Interannual pteropod variability in sediment traps deployed above and below the aragonite saturation horizon in the Sub-Antarctic Southern Ocean

• Published in: Polar biology Vol. 34; no. 11; pp. 1739 - 1750
• Main Authors: Roberts, Donna, Howard, William R., Moy, Andrew D., Roberts, Jason L., Trull, Thomas W., Bray, Stephen G., Hopcroft, Russell R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-11-2011; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Anthropogenic factors; Aquatic life; Biological and medical sciences; Biomedical and Life Sciences; Calcite crystals; Carbon dioxide; Chemical oceanography; Clio recurva; Ecology; Fundamental and applied biological sciences. Psychology; Life Sciences; Limacina helicina; Marine; Marine ecology; Marine ecosystems; Microbiology; Mollusca; Mollusks; Natural populations; Ocean; Oceanography; Opacity; Original Paper; Particular ecosystems; Plankton; Plant Sciences; Polar waters; Sea water ecosystems; Sediments (Geology); Shellfish; Synecology; Wildlife management; Zoology; Antarctic Ocean; Southern Ocean; PS, Antarctica; PS, Antarctic Ocean; Aragonite saturation horizon; Aragonite; Pteropod; Zooplankton; Sub-Antarctic; Southern Ocean; Marine environment; Sediment trap; Polar region; Subpolar zone
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-011-1024-z

Anthropogenic inputs of CO
2
are altering ocean chemistry and may alter the role of marine calcifiers in ocean ecosystems. Laboratory research and ocean models suggest calcifiers in polar waters are especially at risk, particularly pteropods: pelagic aragonite-shelled molluscs. However, baseline data for natural populations of pteropods are limited, especially for polar and sub-polar waters. In order to establish baseline data on diversity, preservation state and shell flux of in situ populations of Sub-Antarctic Southern Ocean pteropods, we deployed sediment traps above (1,000 m) and below (2,000 m) the aragonite saturation horizon (ASH) (currently at 1,200 m) from 1997 to 2006 at 47°S, 142°E. We identified seven pteropod taxa. We applied a shell opacity index to each shell collected and found 50% of shells collected above the ASH to be in pristine condition but only 3% of the shells collected below the ASH showed such a high degree of preservation. We estimated pteropod shell mass fluxes for the region (0.17–4.99 mg m
−2
 day
−1
), and we identified significant reductions in shell flux for
Limacina helicina antarctica
forma
rangi
and
Clio recurva
to the trap series above the ASH and for
Limacina helicina antarctica
forma
rangi
and
Limacina helicina antarctica
forma
antarctica
to the trap series below the ASH over the interval 1997–2006. Our data establish a temporal and vertical snapshot of the current Sub-Antarctic pelagic pteropod community and provide a baseline against which to monitor Southern Ocean pteropods responses, if any, to changing ocean conditions projected for the region in the coming decades.