Archive for April, 2013

UW researchers conduct ocean acidification experiment

The world’s oceans are always changing, and with ocean acidification adding to this process, it is unclear how these changes will affect oceanic and terrestrial life.

This is what James Murray, a UW chemical oceanography professor, hopes to clarify.

Murray is working with several researchers and students at the UW marine research facility in Friday Harbor to conduct a quarter-long experiment centered on the use of mesocosms. This is the third experiment of its kind performed at Friday Harbor, which remains the only place in the United States to use this technique.

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Across time and space: implications of ocean acidification

Ocean acidification has been a hot topic in Willapa since 2005, but the implications that ocean acidification has on marine ecosystems is global in scope. A study done by Havenhand et al. (2008) found that gametes and larvae of sea urchins are negatively impacted by -0.4 pH units (the upper limit of predictions for 2100). The effects included significant reductions in sperm speed and motility. These species are commonly found in the southern inshore waters of Australia. It is interesting to note, that this is a future projected analysis, thus, these affects are not occurring momentarily. A study done by Anthony et al. (2008) found that an increase of CO2 induces coral bleaching, and productivity. Furthermore, the same study found that ocean acidification impacts bleaching and productivity more than it impacts calcification. Similarly to Havenhand et al (2008), this study also manipulated CO2 levels to simulate IPCC’s projected increases for 2100.

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Major pan-European study conducted on ocean acidification

More than 160 researchers across 10 European countries joined together, in what is being hailed as the first international project to focus on ocean acidification and its consequences.

According to the partners in the EPOCA project (‘European Project on Ocean Acidification’) marine research was a relatively new field when they initiated the project four years ago. It brought together scientists who were concerned about the possible risks associated with ocean acidification for marine organisms and ecosystems.

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Call for members for the new Ocean Acidification international Reference User Group (OA-iRUG)

The Chair and Deputy Chair of the new Ocean Acidification international Reference User Group (OA-iRUG) welcome nominations for members of this group before 6 May.

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Interactive effects of global climate change and pollution on marine microbes: the way ahead

Global climate change has the potential to seriously and adversely affect marine ecosystem functioning. Numerous experimental and modeling studies have demonstrated how predicted ocean acidification and increased ultraviolet radiation (UVR) can affect marine microbes. However, researchers have largely ignored interactions between ocean acidification, increased UVR and anthropogenic pollutants in marine environments. Such interactions can alter chemical speciation and the bioavailability of several organic and inorganic pollutants with potentially deleterious effects, such as modifying microbial-mediated detoxification processes. Microbes mediate major biogeochemical cycles, providing fundamental ecosystems services such as environmental detoxification and recovery. It is, therefore, important that we understand how predicted changes to oceanic pH, UVR, and temperature will affect microbial pollutant detoxification processes in marine ecosystems. The intrinsic characteristics of microbes, such as their short generation time, small size, and functional role in biogeochemical cycles combined with recent advances in molecular techniques (e.g., metagenomics and metatranscriptomics) make microbes excellent models to evaluate the consequences of various climate change scenarios on detoxification processes in marine ecosystems. In this review, we highlight the importance of microbial microcosm experiments, coupled with high-resolution molecular biology techniques, to provide a critical experimental framework to start understanding how climate change, anthropogenic pollution, and microbiological interactions may affect marine ecosystems in the future.

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Effects of ocean acidification on the larval growth of olive flounder (Paralichthys olivaceus)

Little is known about how marine fishes respond to the reduced pH condition caused by the increased CO2 in the atmosphere. We investigated the effects of CO2 concentration on the growth of olive flounder (Paralichthys olivaceus) larvae. Newly hatched larvae were reared in three different concentrations of CO2 (574, 988 and 1297 μatm CO2) in temperature-controlled water tanks until metamorphosis (4 weeks). Body lengths, weights, and the concentration of some chemical elements in larval tissue were measured at the completion of each experiment, and experiment was repeated three times in May, June, and July 2011. Results indicated that body length and weight of flounder larvae were significantly increased with increasing CO2 concentration (P < 0.05). Daily growth rates of flounder larvae were higher (0.391 mm) from the high CO2 concentration (1297 μatm) than those (0.361 mm and 0.360 mm) from the lower ones (988 and 574 μatm).The measurement on some chemical elements (Ca, Fe, Cu, Zn and Sr) in fish tissue also revealed the increasing tendency of element concentration with increasing CO2 in seawater, although statistical significance cannot be tested due to the single measurement. It suggests that there are enrichment processes of these cations in larval tissue in the low pH condition.

