Archive for July, 2018

Analysis of Na+/K+ -ATPase gene expression and physiological parameters in the crab Callinectes danae submitted to future scenarios of ocean acidification in the laboratory (in Portuguese)

Oceanic acidification, a process resulting from the emission of carbon dioxide (CO2) in the atmosphere by activities of anthropic nature, has been causing in recent decades a change in the chemical balance of the bicarbonate / carbonate system and consequently a decrease in the pH of the oceans. Estimates indicate that this decrease can be 0.7 units per year of 2300, which can affect the growth, reproduction and even survival of the species. In this sense, studies are needed to evaluate the impact of oceanic acidification on physiological and molecular levels in different marine species. The Callinectes danae crab is an important ecological and economic resource of the Region of the Baixada Santista and inhabitant of different ranges of salinity. The present study evaluated the effects of ocean acidification on C. danae crab on a set of physiological parameters (oxygen consumption, ammonia excretion, O: N ratio, hepatosomatic index and osmo-and ionoregulatory capacity of hemolymph), and gene expression of Na + / K + – ATPase, an important enzyme in the process of osmoregulation and acid base balance. The animals were kept at different salinities (20, 25, 30, 35 and 40) and at pHs 8.0 (control) and 7.3 (acidified) for a period of three and thirty days. It was observed an increase in the oxygen consumption in salinities 25 (3 days), 20 and 40 (30 days) probably due to a greater energy requirement for the maintenance of systems related to acid-base regulation. Metabolic depression was also observed at the salinity of 30 (30 days). Ammonia excretion decreased in salinities 30 (3 days), 25, 30 and 35 (30 days) possibly due to competition between Na + / H + and Na + / NH + 4 transporters. The hepatosomatic index had an increase in salinities of 30 (3 days) and 40 (30 days) due to a possible accumulation of reserves in stressful situations. The energy substrate and the osmoregulatory pattern remained unchanged in all treatments. However, the Cl- and Na + concentrations were reduced at the salinity of 25 and 35 (30 days), probably due to some changes in their transporters. Molecularly, a regulation of Na + / K + ATPase expression was observed, with a decrease in salinities of 35 and 40 (3 days), and a subsequent increase in the period of 30 days. The work was the first to evaluate the physiological and molecular parameters of C.danae in different salinities. Animals that remained longer on exposure to high pCO2 are more negatively affected than animals that were exposed in 3 days. The observed changes may indicate that although C. danae is an eurialan animal and inhabits different environments, ocean acidification can alter its physiological and molecular patterns, taking organisms out of their homeostasis, having consequences on the growth, development and distribution of the species.

Continue reading ‘Analysis of Na+/K+ -ATPase gene expression and physiological parameters in the crab Callinectes danae submitted to future scenarios of ocean acidification in the laboratory (in Portuguese)’

Variability and trends in surface seawater pCO2 and CO2 flux in the Pacific Ocean

Variability and change in the ocean sink of anthropogenic carbon dioxide (CO2) have implications for future climate and ocean acidification. Measurements of surface seawater CO2 partial pressure (pCO2) and wind speed from moored platforms are used to calculate high‐resolution CO2 flux time series. Here we use the moored CO2 fluxes to examine variability and its drivers over a range of time scales at four locations in the Pacific Ocean. There are significant surface seawater pCO2, salinity, and wind speed trends in the North Pacific subtropical gyre, especially during winter and spring, which reduce CO2 uptake over the 10 year record of this study. Starting in late 2013, elevated seawater pCO2 values driven by warm anomalies cause this region to be a net annual CO2 source for the first time in the observational record, demonstrating how climate forcing can influence the timing of an ocean region shift from CO2 sink to source.

Continue reading ‘Variability and trends in surface seawater pCO2 and CO2 flux in the Pacific Ocean’

Two threatened Caribbean coral species have contrasting responses to combined temperature and acidification stress

There is growing evidence that different coral species and algal symbionts (Symbiodinium spp.) can vary greatly in their response to rising temperatures and also ocean acidification. In a fully crossed factorial experimental design, two threatened Caribbean reef‐building coral species, Acropora cervicornis hosting a mixture of Symbiodinium clades A and C and Orbicella faveolata hosting Symbiodinium D, were exposed to combinations of a normal (26°C) and elevated (32°C) temperature and normal (380 ppm) and elevated (800 ppm) CO2 for 62 d and then recovered at 26°C and 380 ppm or 32°C and 380 ppm for an additional 56 d. CO2 enrichment did not confer enhanced thermal tolerance as had been suggested in other studies. A. cervicornis was more sensitive to heat stress (maximum monthly mean + 1.5°C) experiencing 100% mortality after 25 d while all O. faveolata survived. Conversely, O. faveolata was more sensitive to high CO2 experiencing a 47% reduction in growth while A. cervicornis experienced no significant reduction. It is predicted that A. cervicornis is unlikely to survive past 2035. O. faveolata with D symbionts might survive to 2060 and later but its abundance will be impacted by CO2 effects on recruitment potential.

