URBAN HABITATS, VOLUME 2, NUMBER 1  ISSN 1541-7115 http://www.urbanhabitats.org Spartina alterniflora and Phragmites australis as Habitat for the Ribbed Mussel, Geukensia demissa, in Saw Mill Creek of New Jerseys Hackensack Meadowlands - 83 - Spartina alterniflora and Phragmites australis as Habitat for the Ribbed Mussel, Geukensia demissa (Dillwyn), in Saw Mill Creek of New Jerseys Hackensack Meadowlands * Marion McClary Jr. Fairleigh Dickinson University, School of Natural Sciences, 1000 River Road, H-DH4-03, Teaneck, NJ 07666; mcclary@fdu.edu * Published online November 4, 2004 Abstract Abstract Abstract Abstract In areas where the cordgrass Spartina alterniflora and the invasive common reed, Phragmites australis, coexist, P. australis is often regarded as the salt- marsh grass less populated by fauna. Although it is known that the ribbed mussel, Geukensia demissa, utilizes S. alterniflora as habitat, it was not known whether S. alterniflora is a preferred habitat for the mussel when both the cordgrass and P. australis occupy an area. To determine this, I calculated the mean number of G. demissa in four replicate quadrats near P. australis and four replicate quadrats near S. alterniflora in Saw Mill Creek of the Hackensack Meadowlands, New Jersey, in March, June, and October 2002 and June 2003. Ribbed mussels were significantly more numerous near P. australis than near S. alterniflora in March 2002 and tended to be somewhat more numerous near P. australis on the other three sampling dates, suggesting that P. australis provides as good, if not better, habitat for G. demissa as S. alterniflora. Since Saw Mill Creek is a unique ecosystem due to human intervention, the results of this study should not be assumed to be true in areas where S. alterniflora and P. australis coexist and similar human influence is absent. Keywords: common reed; cordgrass; Geukensia; habitat; Phragmites; ribbed mussel; Spartina. Introduction Introduction Introduction Introduction There has been much concern about the effects the invasion of the common reed, Phragmites australis, has on salt marshes that have been dominated by the cordgrass Spartina alterniflora. The common reed flattens the marsh surface, lowers the water table and the salinity of the soil (Windham & Lathrop, 1999), and converts mosaics of vegetation into dense monotypic stands (Marks, Lapin & Randall, 1994; Chambers, Meyerson & Saltonstall, 1999; Galatowitsch, Anderson & Ascher, 1999; Windham & Lathrop, 1999; Rice, Rooth & Stevenson, 2000). It may also increase sedimentation (Buttery & Lambert, 1965) and build up the marsh plain (Windham, 1995). These actions, and possibly others, may be altering habitat for salt-marsh plants and animals. Marks, Lapin, and Randall (1993) found that several rare and endangered plant populations were threatened by P. australis invasion. Benoit and Askins (1999) found that the biodiversity of flowering plants and birds was reduced in P. australisdominated marshes. Phragmites australis is