Friday, January 1, 2016
This study looked at the connectivity of the Missouri River at Eagle Bluffs Conservation Area and the amount of fish the moved in and out of the floodplain.
Restoration projects along the lower Missouri River (LMOR), Missouri, are undertaken to mitigate past channelization and levee construction that severed riverfloodplain connectivity and denied riverine fishes access to adjacent seasonally flooded wetlands. Two actively managed wetland pools were constructed for riverine fish spawning and nursery at Eagle Bluffs Conservation Area (EBCA) as part of the Missouri River Recovery Program. These pools were designed with water-control structures to enable controlled ingress and egress of riverine fishes. Lateral fish movements during temporary connectivity events between LMOR and these wetlands were investigated during two consecutive spring-summers. Over 60 species used the wetlands during the two study years, but only 12 taxa composed >1% of the export fish assemblage either year. Fish biomass exported from EBCA to LMOR was high (2007: 509 kg/h; 2008: 1458 kg/h) and dominant fish lengths <200 mm demonstrated substantial recruitment of young-of-year and juvenile fishes during wetland inundation and isolation. Fish assemblages associated with uncontrolled and controlled flooding of the wetland were moderately similar due to sharing 37 taxa, with 58 taxa present after uncontrolled, leveetopping connectivity in 2007 and 40 taxa present after controlled, backflooding connectivity in 2008. This is one of the few studies to quantify biomass export to a large river from a floodplain wetland and demonstrates the value of managed floodplain wetlands to annual recruitment of riverine fishes.
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