青海湖入湖河流大型底栖动物时空分布及渔产潜力估算

Tempora-spatial Distribution and Potential Fish Production Capacityof Macrozoobenthos in the Main Inflow Rivers of Qinghai Lake

探究青海湖及其入湖河流底栖动物的群落结构与时空分布,根据底栖动物现存量估算渔产潜力,可为青海湖裸鲤(Gymnocypris przewalskii)的增殖放流和种群持续恢复提供科学依据。以青海湖5条主要入湖河流(黑马河、布哈河、泉吉河、沙柳河、哈尔盖河)为研究对象,于2019年在青海湖裸鲤洄游前期、中期和后期对18个断面进行采样调查。结果表明,调查共记录底栖动物101种(属),隶属于5门7纲9目44科。空间分布上,黑马河种类最多,有56种(属),哈尔盖河最少仅27种(属),且EPT(蜉蝣目、襀翅目和毛翅目)自上游至下游呈减少趋势;密度和生物量均以泉吉河最高(544个/m2,4.77 g/m2),生物多样性各指数以黑马河最高。时间尺度上,青海湖裸鲤洄游前期、中期和后期,大型底栖动物种类数无明显变化,但密度和生物量均呈增加趋势,生物多样性各指数呈降低趋势。影响大型底栖动物密度和生物量分布的主要因素为底质类型、海拔高度、水温、浊度和电导率(P?0.05)。基于大型底栖动物估算的渔产潜力以布哈河最高(285 129 kg),其次是泉吉河(20 694 kg)和沙柳河(18 857 kg),与青海湖裸鲤密度及产卵场空间分布较为一致,这与亲鱼洄游产卵需要大量的食物来源有很大关系。

In this study,the five primary inflow rivers to Qinghai Lake(Heima River,Buha River,Quanji River,Shaliu River,Ha'ergai River)were investigated.The temporal-spatial distribution characteristics of the macrozoobenthos community in the five rivers were characterized,and potential fishery production was then estimated based on the macrozoobenthos stock.The aim was to provide scientific guidance for resource enhancement and the sustainable recovery of Gymnocypris przewalskii in Qinghai Lake.In 2019,during the early,middle and late migration period of G.przewalskii,the microzoobenthos and environmental parameters were investigated at 18 sampling transects in the upper,middle and lower reaches of the five rivers.A total of 101 microzoobenthos taxa(species/genus)belonging to 44 families,9 orders,7 classes and 5 phyla were observed during the investigation,with absolute dominance by aquatic insects(86 species/genus,accounting for 85.1%of the total species).Spatially,species richness was highest in Heima River(56 species/genus)and lowest in Ha'ergai River(27 species/genus).The taxa number of EPT(Ephemeroptera,Plecoptera and Trichoptera)decreased from upstream to downstream.Microzoobenthos density and biomass were both highest in Quanji River(544 ind/m2,4.77 g/m2)and lowest in Ha’ergai River(85 ind/m2,0.31 g/m2),while the Shannon-Wiener and Simpson diversity,Pielou evenness and Margalef richness indices were highest in Heima River.Temporally,total taxa number and biodiversity indices of microzoobenthos decreased with each of the three successive migration periods,while the density and biomass increased.The primary environmental parameters influencing the distribution of macrozoobenthos density and biomass were substrate,altitude,water temperature,turbidity,and conductivity.The estimated potential fishery production capacity,based on macrozoobenthos,was highest in Buha River(285129 kg),followed by Quanji River(20694 kg)and Shaliu River(18857 kg),and consistent with the distribution of G.przewalskii density in the different spawning grounds.Our findings indicate that macrozoobenthos can provide an adequate source of food for parent G.przewalskii during migration and spawning.