Archive for April, 2014



The photo-physiological response of a model cnidarian–dinoflagellate symbiosis to CO2-induced acidification at the cellular level

We measured the relationship between CO2-induced seawater acidification, photo-physiological performance and intracellular pH (pHi) in a model cnidarian–dinoflagellate symbiosis – the sea anemone Aiptasia sp. – under ambient (289.94 ± 12.54 μatm), intermediate (687.40 ± 25.10 μatm) and high (1459.92 ± 65.51 μatm) CO2 conditions. These treatments represented current CO2 levels, in addition to CO2 stabilisation scenarios IV and VI provided by the Intergovernmental Panel on Climate Change (IPCC). Anemones were exposed to each treatment for two months and sampled at regular intervals. At each time-point we measured a series of physiological responses: maximum dark-adapted fluorescent yield of PSII (Fv/Fm), gross photosynthetic rate, respiration rate, symbiont population density, and light-adapted pHi of both the dinoflagellate symbiont and isolated host anemone cell. We observed increases in all but one photo-physiological parameter (Pgross:R ratio). At the cellular level, increases in light-adapted symbiont pHi were observed under both intermediate and high CO2 treatments, relative to control conditions (pHi 7.35 and 7.46 versus pHi 7.25, respectively). The response of light-adapted host pHi was more complex, however, with no change observed under the intermediate CO2 treatment, but a 0.3 pH-unit increase under the high CO2 treatment (pHi 7.19 and 7.48, respectively). This difference is likely a result of a disproportionate increase in photosynthesis relative to respiration at the higher CO2 concentration. Our results suggest that, rather than causing cellular acidosis, the addition of CO2 will enhance photosynthetic performance, enabling both the symbiont and host cell to withstand predicted ocean acidification scenarios.

Continue reading ‘The photo-physiological response of a model cnidarian–dinoflagellate symbiosis to CO2-induced acidification at the cellular level’

Mixed effects of elevated pCO2 on fertilisation, larval and juvenile development and adult responses in the mobile subtidal scallop Mimachlamys asperrima (Lamarck, 1819)

Ocean acidification is predicted to have severe consequences for calcifying marine organisms especially molluscs. Recent studies, however, have found that molluscs in marine environments with naturally elevated or fluctuating CO2 or with an active, high metabolic rate lifestyle may have a capacity to acclimate and be resilient to exposures of elevated environmental pCO2. The aim of this study was to determine the effects of near future concentrations of elevated pCO2 on the larval and adult stages of the mobile doughboy scallop, Mimachlamys asperrima from a subtidal and stable physio-chemical environment. It was found that fertilisation and the shell length of early larval stages of M. asperrima decreased as pCO2 increased, however, there were less pronounced effects of elevated pCO2 on the shell length of later larval stages, with high pCO2 enhancing growth in some instances. Byssal attachment and condition index of adult M. asperrima decreased with elevated pCO2, while in contrast there was no effect on standard metabolic rate or pHe. The responses of larval and adult M. asperrima to elevated pCO2 measured in this study were more moderate than responses previously reported for intertidal oysters and mussels. Even this more moderate set of responses are still likely to reduce the abundance of M. asperrima and potentially other scallop species in the world’s oceans at predicted future pCO2 levels.

Continue reading ‘Mixed effects of elevated pCO2 on fertilisation, larval and juvenile development and adult responses in the mobile subtidal scallop Mimachlamys asperrima (Lamarck, 1819)’

Ocean action: a different kind of tipping point

Recently you may have noticed the ever-increasing number of international conferences, talks, meetings and reports on the ocean and its declining health.

Just in the last two years, we have had two excellent World Ocean Summits hosted by The Economist, which brought together a rich audience of politicians, business leaders, NGOs and experts to focus on the evidence, challenges and solutions to the changes being observed in our oceans.

Continue reading ‘Ocean action: a different kind of tipping point’

Postdoc (10 months, 66 %, maternity leave): Ocean acidification modeling

Job Summary

Sector: Academic
Categories: Climate and Paleoclimatology, Ocean Sciences
Employer / Location: Institute of Geosciences, University of Kiel, Germany
Preferred Education: PhD
Application Deadline: Open until the position is filled

Continue reading ‘Postdoc (10 months, 66 %, maternity leave): Ocean acidification modeling’

Temple scientists hit Gulf of Mexico to explore human-generated deep-sea acidification (text and audio)

Scientists from Temple University are about to head out on a three-week research cruise into the Gulf of Mexico. Their goal? To look at how carbon dioxide is impacting organisms such as deepwater coral reefs down on the ocean floor.

The Pulse’s Maiken Scott sat down with lead researcher Erik Cordes to find out more about ocean acidification and life in the Alvin submersible. Here are excerpts from their conversation.

So tell me about this mission you’re about to embark on.

This is a voyage out to the middle of the Gulf of Mexico on the research vessel Atlantis with two submersibles — the Alvin submersible, which is one of the most famous ones in the world, and an autonomous underwater vehicle, which is a really new type of technology, called Sentry.

Continue reading ‘Temple scientists hit Gulf of Mexico to explore human-generated deep-sea acidification (text and audio)’

Webinar: Hypoxia, hypercapnia, and other influences on oxygen minimum zone benthos

The Southern California Coastal Water Research Project will be hosting in May 2014 a seminar entitled “Hypoxia, hypercapnia, and other influences on oxygen minimum zone benthos” . Dr. Lisa Levin from the Scripps Institution of Oceanography is the designated guest speaker for this session. The organizers will ensure an integral webcast of the seminar.

