Posts Tagged 'physiology'

Aquatic acidification: a mechanism underpinning maintained oxygen transport and performance in fish experiencing elevated carbon dioxide conditions

Aquatic acidification, caused by elevating levels of atmospheric carbon dioxide (CO2), is increasing in both freshwater and marine ecosystems worldwide. However, few studies have examined how acidification will affect oxygen (O2 ) transport and, therefore, performance in fishes. Although data are generally lacking, the majority of fishes investigated in this meta-analysis exhibited no effect of elevated CO2 at the level of O2 uptake, suggesting that they are able to maintain metabolic performance during a period of acidosis. Notably, the mechanisms that fish employ to maintain performance and O2 uptake have yet to be verified. Here, we summarize current data related to one recently proposed mechanism underpinning the maintenance of O2 uptake during exposure to aquatic acidification, and reveal knowledge gaps that could be targeted for future research. Most studies have examined O2 uptake rates while fishes were resting and did not calculate aerobic scope, even though aerobic scope can aid in predicting changes to whole-animal metabolic performance. Furthermore, research is lacking on different age classes, freshwater species and elasmobranchs, all of which might be impacted by future acidification conditions. Finally, this Review further seeks to emphasize the importance of developing collaborative efforts between molecular, physiological and ecological approaches in order to provide more comprehensive predictions as to how future fish populations will be affected by climate change.

Continue reading ‘Aquatic acidification: a mechanism underpinning maintained oxygen transport and performance in fish experiencing elevated carbon dioxide conditions’

Effects of ocean warming and acidification combined with eutrophication on chemical composition and functional properties of Ulva rigida


• Ocean warming and eutrophication increased total amino acids.
• Ocean warming, acidification, and eutrophication increased total fatty acids.
• Ocean warming enhanced swelling capacity and water holding capacity.
• Ocean warming promoted oil holding capacity.


Ulva is increasingly viewed as a food source in the world. Here, Ulva rigida was cultured at two levels of temperature (14, 18°C), pH (7.95, 7.55, corresponding to low and high pCO2), and nitrate conditions (6 μmol L-1, 150 μmol L-1), to investigate the effects of ocean warming, acidification, and eutrophication on food quality of Ulva species. High temperature increased the content of each amino acid. High nitrate increased the content of all amino acid except aspartic acid and cysteine. High temperature, pCO2, and nitrate also increased content of most fatty acids. The combination of high temperature, pCO2, and nitrate increased the swelling capacity, water holding capacity, and oil holding capacity by 15.60%, 7.88%, and 16.32% respectively, compared to the control. It seems that future ocean environment would enhance the production of amino acid and fatty acid as well as the functional properties in Ulva species.

Continue reading ‘Effects of ocean warming and acidification combined with eutrophication on chemical composition and functional properties of Ulva rigida’

Sand smelt ability to cope and recover from ocean’s elevated CO2 levels


• Sand smelt larvae were exposed to short and long-term acidification scenarios.
• Cope and recover were assessed at behavioural, morphometric and biochemical levels.
• Exposure to high pCO2 induces different responses at distinct exposure times.
• Contrary to biochemical and morphometric responses, lateralization was unaffected.
• Larvae were not able to recover from acidified scenarios within the study period.


Considered a major environmental concern, ocean acidification has induced a recent research boost into effects on marine biodiversity and possible ecological, physiological, and behavioural impacts. Although the majority of literature indicate negative effects of future acidification scenarios, most studies are conducted for just a few days or weeks, which may be insufficient to detect the capacity of an organism to adjust to environmental changes through phenotypic plasticity. Here, the effects and the capacity of sand smelt larvae Atherina presbyter to cope and recover (through a treatment combination strategy) from short (15 days) and long-term exposure (45 days) to increasing pCO2 levels (control: ~515 μatm, pH = 8.07; medium: ~940 μatm, pH = 7.84; high: ~1500 μatm, pH = 7.66) were measured, addressing larval development traits, behavioural lateralization, and biochemical biomarkers related with oxidative stress and damage, and energy metabolism and reserves. Although behavioural lateralization was not affected by high pCO2 exposure, morphometric changes, energetic costs, and oxidative stress damage were impacted differently through different exposures periods. Generally, short-time exposures led to different responses to either medium or high pCO2 levels (e.g. development, cellular metabolism, or damage), while on the long-term the response patterns tend to become similar between them, with both acidification scenarios inducing DNA damage and tending to lower growth rates. Additionally, when organisms were transferred to lower acidified condition, they were not able to recover from the mentioned DNA damage impacts.

Overall, results suggest that exposure to future ocean acidification scenarios can induce sublethal effects on early life-stages of fish, but effects are dependent on duration of exposure, and are likely not reversible. Furthermore, to improve our understanding on species sensitivity and adaptation strategies, results reinforce the need to use multiple biological endpoints when assessing the effects of ocean acidification on marine organisms.

