Temporary connectivity: the relative benefits of large river floodplain inundation in the lower Mississippi River

2014 ◽  
Vol 23 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Quinton E. Phelps ◽  
Sara J. Tripp ◽  
David P. Herzog ◽  
James E. Garvey

2020 ◽  
Vol 25 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Christopher P. Bonvillain ◽  
Quenton C. Fontenot

Abstract Anthropogenic modifications to river-floodplain systems can decouple floodplains from mainstem inputs, alter flood pulse dynamics, and disrupt population dynamics and trophic web stability of aquatic biota. The Atchafalaya River Basin (ARB) receives an annual flood pulse from the Mississippi River that contributes to high crayfish abundance. Conversely, reduced crayfish abundance in the Barataria Basin (BB) is attributed to the system no longer receiving an annual flood pulse from the Mississippi River. Therefore, the purpose of this research was to determine if the absence of an annual flood pulse and reduced crayfish abundance influenced the diets of carnivorous fishes by examining stomach contents of fishes from both basins. Stomach contents were grouped as crayfish, fish, non-crayfish invertebrate, and herpetological. Although the percent occurrence of crayfish in fish stomachs differed between floodplain inundation and low-water periods in the ARB, crayfish were still the major diet constituent of ARB fishes during both periods. Non-crayfish invertebrate was the major diet constituent in BB fishes, with crayfish ranking as the second fewest diet constituent present. Our results demonstrate how flood pulse dynamics influence crayfish, and ultimately trophic webs, in large river-floodplain systems.



Author(s):  
William H. Raymond ◽  
Robert M. Rabin ◽  
Gary S. Wade


<em>Abstract</em>.—The lower Mississippi River encompasses the 1,535-km reach extending from the confluence with the Ohio River at Cairo, Illinois to the Gulf of Mexico. Waters of the lower Mississippi River have historically inundated vast areas of adjacent floodplain during spring flood pulses. Additionally, processes of land building within the river’s deltaic plain supported vast forests and diverse freshwater and salt-marsh habitats. Flood pulses provided a mechanism of lateral exchange of energy and nutrients between the aquatic and terrestrial habitats, while sediment loads continually rebuilt and supported the deltaic plain. As human populations and agriculture expanded throughout the lower Mississippi Valley, construction of flood-protection levee systems and commercial navigational structures severely decreased the connectivity between the lower Mississippi River and its floodplain. The current lower Mississippi River floodplain is more than 90% reduced in area compared to historical conditions. Fluvial dynamics, which are the driving forces that stimulate floodplain function and create diverse habitats, appear to have been altered throughout approximately 80% of the river. As a result, the hydrograph, thermograph, sedimentation patterns, nutrient dynamics, and vegetation communities within the lower Mississippi River floodplain have experienced major changes through time, with many large alterations occurring during the past century. In addition, because most of the sediment load of the lower Mississippi River now enters the northern Gulf of Mexico, land building and associated processes are much reduced in the river’s deltaic plain. This process has allowed intrusion of saltwater into coastal habitats, which has heavily impacted vegetation communities. This paper reviews the consequences of river modification to lower Mississippi River floodplain, current efforts towards restoring the floodplain and deltaic plain, and proposes future strategies towards restoring portions of the historical floodplain.



Wetlands ◽  
2009 ◽  
Vol 29 (2) ◽  
pp. 476-487 ◽  
Author(s):  
Harold L. Schramm ◽  
Michael S. Cox ◽  
Todd E. Tietjen ◽  
Andrew W. Ezell




1900 ◽  
Vol 50 (1301supp) ◽  
pp. 20848-20850
Author(s):  
William Joseph Hardee


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