Low-head dam impoundments modify local habitat and alter fish assemblages; however, to our knowledge, the pattern of how fish assemblages in the impoundments relate to local habitat, tributary position, and dam charac...Low-head dam impoundments modify local habitat and alter fish assemblages; however, to our knowledge, the pattern of how fish assemblages in the impoundments relate to local habitat, tributary position, and dam characteristics is still unclear. We used data collected in 62 impoundments created by low-head dams Jn headwater streams of the Qingyi River, China, to examine relationships between fish assemblages and local habitat, tributary position, and dam characteristics. We also assessed the relative importance of the three groups of factors in determining fish species richness and composition. Linear regression models showed that fish species richness was related to substrate heterogeneity, confluence link, and dam number upstream. Redundancy analysis showed that fish species compositions were influenced by substrate heterogeneity, confluence link, dam height, dam numbers upstream and downstream. Overall, dam characteristics were more important in affecting fish species richness but less important in determining fish species composition than local habitat （i.e., substrate heterogeneity） and tributary position. Our results suggest that low-head dam may affect fish species richness in impoundments by modifying local habitat and constraining fish movement, and the relative abundances of those fish species may depend more on species habitat presences and stream size than on impoundment size and number.展开更多
An intense bloom of Karenia sp.was reported in the Oualidia lagoon,part of Atlantic Moroccan coast.The highest concentrations are 1.04×10^7 cells/L,and have been noted at the park station 7.High nutrient concentr...An intense bloom of Karenia sp.was reported in the Oualidia lagoon,part of Atlantic Moroccan coast.The highest concentrations are 1.04×10^7 cells/L,and have been noted at the park station 7.High nutrient concentrations have been observed,and PO4 was the highest value(av.396.18μg/L)recorded at Parc 7.This massive proliferation caused a red tide which extended over 25 km from the Atlantic coast.This event was accompanied by stranding of macroalgae.展开更多
基金Foundation items： This work was supported by grants from the Natural Science Foundation of China （NSFC 31172120, 31372227, 31500452）
文摘Low-head dam impoundments modify local habitat and alter fish assemblages; however, to our knowledge, the pattern of how fish assemblages in the impoundments relate to local habitat, tributary position, and dam characteristics is still unclear. We used data collected in 62 impoundments created by low-head dams Jn headwater streams of the Qingyi River, China, to examine relationships between fish assemblages and local habitat, tributary position, and dam characteristics. We also assessed the relative importance of the three groups of factors in determining fish species richness and composition. Linear regression models showed that fish species richness was related to substrate heterogeneity, confluence link, and dam number upstream. Redundancy analysis showed that fish species compositions were influenced by substrate heterogeneity, confluence link, dam height, dam numbers upstream and downstream. Overall, dam characteristics were more important in affecting fish species richness but less important in determining fish species composition than local habitat （i.e., substrate heterogeneity） and tributary position. Our results suggest that low-head dam may affect fish species richness in impoundments by modifying local habitat and constraining fish movement, and the relative abundances of those fish species may depend more on species habitat presences and stream size than on impoundment size and number.
文摘An intense bloom of Karenia sp.was reported in the Oualidia lagoon,part of Atlantic Moroccan coast.The highest concentrations are 1.04×10^7 cells/L,and have been noted at the park station 7.High nutrient concentrations have been observed,and PO4 was the highest value(av.396.18μg/L)recorded at Parc 7.This massive proliferation caused a red tide which extended over 25 km from the Atlantic coast.This event was accompanied by stranding of macroalgae.
