Morphological features of the Black Sea turbot (Scophthalmus maeoticus) during the period of embryonic development

• Published in: Marine Biological Journal
• Main Authors: A. N. Khanaychenko, V. E. Giragosov
• Format: Article in Journal/Newspaper
• Language: English; Russian
• Published: A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS 2019
• Subjects: Black Sea turbot; embryogenesis; morphology; Scophthalmus maeoticus; Biology (General); QH301-705.5; Turbot
• Online Access: https://doi.org/10.21072/mbj.2019.04.4.06; https://doaj.org/article/e6093630c77d401facba11075995abb3

Black Sea turbot (hereinafter BST), Scophthalmus maeoticus (Pallas, 1814), is a valuable fish for commercial fishery and promising object of industrial mariculture. Potential fecundity of BST is very high, 3–13 million eggs; however, survival of its progenies during early development in the sea is unpredictable and low (mortality is up to 90 %). In nature fertilized pelagic BST eggs rise to the sea surface in 2–3 hours; BST develop in upper waters being part of neuston till hatching. BST on its early stages of development could be considered the most vulnerable as the embryo is exposed to diverse adverse effects. The survival and physiological state of the larvae at hatching till exogenous feeding depend on the norm of morphological characteristics of the embryos during their development. Our aim was to study the norm of the changes in BST morphological characteristics during embryogenesis. Morphological analysis of the BST embryogenesis stages from fertilization till hatching on the basis of detailed study of intact embryos (> 2000 eggs) sampled from different experimental batches incubated under experimental conditions is presented. Digital photos and videos of alive eggs were taken with Canon PowerShot A720 using binocular microscope MBS-10 at magnification 8×4 and under light inverted microscope Nikon Eclipse TS100, equipped with analog camera, at magnification ×4, ×10, and ×40. The morphological features of embryogenesis in BST before and after fertilization, cleavage, blastulation, gastrulation, epiboly, and neurulation and until hatching are presented by photos with detailed description of transforming embryological structures. Fertilized pelagic BST eggs covered by transparent shell vary from (1.26 ± 0.14) to (1.31 ± 0.15) mm in diameter, have homogenously distributed yolk and a single round transparent oil drop of 0.20–0.21 mm, positioned at the top of the yolk. Scale of timing of morphological changes is presented in relative time units (as a time interval from fertilization until the emergence of ...