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Sensitivity of Antarctic phytoplankton species to ocean acidification: growth, carbon acquisition, and species interaction

Despite the fact that ocean acidification is considered to be especially pronounced in the Southern Ocean, little is known about CO2-dependent physiological processes and the interactions of Antarctic phytoplankton key species. We therefore studied the effects of CO2 partial pressure (PCO2) (16.2, 39.5, and 101.3 Pa) on growth and photosynthetic carbon acquisition in the bloom-forming species Chaetoceros debilis, Pseudo-nitzschia subcurvata, Fragilariopsis kerguelensis, and Phaeocystis antarctica. Using membrane-inlet mass spectrometry, photosynthetic O2 evolution and inorganic carbon (Ci) fluxes were determined as a function of CO2 concentration. Only the growth of C. debilis was enhanced under high PCO2. Analysis of the carbon concentrating mechanism (CCM) revealed the operation of very efficient CCMs (i.e., high Ci affinities) in all species, but there were species-specific differences in CO2-dependent regulation of individual CCM components (i.e., CO2 and uptake kinetics, carbonic anhydrase activities). Gross CO2 uptake rates appear to increase with the cell surface area to volume ratios. Species competition experiments with C. debilis and P. subcurvata under different PCO2 levels confirmed the CO2-stimulated growth of C. debilis observed in monospecific incubations, also in the presence of P. subcurvata. Independent of PCO2, high initial cell abundances of P. subcurvata led to reduced growth rates of C. debilis. For a better understanding of future changes in phytoplankton communities, CO2-sensitive physiological processes need to be identified, but also species interactions must be taken into account because their interplay determines the success of a species.

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Effects of sub-lethal CO2(aq) concentrations on the performance of intensively reared gilthead seabream (Sparus aurata) in brackish water: flow-through experiments and full-scale RAS results

The effects sub-lethal CO2(aq) concentrations were tested for the first time on gilthead seabream (Sparus aurata) juveniles (4 to 25 g; 64 growth days) and adult (∼300-400 g; 71 days) fish, both in fully controlled pilot tests and the latter also as part of full-scale RAS (recirculating aquaculture system) operation. In the pilot experiments (concentration range 5.2 to 56.3 mgCO2/L) the specific growth rate, mortality rate, and physical fish disorders were monitored. In the full scale experiment, two groups of fish, originally from the same batch, were exposed for 197 days to controlled (by NaOH dosage) and uncontrolled pH conditions, resulting in exposure of the fish to significantly different CO2(aq) concentrations. The pilot results showed, as expected, that the seabream fish grew faster at the lower CO2 concentrations and that the growth rate of both juveniles and adult fish was only minimally inhibited up to roughly 20 mg CO2/L (compared to a previously published curve). Mortality rate was considerable only at the highest CO2 concentration (∼56 mgCO2/L). Physical irregularities were not observed, apart from abnormally-high absence of swim bladder at the highest CO2(aq) treatment. The (statistically significant) results from the full-scale RAS operation showed that growing gilthead seabream for 197 days at roughly constant and relatively low (∼16 mg/L) CO2(aq) concentration resulted in fish with ∼10% larger mean weight relative to the fish grown in ponds in which CO2(aq) was not controlled and its concentration fluctuated daily between 19 and 37 mg/L.

Continue reading ‘Effects of sub-lethal CO2(aq) concentrations on the performance of intensively reared gilthead seabream (Sparus aurata) in brackish water: flow-through experiments and full-scale RAS results’

Ozeanversauerung – Der böse Zwilling der Klimaerwärmung (in German)

Zehn Jahre bevor die Fachwelt überhaupt einen Begriff für das Phänomen hatte, erforschten Wissenschaftler am Alfred-Wegener-Institut bereits die Ursachen der Ozeanversauerung. Früh hatten sie erkannt, dass der steigende Anteil von Kohlendioxid in der Luft auch die Chemie der Ozeane verändern würde. Jetzt wollen sie herausfinden, wie sich das saurere Meerwasser auf seine Bewohner auswirkt – und letztlich auch auf uns Menschen.

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Ocean acidification – the evil twin of climate warming

Ten years before the professional world had even found a name for the phenomenon, scientists at the Alfred Wegener Institute were already exploring the causes for ocean acidification. They recognised early on that the growing content of carbon dioxide in the air would also change the chemistry of the oceans. They now wish to find out how the acidic seawater affects its inhabitants and ultimately also humans.

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Ocean acidification in the IPCC AR5 WG II

OUP book