Seasonal variation of fungal biomass in the sediment of a salt marsh in New Brunswick.

In a marsh in New Brunswick, Canada, belowground biomass of Spartina alterniflora consistently exceeded aboveground biomass by a factor of approximately 9. Both values peaked in July. Redox potential of the sediment was negative at all levels tested (2, 6, and 11 cm below surface), and was negatively correlated with depth. Concentrations of ergosterol, a sterol typical of higher fungi, were negatively correlated with redox potential and were highest in roots and rhizomes in July and August, 1-3 cm below the surface. These maxima corresponded to a fungal content of approximately 0.6% per ash-free dry mass of Spartina material. Balsa wood panels buried in anaerobic salt marsh sediment were colonized by fungi within 12 weeks. Eight fungal species isolated from S. alterniflora roots did not grow in the absence of oxygen, but were able to grow downward into an anaerobic medium.