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Outer organic layer and internal repair mechanism protects pteropod Limacina helicina from ocean acidification

Peck, Victoria L.; Tarling, Geraint A.; Manno, Clara; Harper, Elizabeth M.; Tynan, Eithne. 2016 Outer organic layer and internal repair mechanism protects pteropod Limacina helicina from ocean acidification. Deep Sea Research II, 127. 41-52. 10.1016/j.dsr2.2015.12.005

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This article has been accepted for publication and will appear in a revised form in Deep Sea Research II, published by Elsevier. Copyright Elsevier.
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Abstract/Summary

Scarred shells of polar pteropod Limacina helicina collected from the Greenland Sea in June 2012 reveal a history of damage, most likely failed predation, in earlier life stages. Evidence of shell fracture and subsequent re-growth is commonly observed in specimens recovered from the sub-Arctic and further afield. However, at one site within sea-ice on the Greenland shelf, shells that had been subject to mechanical damage were also found to exhibit considerable dissolution. It was evident that shell dissolution was localised to areas where the organic, periostracal sheet that covers the outer shell had been damaged at some earlier stage during the animal’s life. Where the periostracum remained intact, the shell appeared pristine with no sign of dissolution. Specimens which appeared to be pristine following collection were incubated for four days. Scarring of shells that received periostracal damage during collection only became evident in specimens that were incubated in waters undersaturated with respect to aragonite, ΩAr≤1. While the waters from which the damaged specimens were collected at the Greenland Sea sea-ice margin were not Ω Ar ≤1, the water column did exhibit the lowest ΩAr values observed in the Greenland and Barents Seas, and was likely to have approached ΩAr≤1 during the winter months. We demonstrate that L. helicina shells are only susceptible to dissolution where both the periostracum has been breached and the aragonite beneath the breach is exposed to waters of ΩAr≤1. Exposure of multiple layers of aragonite in areas of deep dissolution indicate that, as with many molluscs, L. helicina is able to patch up dissolution damage to the shell by secreting additional aragonite internally and maintain their shell. We conclude that, unless breached, the periostracum provides an effective shield for pteropod shells against dissolution in waters ΩAr≤1, and when dissolution does occur the animal has an effective means of self-repair. We suggest that future studies of pteropod shell condition are undertaken on specimens from which the periostracum has not been removed in preparation.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.dsr2.2015.12.005
Programmes: BAS Programmes > BAS Programmes 2015 > Ecosystems
BAS Programmes > BAS Programmes 2015 > Palaeo-Environments, Ice Sheets and Climate Change
ISSN: 0967-0645
Additional Keywords: Limacina helicina, ocean acidification, Periostracum, Greenland, sea ice, Pteropod
Date made live: 16 Dec 2015 11:35 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/510867

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