Date and time: 2 May 2014, 11:00 AM

Venue: Southern California Coastal Water Research Project, Large Conference Room, 3535 Harbor Blvd., Costa Mesa, CA 92626

Continue reading ‘Webinar: Hypoxia, hypercapnia, and other influences on oxygen minimum zone benthos’

Environmental controls on the Emiliania huxleyi calcite mass (update)

Although ocean acidification is expected to impact (bio) calcification by decreasing the seawater carbonate ion concentration, [CO32−], there is evidence of nonuniform response of marine calcifying plankton to low seawater [CO32−]. This raises questions about the role of environmental factors other than acidification and about the complex physiological responses behind calcification. Here we investigate the synergistic effect of multiple environmental parameters, including seawater temperature, nutrient (nitrate and phosphate) availability, and carbonate chemistry on the coccolith calcite mass of the cosmopolitan coccolithophore Emiliania huxleyi, the most abundant species in the world ocean. We use a suite of surface (late Holocene) sediment samples from the South Atlantic and southwestern Indian Ocean taken from depths lying above the modern lysocline (with the exception of eight samples that are located at or below the lysocline). The coccolith calcite mass in our results presents a latitudinal distribution pattern that mimics the main oceanographic features, thereby pointing to the potential importance of seawater nutrient availability (phosphate and nitrate) and carbonate chemistry (pH and pCO2) in determining coccolith mass by affecting primary calcification and/or the geographic distribution of E. huxleyi morphotypes. Our study highlights the importance of evaluating the combined effect of several environmental stressors on calcifying organisms to project their physiological response(s) in a high-CO2 world and improve interpretation of paleorecords.

Continue reading ‘Environmental controls on the Emiliania huxleyi calcite mass (update)’

Diversity trumps acidification: Lack of evidence for carbon dioxide enhancement of Trichodesmium community nitrogen or carbon fixation at Station ALOHA

We conducted 11 independent short-term carbon dioxide (CO2) manipulation experiments using colonies of the filamentous cyanobacteria Trichodesmium isolated on three cruises in the North Pacific Subtropical Gyre (NPSG). Dinitrogen (N2) and carbon (C) fixation rates of these colonies were compared over CO2 conditions ranging from ∼ 18 Pa (equivalent to last glacial maximum atmospheric ) to ∼ 160 Pa (predicted for ∼ year 2200). Our results indicate that elevated has no consistent significant effect on rates of N2 or C fixation by Trichodesmium colonies in the NPSG under present environmental conditions. Differences between treatments were not modulated by phosphorus amendments, iron amendments, or light level. Sequencing the hetR, nifH, 16S, and internal transcribed spacer genes of Trichodesmium colonies revealed a highly diverse community of Trichodesmium and other N2-fixing colony-associated organisms. The species composition of Trichodesmium demonstrated spatiotemporal variability, but over half of total sequences were phylogenetically closely related (> 99% hetR sequence similarity) to isolate H9-4 of T. erythraeum, which showed no response to elevated in previous laboratory experiments. Our handpicked Trichodesmium colonies included a substantial number of organisms other than Trichodesmium with the metabolic capacity for N2 and C fixation. We suggest that the diverse assemblage of Trichodesmium species and coexisting microorganisms within the colonies can explain the lack of an observed CO2 enhancement of N2 or C fixation rates, because different species are known to have different specific affinities for CO2.

Continue reading ‘Diversity trumps acidification: Lack of evidence for carbon dioxide enhancement of Trichodesmium community nitrogen or carbon fixation at Station ALOHA’

Opportunities for communicating ocean acidification to visitors at informal Science Education Institutions

The broader public is largely unaware of ocean acidification; yet, when provided with basic information about the issue they quickly become concerned.

This finding has its foundation in the national survey results, as supported by the on-site visitor intercepts. The national survey confirmed our sense that unaided awareness of ocean acidification is extremely low. On the aforementioned agreement scale (which runs from 1 [total disagreement] to 100 [total agreement]), the unaided score for “I have heard of the issue of ocean acidification” was a 14 for the public as a whole, rising only slightly to 19 when looking at recent visitors to a zoo, aquarium or museum, and to 31 when looking only at those who already claimed concern about climate change. (…)

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Snapper (Chrysophrys auratus): a review of life history and key vulnerabilities in New Zealand

Snapper (Chrysophrys auratus) is an important coastal fish species in New Zealand for a variety of reasons, but the large amount of research conducted on snapper has not been reviewed. Here, we review life history information and potential threats for snapper in New Zealand. We present information on snapper life history, defining stages (eggs and larvae, juvenile and adult), and assess potential threats and knowledge gaps. Overall we identify six key points: 1. post-settlement snapper are highly associated with certain estuarine habitats that are under threat from land-based stressors. This may serve as a bottleneck for snapper populations; 2. the largest knowledge gaps relate to the eggs and larvae. Additional knowledge may help to anticipate the effects of climate change, which will likely have the greatest influence on these early life stages; 3. ocean acidification, from land-based sources and from climate change, may be an important threat to larval snapper; 4. a greater understanding of population connectivity would improve certainty around the sustainability of fishery exploitation; 5. the collateral effects of fishing are likely to be relevant to fishery productivity, ecosystem integrity and enduser value; 6. our understanding of the interrelationships between snapper and other ecosystem components is still deficient.

Continue reading ‘Snapper (Chrysophrys auratus): a review of life history and key vulnerabilities in New Zealand’


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Ocean acidification in the IPCC AR5 WG II

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