GeoLog

Laura Roberts-Artal

Laura Roberts Artal is the Communications Officer at the European Geosciences Union. She is responsible for the management of the Union's social media presence and the EGU blogs, where she writes regularly for the EGU's official blog, GeoLog. She is also the point of contact for early career scientists (ECS) at the EGU Office. Laura has a PhD in palaeomagnetism from the University of Liverpool. Laura tweets at @LauRob85.

Geosciences Column: Adapting to acidification, scientists add another piece to the puzzle

In the latest Geosciences Column Sara Mynott sheds light on recent research into how ocean acidification is affecting the California Current Large Marine Ecosystem. The findings, published in Biogeosciences, reveal large differences between the abilities of different animals to adapt and highlight the urgent need to understand the way a greater suite of species are responding…

Large Marine Ecosystems (LMEs) are highly productive ocean areas that border the continents. To give you a flavour of just how productive we’re talking, together the world’s LMEs account for 80% of the global marine fisheries catch, making them incredibly important regions both socially and economically. The California Current Large Marine Ecosystem (CCLME) is one such system and covers the length of the US Pacific coast. But, like other ocean ecosystems, the CCLME is under threat from climate change.

Major changes in the carbonate chemistry of the oceans are expected over the next few decades, and changes in the California Current system are to be some of the most rapid. Determining how this system, and indeed other ecosystems, will respond is a significant challenge for biologists, ecologists and climate scientists alike.

In 2010, an interdisciplinary research group known as OMEGAS (Ocean Margin Ecosystems Group for Acidification Studies) set out to find answers by monitoring a ~1300 km stretch of the CCLME that runs from central Oregon to southern California. Because this stretch of ocean can be divided into distinct areas with differing pH and carbonate chemistry, the researchers could compare the characteristics of animals living in more acidic conditions with those living in a less acidic environment and assess their ability to adapt.

Like other LMEs, the California Current system is characterised by upwelling – a process that brings nutrient-rich deep water to the surface. Upwelling waters bring with them a change in pH. In the southern CCLME, there is regular upwelling but in the north it is intermittent. This means animals living off the Oregon coast experience more variable pH, and are exposed to lower pH water more often. By comparing animals in the north with those in the south of the study area, the OMEGAS scientists could effectively peer into the ecosystem’s future. The scientists were substituting space for time.

The California Current Large Marine Ecosystem, showing the sites monitored by OMEGAS for changes in the region’s biology and chemistry. Seawater is coloured according to temperature and land is shown in grey. (Credit: Hoffman et al., 2014)

The California Current Large Marine Ecosystem, showing the sites monitored by OMEGAS for changes in the region’s biology and chemistry. Seawater is coloured according to temperature and land is shown in grey. (Credit: Hoffman et al., 2014)

By matching measurements of ocean properties, including pH, temperature and the amount of CO2 in the water, with information about the way different animals are responding to acidity (e.g. growth rate, shell thickness) and their genetic variation, the team are putting together a picture of how acidification is likely to affect the ecosystem in the future. One such animal is the purple sea urchin, a conspicuously bright spiny mass found throughout the CCLME, and an important control on the amount of algae carpeting the coast.

Purple sea urchin, Strongylocentrotus purpuratus. (Credit: Wikimedia Commons user Taollan83)

Purple sea urchin, Strongylocentrotus purpuratus. (Credit: Wikimedia Commons user Taollan83)

When peering at their skeletons for signs of acidification-related stress, the OMEGAS team found that the urchins differed little between sites – they were all tolerant of the pH range experienced across the CCLME. Urchin larvae travel large distances, rendering populations relatively homogeneous, so it isn’t too surprising. Taking a look at another ecologically important species, the Californian mussel, the team found that they were also made of hardy stuff, as growth in adult mussels was not reduced in low pH regions.

The news wasn’t all good though. A series of complementary experiments revealed that mussel larvae exposed to low pH water showed a decline in both growth and shell strength, similar to that seen in other young marine bivalves. Such a weakness would leave them more susceptible to attack from predators and, as ocean acidification continues, means they will become yet more vulnerable to predation in the future. Purple sea urchin larvae, on the other hand, could tolerate present day CO2 conditions, and higher levels had little influence on their growth and development. What’s more, studies of the sea urchin’s genetics revealed high genetic variation in the purple sea urchin population – a good indicator that they’d be able to adapt to future change.

