Archive for December, 2019

Carbon emissions causing California waters to acidify twice as fast as global average, study says

Scientists have issued a stark new warning about climate change in a study that shows waters off the coast of California are acidifying two times faster than the global average.

The first-of-its-kind study by researchers from the National Oceanic and Atmospheric Administration (NOAA) used thousands of tiny shells called foraminifera pulled from the seafloor outside of Santa Barbara to create a snapshot.

‘By measuring the thickness of the shells, we can provide a very accurate estimate of the ocean’s acidity level when the foraminifera were alive,’ said lead author Emily Osborne.

Continue reading ‘Carbon emissions causing California waters to acidify twice as fast as global average, study says’

Elevated CO2 and food ration affect growth but not the size-based hierarchy of a reef fish

Under projected levels of ocean acidification, shifts in energetic demands and food availability could interact to effect the growth and development of marine organisms. Changes to individual growth rates could then flow on to influence emergent properties of social groups, particularly in species that form size-based hierarchies. To test the potential interactive effects of (1) food availability, (2) elevated CO2 during juvenile development, and (3) parental experience of elevated CO2 on the growth, condition and size-based hierarchy of juvenile fish, we reared orange clownfish (Amphiprion percula) for 50 days post-hatching in a fully orthogonal design. Development in elevated CO2 reduced standard length and weight of juveniles, by 9% and 11% respectively, compared to ambient. Development under low food availability reduced length and weight of juveniles by 7% and 15% respectively, compared to high food. Parental exposure to elevated CO2 restored the length of juveniles to that of controls, but it did not restore weight, resulting in juveniles from elevated CO2 parents exhibiting 33% lower body condition when reared in elevated CO2. The body size ratios (relative size of a fish from the rank above) within juvenile groups were not affected by any treatment, suggesting relative robustness of group-level structure despite alterations in individual size and condition. This study demonstrates that both food availability and elevated CO2 can influence the physical attributes of juvenile reef fish, but these changes may not disrupt the emergent group structure of this social species, at least amongst juveniles.

Continue reading ‘Elevated CO2 and food ration affect growth but not the size-based hierarchy of a reef fish’

Climate change and harmful algal blooms: insights and perspective

Highlights

• Climate change is transforming aquatic ecosystems.

• Coastal waters have experienced progressive warming, acidification, and deoxygenation.

• The impacts of harmful algal blooms (HABs) on coastal systems have increased in recent decades.

• HABs display an expansion in range and frequency in response to climatic and non-climatic drivers.

• This Special Issue considers linkages between climate change and HABs.

Abstract

Climate change is transforming aquatic ecosystems. Coastal waters have experienced progressive warming, acidification, and deoxygenation that will intensify this century. At the same time, there is a scientific consensus that the public health, recreation, tourism, fishery, aquaculture, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past several decades. The extent to which climate change is intensifying these HABs is not fully clear, but there has been a wealth of research on this topic this century alone. Indeed, the United Nations’ Intergovernmental Panel on Climate Change’s (IPCC) Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) approved in September 2019 was the first IPCC report to directly link HABs to climate change. In the Summary for Policy Makers, the report made the following declarations with “high confidence”:

• Harmful algal blooms display range expansion and increased frequency in coastal areas since the 1980s in response to both climatic and non-climatic drivers such as increased riverine nutrients run-off.

• The observed trends in harmful algal blooms are attributed partly to the effects of ocean warming, marine heatwaves, oxygen loss, eutrophication and pollution.

• Harmful algal blooms have had negative impacts on food security, tourism, local economy, and human health.

In addition, the report specifically outlines a series of linkages between heat waves and HABs. These statements about HABs and climate change and the high levels of confidence ascribed to them provides clear evidence that the field of HABs and climate change has matured and has, perhaps, reached a first plateau of certainty. While there are well-documented global trends in HABs being promoted by human activity, including climate change, individual events are driven by local, regional, and global drivers, making it critical to carefully evaluate the conditions and responses at appropriate scales. It is within this context that the first Special Issue on Climate Change and Harmful Algal Blooms is published in Harmful Algae.

Continue reading ‘Climate change and harmful algal blooms: insights and perspective’

Ocean alkalinity, buffering and biogeochemical processes

Alkalinity, the excess of proton acceptors over donors, plays a major role in ocean chemistry, buffering and calcium carbonate precipitation and dissolution. Understanding alkalinity dynamics is pivotal to quantify ocean carbon dioxide uptake during times of global change. Here we review ocean alkalinity and its role in ocean buffering as well as the biogeochemical processes governing alkalinity and pH in the ocean. We show that it is important to distinguish between measurable titration alkalinity and charge-balance alkalinity that is used to quantify calcification and carbonate dissolution and needed to understand the impact of biogeochemical processes on components of the carbon dioxide system. A general treatment of ocean buffering and quantification via sensitivity factors is presented and used to link existing buffer and sensitivity factors. The impact of individual biogeochemical processes on ocean alkalinity and pH is discussed and quantified using these sensitivity factors. Processes governing ocean alkalinity on longer time scales such as carbonate compensation, (reversed) silicate weathering and anaerobic mineralization are discussed and used to derive a close-to-balance ocean alkalinity budget for the modern ocean.

