The impact of species invasion and nutrient dynamics on organic carbon burial in lake ecosystems

The invasion of Neosalanx taihuensis (Nt) into Yunnan Plateau lakes since the late 1970s has profoundly altered biogeochemical cycles and disrupted ecological equilibrium. While climate variability influences native species resilience, the impact of invasive species on carbon burial in these spatially heterogeneous lakes remains poorly quantified. We combine binary and structural equation modeling (SEM) to explore the mechanisms by which species invasion and lake nutrient dynamics drive carbon burial. Results indicate that organic carbon accumulation rates (OCAR) in Yunnan Plateau lakes range from 3.74 g·m⁻²·yr⁻¹ to 148.23 g·m⁻²·yr⁻¹, with more than tripled in four lakes over the past 60 years. Stable isotopes and C/N ratio confirm a post-invasion shift from allochthonous to endogenous organic matter dominance. Notably, Nt exerts a stronger direct effect on OCAR (path coefficient 0.273, p < 0.001) than climate, mediated by nutrient release and planktonic regime shifts. Meanwhile, invasive species amplify organic carbon burial (OCB) via the invasion-eutrophication feedback. These findings highlight how lake hydrology, basin climate and nutrient level directly regulate OCAR while indirectly modulate it through Nt biomass. Furthermore, invasive species act as biogeochemical engineers, reshaping carbon sink dynamics through biotic forcing. This study establishes a predictive framework for assessing climate-invasion synergies in vulnerable plateau lake ecosystems, offering key insights for ecosystem management and conservation.