Posts Tagged 'multiple factors'

Microbial strains isolated from CO2-venting Kolumbo submarine volcano show enhanced co-tolerance to acidity and antibiotics


• The study investigates the effects of volcanic acidification to marine bacteria.

• Deep waters of Kolumbo submarine volcano are CO2-rich and more acidic.

• Pseudomonas strains from Kolumbo seafloor show higher tolerance to acidity.

• Strong correlation between acid and antibiotic tolerance of Pseudomonas species.

• Ocean acidification may lead to marine bacteria with increased antibiotic tolerance.


As ocean acidification intensifies, there is growing global concern about the impacts that future pH levels are likely to have on marine life and ecosystems. By analogy, a steep decrease of seawater pH with depth is encountered inside the Kolumbo submarine volcano (northeast Santorini) as a result of natural CO2 venting, making this system ideal for ocean acidification research. Here, we investigated whether the increase of acidity towards deeper layers of Kolumbo crater had any effect on relevant phenotypic traits of bacterial isolates. A total of 31 Pseudomonas strains were isolated from both surface- (SSL) and deep-seawater layers (DSL), with the latter presenting a significantly higher acid tolerance. In particular, the DSL strains were able to cope with H+ levels that were 18 times higher. Similarly, the DSL isolates exhibited a significantly higher tolerance than SSL strains against six commonly used antibiotics and As(III). More importantly, a significant positive correlation was revealed between antibiotics and acid tolerance across the entire set of SSL and DSL isolates. Our findings imply that Pseudomonas species with higher resilience to antibiotics could be favored by the prospect of acidifying oceans. Further studies are required to determine if this feature is universal across marine bacteria and to assess potential ecological impacts.

Continue reading ‘Microbial strains isolated from CO2-venting Kolumbo submarine volcano show enhanced co-tolerance to acidity and antibiotics’

Low pH reduced survival of the oyster Crassostrea gigas exposed to the Ostreid herpesvirus 1 by altering the metabolic response of the host


  • The susceptibility of Crassostrea gigas to OsHV-1 increased at pH 7.8 in comparison to pH 8.1
  • The amount of OsHV-1 in oyster tissues was the same at both pH, suggesting the role of host metabolic response in differential survival
  • A lower activity of SOD and a basal activity of iNOS at pH 7.8, in comparison to pH 8.1, may have impaired the defence of oysters to OsHV-1 explaining the lower survival


Environmental change in the marine realm has been accompanied by emerging diseases as new pathogens evolve to take advantage of hosts weakened by environmental stress. Here we investigated how an exposure to reduced seawater pH influenced the response of the oyster Crassostrea gigas to an infection by the Ostreid herpesvirus type I (OsHV-1). Oysters were acclimated at pH 8.1 or pH 7.8 and then exposed to OsHV-1. Their survival was monitored and oyster tissues were sampled for biochemical analyses. The survival of oysters exposed to OsHV-1 at pH 7.8 was lower (33.5%) than that of their counterparts at pH 8.1 (44.8%) whereas levels of OsHV-1 DNA were similar. Energetic reserves, fatty acid composition and prostaglandin levels in oyster did not vary consistently with pH, infection or their interactions. However, there was a reduction in the activities of superoxide dismutase (SOD) and nitric oxide synthase (iNOS) in oysters at low pH, which is associated with the observed difference in survival.

Continue reading ‘Low pH reduced survival of the oyster Crassostrea gigas exposed to the Ostreid herpesvirus 1 by altering the metabolic response of the host’

Bottom-up effects on biomechanical properties of the skeletal plates of the sea urchin Paracentrotus lividus (Lamarck, 1816) in an acidified ocean scenario


  • Biomechanical properties of sea urchin test have a great importance in their individual fitness.
  • Combined effect of decreased pH and macroalgal diet highlights potential cascading effects.
  • No direct short-term effect of decreased pH and macroalgal diet on plate mechanical properties.
  • Longer term exposure needed to observe substantial differences on skeletal plate structure.