Continue reading ‘Ocean alkalinity, buffering and biogeochemical processes’

Seabream larval physiology under ocean warming and acidification

The vulnerability of early fish stages represents a critical bottleneck for fish recruitment; therefore, it is essential to understand how climate change affects their physiology for more sustainable management of fisheries. Here, we investigated the effects of warming (OW; +4 °C) and acidification (OA; ΔpH = 0.5) on the heart and oxygen consumption rates, metabolic enzymatic machinery—namely citrate synthase (CS), lactate dehydrogenase (LDH), and ß-hydroxyacyl CoA dehydrogenase (HOAD), of seabream (Sparus aurata) larvae (fifteen days after hatch). Oxygen consumption and heart rates showed a significant increase with rising temperature, but decreased with pCO2. Results revealed a significant increase of LDH activity with OW and a significant decrease of the aerobic potential (CS and HOAD activity) of larvae with OA. In contrast, under OA, the activity levels of the enzyme LDH and the LDH:CS ratio indicated an enhancement of anaerobic pathways. Although such a short-term metabolic strategy may eventually sustain the basic costs of maintenance, it might not be adequate under the future chronic ocean conditions. Given that the potential for adaptation to new forthcoming conditions is yet experimentally unaccounted for this species, future research is essential to accurately predict the physiological performance of this commercially important species under future ocean conditions. View Full-Text

Continue reading ‘Seabream larval physiology under ocean warming and acidification’

The magnitude of surface ocean acidification and carbon release during Eocene Thermal Maximum 2 (ETM‐2) and the Paleocene–Eocene Thermal Maximum (PETM)

Eocene Thermal Maximum 2 (ETM‐2; 54.1 Ma) was the second largest Eocene hyperthermal. Like the Paleocene–Eocene Thermal Maximum (PETM), ETM‐2 was characterized by massive carbon emissions and several degrees of global warming, thus can serve as a case study for assessing the impacts of rapid CO2 emissions on ocean carbonate chemistry, biota and climate. Marine carbonate records of ETM‐2 are better preserved than those of the PETM due to more subdued carbonate dissolution. As yet, however, the magnitude of this carbon cycle perturbation has not been well constrained. Here, we present the first records of surface ocean acidification for ETM‐2, based on stable boron isotope records in mixed‐layer planktic foraminifera from two mid‐latitude ODP Sites (1210 in the N. Pacific and 1265 in the S.E. Atlantic), which indicate conservative minimum global sea surface acidification of –0.20 +0.12/–0.13 pH units. Using these estimates of pH and temperature as constraints on carbon cycle model simulations, we conclude that the total mass of C, released over a period of 15 to 25 kyr during ETM‐2, likely ranged from 2,600 to 3,800 Gt C, which is greater than previously estimated on the basis of other observations (i.e., stable carbon isotopes and carbonate compensation depth) alone.

Continue reading ‘The magnitude of surface ocean acidification and carbon release during Eocene Thermal Maximum 2 (ETM‐2) and the Paleocene–Eocene Thermal Maximum (PETM)’

Analysis of effects of environmental fluctuations on the marine mysid Neomysis awatschensis and its development as an experimental model animal

Highlights

• Investigation of optimized culture conditions in temperature, salinity, and pH for mysid mass-culture and development as a laboratory model

• Identification of strong correlations between growth parameter and 20E level in environmental fluctuations

• Measurement of maternal effects of environmental fluctuations on second generation

