Temperature effects on development and lifelong behavior in zebrafish

In recent decades, global warming has intensified temperature changes, placing substantial pressure on organism survival. Understanding how temperature variations impact development and behavior is crucial for conservation strategies. This study examined how temperature affects zebrafish embryo development and behavior, focusing on mRNA expression changes under thermal challenges. Zebrafish embryos were reared at 27 °C (control), 22 °C, and 30 °C, monitored from 24 to 120 hpf for structural development, and tested for optomotor responses at 7 dpf. Juvenile (30 dpf) and adult (90 dpf) fish reared at 27 °C were subjected to acute temperature shifts (22 °C and 30 °C for 2 h), followed by behavioral assessments and brain sampling for hsp90a and hspb1 mRNA expression analysis. Survival rates were significantly lower at 22 °C, with higher hatching rates at 30 °C but decreased at 22 °C. Developmental abnormalities varied: head malformations were more common at 30 °C, pericardial and yolk sac edema at 22 °C, and tail malformations at both extremes. Optomotor responses were impaired in fish from 22 °C. Social and aggressive behaviors were mostly unaffected, but fish from extreme temperatures showed increased risk-taking and reduced response to alarm substances. hsp90a mRNA expression was elevated in fish raised at 30 °C and those exposed to the 30 °C challenge, while hspb1 mRNA expression remained stable across temperatures. Cooling environments detrimentally affected embryo growth and survival, while warmer conditions induced pronounced growth defects. Elevated temperatures posed greater risks, triggering heightened hsp90a expression crucial for stress adaptation. Understanding thermal variation impacts on embryo development is crucial for mitigating climate change effects on species' viability and reproduction. • Low temperature impacts embryo growth and optomotor response while warming increases malformation. • To fully formed organisms, temperature increase is more harmful than its decrease. • High temperature leads to increased risk-taking behavior and hyperactivity in juveniles and adults. • High temperature increases hsp90a transcriptional abundance, which is related to stress maladaptation.