Hydraulic modeling of mussel habitat at a bridge-replacement site, Allegheny River, Pennsylvania, USA

Influence of hyporheic exchange, substrate distribution, and other physically linked hydrogeomorphic characteristics on abundance of freshwater mussels

“…A large and diverse community of freshwater mussels still exists within the Allegheny River, particularly in the Allegheny's upper and middle reaches (Anderson, 1998;Smith et al, 2001;Fulton et al, 2010). The Allegheny River is~523 km in length with a drainage basin encompassing almost 30 000 km 2 in the northern Allegheny Plateau of New York and Pennsylvania (Figure 1).…”

“…River substrate, hydraulics, and morphology are widely recognized as important factors in mussel distribution (Layzer and Madison, 1995;Hardison and Layzer, 2001;Morales et al, 2006). Previous studies have investigated many of these key physical factors in relation to population densities of mussels within numerous waterways around the United States and the world (Huehner 1987;Layzer and Madison, 1995;Hardison and Layzer, 2001;Morales et al, 2006;Zigler et al, 2008;Fulton et al, 2010). Although preference of specific sediment characteristics can vary depending on mussel species, substrate size and distribution are two major factors found to influence mussel population densities across sites (Vannote and Minshall, 1982;Huehner, 1987;Layzer and Madison, 1995;Brim Box et al, 2002;Steuer et al, 2008;Fulton et al, 2010).…”

“…Previous studies have investigated many of these key physical factors in relation to population densities of mussels within numerous waterways around the United States and the world (Huehner 1987;Layzer and Madison, 1995;Hardison and Layzer, 2001;Morales et al, 2006;Zigler et al, 2008;Fulton et al, 2010). Although preference of specific sediment characteristics can vary depending on mussel species, substrate size and distribution are two major factors found to influence mussel population densities across sites (Vannote and Minshall, 1982;Huehner, 1987;Layzer and Madison, 1995;Brim Box et al, 2002;Steuer et al, 2008;Fulton et al, 2010). Additionally, heterogeneity (sorting) of the sediment plays a significant role in mussel distribution within rivers prone to large flooding events through the creation of behind-boulder eddies that shelter the smaller substrate needed by burrowing mussels (Vannote and Minshall, 1982;Layzer and Madison, 1995;Olsen and Townsend, 2003).…”

“…Because none of these previous studies made direct volumetric measurements of hyporheic exchange at the sediment-water interface, there is a need to quantify the rate, direction, and range of exchange in relation to mussel population density to further clarify its direct influence. Additional research has been specifically called for to determine whether these hyporheic exchange dynamics influence the density of adult mussel populations (Fulton et al, 2010). Therefore, the objective of this study is to evaluate the influences of key physical factors, primarily rate, direction, and range of hyporheic exchange, and secondary substrate characteristics and other hydrogeomorphic variables, on population distributions of adult mussels within the highly diverse community of the middle Allegheny River.…”

Modeling changes in freshwater mussel diversity in an agriculturally dominated landscape

“…At the continental or regional scale, climate, geology, hydrology, and glacial history often account for observed patterns in mussel assemblages (Graf 1997, Haag 2010, Burlakova et al 2011. Within a habitat, substrate size, shear stress, and near-riverbed turbulence are important factors to explain mussel patchiness (Strayer 1999, Brim Box et al 2002, Steuer et al 2008, Fulton et al 2010. At a spatial scale between these 2, such as the watershed, changes in mussel assemblages have been related to land use (Arbuckle and Downing 2002, Diamond et al 2002, McRae et al 2004, Poole and Downing 2004, Brown et al 2010, Hopkins and Whiles 2011, Atkinson et al 2012, channel morphology (Gangloff andFeminella 2007, Brainwood et al 2008), stream-flow stability (McRae et al 2004, Morales et al 2006), water quality, and overloading of fine sediments (see reviews by Strayer et al 2004, Downing et al 2010.…”