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First published online October 19, 2007
Journal of Experimental Biology 210, 3728-3735 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.003251
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Light scattering by selected zooplankton from the Gulf of Aqaba

Y. L. Gagnon*, N. Shashar, E. J. Warrant and S. J. Johnsen

Cell and Organism Biology, Zoology Building, Helgonavagen 3, Lund 223 62, Sweden

* Author for correspondence (e-mail: 12.yakir{at}gmail.com)

Accepted 9 August 2007

Light scattering by zooplankton was investigated as a major factor undermining transparency camouflage in these pelagic animals. Zooplankton of differing transparencies – including the hyperiid amphipod Anchylomera blossevillei, an unknown gammarid amphipod species, the brine shrimp Artemia salina, the euphausiid shrimp Euphausia diomedeae, the isopod Gnathia sp., the copepods Pontella karachiensis, Rhincalanus sp. and Sapphirina sp., the chaetognath Sagitta elegans and an enteropneust tornaria larva – were illuminated dorsally with white light (400–700 nm). Spectral measurements of direct transmittance as well as relative scattered radiances at angles of 30°, 90°, 150° and 180° from the light source were taken. The animals sampled had transparencies between 1.5% and 75%. For all species, the highest recorded relative scattered radiance was at 30°, with radiances reaching 38% of the incident radiance for the amphipod A. blossevillei. Scattering patterns were also found to be species-specific for most animals. Relative scattered radiances were used to estimate sighting distances at different depths. These calculations predict that all of the examined zooplankton are brighter than the background radiance when viewed horizontally, or from diagonally above or below at shallow depths. Thus, in contrast to greater depths, the best strategy for detecting transparent zooplankton in the epipelagic environment may be to search for them from above while looking diagonally downwards, looking horizontally or looking from below diagonally upwards. Looking directly upwards proved to be more beneficial than the other viewing angles only when the viewed animal was at depths greater than 40 m.

Key words: backscattering, model, sighting distance, transmittance


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LIGHT SCATTERING BY ZOOPLANKTON
Laura Blackburn
JEB 2007 210: ii. [Full Text]  



This article has been cited by other articles:


Home page
 J. Exp. Biol.Home page
L. Blackburn
LIGHT SCATTERING BY ZOOPLANKTON
J. Exp. Biol., November 1, 2007; 210(21): ii - ii.
[Full Text] [PDF]


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