Watersipora subtorquata (d'Orbigny, 1852) has been widely reported as a fouling species from tropical to temperate waters. The continued confusion over the correct name for this species led us to provide a redescription of d'Orbigny's type of Cellepora subtorquata, and to make comparisons with other species of Watersipora. We show that the majority of spec-

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% MgCO 3 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% MgCO 3 in calcite in bryozoan skeletons was statistically different among sites for all study species. The difference in wt% MgCO 3 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.

Bryozoans exhibit a highly variable geochemistry within their calcium carbonate skeletons. Previous studies have predominantly attributed this variability to differences in seawater temperature influencing the relative deposition of aragonite and calcite, and the extent of magnesium incorporation into the calcite lattice. However, the patterns and scale of this variability have not been examined in detail. We conducted a high-replicate, multi-site study on the skeletal mineralogy of temperate Northern Hemisphere bryozoans to investigate the range of skeletal aragonite and Mg-calcite variability between species and the relative influence of environmental and biological factors on skeletal biogeochemistry. During a cruise in May 2012 in Scapa Flow, Orkney, Northeast Scotland, 480 specimens from 3 bryozoan species were collected by SCUBA diving. Samples were obtained from 5 study sites with similar depths and physical characteristics. All specimens were collected within the same week and were selected to be of similar size, age and breeding status. The results of X-ray diffraction analysis showed that wt% MgCO 3 in calcite and wt% aragonite in total CaCO 3 were statistically different between sites for all species. This may be explained by differential population connectivity between sites influenced by the tidal regimes of Scapa Flow. No temperate bryozoan species showed the expected positive trends of increasing wt% MgCO 3 in calcite or wt% aragonite in total CaCO 3 with seawater temperature. Based on the data generated in this study, we suggest that both environmental and biological factors are involved in the control of skeletal mineralogy in some temperate bryozoan species.

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