California mussels, Mytilus californianus. (Credit: Stephen Bentsen)

California mussels, Mytilus californianus. (Credit: Stephen Bentsen)

The study highlights that the impact of acidification varies widely between species and a greater understanding of how ocean acidification will affect a variety of marine organisms is urgently needed. The OMEGAS team are now figuring out the capacity of other organisms in the CCLME to adapt, including coralline algae, a widely distributed algae with a calcium carbonate skeleton, making it highly vulnerable to ocean acidification.

The team are continuing their work in an effort to find refuges that may be relatively safe from future acidification, populations and life stages that are particularly vulnerable and those that are able to adapt to the rate of change our oceans are currently experiencing. Understanding how multiple species can adapt is critical to creating a coherent picture of how acidification will affect regions such as the CCLME in the future.

 

By Sara Mynott, PhD Student, University of Exeter

 

Reference:

Hofmann, G. E., Evans, T. G., Kelly, M. W., Padilla-Gamiño, J. L., Blanchette, C. A., Washburn, L., Chan, F., McManus, M. A., Menge, B. A., Gaylord, B., Hill, T. M., Sanford, E., LaVigne, M., Rose, J. M., Kapsenberg, L., and Dutton, J. M.: Exploring local adaptation and the ocean acidification seascape – studies in the California Current Large Marine Ecosystem, Biogeosciences, 11, 1053-1064, doi:10.5194/bg-11-1053-2014, 2014.

Imaggeo on Mondays: Trapped air

Can you imagine walking into the depths of an icy, white, long and cavernous channel within a thick glacier? That is exactly what Kay Helfricht did in 2012 to obtain this week’s Imaggeo on Mondays photograph.

Tellbreen Glacier is a small glacier (3.5Km long) in the vicinity of the Longyearbyen valley in the Svalbard region of Norway. Despite its limited size, it is an important glacier. One of the key parameters scientist use to understand how glaciers are affect by a warming climate is how the melt water is transported through to the front of the glacier. The majority of models utilise data from temperate or polythermal glaciers, i.e., glaciers which have free water within the icy matrix. Tellbreen is a cold glacier, meaning the basal layers of ice are frozen to the glacier bed; despite the traditional view that cold glaciers are not able to store, transport and release water, Baelun and Benn, 2011 found Tellbreen does this year round.

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Kay visited Tellbreen whilst at the Artic Glaciology course at the University Centre in Svalbard. ‘Each weak one excursion led us to glaciers in the vicinity of Longyearbyen’ says Kay, ‘this day we visited the glacier Tellbreen. Near the tongue of the glacier the outlet of an englacial channel enabled us to explore the inside of the glacier. We went for some tens of meters into the channel.’

What the group found were that the walls of ice either side of the channel contained impurities, from stones to gravel, as well as mud and also water. The image above shows ‘air trapped in the ice-walls of the conduit at a time when the conduit would have been filled with meltwater of the glacier’ explains Kay. Air accumulated in bubbles at the roof of the conduit. When the water in the conduit started to refreeze along the side-walls, these smooth lenticular bubbles were trapped and stored in the ice. Studying the bubbles and other impurities in the ice can give hints on the history of the glaciers ice flow and its thermal regime over several decades.

References

Baelum. K., Benn. D.I.: Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar, The Cyosphere, 5, 139-149, 2011

Naegeli. K., Lovell. H., Zemp. M., Benn, I. The hydrological system of Tellbreen, a cold-based valley glacier on Svalbard, investigated by using a systematic glacio-speleologicalapproach, Geophysical Research Abstracts, 16, EGU2014-6149, 2014 (conference abstract)

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

The known unknowns – the outstanding 49 questions in Earth sciences (Part I)

The Northern Hemisphere (Credit: Maximilian Reuter, www.imaggeo.eu)

The Northern Hemisphere
(Credit: Maximilian Reuter, via imaggeo.egu.eu)

Science is about asking questions, as much as it is about finding answers. Most of the time spent by scientists doing research is used to constrain and clarify what exactly is unknown – what does not yet form part of the consensus among the scientific community. Researchers all over the globe are working tirelessly to answer the unresolved questions about the inner workings of our planet, but inevitably new answers only lead to new questions. What are the main questions that will keep Earth scientists busy for many years to come?

