Embryo Development and Behavior in Sea Urchin (Tripneustes gratilla) Under Different Light Emitting Diodes Condition

Abstract

This study aims to evaluate the effect of light-emitting diodes (LEDs) of different wavelengths on the embryonic development, covering behavior, righting behavior, and phototaxis of collector urchins (Tripneustes gratilla). The collector urchins were divided into three groups according to the type of LED illumination they received: full-spectrum (400–750 nm wavelength), red light (630 nm), or blue light (450 nm). The results of the embryonic development experiment indicated that the blue LED group had the highest proportion of embryos reaching the prism stage at the 24th hour and the highest proportion of embryos entering the 4-arm pluteus stage, but it also had the highest death rate at the 48th hour. The full-spectrum and red LED groups exhibited similar speeds of embryonic development. In the experiment on covering behavior performed on adult urchins, our findings indicated that the blue LED group gripped the most acrylic sheets for cover, exhibiting the most covering behavior, followed by the full-spectrum group and then the red LED group. Moreover, behavior varied with coloration, as collector urchins with a lower level of melanin exhibited more covering behavior than those with a higher melanin level. In addition, the righting behavior experiments demonstrated that the blue LED group spent the longest time righting themselves. It is possible that the relatively strong stimulation from the blue LED illumination led to a higher level of stress in the collector urchins and hence slowed their righting. The phototaxis experiment revealed the most significant negative phototactic response in collector urchins when they were under the blue LED light, followed by the full-spectrum light; the red LED light did not induce any positive or negative phototactic response in the collector urchins. This experimental result verified collector urchins’ high sensitivity to and dislike of the blue LED light. The study results confirmed that the blue LED light environment accelerated the embryonic development of collector urchins; however, the relatively strong stimulation from that light also caused them to engage in covering behavior or move away from the light. These results indicate that short-wavelength irradiation significantly affects the embryonic development and behavior pattern of this species.

The Welfare of Nile Tilapia (Oreochromis niloticus, GIFT Strain) Juveniles Cultured in Different Light Spectra

“…It has considerable practical significance for understanding the behavioral ecology and improving breeding protocols for fish, so the behavior should be considered when assessing fish welfare (Barreto et al, 2022). The light spectrum is an external environmental factor affecting farmed fish behavior (Li et al, 2021). Lighting conditions strongly affected the behavioral responses of European sea bass larvae (Villamizar et al, 2011b).…”

“…Exposure to ultraviolet light affected the behavior of virile (F. virilis) and rusty (F. rusticus) crayfishes, and the duration of time spent fighting and the number of fights significantly increased (Jackson and Moore, 2019). Collector urchins are highly sensitive to and dislike blue LED light, exhibiting the most hiding behavior with a lower level of melanin expression (Li et al, 2021). These results indicate that aquatic animals exhibit different preferred light spectra and that preferred light spectra for different species at different developmental stages should be determined and provided in culture systems.…”

“…Higher light intensities and ultraviolet light altered virile (Faxonius virilis) and rusty (Faxonius rusticus) crayfish social interactions (Jackson and Moore, 2019). Collector urchins (Tripneustes gratilla) are highly sensitive to and dislike blue LED light, exhibiting the most hiding behavior and expressing a lower level of melanin (Li et al, 2021). Blue and white light could improve sea urchins' (Strongylocentrotus intermedius) foraging and feeding abilities (Yang et al, 2020).…”