Effects of light quality and intensity on the juvenile physiological metabolism of Babylonia areolata

Abstract

Babylonia areolata lives in bottom sediments during the day and emerges at night to forage. This study examined how different light qualities (blue, white, green, and red light) and intensities (0 and 2–32 μmol·m s−1) influence the growth and physiological activity of B. areolate juveniles. Changes in the activity of digestive enzymes, such as pepsin (PPS), lipase (LPS), and amylase (AMS), as well as energy metabolic enzymes, such as hexokinase (HK), pyruvate kinase (PK), lactic dehydrogenase (LDH) and succinic dehydrogenase (SDH), were also studied. The result showed that juveniles exhibited substantial variations under different light conditions. Specifically, the maximum bodyweight specific growth rates (SGR) under green, blue, red, and white light conditions were 3.56 ± 0.45 %·d−1, 3.03 ± 0.68 %·d−1, 3.01 ± 0.72 %·d−1 and 2.99 ± 0.73 %·d−1 at light intensities of 2 μmol·m−2·s−1, 4 μmol·m−2·s−1, 8 μmol·m−2·s−1 and 2 μmol·m−2·s−1, respectively. The shell length SGR, shell width SGR and body weight SGR in the dark group were not statistically different from those in the red light group at 2 μmol·m−2·s−1 (p > 0.05), while the body weight SGR of the dark group was significantly lower than that in other groups (p < 0.05). At the light intensity of 2 μmol·m−2·s−1, the activity of PPS in green and blue light was significantly higher than in red light (p < 0.05). The activity of HK in green light was considerably higher than that in darkness (p < 0.05), and there was no significant difference in the activity of LDH between the dark group and the red light group (p > 0.05), although the results of both groups were significantly higher than those of the blue and white light (p < 0.05). In addition, the activity of PPS, AMS, HK, PK, and LDH was considerably higher in darkness than in other light qualities (p < 0.05). Under different light qualities, the activity of all enzymes at the low light intensity was significantly higher than that at the high light intensity (p < 0.05), which coincided with growth characteristics. Therefore, blue and green light promoted the growth of juveniles at low light intensity (2 μmol·m−2·s−1), but darkness inhibited their growth. The findings of this study could be used as a foundation for optimizing lighting conditions and figuring out the optimum conditions for the growth and survival of B. areolata. Furthermore, this study could help explain how to control lighting conditions in real-world breeding situations.