Present address: Department of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.
LIGHT-INDUCED MOTILE RESPONSES OF THE ESTUARINE BENTHIC DIATOMS NAVICULA PERMINUTA AND CYLINDROTHECA CLOSTERIUM (BACILLARIOPHYCEAE)1
Article first published online: 21 MAY 2009
© 2009 Phycological Society of America
Journal of Phycology
Volume 45, Issue 3, pages 592–599, June 2009
How to Cite
McLachlan, D. H., Brownlee, C., Taylor, A. R., Geider, R. J. and Underwood, G. J. C. (2009), LIGHT-INDUCED MOTILE RESPONSES OF THE ESTUARINE BENTHIC DIATOMS NAVICULA PERMINUTA AND CYLINDROTHECA CLOSTERIUM (BACILLARIOPHYCEAE). Journal of Phycology, 45: 592–599. doi: 10.1111/j.1529-8817.2009.00681.x
Received 4 April 2008. Accepted 28 January 2009.
- Issue published online: 5 JUN 2009
- Article first published online: 21 MAY 2009
Motility of estuarine epipelic (mud-inhabiting) diatoms is an important adaptation to living in biofilms present within fine sediments. Motility allows cells to migrate within the photic zone in response to a wide range of environmental stimuli. The motile responses of two species of benthic diatoms to photon fluence rates and spectral quality were investigated. Cultures of Navicula perminuta (Grunow) in van Heurck and Cylindrotheca closterium (Ehrenb.) J. C. Lewin et Reimann both exhibited photoaccumulation at ∼200 μmol · m−2 · s−1 and photodispersal from photon flux densities (PFDs) of ∼15 μmol · m−2 · s−1. Photokinesis (changing cell speed) contributed toward photodispersal for both species, and red light (λ = 681–691 nm) was most effective at inducing this process. N. perminuta showed a phototactic (directional) response, with active movement in response to a light gradient. Although this response was exhibited in white light, these directional responses were only elicited by wavelengths from 430 to 510 nm. In contrast, C. closterium did not exhibit phototaxis under any light conditions used in this study. Motile benthic diatoms thus exhibit complex and sophisticated responses to light quantity and quality, involving combinations of photokinesis and phototaxis, which can contribute toward explaining the patterns of large-scale cell movements observed in natural estuarine biofilms.