Latitudinal variation in calcification: Vulnerability of Antarctic benthic calcifiers to ocean acidificationSue-Ann Watson1,2, Prof Lloyd Peck2 & Prof Paul Tyler1

1National Oceanography Centre, Southampton 2British Antarctic Survey6 October 2008

Talk outline

• Background

• Sample sites and species

• Trends in calcification

• Shell structure & composition

• Cost of shell production

• Vulnerability of Antarctic benthic calcifiers

Background

• Calcified marine benthic invertebrates

– Molluscs, brachiopods, echinoderms

• Very abundant in worlds oceans – key species in marine ecosystems

• Commercial value – shellfish aquaculture, pearl industry

• Staple food source for indigenous communities

Existing knowledge

• Poleward trends

– In snails: thinner shells (Graus, 1973) & a reduction in ornamentation (Nicol, 1965; Nicol, 1967)

1) At high latitudes, shell-building materials (Ca2+) are more difficult to remove from seawater (Clarke, 1990; Clarke, 1993) because of the saturation state of CaCO3

Dissolution: annual loss 3-40 µm in thickness at 0°C (Harper, 2000)

© Lovrich et al, 2007

2) Fewer predators (MacArthur, 1972; Paine, 1996)

– Absence of shell damaging predators

From Orr et al, 2005

© A. Yool from GLODAP

CaCO3 saturation state

• Lower saturation state in polar regions

• Climate change likely to have a large impact on polar regions. Acidification (Orr et al., 2005) and ocean warming (Clarke et al., 2007)

Sample locations78.95°N Arctic, Svalbard

50.95°N Southampton, UK

1.22°N Singapore

19.13°S Townsville, Australia

37.49°S Melbourne, Australia

67.34°S Rothera, Antarctica

51.67°S Falkland Islands

45.87°S Dunedin, New Zealand

Samples were collected by SCUBA or from the intertidal (shallow 0 – 30 m depth)

Gastropod snailsSuperfamily: Buccinoidea

Bivalve clamsGenus: Laternula

BrachiopodsGenus: Liothyrella

UrchinsFamily: Echinidae

TR

OP

ICA

L

Antarctic interest: chose most abundant Antarctic benthic calcifiersPhylogenetically constrained: closely-related species (congeneric, confamilial)

Cantharus fumosus

L.boschasina

L. truncataScale bars = 1 cm

TE

MP

ER

AT

E

Buccinum undatum L. recta Liothyrella neozelanica Psammechinus miliaris

PO

LA

R

L. elliptica Liothyrella uvaNeobuccinum eatoni Sterechinus neumayeri

Sorry, unpublished data have been removed from this presentation. We expect these data to be published next year. For further information please contact Sue-Ann Watson at suwa@noc.soton.ac.uk

All photos © Sue-Ann Watson, unless otherwise stated

Thanks to collaborators Dr. Simon Morley, Prof. Paul Southgate, Dr. Rob Day, Dr. Tan Koh Siang, Stephanie Martin & the Rothera Research Station team 2006-07

Contact: suwa@noc.soton.ac.uk

This work is funded by a NERC studentship with BAS CASE support and an AFI CGS

grant for Antarctic fieldwork

ReferencesClarke, A. (1990). Temperature and Evolution. In Kerry, K. R. & Hempel G. (eds) Antarctic Ecosystems: Ecological Change and Conservation. Springer-Verlag Berlin Heidelberg.Clarke, A. (1993). Paleobiology, 19: 499-518.Clarke, A. et al. (2007). Phil. Trans. R. Soc. B. , 362: 149-166Graus, R. R. (1974). Lethaia 7: 303-314.Harper, L. (2000). J. Zool., Lond. 251: 179-186MacArthur, R. H. (1972). Geographical ecology: patterns in the distribution of species. New York: Harper and Row.Meredith, M. & King, J. (2005). Geophys. Res. Lett. 32Nicol, D. (1965). Nautilus 78: 109-116.Nicol, D. (1967). Journal of Paleontology, 41: 1330-1340.Orr J. et al. (2005). Nature, 437: 681-686Paine, R. T. (1996). American Naturalist, 100: 65-75.Palmer, R. (1992). PNAS, 89: 1379-1382Powell, D. et al., (2001). MEPS, 215: 191-200.Thatje, S. et al. (2008). Polar Biol, 31: 1143-1148