Abstract

Mysids are experimental models and are among the most important food items for animals in aquaria and that support fisheries, and even for humans, but information on their performance in controlled culture systems is still limited. We reared the marine mysid Neomysis awatschensis in a controlled laboratory system, and measured its growth, 20–hydroxyecdysone (20E) levels, molting, and survival in response to environmental fluctuations in temperature, pH, and salinity, and inferred their potential associations based on annual field sampling. The 20E levels were significantly elevated during the postnauplioid stages, and even higher levels of 20E were maintained in the adult stages than in the nauplioid stages. Values of growth parameters (i.e. total length and the lengths of the antennal scale, expod, endopod, and telson) and 20E levels were higher during a 40-day period at 25 °C than at other temperatures, with shorter intermolt intervals, although morality was also increased. Among the surviving mysids, the number of newly hatched juveniles produced was higher for females exposed to 20 °C than that in other groups. Relatively higher growth and survival rates were measured at salinities over 25 practical salinity, while lower salinities under 15 practical salinity significantly reduced growth and survival. The number of newly hatched juveniles was lower at salinities under 15 practical salinity compared to those over 20 practical salinity. Overall, low temperature and salinity reduced mysid reproduction and the maintenance of the second generation. In the case of pH variation (pH of 7.0–8.0), there were no significant effects on growth and the number of newly hatched juveniles, although the survival rate was slightly lower and the 20E level fluctuated at a pH of 7.0. We believe that these associations between growth and environmental conditions can provide crucial information for optimizing mass mysid culture for experimental and ecotoxicological usage in the laboratory.

Continue reading ‘Analysis of effects of environmental fluctuations on the marine mysid Neomysis awatschensis and its development as an experimental model animal’

Mitigation effects of CO2-driven ocean acidification on Cd toxicity to the marine diatom Skeletonema costatum

Highlights

• OA significantly alleviated the toxicity of Cd to S. costatum.

• OA rescued S. costatum from inhibition of Cd on photosynthesis and pyruvate metabolism.

• OA detoxified Cd through upregulating genes in production of non-protein thiol compounds.

Abstract

Ocean acidification (OA) is a global problem to marine ecosystems. Cadmium (Cd) is a typical metal pollutant, which is non-essential but extremely toxic to marine organisms. The combined effects of marine pollution and climate-driven ocean changes should be considered for the effective marine ecosystem management of coastal areas. Previous reports have separately investigated the influences of OA and Cd pollution on marine organisms. However, little is known of the potential combined effects of OA and Cd pollution on marine diatoms. We investigated the sole and combined influences of OA (1,500 ppm CO2) and Cd exposure (0.4 and 1.2 mg/L) on the coastal diatom Skeletonema costatum. Our results clearly showed that OA significantly alleviated the toxicity of Cd to S. costatum growth and mitigated the oxidant stress, although the intercellular Cd accumulation still increased. OA partially rescued S. costatum from the inhibition of photosynthesis and pyruvate metabolism caused by Cd exposure. It also upregulated genes involved in gluconeogenesis, glycolysis, the citrate cycle (TCA), Ribonucleic acid (RNA) metabolism, and especially the biosynthesis of non-protein thiol compounds. These changes might contribute to algal growth and Cd resistance. Overall, this study demonstrates that OA can alleviate Cd toxicity to S. costatum and explores the potential underlying mechanisms at both the cellular and molecular levels. These results will ultimately help us understand the impacts of combined stresses of climate change and metal pollution on marine organisms and expand the knowledge of the ecological risks of OA.

Continue reading ‘Mitigation effects of CO2-driven ocean acidification on Cd toxicity to the marine diatom Skeletonema costatum’

Elevated CO2 affects anxiety but not a range of other behaviours in juvenile yellowtail kingfish

Highlights

  • The effects of elevated CO2 on behaviours of kingfish were trait specific.
  • Elevated CO2 increased anxiety in kingfish.
  • Exposure to high temperature in isolation had no significant effect on any trait.

Abstract

Elevated seawater CO2 can cause a range of behavioural impairments in marine fishes. However, most studies to date have been conducted on small benthic species and very little is known about how higher oceanic CO2 levels could affect the behaviour of large pelagic species. Here, we tested the effects of elevated CO2, and where possible the interacting effects of high temperature, on a range of ecologically important behaviours (anxiety, routine activity, behavioural lateralization and visual acuity) in juvenile yellowtail kingfish, Seriola lalandi. Kingfish were reared from the egg stage to 25 days post-hatch in a full factorial design of ambient and elevated CO2 (∼500 and ∼1000 μatm pCO2) and temperature (21 °C and 25 °C). The effects of elevated CO2 were trait-specific with anxiety the only behaviour significantly affected. Juvenile S. lalandi reared at elevated CO2 spent more time in the dark zone during a standard black-white test, which is indicative of increased anxiety. Exposure to high temperature had no significant effect on any of the behaviours tested. Overall, our results suggest that juvenile S. lalandi are largely behaviourally tolerant to future ocean acidification and warming. Given the ecological and economic importance of large pelagic fish species more studies investigating the effect of future climate change are urgently needed.

Continue reading ‘Elevated CO2 affects anxiety but not a range of other behaviours in juvenile yellowtail kingfish’

Ocean acidification project at MMA (video)

NOAA experiment uses Mass Maritime Aquacuture lab

Continue reading ‘Ocean acidification project at MMA (video)’


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