Daily variations of the saccular endolymph and plasma compositions in the turbot Psetta maxima: relationship with the diurnal rhythm in otolith formation

• Published in: Marine Ecology Progress Series
• Main Authors: Edeyer, Anaick, De Pontual, Helene, Payan, P, Troadec, Herve, Severe, Armelle, Mayer-gostan, N
• Format: Article in Journal/Newspaper
• Language: English
• Published: Inter-research 2000
• Subjects: daily cycle; endolymph; otolith; chemical composition; teleost; Turbot
• Online Access: https://archimer.ifremer.fr/doc/00000/10572/7603.pdf; https://doi.org/10.3354/meps192287; https://archimer.ifremer.fr/doc/00000/10572/

We studied the circadian variations of the ionic composition ([Na+], [K+], [Cl-]), total CO2 ([tot CO2]), and protein concentration ([protein]) in the plasma and endolymph in the distal and proximal sides of the sacculus in the turbot Psetta maxima. Daily variations in total plasma calcium ([tot Ga]) were also recorded. Significant diurnal fluctuations occurred in most parameters and the spatial heterogeneity of the endolymph composition was maintained throughout a 24 h period. The main parameters implicated in otolith calcification, endolymph [tot CO2] and endolymph [protein], fluctuated diurnally, [tot CO2] was highest and [protein] lowest at night; the relative concentrations were reversed during the day. The inverse, alternating relationship of maximal and minimal [tot CO2] and [protein] implies that calcium carbonate and organic matrix rates of deposition vary in antiphase. We therefore propose that in the turbot P. maxima, in autumn, the incremental zone (L-zone) is formed at night whereas the discontinuous zone (D-zone) is formed during the daytime.