A temperature shift during embryogenesis impacts prevalence of deformity in diploid and triploid Atlantic salmon (Salmo salarL.)

Abstract

The study investigated the effects of a temperature shift during embryogenesis on diploid and triploid Atlantic salmon (Salmo salar L.) embryo development and juvenile skeletal deformities. From fertilization, sibling populations were incubated under one of three temperatures (6, 8 or 11°C) until 400 °days when all fish were then reared under a common temperature until smolt. Survival was negatively impacted by increasing temperatures irrespective of ploidy. There was no effect of incubation temperatures on growth in diploids, but triploids incubated at 6°C had improved growth rates (thermal growth coefficient, TGC: 6°C: 1.05, 8°C: 0.94, 11°C: 0.48). Fish from 11°C in both ploidies showed increased jaw and vertebral deformity prevalence. In response to the temperature change at 400 °days post fertilization, upregulation of bmp2, bmp4, col2a1, mmp13, opn and sparc, and downregulation of ocn further suggest that bone and cartilage formation is compromised after experiencing a thermal shift. The data show that temperature profile during embryogenesis strongly influences future growth and deformity prevalence. Triploids appear to require a lower incubation temperature than the current industry standard of 8°C to promote better overall performance; however, a thermal shift during embryogenesis was shown to impact expression of important developmental genes.

Comparison of Diploid and Triploid Atlantic Salmon (Salmo salar) Physiological Embryonic Development

“…Our observed mortality did not deviate significantly from previous literature. Clarkson et al [14] reported a mortality of 16.4% ± 19.2% for diploids and 22.3% ± 21.9% for triploids from fertilisation to 400 DD at 6 °C, compared to 10.93% and 19.89%, respectively, for the current experiment. The reasons for the higher rate of mortality seen in triploids during embryogenesis are multifaceted.…”

“…The reasons for the higher rate of mortality seen in triploids during embryogenesis are multifaceted. Triploids tend to suffer increased mortality at higher incubation temperatures [14,15]. Triploids also suffer from increased sensitivity to egg quality [33].…”

“…Triploids tend to display a higher susceptibility to a variety of deformities, including those affecting the vertebrae [11], lower jaw [12], eyes [13], and heart [10]. They require lower incubation temperatures [10,14,15] and ploidyspecific diets with increased histidine [13,16,17], phosphorus [11,18,19], and protein [18].…”

A Review of Factors Affecting Farmed Atlantic Salmon (Salmo salar) Welfare in Australia and Beyond

“…Other experiments demonstrate that even when induction of triploidy is successful, chromosome aberrations are present that may affect gene expression (Glover et al 2020). Triploids appear to require a lower incubation temperature than the current industry standard of 8 °C (Clarkson et al 2021), thus temperature control is one way to minimise otherwise emergent deformities in triploids. Large triploid Atlantic salmon have been shown to perform better at colder water temperatures compared to diploids (Sambraus et al 2018).…”

Temperature Significantly Regulates Gene Expressions of Vertebrae Chondrocytes and Osteoblasts in Juvenile Golden Pompano (Trachinotus ovatus)

“…Proper warming can stimulate the up-regulation of Col2a1 transcription level in cultured dedifferentiated chondrocytes in vitro and promote the redifferentiation of cartilage tissue (Ito et al, 2015). Studies in Atlantic salmon have shown that thermal stimulation during embryogenesis affects the expression of important developmental genes such as Col2a1, and this effect continues into subsequent development in fish (Clarkson et al, 2020). Ytteborg et al (2010a) showed that Col2a1 transcription decreased in Atlantic salmon reared at HT.…”