidified conditions, organisms would spend less energy on reproduction and somatic growth to repair the damage. Therefore, we analysed the physiological responses of the intertidal gastropod Tritia reticulata during shell regeneration under OA conditions. We simulated a sub-lethal predation event (a notch in the outer lip of the shell) and individuals were exposed to control (pH 8.08) and low pH scenarios (pH 7.88 and 7.65). After two months exposure, all individuals showed shell repair, with a full repair rate observed in 75% of individuals. Contrary to expectations, shell repair following sub-lethal damage and OA had no apparent impact on physiological state in terms of energy reserves (as measured by whole-animal Carbon/Nitrogen) or growth potential (as measured by whole-animal RNA:Protein and RNA:DNA ratios). As an intertidal organism, T reticulata could be resilient to future global environmental change because of compensatory mechanisms that are inherent in intertidal animals, and may represent a robust species with which to study future scenarios of OA in temperate coastal ecosystems. However, unrestricted food availability during experiment could have played a role in the results and therefore food limitation should be considered in future studies regarding shell repair and metabolism under the effects of OA.

Continue reading ‘Sub-lethal predatory shell damage does not affect physiology under high CO2 in the intertidal gastropod Tritia reticulata’

Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel, Mytilus edulis

In mosaic marine habitats such as intertidal zones ocean acidification (OA) is exacerbated by high variability of pH, temperature, and biological CO2 production. The non-linear interactions among these drivers can be context-specific and their effect on organisms in these habitats remains largely unknown, warranting further investigation. We were particularly interested in Mytilus edulis (the blue mussel) from intertidal zones of Gulf of Maine (GOM), USA for this study. GOM is a hot spot of global climate change (average SST increasing by > 0.2 °/y ) with > 60% decline in mussel population over the past 40 years. Here, we utilize bioenergetic underpinnings to identify limits of stress tolerance in M. edulis from GOM exposed to warming and OA. We have measured whole-organism oxygen consumption rates and metabolic biomarkers in mussels exposed to control and elevated temperatures (10 vs. 15 °) and moderate PCO2 levels (~ 400 vs. 800 μatm). Our study demonstrates that adult M. edulis from GOM are metabolically resilient to the moderate OA scenario but responsive to warming as seen in changes in metabolic rate, energy reserves, metabolite profiles and enzyme activities. Our results are in agreement with recent literature that OA scenarios for the next 100-300 years do not affect this species, possibly as a consequence of maintaining its in vivo acid-base balance.

Continue reading ‘Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel, Mytilus edulis’

Oysters reared in Atlantic Canada show tolerance to ocean acidification

Oysters in Atlantic Canada may have developed resistance to ocean acidification due to their long history of exposure to low pH conditions, a new study shows.

Ocean acidification describes the decrease in seawater pH due to the oceans absorbing excess carbon dioxide from the atmosphere. The deaths of millions of oyster larvae in the Pacific Northwest in 2007 due to ocean acidification highlighted how climate change, found to be the culprit behind the phenomenon, could devastate the industry and coastal economies.

“The change in ocean pH presents a challenge for marine life. A major consequence is that shellfish, like oysters, have a harder time making shells,” says Jeff Clements, research scientist at Fisheries and Oceans Canada and lead author of the study.

Continue reading ‘Oysters reared in Atlantic Canada show tolerance to ocean acidification’

UNFCCC ocean and climate change dialogue

Taking place 2-3 December 2020, the Ocean and Climate Change Dialogue as mandated by COP25, will invite Parties and non-Party stakeholders to consider approaches to strengthening ocean related adaptation and mitigation action across the UNFCCC.

The Dialogue will provide a space to discuss actions, drawing upon the knowledge and scientific findings from IPCC Special Report on the Ocean and Cryosphere in a Changing Climate and the submissions from Parties and non-Party stakeholders.

Ocean acidification is a direct result of human-caused carbon dioxide (CO2) emissions and is altering the chemical balance of seawater that marine life depends upon for survival.   Only by explicitly including impacts of increasing acidification—and ocean change more broadly—within mitigation targets and adaptation strategies can the UNFCCC and Parties accurately assess the full suite of change and vulnerability directly caused by increasing anthropogenic CO2.

