Dislodgement force and shell morphology vary according to wave exposure in a tropical gastropod (Cittarium pica)

ABSTRACT

Wave exposure has strong influences on population density, morphology and behaviour of intertidal species in temperate zones, but little is known about how intertidal organisms in tropical regions respond to gradients in wave exposure. We tested whether dislodgement force and shell shape of a tropical gastropod, Cittarium pica, differs among shores that vary in wave exposure. After adjusting for body size, we found that C. pica from exposed shores required greater dislodgement force to remove them from the shore, had slightly larger opercula (the closure to the shell aperture), and were slightly squatter in shape (reduced in shell height relative to shell width) than C. pica from sheltered shores. These morphological adjustments are consistent with those observed in temperate gastropods, which are argued to represent adaptive responses to the risk of mortality associated with dislodgement.

RESPONSIBLE EDITOR:

• Rachel Collin

KEYWORDS:

• Adaptation
• intertidal
• shell shape
• topshell

Acknowledgements

Thanks to Lianna Jarecki and the Guana Island staff for help with logistics, and to Maggie Chan, Dennis Conetta, Russell Dauksis, Linda Forrester, Fiona Forrester, Katherine Forrester and Alicia Siravo for help with fieldwork.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding was provided by the University of Puerto Rico Sea Grant College Program and the Falconwood Foundation. Student co-authors were supported by the URI Cobb Endowment Independent Study Award (Allison Holevoet), URI Undergraduate Research Initiative Award (Allison Holevoet), and the URI EPSCoR SURF Fellowship (Allison Holevoet and Sarah Merolla).