Fish communities associated with a complex Mississippi stream system.

Authors: Knight, Scott; Shields Jr, Fletcher

Submitted to: International Journal of Ecological Science and Environmental Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2014
Publication Date: 11/20/2014
Publication URL: http://handle.nal.usda.gov/10113/60067
Citation: Knight, S.S., Shields Jr, F.D. 2014. Fish communities associated with a complex Mississippi stream system. International Journal of Ecological Science and Environmental Engineering. 1(3):73-79.

Interpretive Summary: Flooding of rivers and streams into off-channel aquatic habitats such as sloughs, oxbows, and wetlands provide important resources for fish survival, feeding, and reproduction. While constricting a river between levees can negatively impact fish diversity borrow pits excavated for levee construction may add to the overall diversity of life in a stream corridor especially if those pits are occasionally connected to the river during periods of high water. Fish were collected in both Abiaca Creek, MS channel and borrow pits excavated for levee construction to examine the value of these pools as a backwater resource. Quiescent aquatic habitats created by borrow pit excavation contributed to the overall diversity. Borrow pits provided additional backwater habitats that improved overall taxa richness supporting 11 species not found in stream channel sites. Additionally catch by weight was higher in the pits which contained a higher proportion of species that reached larger adult sizes while number by number was higher in the upper channel site. This research is important because it demonstrates that structures like borrow pits mitigate some negative impacts often associated with flood control projects and provides watershed managers with an additional tool to improve species diversity in aquatic resources.

Technical Abstract: Complex habitats such as sloughs, oxbows, and wetlands provide important ecosystem services for fish communities. While human manipulation of rivers and streams for flood control often reduce this complexity, some construction practices may provide an unexpected benefit. Structures such as borrow pits excavated for levee construction may mimic the functions of other back water features like oxbows or sloughs. Fish were collected in both Abiaca Creek channel and borrow pits created during the construction of a 360 ha floodway to examine the value of borrow pits as a backwater resource. Taxa richness, true diversity and other diversity indices were calculated to compare the communities of fish at the various sample locations. Lentic habitats created by borrow pit excavation contributed to the overall diversity. Greatest fish diversity was in the unaltered upper channel site while lowest was in the lower channelized sample reach. One of the borrow pits with relatively low diversity was found to support a strong sports fishery and exhibited characteristics of a managed resource. Catch per unit effort was higher in the pits which contained a higher proportion of species that reached larger adult sizes while number per unit of effort was higher in the upper channel site.