Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 348:47-54 (2007) - DOI: https://doi.org/10.3354/meps07058 Calcification morphotypes of the coccolithophorid Emiliania huxleyi in the Southern Ocean: changes in 2001 to 2006 compared to historical data J. C. Cubillos1, S. W. Wright2,3, G. Nash2, M. F. de Salas1, B. Griffiths3,4, B. Tilbrook3,4, A. Poisson5, G. M. Hallegraeff1,* 1School of Plant Science, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia 2Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia 3Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia 4Wealth from Oceans Flagship, CSIRO, GPO Box 1538, Hobart, Tasmania 7001, Australia 5Laboratoire dOcéanographie et du Climat: Expérimentations et Approches Numériques, Université Pierre et Marie Curie, 75252 Paris, France *Corresponding author. Email: hallegraeff@utas.edu.au ABSTRACT: We conducted a scanning electron microscopic survey of morphological variations in the calcareous nanoplankton species Emiliania huxleyi in Southern Ocean surface water samples collected along a transect from 43 to 64°S and 141 to 145°E during November 2001, October to February 2002/2003, 2003/2004, 2004/2005 and 2005/2006. The results were compared with historical data from a similar transect occupied in December to January 1983/1984 and January to February 1994 and 1995. While E. huxleyi was absent or extremely sparse (0.1 to 1 cells ml1) south of 60°S in 1983/1984 and 1994/1995, this species was consistently present at about 100 cells ml1 between 60 and 65°S during 2002 to 2006. The extended geographic range and/or increased southward abundance of this keystone species suggests a significant shift in Southern Ocean ecology over the past 2 decades, analogous to an observed recent range extension into the Bering Sea. Morphotype A overcalcified mainly occurred north of the Subantarctic Front and was replaced by the weakly calcified Morphotype B/C between the Subantarctic Front and Southern Antarctic Circumpolar Current Front. This northsouth shift in E. huxleyi calcification morphotypes closely tracked the northsouth decline in the calcite saturation state as calculated from carbonate system measurements. Based on current evidence, no significant changes are apparent in the calcification status of E. huxleyi in the Southern Ocean during the past 12 yr. All cultured isolates from north of the Polar Front belonged to Morphotype A, while all strains isolated south of the Polar Front belonged to Morphotype B/C and their morphologies appeared conservative in culture. The northsouth trend of decreased calcification of E. huxleyi in the Southern Ocean thus reflects the shift in dominance of one ecotype to another, rather than the environmental effect of decreased carbonatre ion concentrations and calcite saturation state on a single, apparently cosmopolitan, population. KEY WORDS: Southern Ocean · Emiliania huxleyi · Calcite saturation state · Ocean acidification Full text in pdf format PreviousNextCite this article as: Cubillos JC, Wright SW, Nash G, de Salas MF and others (2007) Calcification morphotypes of the coccolithophorid Emiliania huxleyi in the Southern Ocean: changes in 2001 to 2006 compared to historical data. Mar Ecol Prog Ser 348:47-54. https://doi.org/10.3354/meps07058 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 348. Online publication date: October 25, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.
Highlights
Half of the anthropogenic CO2 released to the atmosphere since the beginning of the industrial revolution has dissolved in the ocean, leading to a reduction of surface pH by 0.1 U (Riebesell et al 2000, Orr et al 2005)
While Emiliania huxleyi was absent or extremely sparse south of 60° S in 1983/1984 (Nishida 1986) and 1994/1995 (Findlay & Giraudeau 2000), this species was consistently present at about 100 cells ml–1 between 60 and 65° S during our surveys in the Australian sector of the Southern Ocean from 2002 to 2006
Hasle (1960) first reported the complete absence of E. huxleyi in the Antarctic Pacific based on a grid of stations at 53 to 70° S, 90 to 174° W covered by the 1947 to 1948 Norwegian Brategg Expedition
Summary
Half of the anthropogenic CO2 released to the atmosphere since the beginning of the industrial revolution has dissolved in the ocean, leading to a reduction of surface pH by 0.1 U (Riebesell et al 2000, Orr et al 2005). Under the IS92a scenario of continuing global CO2 emissions from human activities, the average pH of the upper ocean is predicted to fall by 0.4 U to pH 7.8 by the year 2100 This pH is lower than has been experienced for millennia, and, critically, the predicted rate of change is 100 times. Diminished calcification of E. huxleyi was accompanied by an increased proportion of malformed coccoliths and incomplete coccospheres Extrapolation of these observations to the world’s oceans raises the concern that ocean acidification will increase dissolution of calcium carbonate, causing a shift in the composition of the plankton community towards non-calcifying species. Emiliania huxleyi first appeared in the geological record 270 000 yr ago and is the dominant coccolithophorid in the world’s oceans This species is widely considered to be a ubiquitous cosmopolitan marine microalga, occurring from tropical to polar waters. Widespread concern about the potential effect of ocean acidification triggered a careful scanning electron microscopic analysis of E. huxleyi morphotypes in Southern Ocean samples collected from 43 to 64° S, 141 to 145° E, during November 2001 and October to February 2002/2003, 2003/2004, 2004/2005 and 2005/2006 and comparison with historic data from the same transect occupied from December to January 1983/1984 (Nishida 1986) and 1994/1995 (Findlay & Giraudeau 2000)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
