Relationship Between Macroinvertebrates And Water Environment In The Babian River Basin Based On Functional Traits

The Babian River is a tributary of the Red River Basin,and after the confluence of the AMo River for the Lixian River.The Babian Riveri is located between Ailao Mountain and Wuliang Mountain,which is the remnant of Hengduan Mountain.It is rich in natural resources and is a hot spot of biodiversity protection.Recently,due to the influence of human activities,the water environment of the Babian Rive has been deteriorating.As an important part of the water ecosystem,the diversity of macroinvertebrates has decreased sharply,which may affect the health of the river ecosystem.Therefore,the study of the relationship between macroinvertebrates and the water environment in the Babian River Basin can provide important reference for the management and restoration of damaged rivers.However,most of the studies on the relationship between macroinvertebrates and the water environment in China are conducted at the taxonomic level,and relatively few studies are conducted from the perspective of species function and community function.Studies based on functional traits can reveal the relationship between macroinvertebrates and the water environment in a more profound way.In this study,the Babian River Basin was selected as the study area.Field surveys were carried out in September 2019,and data on macroinvertebrates and the basin environment were collected.Based on species identification and species richness measurement,four functional traits of macroinvertebrates,including Life history,Mobility,Morphology and Ecology,were determined.There were 9 functional traits including Development ability（L1）,Swimming ability（S1）,Armoring（M1）,Shape（M2）,Respiration（M3）,Size at maturity（M4）,Thermal preference（E1）,Habit（E2）and Trophic habit（E3）.The water environment indicators were selected from the aspects of Hydrology,Physics,Hydrochemistry,and Nutrients,including Velocity（V）,Water temperature（Temp）,Electrical conductivity（EC）,Suspended solids（SS）,Dissolved oxygen（DO）,p H,Chlorophyll-a（Chl-a）,Total phosphorus（TP）,Ammonia nitrogen（NH₄⁺-N）,and Nitrate nitrogen（NO₃^--N）.Canonical correspondence analysis（CCA）was used to determine the main water environment variables affecting macroinvertebrates communities in the study area.RLQ analysis combined with fourth-corner analysis was used to determine the response relationship between key water environmental factors and sensitive functional traits.On this basis,the functional groups of macroinvertebrates in the study area were divided to indicate and reflect the corresponding environmental conditions.The main conclusions of the study are as follows:A total of 588 macroinvertebrates were collected,belonging to 6 classes,14 orders and 24 families.Hydropsychidae,Heptageniidae,and Phelyganeidae are the dominant taxa of macroinvertebrates in this basin,and all of them are sensitive groups.CCA analysis showed that Suspended solids（SS）,Nitrate nitrogen（NO₃^--N）,Ammonia nitrogen（NH₄⁺-N）,Total phosphorus（TP）,Chlorophyll-a（Chl-a）were the main environmental factors affecting the macroinvertebrates community in the study area.The functional traits of macroinvertebrates in the study area showed that most of the species had slow Development ability（L1）,and the Size at maturity（M4）were mainly small and medium sized.Body shape（M2）is more streamlined,but the individual Swimming ability（S1）is generally weak.In addition,most species have no Armoring（M1）.Correlation analysis of functional traits showed that Swimming ability（S1）was significantly positive correlated with morphological functional traits,and Development ability（L1）was significantly correlated with other functional traits.The analysis results of RLQ and Forth-corner showed that Water temperature（Temp）,Velocity（V）and Chlorophyll-a（Chl-a）content were the three key water environmental factors affecting functional traits.There were significant correlations between the four functional traits and the three key water environmental factors:Habit（E2）,Tropic habit（E3）and Chlorophyll-a negatively correlated;Body shape（M2）is negatively correlated with Velocity.The Size at maturity（M4）is positively correlated with Water temperature.Using Ward’s minimum variance clustering method,the functional groups of macroinvertebrates in the study area were divided into five functional groups according to the four functional traits that were sensitive to response.Among them,the Size at maturity of functional group A were longer and had better adaptability to high water temperature.The species traits of functional group B were mainly medium and large Size at maturity,which had a wide range of adaptation to water temperature changes.Functional group C and functional group D showed a wide range of adaptation to chlorophyll-a environmental changes,covering various Habit and different Tropic habit.Functional group C covers swimming species,and is well adapted to the rapid environment.Functional group D is characterized by streamlined form,which indicates that this functional group has good adaptability to velocity change.Most species in functional group E were non-streamlined,and sclined habitat preference had a narrow range of adaptation to flow velocity.The Size at maturity is varies greatly,and the types of Tropic habit are varied,showing a better ability to adapt to the changes of water temperature and chlorophyll-a.