Evidence for Carbonate System Mediated Shape Shift in an Intertidal Predatory Gastropod

Abstract

<jats:p>Phenotypic plasticity represents an important first-line organism response to newly introduced or changing environmental constraints. Knowledge about structural responses to environmental stressors could thus be an essential measure to predict species and ecosystem responses to a world in change. In this study, we combined morphometric analyses with environmental modelling to identify direct shape responses of the predatory gastropod <jats:italic>Nucella lapillus</jats:italic> to large-scale variability in sea surface temperature and the carbonate system. Our models suggest that the state of the carbonate system and, more specifically, the substrate inhibitor ratio <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im1"><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mi>H</mml:mi><mml:mi>C</mml:mi><mml:msubsup><mml:mi>O</mml:mi><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:mrow><mml:mo>]</mml:mo></mml:mrow><mml:msup><mml:mrow><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:msup><mml:mi>H</mml:mi><mml:mo>+</mml:mo></mml:msup></mml:mrow><mml:mo>]</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math></jats:inline-formula> (SIR) has a dominant effect on the shell shape of this intertidal muricid. Populations in regions with a lower SIR tend to form narrower shells with a higher spire to body whorl ratio, whereas populations in areas with a higher SIR form wider shells with a much lower spire to body whorl ratio. These results indicate that a widespread phenotypic response of <jats:italic>N. lapillus</jats:italic> to continuing ocean acidification can be expected, potentially altering the phenotypic response pattern to predator or wave exposure regimes with profound implications for North Atlantic rocky shore communities.</jats:p>