Archive for July, 2013

Minor impact of ocean acidification to the composition of the active microbial community in an Arctic sediment

Effects of ocean acidification on the composition of the active bacterial and archaeal community within Arctic surface sediment was analysed in detail using 16S rRNA 454 pyrosequencing. Intact sediment cores were collected and exposed to one of five different pCO2 concentrations (380 (present day), 540, 750, 1120 and 3000 μatm) and RNA extracted after a period of 14 days exposure. Measurements of diversity and multivariate similarity indicated very little difference between pCO2 treatments. Only when the highest and lowest pCO2 treatments were compared were significant differences evident, namely increases in the abundance of OTUs most closely related to the Halobacteria and differences to the presence/absence structure of the Planctomycetes. The relative abundance of members of the classes Planctomycetacia and Nitrospira increased with increasing pCO2 concentration, indicating that these groups may be able to take advantage of changing pH or pCO2 conditions. The modest response of the active microbial communities associated with these sediments may be due to the low and fluctuating pore-water pH already experienced by sediment microbes, a result of the pH buffering capacity of marine sediments, or due to currently unknown factors. Further research is required to fully understand the impact of elevated CO2 on sediment physico-chemical parameters, biogeochemistry and microbial community dynamics.

Continue reading ‘Minor impact of ocean acidification to the composition of the active microbial community in an Arctic sediment’

Lyckat experiment om havsförsurning avslutat (in Swedish)

Den 26 juni hade KOSMOS-teamet, efter 107 dagars provtagning, den sista och därmed avslutades fem månader intensivt arbete för gruppen. Under lördagen den 20 juli plockades de sista mesokosmerna upp ur Gullmarn och den experimentella delen av KOSMOS 2013 är därmed avslutad. Sedan vintern har 69 forskare från 12 länder deltagit i en av världens största studier av havsförsurningens effekt på planktonsamhället.

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Eine Reise in den Ozean der Zukunft (in German)

Fünfmonatiges Experiment zu Auswirkungen der Ozeanversauerung erfolgreich beendet

22.07.2013/Kiel, Kristineberg. Wie reagiert die marine Lebensgemeinschaft auf die Ozeanversauerung? Können sich Ökosysteme im Meer an veränderte Umweltbedingungen anpassen? In einem bislang einmaligen Langzeit-Experiment untersuchten 69 Wissenschaftler unter der Leitung des GEOMAR Helmholtz-Zentrums für Ozeanforschung Kiel, wie sich die Planktongemeinschaft und Fischlarven im saureren Wasser entwickeln. Nach dem erfolgreichen Abschluss der Studie bringt das deutsche Forschungsschiff ALKOR jetzt die zehn KOSMOS Mesokosmen und umfangreiches Probenmaterial zurück nach Kiel. Die Arbeiten fanden im Rahmen des deutschen Forschungsprojekts zur Ozeanversauerung BIOACID (Biological Impacts of Ocean ACIDification) statt.

Continue reading ‘Eine Reise in den Ozean der Zukunft (in German)’

A journey into the future ocean

Five-months long experiment on the effects of ocean acidification successfully complete

22.07.2013/Kiel, Kristineberg. How do marine ecosystems respond to ocean acidification? Can marine communities adapt to a changing environment? In an unprecedented long-term experiment, 69 scientists from 12 European research institutes and universities studied the development of the plankton community and fish larvae in acidified waters. After the successful completion of the study, the German research vessel ALKOR returns the ten KOSMOS mesocosms and a large number of samples to Kiel. The work was carried out in the framework of the German project on ocean acidification BIOACID (Biological Impacts of Ocean ACIDification), and lead by GEOMAR Helmholtz Centre for Ocean Research Kiel.

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Evidence of prolonged aragonite undersaturations in the bottom waters of the southern Bering Sea shelf from autonomous sensors

The southeastern shelf of the Bering Sea is a dynamic area that experiences seasonal variability in primary production and remineralization of organic matter, both of which control the carbon biogeochemistry of the water column. Surface-water partial pressure of carbon dioxide (pCO2) is greatly reduced in summer by biological production, which increases carbonate mineral saturation states (Ω). In contrast, the export of large quantities of organic matter from surface blooms drives an active remineralization loop that sharply increases pCO2 near the bottom, lowering pH and suppressing Ω. New observations from moored biogeochemical sensors in 2011 showed that seasonal net community production lowers surface-water pCO2, causing large gradients between the ocean and atmosphere that are sustained throughout the summer, confirming that these waters likely remain supersaturated with respect to aragonite throughout the open-water season. On the other hand, moored sensors deployed near the bottom showed that pCO2 levels exceed 500 μatm by early June and remain at these high levels well into the autumn months, indicating that the bottom waters are likely continuously undersaturated in aragonite for at least several months during each year. Only a small fraction of the increased pCO2 can currently be attributed to the intrusion of anthropogenic CO2 from the atmosphere, while the majority is due to natural respiration processes. The biological impacts, along with the timing and duration of these undersaturation events, could play a role in the development of larval and juvenile calcifiers in the region and will change as anthropogenic CO2 concentrations continue to rise.

