Archive for May, 2018

Job opportunity: Research Assistant, Ocean Acidification Community of Practice Coordinator, University of Calgary

Position: Research Assistant, Ocean Acidification Community of Practice Coordinator (full-time fixed term position for approximately 1 year, based on length of grant funding, with the possibility of extension)

Location: Department of Geography, Faculty of Arts, University of Calgary

Application Deadline: 9 June 2018

Continue reading ‘Job opportunity: Research Assistant, Ocean Acidification Community of Practice Coordinator, University of Calgary’

Volcanic study finds coral changes in high CO₂

Large-scale experiment off Papua New Guinea suggests reefs will look very different under global warming. Andrew Masterson reports.

Some of the coral communities used in the experiment. Those on the lower line were close to volcanic vents, and those on the upper line a control sites.

Some of the coral communities used in the experiment. Those on the lower line were close to volcanic vents, and those on the upper line a control sites.
Credit: Noonan, et al

Scientists have been growing coral next to volcanic vents to test the effects of increased levels of marine carbon dioxide, and the results don’t look good. In paper published in the journal PLOS One, researchers from the Australian Institute for Marine Science (AIMS) in Queensland, and the University of Otago in New Zealand, describe a large-scale experiment to test how coral respond to high levels of carbon dioxide – a scenario predicted in global warming models.

The scientists established 90 small coral communities on PVC tiles. Half of them were positioned close to two shallow-water volcanic carbon dioxide seeps off the coast of Papua New Guinea, with the rest placed a short distance away at control sites.

Continue reading ‘Volcanic study finds coral changes in high CO₂’

Ocean acidification alters early successional coral reef communities and their rates of community metabolism

Ocean acidification is expected to alter community composition on coral reefs, but its effects on reef community metabolism are poorly understood. Here we document how early successional benthic coral reef communities change in situ along gradients of carbon dioxide (CO2), and the consequences of these changes on rates of community photosynthesis, respiration, and light and dark calcification. Ninety standardised benthic communities were grown on PVC tiles deployed at two shallow-water volcanic CO2 seeps and two adjacent control sites in Papua New Guinea. Along the CO2 gradient, both the upward facing phototrophic and the downward facing cryptic communities changed in their composition. Under ambient CO2, both communities were dominated by calcifying algae, but with increasing CO2 they were gradually replaced by non-calcifying algae (predominantly green filamentous algae, cyanobacteria and macroalgae, which increased from ~30% to ~80% cover). Responses were weaker in the invertebrate communities, however ascidians and tube-forming polychaetes declined with increasing CO2. Differences in the carbonate chemistry explained a far greater amount of change in communities than differences between the two reefs and successional changes from five to 13 months, suggesting community successions are established early and are under strong chemical control. As pH declined from 8.0 to 7.8, rates of gross photosynthesis and dark respiration of the 13-month old reef communities (upper and cryptic surfaces combined) significantly increased by 10% and 20%, respectively, in response to altered community composition. As a consequence, net production remained constant. Light and dark calcification rates both gradually declined by 20%, and low or negative daily net calcification rates were observed at an aragonite saturation state of <2.3. The study demonstrates that ocean acidification as predicted for the end of this century will strongly alter reef communities, and will significantly change rates of community metabolism.

Continue reading ‘Ocean acidification alters early successional coral reef communities and their rates of community metabolism’

Consequences of spatially variable ocean acidification in the California Current: lower pH drives strongest declines in benthic species in southern regions while greatest economic impacts occur in northern regions

Highlights

• Impacts of ocean acidification change with latitude in the California Current.
• Vulnerable species (e.g., calcifying invertebrates) and their predators decline most.
• Decline in revenue projected, mainly from lower Dungeness crab catch in the north.
Abstract

Marine ecosystems are experiencing rapid changes driven by anthropogenic stressors which, in turn, are affecting human communities. One such stressor is ocean acidification, a result of increasing carbon emissions. Most research on biological impacts of ocean acidification has focused on the responses of an individual species or life stage. Yet, understanding how changes scale from species to ecosystems, and the services they provide, is critical to managing fisheries and setting research priorities. Here we use an ecosystem model, which is forced by oceanographic projections and also coupled to an economic input-output model, to quantify biological responses to ocean acidification in six coastal regions from Vancouver Island, Canada to Baja California, Mexico and economic responses at 17 ports on the US west coast. This model is intended to explore one possible future of how ocean acidification may influence this coastline. Outputs show that declines in species biomass tend to be larger in the southern region of the model, but the largest economic impacts on revenue, income and employment occur from northern California to northern Washington State. The economic consequences are primarily driven by declines in Dungeness crab from loss of prey. Given the substantive revenue generated by the fishing industry on the west coast, the model suggests that long-term planning for communities, researchers and managers in the northern region of the California Current would benefit from tracking Dungeness crab productivity and potential declines related to pH.

