Archive for February, 2014



Trichodesmium’s strategies to alleviate P-limitation in the future acidified oceans

Global warming may exacerbate inorganic nutrient limitation, including phosphorus (P), in the surface-waters of tropical oceans that are home to extensive blooms of the marine diazotrophic cyanobacterium, Trichodesmium. We examined the combined effects of P-limitation and pCO2, forecast under ocean acidification scenarios, on Trichodesmium erythraeum IMS101 cultures. We measured nitrogen acquisition, glutamine synthetase (GS) activity, C uptake rates, intracellular ATP concentration and the pool sizes of related key proteins. Here we present data supporting the idea that cellular energy reallocation enables the higher growth and N2 fixation rates detected in Trichodesmium cultured under high pCO2. This is reflected in altered protein abundance and metabolic pools. Also modified are particulate organic carbon and nitrogen production rates, enzymatic activities, and cellular ATP concentrations. We suggest that adjusting these cellular pathways to changing environmental conditions enables Trichodesmium to compensate for low P availability and to thrive in acidified oceans. Moreover, elevated pCO2 could provide Trichodesmium with a competitive dominance that would extend its niche, particularly in P-limited regions of the tropical and subtropical oceans.
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Impacts of natural and manipulated variations in temperature, pH and light on photosynthetic parameters of coralline–kelp assemblages

Increasing absorption of CO2 by the world’s oceans is lowering seawater pH and may have severe consequences for marine calcifying organisms. Understanding the ecological consequences of anthropogenic CO2 emissions will require examination of how calcifying organisms and their associated communities respond to natural variation in CO2 concentration. Many macroalgae may respond positively or neutrally to ocean acidification, but calcifying species such as coralline algae are predicted to be some of the most susceptible organisms to changing CO2. Here I test the impacts of temperature and pH variation on important photosynthetic metrics of macroalgal assemblages composed of coralline turf, Corallina vancouveriensis and the associated canopy-forming kelp, Saccharina sessilis using in situ photorespirometry and laboratory mesocosms. In situ photorespirometry was done at two locations on the Oregon (USA) coast, an area with variable upwelling of high CO2, low pH water. To complement in situ measurements, a series of laboratory mesocosms were used to disentangle the effects of pH and temperature on photosynthetic parameters across a light gradient. The acute effects of low pH were also tested across a temperature gradient, revealing an exacerbated effect of short duration, low pH events on respiration rates at increasing temperature. NPP (net primary productivity) was reduced by 10–20% within in situ coralline assemblages across a natural gradient of pH (8.1–7.9), but there was a mostly neutral effect of low pH on NPP of coralline–kelp assemblages. These results indicate varied responses of coralline and coralline–kelp assemblages to temperature and pH gradients, but under limiting light conditions primary production and growth of corallines are likely to decrease under modest scenarios of CO2 increase. Assemblage composition could play an important role in modulating the impacts of ocean acidification on calcifying organisms, and results from this study suggest that canopy and sub-canopy interactions could determine the response of susceptible species to changing climatic parameters.
Continue reading ‘Impacts of natural and manipulated variations in temperature, pH and light on photosynthetic parameters of coralline–kelp assemblages’

Acidic ocean deadly for Vancouver Island scallop industry (text and video)

scallops-dying-in-acidic-watersMillions of shellfish are dying off before they can be harvested at Island Scallops.

The deteriorating health of B.C.’s oceans is impacting not only the province’s marine life, but also its economy. Millions of shellfish are dying off before they can be harvested at Island Scallops, near Parksville, B.C., due to increased acidity levels in the ocean.

One-third of the workforce at Island Scallops — 20 people — are being laid off because the business has lost more than 10 million scallops before they were able to reach maturity since 2009.
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Crabs & climate change pose threat to Maine shellfish (text and video)

One of Maine’s oldest commercial fisheries is in trouble, and the reason appears to be a very aggressive and very hungry predator. (…) Scientists say green crabs aren’t the only threat to Maine shellfish. They also point to a change in the ocean water itself, called ocean acidification. State Rep. Mick Devin, a researcher at the University of Maine Darling Marine Center, says increasing amounts of carbon are going into the ocean as a result of climate change. He says that carbon turns into carbolic acid in the salt water, which then lowers the pH and makes the water more acidic.
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La acidificación de los océanos, el “experimento químico más grande del mundo” (in Spanish)

20140224000526_0El vertiginoso aumento de la concentración de dióxido de carbono en la atmósfera de nuestro planeta no solamente está causando un calentamiento global y consecuente cambio climático, sino también altera la química de los océanos del mundo en una forma dramática, con consecuencias para los ecosistemas marinos todavía poco comprendidas.

Los océanos ya son un 26% más ácidos comparados con tiempos pre-industriales y la actual tasa de acidificación es 10 veces más alta que hace 55 millones de años, cuando ocurrió una extinción en masa de especies marinas.

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Ocean Acidification Workshop, Surfrider Foundation’s Washington Coast Blog

To inform public knowledge and engagement on issues that affect ocean health and coastal communities

April 8th, 2014, Log Cabin Pavillion, Aberdeen, WA

Tentative Agenda

9AM-12PM: Reducing Carbon, Nitrogen, and Phosphorus Pollution with Phytoremediation
While there is little we can do to reduce global carbon emissions, the primary cause of ocean acidification (OA), there is much we can do to reduce the local pollutants that worsen OA and to lessen the effects of OA in our coastal waters. This session focuses on how plants in diverse ecosystems can both sequester carbon emissions at extremely high rates (as much as five times greater than tropical forests) and “sweeten” the water to reduce hypoxia, acidification, eutrophication and a host of other threats to marine life. We will look at how salt marshes, sea grasses, and macroalgae can help us adapt to living in a high CO2 world and your role in making it happen.
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Balancing act: otters, urchins and kelp

Learn about the connections among sea otters, sea urchins, kelp forests, and climate change. This video shows how conservation of wildlife can have an impact on global climate change. It provides examples of how healthy, balanced ecosystems will be the best offense in a rapidly changing ocean environment. This video is part of our Ocean Acidification Education series.
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Pteropods: very small and very important (text and video)

Pteropods are very small free-floating marine snails that play a very big part in oceanic ecosystems. Although tiny, these creatures are extremely important because they make up an important part of the oceanic food web. Scientists have seen the negative effects of ocean acidification on pteropods and are studying these organisms to better understand the problem. This slideshow is part of our Ocean Acidification Education series.
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Ocean acidification: the basics (text and animation)

Screen shot 2014-02-26 at 3.15.00 PM

Animation by Sara Cooley, WHOI

Carbon dioxide is naturally present in tiny amounts in the atmosphere; however, since humans started burning fossil fuels at the beginning of the industrial age, carbon dioxide levels have increased dramatically. Carbon dioxide is a gas that plants combine with energy from the sun to create food. It is also a greenhouse gas: it traps the heat of the sun and keeps it from reflecting back into space. Today the oceans absorb about 25 percent of the CO2 released every year. Initially, scientists focused on the benefits of removing the greenhouse gas from the atmosphere, but in the last decade research has shown that the excess CO2 absorbed by the oceans is changing the chemistry — the pH — of the seawater in a process called ocean acidification.
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Ocean acidification: vocabulary game

Test your knowledge of ocean acidification vocabulary. There are 14 vocabulary words associated with ocean acidification. The definition of each word is revealed when a player clicks on a vocabulary card. This can be used as a pre-test, to reinforce the vocabulary, and/or to check what students have learned. The game may be played on screen or the cards may be printed and cut out. This game is part of (…) Ocean Acidification Education series.
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