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Author Gerrish, G.A.; Morin, J.G.; Rivers, T.J.; Patrawala, Z.
Title Darkness as an ecological resource: the role of light in partitioning the nocturnal niche Type Journal Article
Year 2009 Publication Oecologia Abbreviated Journal Oecologia
Volume 160 Issue 3 Pages 525-536
Keywords Age Factors; Animals; Belize; Crustacea/*physiology; *Darkness; *Ecosystem; Feeding Behavior/physiology; Linear Models; Motor Activity/*physiology; Photoperiod; Sexual Behavior, Animal/physiology; Water Movements
Abstract Nocturnal behaviors that vary as a function of light intensity, either from the setting sun or the moon, are typically labeled as circadian or circalunar. Both of these terms refer to endogenous time-dependent behaviors. In contrast, the nightly reproductive and feeding behaviors of Vargula annecohenae, a bioluminescent ostracod (Arthropoda: Crustacea) fluctuate in response to light intensity, an exogenous factor that is not strictly time-dependent. We measured adult and juvenile activity of V. annecohenae throughout lunar cycles in January/February and June 2003. Overnight and nightly measurements of foraging and reproductive behavior of adult V. annecohenae indicated that activity was greatest when a critical “dark threshold” was reached and that the dark threshold for adult V. annecohenae is met when less than a third of the moon is visible or at the intensity of light 2-3 min before the start of nautical twilight when no moon is illuminated. Juvenile V. annecohenae were also nocturnally active but demonstrated little or no response to lunar illumination, remaining active even during brightly moonlit periods. In addition to light level, water velocity also influenced the behaviors of V. annecohenae, with fewer juveniles and adults actively foraging on nights when water velocity was high (>25 cm/s). Our data demonstrate that the strongest environmental factor influencing adult feeding and reproductive behaviors of V. annecohenae is the availability of time when illumination is below the critical dark threshold. This dependence on darkness for successful growth and reproduction allows us to classify darkness as a resource, in the same way that the term has been applied to time, space and temperature.
Address Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA. ggerrish@nd.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0029-8549 ISBN Medium
Area Expedition Conference
Notes PMID:19330516 Approved no
Call Number IDA @ john @ Serial 16
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