Sea urchins, ecologically important herbivores of shallow subtidal temperate reefs, are considered particularly threatened in a future ocean acidification scenario, since their carbonate structures (skeleton and grazing apparatus) are made up of the very soluble high-magnesium calcite, particularly sensitive to a decrease in pH. The biomechanical properties of their skeletal structures are of great importance for their individual fitness, because the skeleton provides the means for locomotion, grazing and protection from predators. Sea urchin skeleton is composed of discrete calcite plates attached to each other at sutures by organic ligaments. The present study addressed the fate of the sea urchin Paracentrotus lividus (Lamarck, 1816) skeleton in acidified oceans, taking into account the combined effect of reduced pH and macroalgal diet, with potential cascading consequences at the ecosystem level. A breaking test on individual plates of juvenile specimens fed different macroalgal diets has been performed, teasing apart plate strength and stiffness from general robustness. Results showed no direct short-term effect of a decrease in seawater pH nor of the macroalgal diet on single plate mechanical properties. Nevertheless, results from apical plates, the ones presumably formed during the experimental period, provided an indication of a possible diet-mediated response, with sea urchins fed the more calcified macroalga sustaining higher forces before breakage than the one fed the non-calcified algae. This, on the long term, may produce bottom-up effects on sea urchins, leading to potential shifts in the ecosystem equilibrium under an ocean acidified scenario.

Continue reading ‘Bottom-up effects on biomechanical properties of the skeletal plates of the sea urchin Paracentrotus lividus (Lamarck, 1816) in an acidified ocean scenario’

Divergent responses of Atlantic cod to ocean acidification and food limitation

In order to understand the effect of global change on marine fishes, it is imperative to quantify the effects on fundamental parameters such as survival and growth. Larval survival and recruitment of the Atlantic cod (Gadus morhua) was found to be heavily impaired by end‐of‐century levels of ocean acidification. Here, we analysed larval growth among 35‐36 days old surviving larvae, along with organ development and ossification of the skeleton. We combined CO2‐treatments (ambient: 503 μatm, elevated: 1179 μatm) with food availability in order to evaluate the effect of energy limitation in addition to the ocean acidification stressor. As expected, larval size (as a proxy for growth) and skeletogenesis were positively affected by high food availability. We found significant interactions between acidification and food availability. Larvae fed ad libitum showed little difference in growth and skeletogenesis due to the CO2 treatment. Larvae under energy limitation were significantly larger and had further developed skeletal structures in the elevated CO2 treatment compared to the ambient CO2 treatment. However, the elevated CO2 group revealed impairments in critically important organs, such as the liver, and had comparatively smaller functional gills indicating a mismatch between size and function. It is therefore likely that individual larvae that had survived acidification treatments, will suffer from impairments later during ontogeny. Our study highlights important allocation trade‐off between growth and organ development, which is critically important to interpret acidification effects on early life‐stages of fish.

Continue reading ‘Divergent responses of Atlantic cod to ocean acidification and food limitation’

Feeding plasticity more than metabolic rate drives the productivity of economically important filter feeders in response to elevated CO2 and reduced salinity

Climate change driven alterations in salinity and carbonate chemistry are predicted to have significant implications particularly for northern costal organisms, including the economically important filter feeders Mytilus edulis and Ciona intestinalis. However, despite a growing number of studies investigating the biological effects of multiple environmental stressors, the combined effects of elevated pCO2 and reduced salinity remain comparatively understudied. Changes in metabolic costs associated with homeostasis and feeding/digestion in response to environmental stressors may reallocate energy from growth and reproduction, affecting performance. Although these energetic trade-offs in response to changes in routine metabolic rates have been well demonstrated fewer studies have investigated how these are affected by changes in feeding plasticity. Consequently, the present study investigated the combined effects of 26 days’ exposure to elevated pCO2 (500 µatm and 1000 µatm) and reduced salinity (30, 23, and 16) on the energy available for growth and performance (Scope for Growth) in M. edulis and C. intestinalis, and the role of metabolic rate (oxygen uptake) and feeding plasticity [clearance rate (CR) and absorption efficiency] in this process. In M. edulis exposure to elevated pCO2 resulted in a 50% reduction in Scope for Growth. However, elevated pCO2 had a much greater effect on C. intestinalis, with more than a 70% reduction in Scope for Growth. In M. edulis negative responses to elevated pCO2 are also unlikely be further affected by changes in salinity between 16 and 30. Whereas, under future predicted levels of pCO2C. intestinalis showed 100% mortality at a salinity of 16, and a >90% decrease in Scope for Growth with reduced biomass at a salinity of 23. Importantly, this work demonstrates energy available for production is more dependent on feeding plasticity, i.e. the ability to regulate CR and absorption efficiency, in response to multiple stressors than on more commonly studied changes in metabolic rates.

