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Marine Ecology Progress Series

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MEPS 507:169-180 (2014)  -  DOI:

Variability of Mg-calcite in Antarctic bryozoan skeletons across spatial scales

Jennifer Loxton1,2,3, Piotr Kuklinski2,4, David K. A. Barnes5, Jens Najorka2, Mary Spencer Jones2, Joanne S. Porter1,2,*

1Centre for Marine Biodiversity and Biotechnology, School of Life Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK
2Natural History Museum, London SW7 5BD, UK
3University Marine Biological Station Millport, Isle of Cumbrae KA28 0EG, UK
4Institute of Oceanology, Polish Academy of Sciences, PL-81-712 Sopot, Poland
5British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK
*Corresponding author:

ABSTRACT: Bryozoans exhibit a highly variable chemistry within their calcium carbonate skeletons. Previous studies have shown that the level of Mg-calcite in skeletons increases with increasing seawater temperature. For high-latitude regions such as the Antarctic, which have a low range of annual sea-temperature variation, there have been no studies on bryozoan skeletons with replicated sampling approaches suitable for statistical testing. Our aim was to conduct high-replicate, multi-site sampling to determine the variability in skeletal mineralogy of bryozoans from a site in Antarctica. During an expedition in January 2012, a total of 584 specimens representing 4 bryozoan species were collected from 8 sites at Adelaide Island, West Antarctic Peninsula, by SCUBA diving. All specimens were sampled within a 3 wk period and were selected to be of similar size, age and breeding status. We compared the variability in the wt% MgCO3 in calcite of skeletons among species and investigated the relative influence of environmental and biological factors on skeleton chemistry. The results of X-ray diffraction analysis showed that the wt% MgCO3 in calcite in bryozoan skeletons was statistically different among sites for all study species. The difference in wt% MgCO3 among sites may be explained by habitat fragmentation driving directional adaptation of isolated populations to local environmental conditions. The relationship between Mg-calcite and temperature was inconsistent among species, and the predicted positive correlation between seawater temperature and Mg-calcite was not exhibited in any of the species examined. On this basis, we suggest that Antarctic bryozoan Mg-calcite should not be considered a reliable indicator of paleo-temperature.

KEY WORDS: Antarctica · Bryozoans · Mineralogy · Mg-calcite · Paleo-temperature · Magnesium

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Cite this article as: Loxton J, Kuklinski P, Barnes DKA, Najorka J, Spencer Jones M, Porter JS (2014) Variability of Mg-calcite in Antarctic bryozoan skeletons across spatial scales. Mar Ecol Prog Ser 507:169-180.

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