Continue reading ‘Two threatened Caribbean coral species have contrasting responses to combined temperature and acidification stress’

Aragonite saturation state variation and control in the river-dominated marginal BoHai and Yellow seas of China during summer

Highlights

• Dynamics of seawater Ωarag were investigated in the BoHai and Yellow seas.
• Riverine freshwater input decreased Ωarag in the Changjiang and Yalu river estuaries.
• Freshwater input from the Yellow River induced high Ωarag in the estuary.
• Seawater with Ωarag above 2.0 will likely disappear by the year 2100.

Abstract

Based on a survey conducted from June to July 2013, aragonite saturation state variation and control in the river-dominated marginal BoHai and Yellow seas were investigated. Surface water Ωarag ranged from 2.0–3.8, whereas subsurface water Ωarag was generally lower than 2.0. Temperature changes had a strong influence on Ωarag through induced CO2 solubility changes in seawater. Riverine freshwater input decreased Ωarag in the Changjiang and Yalu river estuaries, but induced higher Ωarag in the Yellow River estuary. Biological processes had opposite effects on Ωarag, whereby elevated biological production led to the highest Ωarag in the South Yellow Sea surface water, whereas net community respiration/remineralization induced low Ωarag in subsurface water. Stratification affected the level and scale of low Ωarag in subsurface water. By the year 2100, surface water with Ωarag > 2.0 will disappear except for the Yellow River estuary, and most of the subsurface water will develop substantial aragonite undersaturation.

Continue reading ‘Aragonite saturation state variation and control in the river-dominated marginal BoHai and Yellow seas of China during summer’

Delineation of metals and radionuclides bioconcentration in eggs of seabream Sparus aurata and effect of environmental pCO2

Highlights

• The uptake of Ag, Am, Cd, Co and Zn has been delineated in seabream eggs.
• The 110mAg is strongly accumulated and retained in embryo and larvae, respectively.
• We tested the effect of seawater acidification on radionuclides bioaccumulation.
• The 60Co and 65Zn concentration factors seem to be enhanced with increasing pCO2.
• Our results raise the question of increased risk toward ionizing radiation for fish embryo.

Abstract

Considered as the most vulnerable ontogenic stages to environmental stressors, the early-life stages of fish paid a peculiar attention with respect to their vulnerability to metal and radionuclides contamination. Concomitantly, the increasing anthropogenic CO2 release in the atmosphere will cause major change of the seawater chemistry that could affect the trace elements and radionuclides bioconcentration efficiencies by marine organisms. The aim of this work was to 1) delineate the uptake behaviours of Ag, Am, Cd, Co and Zn in seabream eggs during 65 h of development and retention by newly hatched and 7 h-old larvae maintained in clean seawater, respectively, and 2) investigate the effects of elevated pCO2 on the bioconcentration efficiencies of these elements in eggs. Besides differing in terms of maximal concentration factors values, the uptake kinetics showed element-specific patterns with Am being linearly bioconcentrated and Co and Zn showing a saturation state equilibrium. The 110mAg and 109Cd uptake kinetics shared a two-phases pattern being best described by a saturation equation during the first 24 h of development, and then an exponential loss of accumulated elements although the radiotracer concentrations in the surrounding water remained constant. At hatching time, the radioactivity of 110mAg was the highest among radiotracers detected in the larvae. After 7 h in depuration conditions, 60% of this metal was still detected whereas 241Am, 60Co and 65Zn were almost totally lost, suggesting an efficient incorporation of Ag in the embryo during the egg development. Finally, this study brought first qualitative data on the effect of pCO2/pH on metal bioconcentration in eggs, raising the need to unravel chemical and biological processes to predict a potential shift of the toxicity of environmental contamination of fish early life stages with future ocean change.

Continue reading ‘Delineation of metals and radionuclides bioconcentration in eggs of seabream Sparus aurata and effect of environmental pCO2’

Photoperiod mediates the effects of elevated CO2 on the growth and physiological performance in the green tide alga Ulva prolifera

Highlights

• Grown rate of U. prolifera was significantly enhanced by increased CO2 under the three light:dark regimes, indicating that growth was C-unsaturated at present CO2 levels.
U. prolifera showed a significantly higher growth rate and lower dark respiration rate under longer daylength conditions.

Abstract

Ulva spp., an increasingly important food, are the dominant species of the large-scale green tides. In this study, both the growth and the physiological responses of the Ulva prolifera were studied after cultured in three different light and dark regimes (12:12, 14:10 and 16:8-h light/dark) in combination with current (420 μatm; LC) and increased (1000 μatm; HC) levels of atmospheric CO2. Grown rate of U. prolifera was significantly enhanced by increased CO2 under the three light:dark regimes, especially under 16:8 h-light:dark, indicating that growth was C-unsaturated at present CO2 levels. U. prolifera showed a significantly higher growth rate and lower dark respiration rate (Rd) at 16:8 h-light:dark treatment than at 12:12 h-light/dark treatment, regardless of the CO2 treatment. The photochemical performance was largely unaffected by elevated CO2 and daylength. These results suggest that U. prolifera in a future CO2 enriched coastal water, seems to be resilient to higher CO2 concentrations, and this could be enhanced by longer daylength.

