Effects of elevated temperature on fish sperm quality: A meta-analysis

Abstract

Climate change, particularly global warming, poses a great threat to animal reproduction, which is very sensitive to increases in temperature. Studies revealed that elevated water temperature could hinder sperm production, damage sperm functioning across generations and reduce sperm competitiveness in many species. Following a systematic review of the literature, a meta-analysis was performed to explore how the elevated water temperature would influence some selected sperm traits such as sperm density, morphology, motility, survival rate, velocity and volume in different fish species. The PRISMA screening process was followed and 33 studies were finally eligible for the meta-analysis. The meta-analyses showed that sperm density, survival rate and velocity were significantly affected by the elevated water temperature, while sperm morphology, motility and volume were not significantly influenced by it. The sperm density data revealed a significant negative effect size because of elevated water temperature, whereas sperm survival rate and velocity showed a significant positive effect size. Overall, the findings suggest a clear evidence of profound influence of elevated water temperature on some sperm traits in different fish species that may affect fertilization success and offspring fitness of these species.