Journal of the Marine Biological Association of the United Kingdom

Research Article

Geographical variation in shell morphology of juvenile snails (Concholepas concholepas) along the physical–chemical gradient of the Chilean coast

Laura Ramajoa1a2, Ángel Baltanása2, Rodrigo Torresa3, Patricio H. Manríqueza4, Alejandro Rodriguez-Navarroa5 and Nelson A. Lagosa1 c1

a1 Laboratorio de Ecología y Cambio Climático (LEC2), Facultad de Ciencias, Universidad Santo Tomás, Santiago, Chile

a2 Departamento de Ecología, Facultad de Ciencias. Universidad Autónoma de Madrid, Madrid, Spain

a3 Centro de Investigación de Ecosistemas de la Patagonia (CIEP), Universidad Austral de Chile, Valdivia, Chile

a4 Instituto de Ciencias Marinas, Laboratorio Costero de Recursos Acuaticos de Calfuco, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile

a5 Departamento de Mineralogía y Petrología, Universidad de Granada, Spain

Abstract

Changes in phenotypic traits, such as mollusc shells, are indicative of variations in selective pressure along environmental gradients. Recently, increased sea surface temperature (SST) and ocean acidification (OA) due to increased levels of carbon dioxide in the seawater have been described as selective agents that may affect the biological processes underlying shell formation in calcifying marine organisms. The benthic snail Concholepas concholepas (Muricidae) is widely distributed along the Chilean coast, and so is naturally exposed to a strong physical–chemical latitudinal gradient. In this study, based on elliptical Fourier analysis, we assess changes in shell morphology (outlines analysis) in juvenile C. concholepas collected at northern (23°S), central (33°S) and southern (39°S) locations off the Chilean coast. Shell morphology of individuals collected in northern and central regions correspond to extreme morphotypes, which is in agreement with both the observed regional differences in the shell apex outlines, the high reclassification success of individuals (discriminant function analysis) collected in these regions, and the scaling relationship in shell weight variability among regions. However, these extreme morphotypes showed similar patterns of mineralization of calcium carbonate forms (calcite and aragonite). Geographical variability in shell shape of C. concholepas described by discriminant functions was partially explained by environmental variables (pCO2, SST). This suggests the influence of corrosive waters, such as upwelling and freshwaters penetrating into the coastal ocean, upon spatial variation in shell morphology. Changes in the proportion of calcium carbonate forms precipitated by C. concholepas across their shells and its susceptibility to corrosive coastal waters are discussed.

(Received January 21 2012)

(Accepted June 13 2013)

(Online publication August 06 2013)

Keywords

  • outline analysis;
  • elliptic Fourier analysis;
  • upwelling;
  • ocean acidification;
  • carbonate system parameters;
  • shell mineralization

Correspondence

c1 Correspondence should be addressed to: N. A. Lagos, Laboratorio de Ecología y Cambio Climático (LEC2), Facultad de Ciencias, Universidad Santo Tomás, Santiago, Chile email: nlagoss@ust.cl