Continue reading ‘Feeding plasticity more than metabolic rate drives the productivity of economically important filter feeders in response to elevated CO2 and reduced salinity’

Obligate ectosymbionts increase the physiological resilience of a scleractinian coral to high temperature and elevated pCO2

Invertebrate ectosymbionts within the coralla of scleractinians enhance host fitness through protection from corallivores and nutrient addition. Here, we explore the ectosymbiotic relationship between the coral Pocillopora verrucosa and the crab Trapezia serenei and the shrimp Alpheus spp., to test for effects on coral calcification under contrasts of seawater temperature (27.7 °C and 29.9 °C) and pH (ambient, 8.0 and reduced, 7.7). Regardless of temperature, ectosymbionts depressed calcification by 55% (vs without ectosymbionts) at ambient pH; however, ectosymbionts only depressed calcification under ambient pH but not at reduced pH. These results suggest that P. verrucosa grows fastest at ambient pH without ectosymbionts, but when ectosymbionts are present, colonies are protected from further declines in calcification at reduced pH. This implies that there may be a change from a currently parasitic ectosymbiont–coral relationship to a commensal relationship that could increase fitness advantages for corals hosting crustacean ectosymbionts under ocean acidification conditions.

Continue reading ‘Obligate ectosymbionts increase the physiological resilience of a scleractinian coral to high temperature and elevated pCO2’

Individual and combined effects of low dissolved oxygen and low pH on survival of early stage larval blue crabs, Callinectes sapidus

A large number of coastal ecosystems globally are subjected to concurrent hypoxic and acidified conditions that will likely intensify and expand with continued climate change. In temperate regions, the spawning of many important organisms including the Atlantic blue crab Callinectes sapidus occurs during the summer months when the severity of coastal hypoxia and acidification is the greatest. While the blue crab earliest larval stage can be exposed to co-occurring hypoxia and acidification observed in many coastal ecosystems, the effects of these concurrent stressors on larval blue crab survival is unknown. This study investigated the individual and combined consequences of low dissolved oxygen (DO) and low pH on blue crab larvae survival through a series of short-term experiments. During 14-day experiments with moderately hypoxic conditions (117–127 μM O2 or 3.74–4.06 mg L-1) and acidified conditions (pH on total scale of 7.16–7.33), low DO and low pH individually and significantly reduced larval survival by 60% and 49%, respectively, with the combination of stressors reducing survival by 87% compared to the control treatment (210–269 μM O2 or 6.72–8.61 mg L-1, 7.91–7.94 DO and pH, respectively). During 4-day experiments with lower DO levels (68–83 μM O2 or 2.18–2.62 mg L-1) and comparable pH levels of 7.29–7.39, low DO individually reduced survival by >90% compared to the control (261–267 μM O2 or 8.35–8.54 mg L-1, 7.92–7.97 DO and pH, respectively), whereas low pH had no effect and there was no interaction between stressors. Over a 4-day period, the DO threshold at which 50% of the larval blue crab population died (LC50) was 121 μM O2 (3.86 mgL-1). In 14-day experiments, the DO and pH effects were additive, yielding survival rates lower than the individual treatments, and significantly correlated with DO and pH concentrations. Collectively, these findings indicate that blue crab sensitivity to both low DO and low pH are acute within the larval stage, depend on the intensity and duration of exposure, and leads to mortality, thereby potentially contributing to the interannual variability and possible regional declines of this fishery.

Continue reading ‘Individual and combined effects of low dissolved oxygen and low pH on survival of early stage larval blue crabs, Callinectes sapidus’

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Ocean acidification in the IPCC AR5 WG II

OUP book