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Constant and oscillating egg incubation temperatures on embryonic development and early larval morphology were studied in longfin yellowtail (Seriola rivoliana Valenciennes). We investigated the effects of constant temperatures from 16 to 32°C on embryo development and larval morphology at hatch, and whether oscillating temperature during embryogenesis could lead to larval morphological variations. After hatching, larval morphology and development during yolk sac (YS) utilization were examined in larvae at constant temperatures and larvae at 25°C that had oscillating temperature during egg incubation. Hatching rates were > 75%, only decreasing to ~ 50% at 30°C. At constant temperatures, the largest larvae occurred at 22 and 24°C. The oscillating temperature did not affect the timing of embryo development but resulted in larger and smaller larvae with a smaller and bigger YS, respectively, with a similar hatching time. Therefore, a growth response occurred in embryos during a window of development before hatching, depending on the adaptive response to temperature (spawn‐specific). After hatching, most of the YS was absorbed within 24 hr in all treatments, and the growth of the larval head was a priority with an optimal development at 26°C. There was compensatory growth in smaller larvae resulting in similar sizes after YS utilization, but larvae showed variations in body structure that could be important in further aquaculture research. [ABSTRACT FROM AUTHOR]

In spring, peripheral blood of mature-ripe female leopard groupers showed leukophilia after an increase of lymphocytes and thrombocytes, followed by a differential increase of monocytes and granulocytes. In mature-ripe males, granulophilia and thrombophilia were evident. Leukocytes were distinguishable in some ovarian blood vessels where post-ovulatory follicles were present. These observations suggest coordination of endocrine-immune activity, where, after one spawning event, leukocytes infiltrate the gonad tissue from the peripheral blood to aid with immune surveillance and phagocyte activity, while a feedback of sex steroids and vitellogenesis occurs in preparation for the next spawning. An abundance of leukocytes may also aid in gonad reabsorption during post-spawning. Leukophilia coincided with high plasma concentrations of oestradiol and testosterone, which together with leukocytes, decreased greatly in immature-active groupers in summer. Blood cell counts, erythroblasts, and haematocrit of mature-ripe groupers in spring were significantly lower than immature-active groupers in summer, suggesting mild anorexia induced by reproductive behaviour. [ABSTRACT FROM AUTHOR]