Continue reading ‘Consequences of spatially variable ocean acidification in the California Current: lower pH drives strongest declines in benthic species in southern regions while greatest economic impacts occur in northern regions’

Saildrones monitor plant growth and acidification in remote Arctic waters

Over the past few years, NOAA’s Pacific Marine Environmental Laboratory has partnered with a private technology company to deploy a new autonomous vehicle for ocean observations: the saildrone. The new platform will fill a unique niche in the agency’s observational fleet. It’s a nimble vehicle that is tough enough explore some of the planet’s most remote oceans. Case in point: the Arctic. Continue reading ‘Saildrones monitor plant growth and acidification in remote Arctic waters’

Ocean acidification reduces mechanical properties of the Portuguese oyster shell with impaired microstructure: a hierarchical analysis

The rapidly intensifying process of ocean acidification (OA) in coastal areas due to anthropogenic CO2 is not only depleting carbonate ions necessary for calcification but also causing acidosis and disrupting internal pH homeostasis in several marine organisms. These negative consequences of OA on marine communities, particularly to shellfish oyster species, has been very well documented in recent studies, however, the consequences of these reduced or impaired calcification processes on the end-product, shells or skeletons, still remains one of the major research gaps. Shells produced by marine organisms under OA are expected to be corroded with disorganized or impaired crystal orientation or microstructures with reduced mechanical property. To bridge this knowledge gap and to test the above hypothesis, we investigated the effect of OA on shell of the commercially important oyster species (Crassostrea angulata) at ecologically and climatically relevant OA levels (using pH 8.1, 7.8, 7.5, 7.2 as proxies). In decreased pH conditions, a drop of shell hardness and stiffness was revealed by nanoindentation tests, while an evident loosened internal microstructure was detected by scanning electron microscopy (SEM). In contrary, the crystallographic orientation of oyster shell showed no significant difference with decreasing pH by Electron Back Scattered Diffraction (EBSD) analyses. These results indicate the loosened internal microstructure may be the cause of the OA induced reduction in shell hardness and stiffness. Micro-computed tomography analysis (Micro-CT) indicated that an overall “down-shifting” of mineral density in the shell with decreasing pH, which implied the loosened internal microstructure may run through the shell, thus inevitably limiting the effectiveness of the shell defensive function. This study surfaces potential bottom-up deterioration induced by OA on oyster shells, especially in their early juvenile life stage. This knowledge is critical to forecast the survival and production of edible oysters in future ocean.

Continue reading ‘Ocean acidification reduces mechanical properties of the Portuguese oyster shell with impaired microstructure: a hierarchical analysis’

Climate kids delivers ocean acidification activities to Barnard Elementary

On May 1st, the Climate Science Alliance’s Climate Kids program brought science, art, and storytelling to 4th graders at Barnard Elementary to teach them about climate change impacts to local ecosystems.  Barnard Elementary students got to put lab coats on and become scientists for the day by participating in Climate Kids Traveling Trunk hands-on activities and demonstrations about ocean acidification.

Ambassadors from MIssion Bay High School joined in on the fun and engaged students through storytelling and a special ‘Zine’ art activity with recycled paper and nature-themed magazines.  In their ‘Zines,’ the 4th grade students included stories and inspirations about climate-minded choices.  The ambassadors also read the second edition “Here Today Gone Tomorrow,” a book created by Climate Kids in San Marcos which teaches how climate change in affecting endangered animals.

Students also got a chance to visit Cabrillo National Monument tidepools for a special Climate Kids science field trip in late May.

