ABSTRACT
Mycorrhizae are known to exist in salt marshes around the globe (Rozema et al., 1986; van Duin et al., 1989; Sengupta and Chaudhuri, 1990; Hildebrandt et al., 2001, including marshes along the East Coast of the United States (Cooke et al., 1993; Hoefnagels et al., 1993). Within salt marsh plant communities, the colonization of roots by arbuscular mycorrhizae appears to be species-dependent. Consistent reports indicate that species such as Spartina alterniflora are nonmycorrhizal, whereas S. cynosuroides is frequently mycorrhizal (Hoefnagels et al., 1993; Cooke and Lefor, 1998). Spartina alterniflora and S. cynosuroides are similar in growth form and both grow in intertidal marsh elevations on the East Coast. Spartina alterniflora is a dominant grass in high-salinity marshes, while S. cynosuroides is a dominant grass in brackish marshes (Smith and Read, 1997), but they do overlap in their tolerance of brackish water (Parrondo et al., 1978; Stribling, 1998). A variety of factors affect the degree of root colonization by these fungi. Using ergosterol as an indicator of fungal colonization in roots, fungi in living roots of Spartina spp. were confirmed in both North Carolina (Padgett and Celio, 1990) and New Brunswick, Canada (Mansfield and Bärlocher, 1993). Both studies found that the greatest fungal biomass coincided with periods of active root growth. The degree of mycorrhizal colonization in salt marshes is known to vary with season. van Duin et al. (1989) showed that the greatest level of colonization occurred during the summer months when plants were growing maximally. Mansfield and Bärlocher (1993) suggested that fungal activity may depend to some extent on the availability of young feeder roots for colonization by mycorrhizal fungi and influence both in intensity and formation of specific fungal structures (Cooke et al., 1993; Brown and Bledsoe, 1996; Hildebrandt et al., 2001). This variation in
