The relative influences of exotic species and environmental factors

摘要: Spatial variation in the native fish community of lower Guadiana basin (southern Iberia) was related to both biotic (abundance exotic species) and environmental factors using canonical correspondence analysis, CCA. After choosing best predictors among variables, we partitioned total species abundances (18 species-size combinations by 44 sampling locations matrix) into that accounted for (1) solely selected (2) (3) variables together, (4) unexplained. Of 22 initially considered CCA, only RIVER (dummy variable codifying belonging main river), SALT tributaries discharge brackish Guadiana), substrate heterogeneity, macrobenthos abundance were as predictors. In three from eight considered: Micropterus salmoides > 150 mm length (TL), Lepomis gibbosus 100 TL Gambusia holbrooki. The following components: pure (24.4%), (12.4%), shared (9.2%) unexplained (54.0%). There a significant influence on after accounting effect factors.