Effects of Different Light Wavelengths on the Growth of Olive Flounder (Paralichthys olivaceus)

빛의 파장이 넙치 Paralichthys olivaceus의 성장에 미치는 영향

Abstract

To investigate the effects of light on growth in fish, olive flounder (Paralichthys olivaceus) were reared under four kinds of monochromatic light-emitting diodes (LEDs) at violet (400 nm), blue (465 nm), green (508 nm), and red (635 nm) wavelengths, along with a white fluorescent lamp as control. The rearing experiments were carried out with 15 fish per tank under different wavelength illumination at the same intensity. After rearing the fish under a 12 hr:12 hr light:dark photoperiod for 60 days, percentage increases in weight gain of $269.92{\pm}13.02$, $363.21{\pm}3.74$, $433.22{\pm}4.83$, $290.17{\pm}11.83$, and $340.74{\pm}26.58%$ and increases in specific growth rates (SGR) of $2.18{\pm}0.06$, $2.56{\pm}0.07$, $2.79{\pm}0.01$, $2.27{\pm}0.05$, and $2.47{\pm}0.10$ were observed in fish grown under the illumination of red, blue, green, and violet LEDs and the white fluorescent light, respectively. The results show faster growth in fish reared under green LEDs, but slower growth in those reared under red light. Differences in most blood parameters were minor, aside from an increased level of glutamic oxaloacetic transaminase in the fish grown under red LED illumination. Histological analysis of the retina showed few changes in the ratio of photoreceptor layer thickness to total retina thickness in fish reared under the green LEDs compared to those in other illumination groups. These results indicate that green LED light can foster increased growth in olive flounder with no distinct harmful effects on their light-sensitive photoreceptor layers.

빛의 파장이 넙치의 성장에 미치는 영향을 분석하기 위하여 보라색(400 nm), 청색(465 nm), 녹색(508 nm), 그리고 적색(635 nm)의 LED와 백색 형광등하에서 성장 실험을 수행하였다. 수조당 15마리 넙치를 12:12 시간 각 파장 LED의 광주기하에서 60일 동안 사육한 결과, 각기 $269.92{\pm}13.02%$와 $2.18{\pm}0.06$(보라색), $363.21{\pm}3.74%$와 $2.56{\pm}0.07$(청색), $433.22{\pm}4.83%$와 $2.79{\pm}0.01$(녹색), $290.17{\pm}11.83$와 $2.27{\pm}0.05$(적색), 그리고 $340.74{\pm}26.58%$와 $2.47{\pm}0.10$(형광등)의 체중 증가와 일간성장률(SGR: %/day)이 관찰되었다. 본 실험 결과 녹색 LED 하에서 넙치의 성장이 가장 빨랐으며, 적색 조명 하에서는 성장이 느린 것으로 나타났다. 대부분의 혈액 지표는 그룹별 차이가 없으나, 적색 LED조명 하에서 자란 넙치에서 높은 수준의 glutamic oxaloacetic transaminase (GOT)가 관찰되었다. 빛의 1차 감지 기관인 망막의 조직학적 분석 결과 광수용체 층의 상대적 두께에 별다른 영향이 없는 것으로 보아 녹색광이 무해함을 유추할 수 있다.

Fig. 1. (A) Weight gains (%) and (B) specific growth rates of olive flounder (Paralichthys olivaceus) grown under illumination of four different LEDs (red, blue, green, and violet) and white fluorescent light (control) for a period of 60 days.

Fig. 2. Representative photomicrographs of retina specimens prepared from the eyes of olive flounder (Paralichthys olivaceus) reared under illumination of four different LEDs (red, blue, green, and violet) and a white fluorescent lamp (control) for a period of 60 days. The photomicrograph of a retina from a fish grown under blue light illustrates the regions measured for total retina (RT) and photoreceptor layer (PR) thickness. Prepared using H&E staining; 200× magnification; scale bar, 50 μm.

Table 1. Growth performance of olive flounder (Paralichthys olivaceus) reared under illumination of LEDs of four different wavelengths (red, blue, green, and violet) and white fluorescent light (control) for a period of 60 days

Table 2. Levels of glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), glucose (GLU) and total proteins (TP) in the blood plasma. Blood samples were collected from olive flounder (Paralichthys olivaceus) grown under different LED wavelengths (red, blue, green, and violet) and white fluorescent light (control group) for a period of 60 days

Table 3. Thickness (μm) of retina and photoreceptor layers in the eyes of olive flounder (Paralichthys olivaceus) reared under illumination of LEDs at four different wavelengths (red, blue, green, and violet) and a white fluorescent light (control group). Ratios of the thickness of the photoreceptor layer to that of the total retina (PR/RT) were calculated for each sample