Planet Earth online – ocean acidification (audio)

The effects of climate change range from rising temperatures and higher sea levels, to extreme weather and mass extinctions.  If that wasn’t bad enough, there’s a hidden process that’s over the underway in the seas and that is that the oceans are becoming more acidic.  In the latest of our features from the Planet Earth Podcast Team, Richard Hollingham accept reports from the Plymouth Marine Laboratory where scientists were investigating the effects of ocean acidification…

Richard –   Steve Widdicombe’s lab at the Plymouth Marine Laboratory is filled with tanks of water, from rows of deep baths in the centre of the room to a series of ten tanks around the size of oil drums along the side.

Steve –   In those tanks, we can actually change the chemical parameters of the seawater to mimic what the oceans might be like in 100 to 150 years times.  And we do that by adding carbon dioxide.  What we’re trying to do is explore the effects of increased CO2 on marine eco-systems.

Richard –   Kate Delahowe for instance is studying the effects of ocean acidification on the behaviour of hermit crabs.  The crabs is working on or live in periwinkle shells, and right now, it’s time for their lunch.

Kate –   Well with these hermit crabs, I’m looking at how the ability to pick up the odours of foods is affected.  So, what I’ll do is I’ll keep them in certain treatments, but then periodically, I’ll take them out of the treatments, and put them into an observational chamber and then I’ll put in food cues and see whether they can pick them up on the water or not.  Also, they have two pairs of antennae and they have these shorter antennules which they flick through the water very rapidly.  It’s like their sniffing response and it helps them to pick up odours in the water, and it’s quite easy to record that, so that’s also what I’m recording as well.

Richard –   We’ve come out of the laboratory to a little bay just east of the main city of Plymouth and with Nadia Kristen who’s got pan scourers in her hand.  Why?

Nadia –   I’m looking at the effects of ocean acidification on rocky shore communities and what I do with these pan scourers is basically, these are community collectors.  They mimic kelp holdfast, so loads of different invertebrate species will start to colonise these pan scourers so that’s how we can actually collect the rocky shore communities I will need for my experiment.

Richard –   So you’ll put these on the rocks, they will mimic the base of the kelp and you will collect effectively a community of organisms.

Nadia –   There are lots of studies, just looking at one species and the response is quite a lot between different species, so it’s really difficult to predict how communities or even an ecosystem will respond to ocean acidification, and that’s why in my study, I’m looking at the whole community itself.  So, I want to look how the community as a whole responds to ocean acidification.

Richard –   And back in his lab, I asked Steve Widdicombe whether he’d been surprised by what they’d found so far.

Steve –   Often, we are not getting the results we expect and that the more we look into the issue of the effects of high levels CO2 on marine organisms, the more we are astounded by the complexity of the responses that occur, and the trade-offs that occur between different responses.  For example, we’ve had an instance where a marine organism is seen to be unaffected by the exposure to high CO2, but as we looked more closely, we’ve seen the fact that some of its muscles have wasted away because it’s been using energy to respond to that.  So whilst on the surface, things look fine, underneath, that’s not always the case.

Richard –   How important is it to get this sort of information?

Steve –   Well the information we’re providing here, we think is essential because yes, ocean acidification is happening, and part of the effects we’re seeing here will enable people to see the consequences of producing more CO2.  But also, it allows managers the opportunity to see how the oceans might be in 50 to 100 year’s time.  And whilst they may not be in a position to stop it, they are in a position to develop management strategies and mitigation strategies to be able to live with this change.

Steve Widdicombe, The Naked Scientists: Science Radio & Science Podcasts, September 2010. Article and audio.

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