doi:10.1016/j.jembe.2006.02.012


y and Ecology 334 (2006) 316–323
www.elsevier.com/locate/jembe
Journal of Experimental Marine Biolog
A clockwork mollusc: Ultradian rhythms in bivalve activity
revealed by digital photography

David L. Rodland ⁎, Bernd R. Schöne, Samuli Helama, Jan K. Nielsen, Sven Baier

INCREMENTS Research Group, Institute for Geology and Paleontology, Johann Wolfgang Goethe University — Frankfurt am Main,
Senckenberganlage 32, 60325 Frankfurt am Main, Germany

Received 16 June 2005; received in revised form 28 November 2005; accepted 16 February 2006
Abstract

Time-lapse digital images can be acquired and archived using web-cameras, allowing non-invasive analysis of behavior patterns
of bivalve molluscs at ultradian (sub-daily) time-scales over long intervals. These records can be analyzed directly by a human
operator or through properly calibrated image analysis software. Preliminary results using species of marine and freshwater
bivalves identify several ultradian biological rhythms of similar duration. Wavelet analysis indicates strong periodicity in mantle
and siphon activity in the 3 to 7 min range, with longer duration shell contraction periods at 60–90 min. The recurrence of these
rhythms among marine and freshwater bivalve species maintained under constant (but differing) conditions suggests the influence
of common intrinsic drivers (chemico-physical mechanisms or biological clocks). Sub-daily growth increments preserved in the
shells of rapidly growing bivalve species are potentially related to these biological rhythms, with implications for shell growth,
biomineralization, and the temporal resolution of paleoclimate proxy data.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Anodonta cygnea; Arctica islandica; Mytilus edulis; Sclerochronology; Wavelet analysis
1. Introduction

The periodicity of growth increments in the skeletons
of bivalve molluscs has been documented extensively
ranging from tidal cycles to seasonal variability and
annual reproduction breaks, and can even preserve
decadal climatic oscillations (e.g., Richardson, 1988;
Goodwin et al., 2001; Schöne et al., 2004). Because of
their periodicity, these increments have played a critical
role in studies that depend on establishing growth
chronologies. Examples include: establishing the or-
⁎ Corresponding author. Tel.: +49 69 798 22974; fax: +49 69 798
22958.

E-mail address: d.rodland@em.uni-frankfurt.de (D.L. Rodland).

0022-0981/$ - see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jembe.2006.02.012
ganic origin of fossils (e.g., Leonardo da Vinci's
Leicester codex; see Gould, 1997), reconstructing
paleoclimate records (e.g., Schöne, 2004), determining
the seasonality of shellfish predation at prehistoric
human settlements (e.g., Deith, 1983), determining
modes of evolutionary change (e.g., Jones and Gould,
1999), and estimating changes in the distance from the
Earth to the Moon over geologic time (e.g., Barker,
1968).

While the identification of annual bands is well
documented (e.g., Clark, 1974), the precise nature and
origin of smaller growth increments remains a matter of
some dispute. Early work in the field suggested that
these were produced by circadian cycles, entrained by
daily light variations (e.g., Pannella and MacClintock,

mailto:d.rodland@em.unirankfurt.de
http://dx.doi.org/10.1016/j.jembe.2006.02.012

	A clockwork mollusc: Ultradian rhythms in bivalve activity revealed by digital photography
	Introduction
	Materials and methods
	Results
	Arctica islandica
	Mytilus edulis
	Anodonta cygnea

	Discussion
	Acknowledgements
	References