Daniel Garcia-Castellanos (working at the Spanish National Research Council [CSIC] in Barcelona), through online collaboration with other colleagues, has put together a list of the top 49 questions which provide a fully referenced account of the main current scientific questions, disputes and challenges in the geosciences, with special emphasis on the solid Earth. Nevertheless, 49 is a big number, so we’ve split the questions into more manageable sections. What follows is a series of five posts over the next few weeks, detailing key research questions in specific areas.

This series should be your one-stop shop and quick-reference guide of the current hot topics in geosciences. If you are a budding investigator, let it serve as inspiration for the direction you want your research to take and, if you are an established scientist, let it reignite your passion for the subject. For everyone else, marvel at everything we’ve yet to learn. If you think there are other questions that should be added to the list, we’d love to hear from you! Make sure you add your suggestions in the comments section.

We start the series with the fundamental question: How did it all begin?

The Early Earth and the Solar System

New, exciting hypotheses about the early stages of our planet have been driven by advances in our understating of the geochemistry of meteorites, amongst other findings. As per usual, the answers are outnumbered by our numerous knowledge gaps:

1. How did the Earth and other planets form? Were planets formed in situ or in orbits different from their present ones? What determined the different deep layering of the solar planets? (McKinnon, 2012, Science – on Mercury)

2. How did the Moon form? Was there ever a collision of the Earth with another planet (Theia), which might have given birth to our satellite? (Canup, 2013, Science) There is compelling evidence, such as measures of a shorter duration of the Earth’s rotation and lunar month in the past, pointing to a Moon much closer to Earth during the early stages of the Solar System. (Williams, 1991, CSPG Spec. Pubs.)

The Moon. (Credit: Konstantinos Kourtidis, via imaggeo.egu.eu)

The Moon (Credit: Konstantinos Kourtidis, distributed via imaggeo.egu.eu)

3. How hot is the inside of the planet and how did this temperature evolve? How did Earth’s internal temperature decay since it formed by accretion of stony meteorites known as chondrites? How abundant are radiogenic elements in the Earth’s interior and to what extent are they a source of internal heat? Did a “faint young sun” ever warm a “snowball Earth”? (WiredMarty et al., 2013, Science)

4. Why do plate tectonics occur only on Earth? (Martin et al., 2008, Phys. Edu.) How did the planet cool down before the mantle convection lead to plate tectonics? Was the Earth’s crust formed during the early stages of its evolution or is it the result of a gradual distillation of the mantle that continues today along with crustal recycling? Is the crust still growing or does its recycling compensate for crust formation at mid-ocean ridges and other volcanic areas?

Plate_tectonics_map

Plate tectonic map (Source: Wikimedia Commons, Credit: NASA)

5. How inherent to planetary evolution is the development of life conditions? Earth-like planets are now known to be abundant in our galaxy (two out of three stars may have one [for example, Cassan et al., 2012, Nature]), but how many of them develop widespread durable water chemistry? (Zimmer, 2005, ScienceElkins-Tanton, 2013, Nature) How much of our water is supplied by comets or asteroids; when and how did it reach the Earth? [Greene, 2013, Smithsonian Mag.]

Water Drops. (Credit: Jacqueline Isabella Gisen, via imaggeo.egu.eu)

Water drops (Credit: Jacqueline Isabella Gisen, via imaggeo.egu.eu)

Whilst this is likely not an exhaustive list of the questions we have about how our planet came to be and its early development, it no doubt highlights the frontiers of our current understanding.

Next time we explore the Earth’s deep interior. Direct study of samples can only be achieved for the top 12km of the Earth’s crust, so what lies beneath?

 

By Laura Roberts Artal, EGU Communications Officer, based on the article previously posted on RetosTerricolas by Daniel Garcia Castellanos, researcher at ICTJACSIC, Barcelona

Shape the scientific programme at the EGU 2015 General Assembly

Time is running out, so if you have a great idea for a conference session but haven’t quite put it into practice: now’s your chance!

Until this time next week (12th September) you can submit your session ideas and take part in organising the scientific programme for the EGU General Assembly in 2015.

What you need to do:

  1. Take a look at the sessions that have already been suggested within the Programme Group tab in the website – where does your idea fit in?
  2. Suggest a convenor for the session and provide a short description, outlining what the session will cover
  3. Suggest modifications to the skeleton programme
  4. Submit your ideas!

You can make session suggestions and find out more on the EGU 2015 website.

Outside the conference centre during EGU 2014

Outside the conference centre during EGU 2014

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