Continue reading ‘Evidence of prolonged aragonite undersaturations in the bottom waters of the southern Bering Sea shelf from autonomous sensors’

Short-term metabolic and growth responses of the cold-water coral Lophelia pertusa to ocean acidification

Cold-water corals are associated with high local biodiversity, but despite their importance as ecosystem engineers, little is known about how these organisms will respond to projected ocean acidification. Since preindustrial times, average ocean pH has decreased from 8.2 to~8.1, and predicted CO2 emissions will decrease by up to another 0.3 pH units by the end of the century. This decrease in pH may have a wide range of impacts upon marine life, and in particular upon calcifiers such as cold-water corals. Lophelia pertusa is the most widespread cold-water coral (CWC) species, frequently found in the North Atlantic. Here, we present the first short-term (21 days) data on the effects of increased CO2 (750 ppm) upon the metabolism of freshly collected L. pertusa from Mingulay Reef Complex, Scotland, for comparison with net calcification. Over 21 days, corals exposed to increased CO2 conditions had significantly lower respiration rates (11.4±1.39 SE, µmol O2 g−1 tissue dry weight h−1) than corals in control conditions (28.6±7.30 SE µmol O2 g−1 tissue dry weight h−1). There was no corresponding change in calcification rates between treatments, measured using the alkalinity anomaly technique and 14C uptake. The decrease in respiration rate and maintenance of calcification rate indicates an energetic imbalance, likely facilitated by utilization of lipid reserves. These data from freshly collected L. pertusa from the Mingulay Reef Complex will help define the impact of ocean acidification upon the growth, physiology and structural integrity of this key reef framework forming species.

Continue reading ‘Short-term metabolic and growth responses of the cold-water coral Lophelia pertusa to ocean acidification’

Rising carbon dioxide levels causing ‘tooth decay’ in sea organisms

London, July 27:
Rising carbon dioxide levels in the atmosphere are having a catastrophic effect on microscopic marine life.

Experiments by the University of St Andrews show microscopic organisms, called foraminifera (’forams’), suffer the equivalent of tooth decay as seawater becomes more acidic.

Foraminifera are tiny single-celled organisms that build intricate shells to protect themselves. They feed on algal cells called diatoms, which they break open using tooth-like structures on their shells.

Continue reading ‘Rising carbon dioxide levels causing ‘tooth decay’ in sea organisms’

NOAA cruise to study acidification consequences on West Coast

A team of researchers from the National Oceanic and Atmospheric Administration (NOAA) will take and study samples of plankton, water and algae to better understand how acidification is affecting the oceans ecosystems.

The team, which includes biologists and chemists, will cover the US West Coast, sailing from Seattle (Washington) on 29 July and docking in San Diego (California) on 29 August on board NOAA ship Fairweather.

The US West Coast is particularly prone to acidification as the California Current, which runs from British Columbia to Baja California, causes deep waters rich in carbon dioxide (CO2) to interact with surface waters (also rich in CO2) so the marine ecosystems within it are affected.

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Combined effects of two emerging environmental stressors (perfluorooctane sulfonate and carbon dioxide) on estrogenic responses of juvenile Atlantic cod (Gadus morhua)

Predicted climate changes have been suggested to alter future distribution and toxicity of persistent organic pollutants (POPs). Until now, little effort has been put into investigating such interactive effects between POPs and elevated CO2 levels (hypercapnia) in the aquatic environment. In the present study, juvenile Atlantic cod (Gadus morhua) were exposed to the emerging POP perfluorooctane sulfonate (PFOS; 0, 100 and 200 µg/L) for 1 hour/day in 5 days, followed by changes in elevated water CO2 saturation (0, 0.3 and 0.9%) for 3, 6 and 9 days. Endocrine disrupting potential of PFOS and elevated CO2 levels, both singly and in combination, were examined by analyzing levels of sex steroid hormones (E2, T, 11-KT) and transcript expression of estrogen responsive genes (ER-α, Vtg-α, Vtg-β, ZP-2, ZP-3), in addition to steroid and xenobiotic metabolism (CYP1A, CYP3A) and hypoxia-inducible factor (HIF-1α). Elevated CO2 produced increased levels of sex steroid hormones (E2, T, 11-KT) with concomitant increases in transcriptional expression of estrogen responsive genes. PFOS produced a weak time- and dose-dependent estrogenic effect as measured in mRNA expression of estrogen responsive genes, but no effect on steroid hormone levels. Exposure to elevated CO2 and PFOS in combination produced gene expression patterns that are different from the effects observed for CO2 and PFOS alone, indicating interactive effects. These observations suggest that hypercapnia and emerging POPs such as PFOS in combination could modulate the estrogen signaling in juvenile Atlantic cod (Gadus morhua), with potential consequences for sexual development and reproduction. To the best of our knowledge, this is the first study to report hypercapnia-induced sex steroid disruption in any fish species or lower vertebrate. These findings suggest a potential for adverse effects of increased anthropogenic CO2 emissions on sexual development and reproduction in fish. This also raises the question whether such interactive effects might be observed in other aquatic species and with other endocrine disrupters and POPs as well. Such findings could have implications for the accuracy of current risk assessments of emerging POPs, under changing climatic conditions.

Continue reading ‘Combined effects of two emerging environmental stressors (perfluorooctane sulfonate and carbon dioxide) on estrogenic responses of juvenile Atlantic cod (Gadus morhua)’

Potential impacts of ocean acidification on the Puget Sound food web

Ecosystem impacts of ocean acidification (OA) were explored by imposing scenarios designed to mimic OA on a food web model of Puget Sound, a large estuary in northwestern USA. The productivity of functional groups containing mostly calcifiers was decreased while still allowing other species groups to respond to the scenarios in a dynamic way through indirect effects. Results focus on changes in ecosystem services and structure. Sometimes the direct and indirect effects of OA countered each other due to interactions between predators and prey within the food web, leading to little change in the food web. In other cases, direct and indirect effects caused greater change in the food web than anticipated from direct effects alone. Results were strongly affected by the group on which OA was directly imposed, with changes in copepod productivity being the most influential. While there is much uncertainty in our predictions, focusing on the complex interactions among species, and between species and their environment, will yield better understanding of how ecosystems may respond to OA.

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Ocean acidification in the IPCC AR5 WG II

OUP book