Archive for August, 2013

Where can coral reefs relocate to escape the heat?

The best real estate for coral reefs over the coming decades will no longer be around the equator but in the sub-tropics, new research from the University of Bristol suggests.

Fossil fuel emissions are impacting corals through high temperatures which can cause their deaths and ocean acidification which makes it difficult for them to produce their skeletons.  In a study published today in Global Change Biology, Dr Elena Couce, Professor Andy Ridgwell and Dr Erica Hendy used computer models to predict future shifts in the global distribution of coral reef ecosystems under these two stressors.

The researchers found that warming impacts were dominant, with a significant decline in suitability for corals near the equator.

Continue reading ‘Where can coral reefs relocate to escape the heat?’

Scientists studying ocean acidity to take regional approach

SALEM — Gov. John Kitzhaber announced Thursday that Oregon is joining with the state of California to establish a new panel to focus on the extent, causes, and effects of ocean acidification and hypoxia along the Pacific coastline.

The West Coast Ocean Acidification and Hypoxia Science Panel will bring together scientists from Oregon, California, Washington, and British Columbia to develop strategic recommendations for researching and monitoring ocean acidification and hypoxia in the Pacific Ocean.

Continue reading ‘Scientists studying ocean acidity to take regional approach’

Ocean acidification could affect rising temperatures

New research shows the two aren’t entirely separate.

Climate change’s oft ignored twin, ocean acidification, is usually thought of as a biological rather than a climatic problem. They’re seen as parallel (carbon dioxide emissions are a cause of each) but separate (the effects of ocean acidification don’t depend on changes in climate). Some recent studies are showing that, true to the interconnected nature of, well, nature, ocean acidification may actually have a climatic effect of its own.

Ocean acidification is a decrease in the pH and carbonate concentration of ocean water caused by CO2 pumped into the atmosphere. It’s generally bad news for critters with calcium carbonate shells or skeletons, and acidification has even been shown to affect fish. Studies in which CO2 is added to closely monitored sections of marine habitat have shown that one of the many outcomes appears to be a decrease in dimethylsulfide produced by phytoplankton.

Continue reading ‘Ocean acidification could affect rising temperatures’

The effects of thermal and high-CO2 stresses on the metabolism and surrounding microenvironment of the coral Galaxea fascicularis

The effects of elevated temperature and high pCO2 on the metabolism of Galaxea fascicularis were studied with oxygen and pH microsensors. Photosynthesis and respiration rates were evaluated from the oxygen fluxes from and to the coral polyps. High-temperature alone lowered both photosynthetic and respiration rates. High pCO2 alone did not significantly affect either photosynthesis or respiration rates. Under a combination of high-temperature and high-CO2, the photosynthetic rate increased to values close to those of the controls. The same pH in the diffusion boundary layer was observed under light in both (400 and 750 ppm) CO2 treatments, but decreased significantly in the dark as a result of increased CO2. The ATP contents decreased with increasing temperature. The effects of temperature on the metabolism of corals were stronger than the effects of increased CO2. The effects of acidification were minimal without combined temperature stress. However, acidification combined with higher temperature may affect coral metabolism due to the amplification of diel variations in the microenvironment surrounding the coral and the decrease in ATP contents.

Continue reading ‘The effects of thermal and high-CO2 stresses on the metabolism and surrounding microenvironment of the coral Galaxea fascicularis’

Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems

Algal toxins or red-tide toxins produced during algal blooms are naturally-derived toxic emerging contaminants (ECs) that may kill organisms, including humans, through contaminated fish or seafood. Other ECs produced either naturally or anthropogenically ultimately flow into marine waters. Pharmaceuticals are also an important pollution source, mostly due to overproduction and incorrect disposal. Ship breaking and recycle industries (SBRIs) can also release various pollutants and substantially deteriorate habitats and marine biodiversity. Overfishing is significantly increasing due to the global food crisis, caused by an increasing world population. Organic matter (OM) pollution and global warming (GW) are key factors that exacerbate these challenges (e.g. algal blooms), to which acidification in marine waters should be added as well. Sources, factors, mechanisms and possible remedial measures of these challenges to marine ecosystems are discussed, including their eventual impact on all forms of life including humans.

Continue reading ‘Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems’

Papers find mixed impacts on ocean species from rising CO2

Britain’s Royal Society has published a helpful new collection of papers in Philosophical Transactions of the Royal Society B that provide fresh insights on how the global buildup of carbon dioxide released by human activities could affect ocean ecology.

The work adds to a growing body of science pointing to large changes, with some types of marine organisms and ecosystems seemingly able to adjust and even thrive, while others ail. And it’s quite clear that regions already heavily affected by other human activities (coastal pollution, overfishing, etc.) are — no surprise — likely to feel more stress from acidification.

The nine new studies in the Royal Society journal provide valuable detail and find a mix of impacts. Experiments transplanting certain worms around a volcanic carbon dioxide vent in the sea floor near Naples show remarkable adaptability in these organisms, both through shifts in metabolism and genetics. A poles-to-tropics assay of sea urchins shows significant impacts on larvae.

