Seasonal bias and overlooked climate impacts in mangrove ichthyoplankton research: emerging threats and knowledge gaps

Mangrove ecosystems are among the most productive coastal habitats and serve as key nursery zones for fish eggs and larvae (ichthyoplankton). While seasonal variation in ichthyoplankton has been relatively well studied, the impacts of extreme climate events remain poorly understood. This perspective paper presents a narrative literature review and interpretative synthesis of 80 studies at a global scale on mangrove ichthyoplankton. We identified general ecological patterns and potential effects of climate-driven disturbances on fish eggs and larvae. Four main research themes emerged: seasonal variation (63 studies), human-induced changes in ichthyoplankton dynamics (7 studies), advances in identification through molecular versus morphological approaches (8 studies), and impacts of climate change (2 studies). Seasonal variation dominated the literature, whereas human-induced effects were mostly reported in Malaysian mangroves. Human impacts approaches provided insights into larval resilience to pollution, including microplastics. Only a few studies directly addressed climate extremes. Research on the consequences of extreme climatic extremes in mangrove-ecosystems suggest that, by altering water quality and habitat integrity, these events probably compromise the nursery function of mangroves and affect fisheries and estuarine food webs. Despite their ecological importance, the lack of long-term studies limits understanding of climate extremes on mangrove ichthyoplankton. Future research should include long-term monitoring, predictive modeling, and molecular tools to assess resilience. Strengthening research in this field is essential for designing conservation strategies that maintain mangroves as nurseries and support fisheries and coastal livelihoods under global climate change.