The OA Alliance has highlighted key takeaways from our official submission made to the Ocean and Climate Change Dialogue, which you can access here: “Ocean Acidification within UNFCCC Ocean Climate Dialogue (FINAL).

Continue reading ‘UNFCCC ocean and climate change dialogue’

Boron isotope records from Pacific microatolls: modifications in Porites lutea calcifying fluid composition under anthropogenic ocean acidification and natural pH variability

Anthropogenic ocean acidification (OA) has compromised the ability of marine organisms to calcify. However, many coastal environments naturally exhibit high variability in seawater pH (pHsw) and the impact of OA on these environments is unclear. For instance, sub-tropical corals can modify the pH of the calcifying fluid (pHcf) from which they precipitate their skeleton. This study examines the influence of OA on pHcf upregulation of Porites lutea microatolls inhabiting reef flat environments. Environmental measurements including pHsw and temperature were performed on reef flats and adjacent fore-reefs on Kiritimati Island (Kiribati), Arno Atoll (Marshall Islands), and Rarotonga (Cook Islands) to quantify the temporal and spatial variability of these parameters. Slabs were removed from microatolls to construct multi-decadal (1938 – 2018) records of their boron isotopic (δ11B) and geochemical composition. The sensitivity of microatoll pHcf upregulation to ambient pHsw was evaluated by comparing annual band δ11B with synchronously recorded pHsw and temperature, and microatoll records were compared to a fore-reef record of similar age. Although daily means in pHsw on reef flats and fore-reefs were relatively similar, large diurnal cycles in pHsw (ΔpHsw = 0.28) and temperature (ΔT = 2.0°C) were found on reef flats exceeding that on fore-reefs by far (ΔpHsw = 0.07, ΔT = 0.7°C). Furthermore, spatial variations in pHsw and temperature were observed that were linked to reef flat hydrodynamics. Microatoll pHcf revealed a higher correlation to ambient seawater temperatures than to pHsw and only the fore-reef core showed a long-term trend in pHcf (-0.0003±0.0009 year-1) that is indicative of OA, while microatoll records revealed variable long-term trends unlikely reflecting ocean conditions (-0.0030±0.0005 to +0.0007±0.0003 year-1). Corals from the three sites revealed similar mean pHcf ≈ 8.44 although the difference in pHsw between the locations (ΔpHsw = 0.17) noticeably exceeded the decline in pHsw due to OA (ΔpHsw = 0.10). In conclusion, Porites lutea microatoll pHcf appeared to be relatively insensitive to OA. This is likely a result of the large variability in seawater conditions on reef flats that supersede OA, and the strong modification of coral pHcf by physiological processes.

Continue reading ‘Boron isotope records from Pacific microatolls: modifications in Porites lutea calcifying fluid composition under anthropogenic ocean acidification and natural pH variability’

Elevated temperature, but not decreased pH, impairs reproduction in a temperate fish

Fish reproductive success is linked to the ability of couples to mate and produce clutches that successfully hatch. Environmental stressors like high temperature and low pH can jeopardize this energetically costly process. In this study, exposure to high temperature and low pH was tested on a marine temperate species, Gobiusculus flavescens, to evaluate effects on reproductive performance. Breeding pairs were assigned to different temperatures (+ 0 °C, + 3 °C relative to in situ temperature) and pH levels (8.0, 7.6), in a cross-factorial design for a 3-month period. Reproduction activity, success, and paternal investment were measured throughout the exposure period. Results show reproduction is impaired by elevated temperature, while low pH had little impact. Breeding pairs under high temperature had 3% to 10% hatching success, up to 30% less eggs and eggs up to 20% smaller. Although paternal investment was not affected by tested parameters, males of breeding pairs exposed to elevated temperature had smaller gonadosomatic indexes, which might indicate a lack of investment in the reproductive process. Overall, results show that elevated temperature, expected more frequently in the near future, as a consequence of global warming, may impair key processes like reproduction in temperate fish, with potential consequences for fitness and population replenishment.

