Is the Use of Underwater Polarized Light by Fish Restricted to Crepuscular Time Periods?

Abstract

We measured the spectral distributions of the underwater total and polarized light fields in the upper photic zone of meso-eutrophic waters (i.e., blue-green waters containing medium to high chlorophyll a concentrations). Per cent polarization levels during the day were always lower than 40%, but at crepuscular times these values could increase to 67%. A corresponding change occurred in the spectral distribution, with proportionately more shorter wavelength photons contributing to the total spectrum during crepuscular periods. Electrophysiological recordings from the optic nerve of rainbow trout subjected to light stimuli of varying polarization percentages show that the animal's threshold for detecting polarized light is between 63 and 72%. These physiological findings suggest that the use of water-induced polarized light cues by rainbow trout and similar percomorph fish should be restricted to crepuscular time periods.

Retinal processing and opponent mechanisms mediating ultraviolet polarization sensitivity in rainbow trout (Oncorhynchus mykiss)

“…The visual world of fish is a complex environment, where colour, intensity and polarization of light are available to guide behaviours (Cronin and Shashar, 2001;Parkyn et al, 2003;Novales Flamarique and Hawryshyn, 1997;McFarland and Munz, 1975a;Pomozi et al, 2001). The complexity of the underwater photic environment is mirrored by the diversity of visual adaptations that have evolved to perceive these qualities of light (Barry and Hawryshyn, 1999;McFarland and Munz, 1975b;Novales Flamarique and Hawryshyn, 1993).…”

Underwater linear polarization: physical limitations to biological functions

“…Indeed such contrast is the key component in shore detection tasks. Previous studies have indicated that the minimum per cent polarization detected by salmonids ranges between 60 and 70 per cent under laboratory conditions [19,47,48] and 45 per cent in field conditions (reviewed by [49]); however, when considering fish UV polarization sensitivity the value could be lower (N. S. Hawryshyn 2008, personal communication). However, the small planktonic crustacean Daphnia pulex detects a polarization signal that is only 37 per cent polarized [16].…”

Electrophysiological evidence for polarization sensitivity in the camera-type eyes of the aquatic predacious insect larva,Thermonectus marmoratus(Coleoptera: Dytiscidae)

“…Instead, almost all polarization emerges from the scattering of light in bulk media, resulting in polarization patterns that are more predictable but also more complex than those found in air. The complexity arises from factors such as depth, line of view, elevation of the sun, wavelength of the light, visibility of the bottom, proximity of the shore, and water as well as weather conditions (Waterman and Westell, 1956;Ivanoff and Waterman, 1958;Novales Flamarique and Hawryshyn, 1997). However, it is precisely the predictability of polarization patterns that allows for exploitation of polarization sensitivity for orientation, contrast enhancement, and for using the polarization features of animals as reliable visual cues for communication or prey detection (Cronin, 2006;Wehner and Labhart, 2006;Shashar et al, 2011).…”

“…In this line of view the polarization of light can be primarily explained by the refractive angle of the incident light. Additionally, it is influenced by weather and water conditions, the wavelength of the light, the albedo of a visible bottom, and the proximity to the shore (Waterman and Westell, 1956;Ivanoff and Waterman, 1958;Novales Flamarique and Hawryshyn, 1997). Overall, the percent polarization during the day might reach up to 40% and the e-vector of the polarized light during the day is approximately horizontal as long as the sun zenith angle is not too large (Novales Flamarique and Hawryshyn, 1997).…”

“…Additionally, it is influenced by weather and water conditions, the wavelength of the light, the albedo of a visible bottom, and the proximity to the shore (Waterman and Westell, 1956;Ivanoff and Waterman, 1958;Novales Flamarique and Hawryshyn, 1997). Overall, the percent polarization during the day might reach up to 40% and the e-vector of the polarized light during the day is approximately horizontal as long as the sun zenith angle is not too large (Novales Flamarique and Hawryshyn, 1997). In the presence of polarized light, zooplankton and many other small transparent organisms that possess polarization-active body parts are potentially more visible to a polarization-sensitive predator .…”