Continue reading ‘Climate kids delivers ocean acidification activities to Barnard Elementary’

Effects of elevated CO2 and temperature on phytoplankton community biomass, species composition and photosynthesis during an experimentally induced autumn bloom in the western English Channel (update)

The combined effects of elevated pCO2 and temperature were investigated during an experimentally induced autumn phytoplankton bloom in vitro sampled from the western English Channel (WEC). A full factorial 36-day microcosm experiment was conducted under year 2100 predicted temperature (+4.5 °C) and pCO2 levels (800 µatm). Over the experimental period total phytoplankton biomass was significantly influenced by elevated pCO2. At the end of the experiment, biomass increased 6.5-fold under elevated pCO2 and 4.6-fold under elevated temperature relative to the ambient control. By contrast, the combined influence of elevated pCO2 and temperature had little effect on biomass relative to the control. Throughout the experiment in all treatments and in the control, the phytoplankton community structure shifted from dinoflagellates to nanophytoplankton . At the end of the experiment, under elevated pCO2 nanophytoplankton contributed 90 % of community biomass and was dominated by Phaeocystis spp. Under elevated temperature, nanophytoplankton comprised 85 % of the community biomass and was dominated by smaller nanoflagellates. In the control, larger nanoflagellates dominated whilst the smallest nanophytoplankton contribution was observed under combined elevated pCO2 and temperature ( ∼  40 %). Under elevated pCO2, temperature and in the control there was a significant decrease in dinoflagellate biomass. Under the combined effects of elevated pCO2 and temperature, dinoflagellate biomass increased and was dominated by the harmful algal bloom (HAB) species, Prorocentrum cordatum. At the end of the experiment, chlorophyll a (Chl a) normalised maximum photosynthetic rates (PBm) increased  >  6-fold under elevated pCO2 and  >  3-fold under elevated temperature while no effect on PBm was observed when pCO2 and temperature were elevated simultaneously. The results suggest that future increases in temperature and pCO2 simultaneously do not appear to influence coastal phytoplankton productivity but significantly influence community composition during autumn in the WEC.

Continue reading ‘Effects of elevated CO2 and temperature on phytoplankton community biomass, species composition and photosynthesis during an experimentally induced autumn bloom in the western English Channel (update)’

Ocean acidification stimulates particulate organic carbon accumulation in two Antarctic diatom species under moderate and high natural solar radiation

Impacts of rising atmospheric CO2 concentrations and increased daily irradiances from enhanced surface water stratification on phytoplankton physiology in the coastal Southern Ocean remain still unclear. Therefore, in the two Antarctic diatoms Fragilariopsis curta and Odontella weissflogii the effects of moderate and high natural solar radiation combined with either ambient or future pCO2 on cellular particulate organic carbon (POC) contents and photophysiology were investigated. Results showed that increasing CO2 concentrations had greater impacts on diatom physiology than exposure to increasing solar radiation. Irrespective of the applied solar radiation regime, cellular POC quotas increased with future pCO2 in both diatoms. Lowered maximum quantum yields of photochemistry in PSII (Fv/Fm) indicated a higher photosensitivity under these conditions, being counteracted by increased cellular concentrations of functional photosynthetic reaction centers. Overall, our results suggest that both bloom‐forming Antarctic coastal diatoms might increase carbon contents under future pCO2 conditions despite reduced physiological fitness. This indicates a higher potential for primary productivity by the two diatom species with important implications for the CO2 sequestration potential of diatom communities in the future coastal Southern Ocean.

Continue reading ‘Ocean acidification stimulates particulate organic carbon accumulation in two Antarctic diatom species under moderate and high natural solar radiation’

Climate change and fish performance: how can aquatic acidification affect oxygen transport and swim performance?

Increasing levels of atmospheric CO2 have led to changes in ocean pH (Plumbago AnnualpHChange. Digital image. Wikimedia. N.p., Apr. 2009. Web. 23 Mar. 2018).

Climate change is becoming an ever-more pressing concern. The concentration of atmospheric carbon dioxide (CO2) has rapidly increased to about 400 ppm in 2015; this is the highest it’s been 800,000 years (Luthi et al., 2008). When we think about the effects these high concentrations have on our earth’s systems, we might only consider the atmosphere and weather patterns. However, it is important to remember that the ocean is the largest carbon sink on earth. We are already starting to see the effects of increased carbon dioxide concentrations, as well as increased partial pressure coming from CO2, in the form of ocean acidification and coral bleaching. However, not much information has been gathered on the effect of increased partial pressure from carbon dioxide (PCO2) on fish metabolic performance, which is an important benchmark of their ability to survive.

Continue reading ‘Climate change and fish performance: how can aquatic acidification affect oxygen transport and swim performance?’


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Ocean acidification in the IPCC AR5 WG II

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