Changes in pteropod distributions and shell dissolution across a frontal system in the California Current System

Scanning electronic micrographs illustrating different types of shell dissolution.
TitleChanges in pteropod distributions and shell dissolution across a frontal system in the California Current System
Publication TypeJournal Article
Year of Publication2015
AuthorsBednarsek N., Ohman MD
JournalMarine Ecology Progress Series
Date Published2015/03
Type of ArticleArticle
ISBN Number0171-8630
Accession NumberWOS:000351452700008
Keywordsocean fronts; Pteropoda; Shell dissolution; Vertical distribution

We tested the sensitivity of the vertical distributions and shell dissolution patterns of thecosome pteropods to spatial gradients associated with an eddy-associated front in the southern California Current System. The aragonite saturation horizon (Omega(arag) = 1.0) shoaled from > 200 to <75 m depth across the front. The vertical distribution of thecosome pteropods tracked these changes, with all 5 species showing reduced occurrence at depths below 100 m where waters were less saturated with respect to aragonite. Shell dissolution patterns of the numerically dominant thecosome Limacina helicina corresponded to the cross-frontal changes in Omega(arag) saturation state. Severe shell dissolution ( categorized here as Type II and Type III) was low in near-surface waters where Omega(arag) > 1.4, while peak dissolution occurred in depths where Omega(arag) = 1.0 to 1.4. Vertical habitat compression and increased shell dissolution may be expected to accompany future shoaling of waters that are undersaturated with respect to aragonite.


While we cannot establish unequivocally that the changes in habitat were attributable to changes in geochemical variables alone, several lines of evidence suggest that carbonate chemistry is a dominant controlling factor.  A more restricted vertical habitat for pteropods in the future may have consequences for some fish species that depend on them for prey


Student Publication: