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

Outer organic layer and internal repair mechanism protects pteropod Limacina helicina from ocean acidification
Outer organic layer and internal repair mechanism protects pteropod Limacina helicina from ocean acidification
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, ?Ar?1. While the waters from which the damaged specimens were collected at the Greenland Sea sea–ice margin were not ?Ar?1, the water column did exhibit the lowest ?Ar values observed in the Greenland and Barents Seas, and was likely to have approached ?Ar?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 ?Ar?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 ?Ar?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.
Limacina helicina, Ocean acidification, Periostracum, Greenland, Sea ice, Pteropod
0967-0645
41-52
Peck, Victoria L
ef364d83-c135-4d7c-b43e-b936b83f2418
Tarling, Geraint A
b9eb0007-1e5b-4ced-b733-10310225c8a6
Manno, Clara
c49cdab0-866e-44fe-b504-e3c9a9924d86
Harper, Elizabeth M
a365be7f-8523-43e2-a102-720eaed6c856
Tynan, Eithne
dfed4bbd-ea2a-4ff9-81f5-de2af563943b
Peck, Victoria L
ef364d83-c135-4d7c-b43e-b936b83f2418
Tarling, Geraint A
b9eb0007-1e5b-4ced-b733-10310225c8a6
Manno, Clara
c49cdab0-866e-44fe-b504-e3c9a9924d86
Harper, Elizabeth M
a365be7f-8523-43e2-a102-720eaed6c856
Tynan, Eithne
dfed4bbd-ea2a-4ff9-81f5-de2af563943b

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

Record type: Article

Abstract

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, ?Ar?1. While the waters from which the damaged specimens were collected at the Greenland Sea sea–ice margin were not ?Ar?1, the water column did exhibit the lowest ?Ar values observed in the Greenland and Barents Seas, and was likely to have approached ?Ar?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 ?Ar?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 ?Ar?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.

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Peck et al - Outer organic layer and internal repair mechanism AAM.pdf - Accepted Manuscript
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More information

e-pub ahead of print date: 15 December 2015
Published date: May 2016
Keywords: Limacina helicina, Ocean acidification, Periostracum, Greenland, Sea ice, Pteropod
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 395179
URI: http://eprints.soton.ac.uk/id/eprint/395179
ISSN: 0967-0645
PURE UUID: a9c937f5-d5d9-4c50-8ac4-281fa970d559

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Date deposited: 23 May 2016 12:42
Last modified: 10 Jan 2022 06:12

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Contributors

Author: Victoria L Peck
Author: Geraint A Tarling
Author: Clara Manno
Author: Elizabeth M Harper
Author: Eithne Tynan

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