Trophic ecology underpins energy storage in demersal fishes from the Zhoushan Archipelago, East China Sea: insights from fatty acid biomarkers

Marine fish, constituting critical components for marine ecosystems, exhibit trophodynamic characteristics in their energy storage strategies. However, evidence of such strategies for demersal fish remains inadequately characterized. Herein, we used seven ecologically and economically important demersal fish species from the coastal waters of the Zhoushan Archipelago (East China Sea) as a model system to investigate the trophodynamic characteristics. Sampled in April 2022, we quantified their muscle energy density, a metric of energy storage status and metabolic efficiency, and evaluated the effects of dietary habits through fatty acid biomarkers. We observed significant differences in the energy storage capacity among the species, with energy density ranging from 16.52 to 26.15 kJ g −1 . Lipid content was the principal physiological correlate, explaining a substantial proportion (6–38.57%) of the total energetic value and exhibiting species-specific allometric scaling. Analysis of fatty acid profiles revealed interspecific dissimilarity, indicative of divergent feeding habits, and hierarchical modeling demonstrated that dietary composition exerts a significant modulating influence on the energy storage capacity. The muscle energy density was inversely related to zooplanktonivory biomarkers of C16:0, C18:0 and C18:1n9c, but positively correlated with the piscivory biomarker C22:6n3. These findings reveal interspecific variations in the energy storage capacity for the seven demersal fishes, linking to their feeding habits where trophic ecology fundamentally modulates this capacity, with high-quality prey facilitating energy storage. • Interspecific differences among the demersal fishes are significant. • Lipid content drives interspecific differences, explaining up to 38.57% of somatic energy value. • Fatty acid profiles reveal distinct feeding habits across the species. • Energy storage capacity decreases with zooplankton or zooplankton-based prey intake but increases when shifting to piscivorous habit.