Seasonal morphophysiological changes during the reproductive cycle of the tripletail fish Lobotes surinamensis (Perciformes: Lobotidae) in the western South Atlantic

The tripletail Lobotes surinamensis inhabits tropical and subtropical oceans, including the South Atlantic, where information about its reproductive biology is scarce. We combined physiological and morphological tools to study the reproductive cycle of L. surinamensis in the western South Atlantic. Adult females and males were sampled in Paraty Bay (Rio de Janeiro, southeastern Brazil) for 2 years, and the animals were grouped into three seasons: spring, summer, and autumn/winter. Gonadal morphology, plasma levels of gonadal steroids, 17 beta-estradiol (E-2), 11-ketotestosterone (11-KT), and 17 alpha-hydroxyprogesterone (17 alpha-OHP) were quantified in females, and testosterone (T) and 11-KT were quantified in males. The gene expression of the beta subunit of pituitary gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were evaluated in all seasons. The histological analysis of the gonads showed that L. surinamensis is a multiple spawner with an asynchronous oocyte development. The gene expression of fsh beta did not change throughout the reproductive cycle in males and females, while the gene expression of lh beta in males was higher in the summer compared to the autumn/winter periods. Plasma E-2 was higher in females and 11-KT in males during spring. Gonadal development, plasma level of E-2 (females), and 11-KT (males) are indicators that L. surinamensis reproduce during the spring and summer in Paraty Bay, while the gene expression levels of gonadotropins in females and fsh beta in males were not useful physiological tools to establish the reproductive season. The results suggest an active expression throughout the year, a profile expected in multiple spawning species, as proposed here for the L. surinamensis.

Automated summary

The study revealed that the tripletail Lobotes surinamensis reproduces during the spring and summer in Paraty Bay, as indicated by gonadal development and plasma levels of E-2 in females, and 11-KT in males. However, the gene expression levels of FSH beta in males and gonadotropins in females were not useful physiological tools for determining the reproductive season.