Continue reading ‘Papers find mixed impacts on ocean species from rising CO2’

Ocean acidification and climate change: advances in ecology and evolution

Atmospheric CO2 concentration [CO2] has increased from a pre-industrial level of approximately 280 ppm to approximately 385 ppm, with further increases (700–1000 ppm) anticipated by the end of the twenty-first century [1]. Over the past three decades, changes in [CO2] have increased global average temperatures (approx. 0.2°C decade−1 [2]), with much of the additional energy absorbed by the world’s oceans causing a 0.8°C rise in sea surface temperature over the past century. The rapid uptake of heat energy and CO2 by the ocean results in a series of concomitant changes in seawater carbonate chemistry, including reductions in pH and carbonate saturation state, as well as increases in dissolved CO2 and bicarbonate ions [3]: a phenomenon defined as ocean acidification. Time-series and survey measurements [46] over the past 20 years have shown that surface ocean pH has reduced by 0.1 pH unit relative to pre-industrial levels, equating to a 26% increase in ocean acidity [3]. Reductions of 0.4–0.5 pH units are projected to occur by the end of the twenty-first century [1] and, while atmospheric [CO2] has consistently fluctuated by 100–200 ppm over the past 800 000 years [7], the recent and anticipated rates of change are unprecedented [8].

Continue reading ‘Ocean acidification and climate change: advances in ecology and evolution’

Carbon-sequestering ocean plants may cope with climate changes over the long run

SAN FRANCISCO — A year-long experiment on tiny ocean organisms called coccolithophores suggests that the single-celled algae may still be able to grow their calcified shells even as oceans grow warmer and more acidic in Earth’s near future.

The study stands in contrast to earlier studies suggesting that coccolithophores would fail to build strong shells in acidic waters. The world’s oceans are expected to become more acidic as human activities pump increasing amounts of carbon dioxide into the Earth’s atmosphere.

But after the researchers raised one strain of the Emiliania huxleyi coccolithorphore for over 700 generations, which took about 12 months, under high temperature and acidified conditions that are expected for the oceans 100 years from now, the organisms had no trouble producing their plated shells.

Continue reading ‘Carbon-sequestering ocean plants may cope with climate changes over the long run’

Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2

Increased atmospheric pCO2 is expected to render future oceans warmer and more acidic than they are at present. Calcifying organisms such as coccolithophores that fix and export carbon into the deep sea provide feedbacks to increasing atmospheric pCO2. Acclimation experiments suggest negative effects of warming and acidification on coccolithophore calcification, but the ability of these organisms to adapt to future environmental conditions is not well understood. Here, we tested the combined effect of pCO2 and temperature on the coccolithophore Emiliania huxleyi over more than 700 generations. Cells increased inorganic carbon content and calcification rate under warm and acidified conditions compared with ambient conditions, whereas organic carbon content and primary production did not show any change. In contrast to findings from short-term experiments, our results suggest that long-term acclimation or adaptation could change, or even reverse, negative calcification responses in E. huxleyi and its feedback to the global carbon cycle. Genome-wide profiles of gene expression using RNA-seq revealed that genes thought to be essential for calcification are not those that are most strongly differentially expressed under long-term exposure to future ocean conditions. Rather, differentially expressed genes observed here represent new targets to study responses to ocean acidification and warming.

Continue reading ‘Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2’

The stunting effect of a high CO2 ocean on calcification and development in sea urchin larvae, a synthesis from the tropics to the poles

The stunting effect of ocean acidification on development of calcifying invertebrate larvae has emerged as a significant effect of global change. We assessed the arm growth response of sea urchin echinoplutei, here used as a proxy of larval calcification, to increased seawater acidity/pCO2 and decreased carbonate mineral saturation in a global synthesis of data from 15 species. Phylogenetic relatedness did not influence the observed patterns. Regardless of habitat or latitude, ocean acidification impedes larval growth with a negative relationship between arm length and increased acidity/pCO2 and decreased carbonate mineral saturation. In multiple linear regression models incorporating these highly correlated parameters, pCO2 exerted the greatest influence on decreased arm growth in the global dataset and also in the data subsets for polar and subtidal species. Thus, reduced growth appears largely driven by organism hypercapnia. For tropical species, decreased carbonate mineral saturation was most important. No single parameter played a dominant role in arm size reduction in the temperate species. For intertidal species, the models were equivocal. Levels of acidification causing a significant (approx. 10–20+%) reduction in arm growth varied between species. In 13 species, reduction in length of arms and supporting skeletal rods was evident in larvae reared in near-future (pCO2 800+ µatm) conditions, whereas greater acidification (pCO2 1000+ µatm) reduced growth in all species. Although multi-stressor studies are few, when temperature is added to the stressor mix, near-future warming can reduce the negative effect of acidification on larval growth. Broadly speaking, responses of larvae from across world regions showed similar trends despite disparate phylogeny, environments and ecology. Larval success may be the bottleneck for species success with flow-on effects for sea urchin populations and marine ecosystems.

Continue reading ‘The stunting effect of a high CO2 ocean on calcification and development in sea urchin larvae, a synthesis from the tropics to the poles’

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Ocean acidification in the IPCC AR5 WG II

OUP book