Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/26630
Title: A habitat improvement plan for the Big Sunflower River, Mississippi
Authors: Miller, Andrew C.
Keywords: Freshwater mussels--Effect of habitat modification on
Freshwater mussels--Mississippi--Big Sunflower River
Unionidae--Mississippi--Big Sunflower River
Publisher: Environmental Laboratory (U.S.)
U.S. Army Engineer Waterways Experiment Station.
Series/Report no.: Technical Report ; EL-95-29
Abstract: A multidisciplinary team, consisting of biologists and engineers from the Mississippi Department of Wildlife, Fisheries and Parks, the U.S. Fish and Wildlife Service, the University of Southern Mississippi, the U.S. Army Engineer District, Vicksburg, and the U.S. Army Engineer Waterways Experiment Station, prepared five habitat improvement plans for the Big Sunflower River, Mississippi. Plans were designed to mitigate for the negative effects of maintenance dredging on freshwater mussels (Family: Unionidae) and their habitat. The goals of the Habitat Improvement Team were to (a.) maintain existing mussel species richness and to improve species diversity and recruitment levels of the community, (b.) improve overall substratum conditions for the freshwater mussels at selected reaches, and (c.) obtain information that can be used to improve other low-gradient rivers in the South. The Big Sunflower River has been altered considerably since the early 1900s. Most notable alterations include a 7.4-rnile-long channel cutoff constructed in 1959 and channel maintenance and dredging completed in the early 1960s. The river flows through agricultural land and is characterized by the presence of deep deposits of fine sand and silt (often greater than 2 ft deep) along much of the shore. Mussel fauna in the river is dominated by the threeridge (Amblema plicata plicata) (49.1 to 90.0 percent), followed by the pimpleback (Quadrula pustulosa pustulosa) (2.0 to 19.4 percent), and the bankclimber (Plectomerus dombeyanus) (3.5 to 29.0 percent). Species richness at selected beds (9 to 12 species) and species diversity (the Shannon index (H'), 0.49 to 1.46) were low. At selected sites, mean density (individuals/square meter) ranged from 28.6 (±2.8, ±Standard Error) to 235.0 (±16.0) and mean biomass (grams/square meter) ranged from 6,590.8 (±636.1) to 52,250.l (±3,284.8). There was virtually no evidence of recent recruitment for any species; less than I percent were less than 30-mm total length. No endangered species were found, although Pleurobema pyramidatum, uncommon in the river, is a candidate for inclusion on the Federal list of Threatened or Endangered species. The Habitat Improvement Team recommended the following improvement features: (a.) dike fields with either three or five dikes, (b.) low-water weirs that reach completely across the river, (c.) gravel bars, (d.) structures made of polyvinyl chloride pipe or logs to attract invertebrates and fishes, (e.) no-work areas where no dredging will occur, and (f.) avoidance areas where dredging will be restricted to protect important mussel assemblages. No-work areas will be located immediately downriver of abandoned Lock and Dam 1 (River Miles (RM) 53.9-54.1) and immediately upriver of the Holly Bluff Cutoff. Avoidance areas will be located immediately downriver of Bay Lake Run on the right descending bank (RM 71.6), upriver of abandoned Lock and Dam 1 on the left descending bank (LDB) (RM 53.9-54.1), and the upper 1 mile, LDB, of the channel excluded by the Holly Bluff Cutoff. Gravel (approximately 1 to 3 in. (2.54 to 7.62 cm) in diameter) would be placed in association with dike fields and weirs and at selected sites to augment existing gravel bars. If necessary, river banks opposite dike fields will be protected with gravel, riprap, and flood-tolerant vegetation. The above improvement features were assembled into five plans that ranged from an estimated $249,808 to $1.3 million. The basic or original plan consisted of 116 separate features, affected 2.5 million square feet of aquatic habitat, and costs an estimated $1.3 million. Plan 2 was similar to Plan 1 except that weirs, possibly with limited value to mussels, were not included. Plans 3 and 4 eliminated habitat features from three reaches of the river with moderate to low mussel density. Plan 5, with an estimated cost of $249,808, included four three-dike fields and no weirs or revegetation. Gravel would only be placed in association with dike fields and at selected sites upriver and immediately downriver of an existing weir in the Holly Bluff Cutoff. Plan 5 would affect 665,000 sq ft of river bottom and contain 55 separate features. The Team designed a 10-year monitoring plan that would assess physical and chemical conditions of water and sediment, measure density, species richness, species diversity, evenness, evidence of recent recruitment, and physical and reproductive condition of the freshwater mussels. Population and community parameters of fishes and non-molluscan invertebrates would also be assessed.
Description: Technical Report
Gov't Doc #: Technical Report EL-95-29
Rights: Approved for Public Release; Distribution is Unlimited
URI: http://hdl.handle.net/11681/26630
Appears in Collections:Technical Report

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