珠江下游城市河流外来种尼罗罗非鱼的种群资源现状研究OA

Biological invasions represent major threats to aquatic biodiversity worldwide.Oreochromis niloticus,in-troduced to China in the last century for aquaculture promotion,has gradually invaded natural waters and sig-nificantly impacted native ecosystems.To evaluate its population status and potential expansion risk in urban rivers,this study provides a comprehensive assessment of O.niloticus in the Huadi River,an urbanised tributary of the lower Pearl River basin.We conducted systematic surveys in 2024 to investigate the dominance,seasonal variations in population structure,sex differences,and population resource status of O.niloticus in the Huadi River basin.Community dominance was quantified using the Index of Relative Importance(IRI),demographic variations were analysed through ANOVA with appropriate post-hoc tests,and population parameters were es-timated through integrated Length Cohort Analysis(LCA),ELEFAN modelling,and Virtual Population Anal-ysis(VPA).The results showed that the survey captured 2 941 fish specimens representing 46 species(inclu-ding subspecies),among which 629 were O.niloticus.O.niloticus was the dominant species in the Huadi River with an annual IRI of 3 821.99.Body length and weight showed significant seasonal differences between summer-winter and autumn-winter periods.A nonlinear growth model was established:W=8.2475×10-5×L2.832,R2=0.962,with allometric growth indices of 2.9156 and 2.8293 for males and females,respectively.Population modelling revealed asymptotic length L∞=270.0 mm,growth coefficient K=0.411 year-1,natural mortality M=0.485 year-1,and fishing mortality F=0.085 year-1,characterising a fast-growing population under min-imal exploitation pressure.Annual abundance for the body length range of 90～235 mm was estimated at 1.258×105 individuals,representing exceptionally high density.Bootstrap validation demonstrated robust precision(CV=12.32%,95%CI:9.76×104～1.552×105),meeting international assessment standards.Multimodal length-frequency distributions indicated continuous recruitment and successful population establishment.The re-sults indicated that O.niloticus has established a stable breeding population and occupies the dominant position in the fish community,with population structure showing significant seasonal fluctuation characteristics and popu-lation abundance reaching high levels,posing a potential risk of further expansion into the Pearl River main-stem.This study systematically assessed the dominant population status and resource conditions of O.niloticus in urban rivers of the lower Pearl River,validated the applicability of the ELEFAN-VPA model in low-exploita-tion urban rivers,provided technical reference for population resource assessment methods of invasive species in urban rivers,and offered a quantitative scientific basis for invasion risk early warning and precise prevention and control of alien species.