Echinoderms contribute to global carbon sink (their impact has been significantly underestimated)

[OKIsItJustMe]

http://www.eurekalert.org/pub_releases/2010-01/nocs-ect010810.php

Public release date: 8-Jan-2010

Contact: Dr. Rory Howlett
[e-mail]
44-238-059-8490
http://www.noc.soton.ac.uk/">National Oceanography Centre, Southampton (UK)

Echinoderms contribute to global carbon sink

Echinoderms and carbon

The impact on levels of carbon dioxide in the Earth's atmosphere by the decaying remains of a group of marine creatures that includes starfish and sea urchin has been significantly underestimated.

"Climate models must take this carbon sink into account," says Mario Lebrato, lead author of the study. The work was done when he was at the National Oceanography Centre, Southampton (NOCS) and affiliated with the University of Southampton's School of Ocean and Earth Science (SOES); he is now at the Leibniz Institute of Marine Science in Germany.

Globally, the seabed habitats occupy more than 300 million million square metres, from the intertidal flats and pools to the mightiest deep-sea trenches at 11,000 meters. The benthos – the animals living on and in the sediments – populate this vast ecosystem.

Calcifying organisms incorporate carbon directly from the seawater into their skeletons in the form of inorganic minerals such as calcium carbonate. This means that their bodies contain a substantial amount of inorganic carbon. When they die and sink, some of the inorganic carbon is remineralised, and much of it becomes buried in sediments, where it remains locked up indefinitely.

Lebrato and his colleagues provide the first estimation of the contributions of starfish, sea urchins, brittle stars, sea cucumbers and sea lilies – all kinds of echinoderm – to the calcium carbonate budget at the seabed. They estimate that the global production from all echinoderms is over a tenth (0.1) of a gigatonne of carbon per year – that is, more than a hundred thousand million kilograms.

This is less than the total biological production in the main water column, or pelagic zone, which scientists believe to be between around 0.6 and 1.8 gigatonnes of carbon per year. But echinoderms apparently deliver more carbon to the sediments than do forams, for example. These microscopic animals live in vast numbers in the oceans and are traditionally regarded along with coccolithophores (single-celled marine plants surrounded by calcium carbonate plates) as one of the biggest contributors to the flux of calcium carbonate from the sunlit surface waters to the ocean's interior – the so-called 'biological carbon pump'.

"Our research highlights the poor understanding of large-scale carbon processes associated with calcifying animals such as echinoderms and tackles some of the uncertainties in the oceanic calcium carbonate budget," says Lebrato: "The realisation that these creatures represent such a significant part of the ocean carbon sink needs to be taken into account in computer models of the biological pump and its effect on global climate."

There is a worry that ocean acidification due to increased carbon dioxide emissions from the burning of fossil fuels could reduce the amount of calcium carbonate incorporated into the skeletons of echinoderms and other calcifying organisms.

However, different echinoderm species respond to ocean acidification in different ways, and the effects of rising temperatures can be as significant as those of rising carbon dioxide. How this will affect the global carbon sink remains to be established.

Lebrato concludes: "The scientific community needs to reconsider the role of benthic processes in the marine calcium carbonate cycle. This is a crucial but understudied compartment of the global marine carbon cycle, which has been of key importance throughout Earth history and it is still at present."

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Contact information:

For more information contact the NOCS Press Officer Dr Rory Howlett on [phone] Email: [e-mail]

Images are available from the NOCS Press Office (Tel. [phone]).

Scientist contact
Mario Lebrato: email [e-mail]; telephone [phone] until 17 January, 0049 431 600 4507 thereafter.
The authors are: Mario Lebrato (NOCS/SOES), Debora Iglesias-Rodríguez (NOCS/SOES), Richard Feely (Pacific Marine Environmental Laboratory/National Oceanic and Atmospheric Administration,, Seattle), Dana Greeley (NOCS/SOES), Daniel Jones (NOCS), Nadia Suarez-Bosche (NOCS/SOES), Richard Lampitt (NOCS), Joan Cartes (Institut de Ciències del Mar de Barcelona), Darryl Green (NOCS) and Belinda Alker (NOCS).

Publication:
Lebrato, M., et al. Global contribution of echinoderms to the marine carbon cycle: a reassessment of the oceanic CaCO3 budget and the benthic compartments. Ecological Monograghs doi: 10.1890/09-0553 (published on-line, 2009).

http://www.esajournals.org/doi/abs/10.1890/09-0553

See also: http://www.nature.com/news/2010/100107/full/news.2009.1041.html

The National Oceanography Centre, Southampton is the UK's focus for ocean science. It is one of the world's leading institutions devoted to research, teaching and technology development in ocean and earth science. Over 500 research scientists, lecturing, support and seagoing staff are based at the centre's purpose-built waterside campus in Southampton along with over 700 undergraduate and postgraduate students.

The National Oceanography Centre, Southampton is a collaboration between the University of Southampton and the Natural Environment Research Council. The NERC royal research ships RRS James Cook and RRS Discovery are based at NOCS as is the National Marine Equipment Pool which includes Autosub and Isis, two of the world's deepest diving research vehicles.

[X_Digger]

1. Some interesting points..

Many echinoderms (urchins especially) shed and replace their spines on a regular basis. These cast-off / broken spines aren't food for other creatures, nor do they dissolve (without ph < 6.7) so they represent quite a large carbon sink. Many of these same urchins are incredible herbivores, so as nitrate rich run-off causes proliferation of algae, urchin populations can rise to meet the supply. Quite the double plus good whammy there.

[HillbillyBob]

2. Ah but the nitrogen run offs do a lot of damage up to the point

they are absorbed by the urchins. We need to control the run off too as its really detrimental to fresh water waterways.

[X_Digger]

3. Oh absolutely, but..

.. nice to know that nature has a way of taking advantage of imbalances to some degree.

[HillbillyBob]

4. True, but we are doing too much too fast for nature to

right itself. If the EPA had been let do their job through the rpigs generations.......
I grew up near the Potomac river, it was dead there was a pulp and paper mill, tire factory, chemical factory along the up stream branches. For years I did not see a live fish other than the occasional catfish or carp and they did not look well. When EPA stepped in in the mid 70s and ordered massive clean ups it only took a few years for the worst of the polution to run out to sea, but there are lingering Dioxins and other stuff in there it is still not safe all these years later.

[joshcryer]

5. We release 30 Gt, they absorb 10 Mt.

Just keeping things in to perspective. This will help the models improve, though.

[phantom power]

6. I think we should eat them all.

Right after the jellyfish.