不同波長可見光譜對海參行為及生理影響之探討

Abstract

海洋環境因子如光照、溫度、海流、棲地和鹽度等會影響海參行為及生理反應，進而造成其不同生長表現。在實驗室環境下，本研究利用不同可見光光譜對海參(Holothuria sp.)觀察其尋找遮蔽物、趨光性和明暗棲地環境之偏好選擇等行為反應，以及是否造成生理上之免疫緊迫，如耗氧率、體腔液細胞吞噬作用和呼吸樹組織損傷觀察。在研究中利用三組LED光源，分別為紅光(波長: 630 nm)、藍光(波長: 450 nm)和白光(波長: 400-750 nm)來進行行為實驗。在藍光和白光照射下，海參傾向尋找遮蔽物躲藏；三種光源在相同距離下，藍光引發海參最強的負趨光性，其次為白光，而紅光則沒有明顯的反應；在明暗棲地偏好選擇實驗中，藍光和白光光譜對大部分海參個體的偏好選擇行為產生了干擾；實驗透過測量不同光波長照明距離下的平均光通量密度(mean photon flux density)值，發現每組海參個體分別為遠離特定波長光源而產生負趨光行為後，直至在光通量密度接近57 μmol s-1 m-2的區域時才減緩其移動行為；反觀紅光組之個體幾乎無移動行為發生，但如果提升紅光組的光通量後，海參個體則明顯產生負趨光行為。所以不同光波長之光照對於海參的移動行為可能是由其光譜所含光子數目之多寡有關。在生理實驗當中，藍光組之海參相對紅光組表現出更高的氧氣消耗率；然而在體腔液細胞吞噬活性試驗中，藍光組和紅光組之間沒有顯著差異；呼吸樹組織切片結果顯示藍光組在實驗第1和2小時結締組織比控制組薄，但在第6小時回復，且呼吸樹組織在所有實驗組別中都無明顯破損。本篇研究結果表明，海參會躲避藍光和白光，而藍光和白光光譜引起的負趨光行為可能是由海參表皮上感光受器在一定的時間和面積中接收的光子數量刺激所致。同時，實驗在生理方面上並未發現短時間的藍光或紅光譜照射明顯對海參造成緊迫或呼吸樹的損傷。

Marine environmental factors such as light, temperature, water currents, habitat, and salinity can influence the behavior and physiological responses of sea cucumbers, consequently resulting in different growth performances. This study investigated the effects of different visible light spectra on the behavior and physiological responses of sea cucumbers (Holothuria sp.). The sea cucumbers were first divided into three groups (red LED: 630 nm wavelength; blue LED: 450 nm; white LED: 400-750 nm) to conduct a series of behavioral experiments. Under blue LED and white LED illumination, the sea cucumbers exhibited shelter-seeking behavior. The phototaxis experiment found that the blue LED light elicited the strongest negative phototaxis, followed by the white LED, while the red LED light elicited no obvious response. In the bottom zone preference experiment, blue LED and white LED illumination affected the bottom preference behaviors of some individuals. By measuring the mean photon flux density (MPFD) values at different illumination distances, the individuals in each group tended to stop moving at a similar MPFD value of 57 μmol s-1 m-2. However, when the photon flux of red LED was raised, individuals of the red LED group exhibited negative phototaxis. Next, we examined the physiological effects of red LED and blue LED illumination on sea cucumbers. Interestingly, the blue LED group exhibited higher oxygen consumption rates and thinner connective tissue in the respiratory tree during the early stage of the experiment. In contrast, no significant differences in coelomocyte phagocytosis were observed between the blue LED and red LED groups. Our findings suggested that the behaviors and physiological responses elicited by the blue or white LED light are likely caused by the number of photons in a specific time and area received by photoreceptors on the integument of sea cucumbers. Furthermore, neither long- nor short-wavelength spectra caused significant stress or damage to sea cucumbers in this study.