Continue reading ‘Elevated temperature, but not decreased pH, impairs reproduction in a temperate fish’

An acidifying ocean spells disaster for marine and human systems

Photo by Luca Bravo on Unsplash

Human communities rely on their relationships with the ocean. Marine systems provide humans with ecosystem services such as pollution filtration and shore protection. Societies living in marine areas also benefit economically through fisheries and tourism. However, humans are indirectly harming marine ecosystems through increased carbon dioxide emissions. When the ocean takes up carbon dioxide from the atmosphere, pH levels drop and the ocean becomes more acidic. This process is called ocean acidification.

Continue reading ‘An acidifying ocean spells disaster for marine and human systems’

What can local governments do to address ocean and coastal acidification?

Municipal governments are on the forefront of experiencing the direct impacts of climate and ocean change as they must continually absorb and prepare for adverse impacts to coastal communities.

Increasing ocean acidification (OA), combined with other stressors like ocean warming and loss of oxygen, threatens marine species and ecosystems that are essential for sustaining jobs and supporting the health coastal economies around the world.  Additionallylocal and land-based contributions along with additional stressors, can exacerbate OA and other climate related changing conditions.

Stakeholders and decision-makers at local, regional, and international scales are collaborating to respond to the accelerating global threat of OA and other climate-ocean impacts.

Local municipalities (counties, cities, ports, regional governance bodies) also have a role to play.

Download Our Infographic:  What Can Local Governments Do To Address Ocean and Coastal Acidification (

Continue reading ‘What can local governments do to address ocean and coastal acidification?’

Introducing the new WOAC website!

View website

Although the Washington Ocean Acidification Center (WOAC) is based in EarthLab at the University of Washington, it serves the entire state. Since its creation in 2013, WOAC has been charged by the State Legislature to lead the state in priority areas of ocean acidification research.

Thank you to the College of the Environment web team for design and development of this new site. Check back often for news and updates regarding ocean acidification and its impact on our region.

Continue reading ‘Introducing the new WOAC website!’

Contrasting effects of constant and fluctuating pCO2 conditions on the exercise physiology of coral reef fishes


  • Coral reefs exhibit natural CO2 fluctuations expected to increase with climate change
  • We measured swimming performance, O2 uptake rates, aerobic scope, and blood variables
  • Three of the four species benefitted under elevated fluctuating CO2 conditions
  • The nocturnal cardinalfish studied may be more sensitive to elevated fluctuating CO2
  • Studies should use ecologically-relevant CO2 when predicting climate change impacts


Ocean acidification (OA) is predicted to affect the physiology of some fishes. To date, most studies have investigated this issue using stable pCO2 levels based on open ocean projections. Yet, most shallow, nearshore systems experience temporal and spatial pCO2 fluctuations. For example, pCO2 on coral reefs is highest at night and lowest during the day, but as OA progresses, both the average pCO2 and magnitude of fluctuations are expected to increase. We exposed four coral reef fishes – Lutjanus fulviflamma, Caesio cuning, Abudefduf whitleyi, and Cheilodipterus quinquelineatus – to ambient, stable elevated, or fluctuating elevated pCO2 conditions for 9-11 days. Then, we measured swimming performance, oxygen uptake rates, and haematological parameters during the day and at night. When compared to ambient pCO2 conditions, L. fulviflamma, C. cuning, and A. whitleyi exposed to fluctuating elevated pCO2 increased swimming performance, maximum oxygen uptake rates, and aerobic scope, regardless of time of day; whereas, the only nocturnal species studied, C. quinquelineatus, decreased maximum oxygen uptake rates and aerobic scope. Our findings suggest that exposure to fluctuating or stable elevated pCO2 can physiologically benefit some coral reef fishes; however, other species, such as the cardinalfish examined here, may be more sensitive to future OA conditions.

Continue reading ‘Contrasting effects of constant and fluctuating pCO2 conditions on the exercise physiology of coral reef fishes’

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Ocean acidification in the IPCC AR5 WG II

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