Continue reading ‘Photoperiod mediates the effects of elevated CO2 on the growth and physiological performance in the green tide alga Ulva prolifera’

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

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 July 2018 edition covers topic such as kelp mitigation, OA and coralline algae, mussels, Pebble Mine, carbon policy, the NSA Annual Meeting, copepods, The Ocean Foundation, and more.

Go to report.

Effects of ocean acidification on 109Cd, 57Co, and 134Cs bioconcentration by the European oyster (Ostrea edulis): Biokinetics and tissue-to-subcellular partitioning

Highlights

• A decrease in pH does not affect the uptake kinetics of 109Cd and 57Co, nor the   depuration of 109Cd and 134Cs.
• Depuration kinetics of 57Co is modified as pC02 conditions change.
• No variation in the subcellular sequestration of these three trace elements under low pH conditions.
• A systematic bleaching of the oyster shells was observed with a drop in pH over 40 days.

Abstract

The uptake and depuration kinetics of dissolved 109Cd, 57Co and 134Cs were determined experimentally in the European flat oyster Ostrea edulis (Linnaeus, 1758) under different pH conditions (i.e., 8.1, 7.8 and 7.5) for 59 days. Uptake and depuration rates were variable within these elements; no effects were observed under different pH conditions for the uptake biokinetics of 109Cd and 57Co and depuration of 109Cd and 134Cs in oyster. The uptake and depuration rate constants of 134Cs differed during the exposure phase between treatments, while the steady state concentration factors (CFss) were similar. The resulting Cs activity that was purged during short- and long-term depuration phases differed, while the remaining activities after thirty-nine days depuration phase (RA39d) were similar. Co-57 depuration was affected by pCO2 conditions: RA39d were found to be significantly higher in oysters reared in normocapnia (pCO2 = 350 μatm) compared to high pCO2 conditions. Co-57 tissue distribution did not differ among the variable pCO2 conditions, while 109Cd and 134Cs accumulated in soft tissue of oysters were found to be higher under the highest pCO2. Additionally, Cd, Co and Cs were stored differently in various compartments of the oyster cells, i.e. cellular debris, metal-rich granules (MRG) and metallothionein-like proteins (MTLP), respectively. The subcellular sequestration of the elements at the end of the depuration phase did not differ among pH treatments. These results suggest that bioconcentration and tissue/subcellular distribution are element-specific in the oyster, and the effects of higher pCO2 driven acidification and/or coastal acidification variably influence these processes.

Continue reading ‘Effects of ocean acidification on 109Cd, 57Co, and 134Cs bioconcentration by the European oyster (Ostrea edulis): Biokinetics and tissue-to-subcellular partitioning’

The impact of ocean acidification and cadmium on the immune responses of Pacific oyster, Crassostrea gigas

Highlights

•  Inhibited phagocytosis rate, combined with increased DNA damage, apoptosis rate and ROS production of hemocytes were observed in oysters under exposure to Cd exposure alone or combined with OA.
•  Significant interactive effects between OA and Cd were observed on ROS production and DNA damage of hemocytes.
•  mRNA expression of genes related to immune responses (TLR pathway and immune factors) was stimulated in oysters exposed to Cd and OA at pH 7.6.

Abstract

Seawater acidification (OA) and cadmium (Cd) has the potential to lead to immunosuppression effect on marine bivalves. However, the interaction between these two environmental stressors on immune system of marine bivalves has received limited attention. In order to evaluate the defense responses of oysters under the combined exposure to OA and cadmium, the oysters Crassostrea gigas were exposed to 10 μg/L Cd at three pH levels (8.1, 7.8 and 7.6) for 31 days. Results showed that OA exposure alone led to increased DNA damage, apoptosis rate and ROS production of hemocytes. However, inhibited phagocytosis rate, combined with increased DNA damage, apoptosis rate and ROS production of hemocytes were observed in oysters under exposure to Cd exposure alone or combined with OA. Significant interactive effects between OA and Cd were observed on ROS production and DNA damage of hemocytes. In addition, there is generally significant increase in the mRNA expression of genes related to immune-related TLR pathway and two immune factors (TNF and integrin beta-1B) in Cd-exposed oysters at pH 7.6. The results revealed that even though the mRNA expression of genes related to immune responses (TLR pathway and immune factors) was stimulated to counteract the immunosuppression caused by acidified seawater and Cd, depressed hemocyte function perhaps sensitized oysters to potential pathogen infection.

Continue reading ‘The impact of ocean acidification and cadmium on the immune responses of Pacific oyster, Crassostrea gigas’

The future doesn’t smell great for fish

Fish may find it harder to use their noses to navigate and find mates or food as the oceans absorb more carbon dioxide.

Continue reading ‘The future doesn’t smell great for fish’


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