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Seasonal zooplankton dynamics in main channel and backwater habitats of the Upper Mississippi River 总被引:2,自引:0,他引:2
This study used stratified random sampling to examine the spatial and temporal distribution of zooplankton communities in
a large floodplain river (Mississippi River, USA). Potential mechanisms controlling zooplankton abundance and community structure
were considered. Main channel and backwater habitats included in this study differed between a turbid upper pool reach where
aquatic macrophytes were sparse and a lower pool reach which was considerably less turbid and had extensive aquatic macrophyte
coverage. Samples were collected monthly during the summer over a 2-year period and multivariate analysis was used to examine
the spatial and temporal distribution of zooplankton. Significant differences were found in zooplankton density and community
composition among habitats and reaches within the pool. Rotifers were the dominant taxa and seasonality was pronounced, with
peak densities often occurring in late-spring. Community structure varied by habitat and reach, which suggests that water
quality, physical habitat characteristics, presence of aquatic macrophytes, and zooplankton sources can all influence the
zooplankton communities of the Upper Mississippi River. Characterization of the zooplankton communities provides a basis for
understanding changes in the river ecosystem and examination of zooplankton communities among habitats provides insight into
the mechanisms affecting zooplankton dynamics. 相似文献
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Hydrobiologia - Competition with invasive species and a warming climate have threatened brook charr (Salvelinus fontinalis) populations throughout their native range. In particular, brown trout... 相似文献
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Although laboratory studies have provided evidence for negative interactions between brook trout and brown trout, it is unknown how these interactions affect larger scale demographics in a natural setting. We tested the effects of invasive brown trout on brook trout demographics by removing brown trout from a sympatric population using a before–after control-impact study design. The study was conducted across a large stream network for a period of 6 years. Abundance of brook trout increased after brown trout removal primarily as a result of increased recruitment and immigration. Size structure also shifted towards larger individuals as a result of increased growth rates and a decrease in emigration of larger trout. Size at maturity and body condition did not change after brown trout removal. Adult brook trout survival increased during the post-treatment period in both the treatment and control reach. A decrease in flood intensity during the post-treatment time period may have led to increased survival. Adult survival may not be the best metric to use when assessing interactions between trout species, especially when the subordinate species has suitable areas to emigrate. 相似文献
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