REPRODUCTION IN NORTHERN KRILL (MEGANYCTIPHANES NORVEGICA SARS)

• Main Author: Roudy, Janine Cuzin
• Other Authors: Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Tarling, GA
• Format: Book Part
• Language: English
• Published: HAL CCSD 2010
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Meganyctiphanes norvegica; Northern krill
• Online Access: https://hal.science/hal-03502077; https://doi.org/10.1016/S0065-2881(10)57007-X

International audience This review presents the current state of knowledge with regard to the reproductive biology of Northern krill (Meganyctiphanes norvegica) Reproduction is limited to a distinct period of the year First development of the ovary occurs at the onset of the season when the stock of primary oocytes issued from the germinal zone starts to accumulate glycoproteic yolk Previtellogenesis continues through out the entire reproductive season but oosorption (the retrieval by the ovary of the yolk constituents from the growing oocytes) may occur in unfavourable conditions and represents an important metabolic process for sustaining females during such periods Oosorption also occurs at the onset of the resting season It has been established that individual females may perform several cycles of reproduction each year Each reproductive cycle spans two moult cycles one in which lipid yolk is accumulated (vitellogenesis) and another when spawning occurs The time of spawning does not coincide with the moult (ecdysis) but with the onset of moult preparation (C Do moult stages) The complete egg batch is spawned well before the moult Storage lipids are accumulated preferentially in the ovary with distinctly high levels of omega 3 polyunsaturated fatty acids in the polar lipid fraction as well as phosphatidylcholine a key component in the development of the embryo There is no difference concerning lipid storage between resting females males and Juvenile krill Beside the ovary the fat body is an important organ involved in the metabolism and storage of the glycoproteins and lipids that will be transformed into the lipoglycoproteins of the yolk platelets in the ovary M norvegica produce large egg batches with the number of mature oocytes in one batch being proportional to the size of the female with a mean number of 1000-1200 eggs per batch The number of reproductive cycles per year is a function of the trophic conditions with the first reproductive cycle being triggered by the first phytoplankton bloom Other ...