Spartina alterniflora and Phragmites australis as Habitat for the Ribbed Mussel, Geukensia demissa, in Saw Mill Creek of New Jersey's Hackensack Meadowlands

by Marion McClary Jr.

Fairleigh Dickinson University, School of Natural Sciences, 1000 River Road, H-DH4-03, Teaneck, NJ 07666


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.

Key words: common reed; cordgrass; Geukensia; habitat; Phragmites; ribbed mussel; Spartina