Continue reading ‘Sand smelt ability to cope and recover from ocean’s elevated CO2 levels’

Shifting balance of protein synthesis and degradation sets a threshold for larval growth under environmental stress

Exogenous environmental factors alter growth rates, yet information remains scant on the biochemical mechanisms and energy trade-offs that underlie variability in the growth of marine invertebrates. Here we study the biochemical bases for differential growth and energy utilization (as adenosine triphosphate [ATP] equivalents) during larval growth of the bivalve Crassostrea gigas exposed to increasing levels of experimental ocean acidification (control, middle, and high pCO2, corresponding to ∼400, ∼800, and ∼1100 µatm, respectively). Elevated pCO2 hindered larval ability to accrete both shell and whole-body protein content. This negative impact was not due to an inability to synthesize protein per se, because size-specific rates of protein synthesis were upregulated at both middle and high pCO2 treatments by as much as 45% relative to control pCO2. Rather, protein degradation rates increased with increasing pCO2. At control pCO2, 89% of cellular energy (ATP equivalents) utilization was accounted for by just 2 processes in larvae, with protein synthesis accounting for 66% and sodium-potassium transport accounting for 23%. The energetic demand necessitated by elevated protein synthesis rates could be accommodated either by reallocating available energy from within the existing ATP pool or by increasing the production of total ATP. The former strategy was observed at middle pCO2, while the latter strategy was observed at high pCO2. Increased pCO2 also altered sodium-potassium transport, but with minimal impact on rates of ATP utilization relative to the impact observed for protein synthesis. Quantifying the actual energy costs and trade-offs for maintaining physiological homeostasis in response to stress will help to reveal the mechanisms of resilience thresholds to environmental change.

Continue reading ‘Shifting balance of protein synthesis and degradation sets a threshold for larval growth under environmental stress’

The detrimental effects of CO2-driven chronic acidification on juvenile Pacific abalone (Haliotis discus hannai)

To test the effects of chronic stress caused by CO2-driven decreases in pH (NBS scale) on molluscs, juvenile Pacific abalone (Haliotis discus hannai), an economically important gastropod, were cultured at pH 8.1 (control), pH 7.9 or 7.7 for 3 months. Eroded shell surfaces, reduced growth rates, and altered biochemical composition and energy metabolism were found in abalone cultured in acidified conditions. Glycogen contents and crude lipid contents were significantly higher in the muscle of abalone from the control treatments than in those from the pH 7.7 treatment, indicating that allocation of tissue energy storage was altered by chronic acidification. The ratio of the oxygen consumption rate to the ammonia excretion rate (O:N ratio) of individuals cultured at two acidified treatments decreased significantly compared with the controls, suggesting a decreased use of body lipid and carbohydrates as a metabolic substrate under chronic acidified conditions. Chronic acidification had detrimental effects on the physiological activity of the Pacific abalone; however, the ability to acclimate varied among individuals. A minority of tested animals incubated at acidified conditions exhibited undiminished performance. The Pacific abalone may face severe challenges in the near future, but they may also hold considerable ability to acclimate to ocean acidification.

Continue reading ‘The detrimental effects of CO2-driven chronic acidification on juvenile Pacific abalone (Haliotis discus hannai)’

Elevated seawater temperature, not pCO2, negatively affects post-spawning adult mussels (Mytilus edulis) under food limitation

Pre-spawning blue mussels (Mytilus edulis) appear sensitive to elevated temperature and robust to elevated pCO2; however, the effects of these stressors soon after investing energy into spawning remain unknown. Furthermore, while studies suggest that elevated pCO2 affects the byssal attachment strength of Mytilus trossulus from southern latitudes, pCO2 and temperature impacts on the byssus strength of other species at higher latitudes remain undocumented. In a 90 day laboratory experiment, we exposed post-spawning adult blue mussels (M. edulis) from Atlantic Canada to three pCO2 levels (pCO2 ~625, 1295 and 2440 μatm) at two different temperatures (16°C and 22°C) and assessed energetic reserves on Day 90, byssal attachment strength on Days 30 and 60, and condition index and mortality on Days 30, 60 and 90. Results indicated that glycogen content was negatively affected under elevated temperature, but protein, lipid, and overall energy content were unaffected. Reduced glycogen content under elevated temperature was associated with reduced condition index, reduced byssal thread attachment strength, and increased mortality; elevated pCO2 had no effects. Overall, these results suggest that the glycogen reserves of post-spawning adult M. edulis are sensitive to elevated temperature, and can result in reduced health and byssal attachment strength, leading to increased mortality. These results are similar to those reported for pre-spawning mussels and suggest that post-spawning blue mussels are tolerant to elevated pCO2 and sensitive to elevated temperature. In contrast to previous studies, however, elevated pCO2 did not affect byssus strength, suggesting that negative effects of elevated pCO2 on byssus strength are not universal.

Continue reading ‘Elevated seawater temperature, not pCO2, negatively affects post-spawning adult mussels (Mytilus edulis) under food limitation’

Short-term exposure of Mytilus coruscus to decreased pH and salinity change impacts immune parameters of their haemocytes

With the release of large amounts of CO2, ocean acidification is intensifying and affecting aquatic organisms. In addition, salinity also plays an important role for marine organisms and fluctuates greatly in estuarine and coastal ecosystem, where ocean acidification frequently occurs. In present study, flow cytometry was used to investigate immune parameters of haemocytes in the thick shell mussel Mytilus coruscus exposed to different salinities (15, 25, and 35‰) and two pH levels (7.3 and 8.1). A 7-day in vivo and a 5-h in vitro experiments were performed. In both experiments, low pH had significant effects on all tested immune parameters. When exposed to decreased pH, total haemocyte count (THC), phagocytosis (Pha), esterase (Est), and lysosomal content (Lyso) were significantly decreased, whereas haemocyte mortality (HM) and reactive oxygen species (ROS) were increased. High salinity had no significant effects on the immune parameters of haemocytes as compared with low salinity. However, an interaction between pH and salinity was observed in both experiments for most tested haemocyte parameters. This study showed that high salinity, low salinity and low pH have negative and interactive effects on haemocytes of mussels. As a consequence, it can be expected that the combined effect of low pH and changed salinity will have more severe effects on mussel health than predicted by single exposure.

Continue reading ‘Short-term exposure of Mytilus coruscus to decreased pH and salinity change impacts immune parameters of their haemocytes’

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Ocean acidification in the IPCC AR5 WG II

OUP book