Fish immunity
: modulation by the light environment and the melatonin hormone in a percid fish, the pike-perch

Student thesis: Doc typesDoctor of Sciences


Pike-perch (Sander lucioperca) is a valuable fish candidate for the expansion of the European aquaculture industry. However, several bottlenecks hamper its development including high mortalities that may reflect a low welfare related to a high stress responsiveness. Because of its tapetum lucidum that is a reflecting layer in the retina, pike-perch is more sensitive to the light environment. Thus, inappropriate light environments in farm conditions was hypothesized to affect its physiology, including a higher stress level and a decrease in immunocompetence and growth.
Light information is perceived by photoreceptors and converted by the pineal gland into a melatonin signal. This hormone conveys the information about the time of the day and the night to cells and organs and it is known to modulate numerous functions in vertebrates including behavior, reproduction and growth. However, while well described in mammals, the modulation of the immune system by melatonin has been poorly investigated in teleosts. We thus hypothesized that this hormone may play a central role by being a relay between the light, the stress axis and the immune system.

Several experiments were designed in order to better characterize the modulation of the immune system by the light environment, with special consideration for the melatonin hormone as a potential intermediate. All the results defined complex interactions between the circadian axis, the stress axis and the immune system in teleosts, as well as a direct action of melatonin on immune targets.
Date of Award16 Sept 2020
Original languageEnglish
Awarding Institution
  • University of Namur
SponsorsFund for Research Training in Industry and Agriculture (FRIA)
SupervisorPatrick Kestemont (Supervisor), Robert Mandiki (Co-Supervisor), Frederik De Laender (President), Manuel Gesto (Jury), Daniel Montero (Jury), Pascal Fontaine (Jury) & Eric MURAILLE (Jury)

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