A Systematic Review of Sperm Competition in Fish Under Biological and Ecohydrological Influence

Abstract

This review aimed to examine the influence of biological and ecohydrological factors on fish sperm during competition and fertilization to offer a future research framework on fish sperm biology under severe ecological perturbation. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, research on fish sperm biology were retrieved from the Scopus database, Web of Science, Google Scholar, African Journals Online, Data Citation Index, MEDLINE, Science4Life, ScienceDirect and JSTOR. The search criteria focused on peer-reviewed publications from 2000 to 2024 on sperm competition and reproductive biology in Teleostei and Chondrichthyes. From the screening, a total of 177 articles were extracted and included in this study. Among ecohydrological variables, environmental temperature remains the primary factor influencing sperm viability and fertilization success across different fish taxa. Different ion concentration levels: potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺) and pH are required for sperm activation and motility across various environmental media. Theoretical and empirical evidence from various studies indicated that the relationship between sperm competition and reproductive success is complex, often nonlinear, and does not follow a consistent pattern across different fish species. This underscores the need for species-specific research on fish sperm biology and how ecohydrological factors affect sperm performance. Understanding these variables is increasingly important for modelling and predicting fish reproductive outcomes under pollution and environmental stress. Finally, integrating fish sperm physiology and biochemical analysis into ecological risk assessments is important for enhanced conservation strategies, particularly in aquatic ecosystems impacted by climate change, eutrophication, habitat fragmentation, and anthropogenic stress.