Behavior and reproduction of the rotifer Brachionus plicatilis species complex under different light wavelengths and intensities

Abstract

We investigated the influence of light on phototactic behavior and reproduction in two species of rotifer from the Brachionus plicatilis species complex (B. plicatilis sensu stricto (s. s.) and Brachionus manjavacas). This was done to understand how light effects these species so that we might use this knowledge to establish a more efficient aquaculture protocol. We used four different light wavelengths (white, with peaks at 460 and 570 nm; blue at 470 nm; green at 525 nm; and red at 660 nm) and four intensities (i.e., 0.5-30.0 W/m 2 ). Using microspectrophotometry we determined that eyespots of these two Brachionus species absorbed blue and green light 5.5 times more than red light. B. plicatilis s. s. showed positive phototaxis under white, blue, and green light at lower light intensities, but no phototaxis under red light at all intensities (0.5, 6.2, 15.0, and 30.0 W/m 2 ). Similar patterns of phototaxis were observed in B. manjavacas and did not differ among mictic, amictic females, and male rotifers. Population growth rate of B. plicatilis s. s. under dark condition was 1.1-1.2 times higher than that under white light condition. No significant differences were observed in population growth rate at 3.8 and 6.2 W/m 2 at all light wavelengths. On the other hand, population growth rates at 0.5 and 1.6 W/m 2 were the lowest under blue light. According to these results, both wavelength and intensity of light affect the population growth of rotifers, which in turn may be influenced by the rotifers' wavelength-dependent phototaxis.

Nutritional effects on the visual system of the rotifer Brachionus plicatilis sensu stricto (Rotifera: Monogononta)

“…Rhodopsin as a visual pigment of rotifers is generally necessary to sense low intensity light in rod cells (Khorana, 1992). The positive phototaxis of rotifers was stronger under relatively weak light intensity (0.5 W m -2 ) at 470 nm (blue), which is the wavelength at which the pigmented area absorbs maximally, and under higher light intensity (15.0 W m -2 ) at 660 nm (red) which is the light wavelength with minimum absorbance (Kim et al, 2014). Therefore, three light intensities (i.e., 0.1, 0.5 and 15.0 W m -2 ) were tested to compare phototaxis patterns at two wavelengths in rotifer subjected to two feeding regimes that resulted in different absorbance of eyespot.…”

“…Phototaxis of Brachionus plicatilis species complex is simultaneously affected by light wavelength and intensity (Kim et al, 2014). Wavelength induced strong positive phototaxis of rotifers was related to maximum absorbance of the pigmented area of the eyespot (Cornillac et al, 1983;Kim et al, 2014).…”

“…Phototaxis of Brachionus plicatilis species complex is simultaneously affected by light wavelength and intensity (Kim et al, 2014). Wavelength induced strong positive phototaxis of rotifers was related to maximum absorbance of the pigmented area of the eyespot (Cornillac et al, 1983;Kim et al, 2014). Moreover, rotifer photokinetic movements were also influenced by the light wavelength and intensity (Clément et al, 1983) and these movement patterns were expected to affect their reproduction (Kim et al, 2014).…”

“…Wavelength induced strong positive phototaxis of rotifers was related to maximum absorbance of the pigmented area of the eyespot (Cornillac et al, 1983;Kim et al, 2014). Moreover, rotifer photokinetic movements were also influenced by the light wavelength and intensity (Clément et al, 1983) and these movement patterns were expected to affect their reproduction (Kim et al, 2014). The rotifer eyespot, cerebral eye consists of two types of pigment-bearing cells: one epithelial cell cup containing accessory pigment and one or more sensory neurons (sensory pigments) with membranous structure (Cornillac et al, 1983).…”

Measurement of Survival Time in <em>Brachionus </em>Rotifers: Synchronization of Maternal Conditions

“…See Snell et al (2014) for details 11 . Typically, use Tetraselmis tetrathele (~2 × 10 5 cells/ml 27,28 ), T. suecica (~6 × 10 5 cells/ml 25,29 ), and Nannochloropsis oculata (~7 × 10 6 cells/ml 30,31 ). Since diet algae (species, culture conditions, biochemical compositions) significantly influences survival time of Brachionus rotifers, use the same lot of microalga in all experimental groups.…”