Responses of Bacterial Assemblages on Standing‐Decaying Blades of Smooth Cordgrass to Additions of Water and Nitrogen

Abstract

Plots of intermediate-height cordgrass (Spurtinn nlterniflora) were fertilized with nitrogen, misted with freshwater, given both misting and N, or left untreated. Bacterial responses on standing-decaying leaf blades were measured as changes in epiphytic mass, rates of shedding of bacterial cells into seawater, and rates of net growth on blades. Epiphytic mass rose with time, and it did so 6-fold more sharply for the combination of fertilization and misting than for control. Since the sediment surface would offer higher N and water availability, this may indicate that movement of leaf material to marsh sediments would strongly favor bacterial activity. Net growth on aerially incubated (15 h), wet blades as percentage of standing bacterial mass was unchanging with duration of decay period, but was affected by treatment (about 0 to +5% h-' for misted treatments, +15% h-' for unmisted treatments). Faster growth on newly wetted, unmisted blades may have been due to release of cells from growth limitation by desiccation. Plot treatment did not affect specific rate of bacterial shedding (about 8 % of standing bacterial epiphytic mass during one h of submergence at 4 weeks, and 149% h-' at 12 weeks). It may be that during high spring tides, bacterial shedding from standing-decaying blades could provide numbers of new cells in the water column near to or greater than those provided by division of bacterioplanktonic cells.

A critical comparison of techniques for estimating bacterial abundance on leaf litter decaying in Oued Zegzel (Morocco)

“…Stomacher and sonication results were lower. But in the present paper the stomacher gave values 100 times greater than the earlier ones (Hossel & Baker 1979, Fry et al 1985 and bath sonication gave values 10 times greater than the other ones, two of which (Velji &Albright 1985, andPalm 1998) were obtained with probes and one (Maamri et al 1999) with a bath.…”

Dynamics of Bacterial and Fungal Communities on Decaying Salt Marsh Grass

“…Although 2000 and 2001 were drought years, the same dominant fungi were found in the S. alterniflora decay system in every year of a previous 3-year (1996 to 1999) seasonal study (during which annual rainfall was normal; 80 to 147 cm), suggesting that the microbial community observed here was not anomalous (24,25). Previous research has suggested that decomposers of S. alterniflora shift from a fungus-dominated to a bacterium-dominated community in response to changing substrate composition, juxtaposition to sediment surfaces, and moisture (27,30). Although it is likely that physical and chemical factors such as detritus age, moisture, temperature, nutrients, and salinity regime indeed have an effect on the composition of the decomposer community, we were unable to link observed shifts in community composition to these parameters in a simple manner.…”

“…Metabolically active bacteria and fungi have been shown to co-occur on Spartina detritus for much of the decomposition process (27). Furthermore, there has been no satisfactory explanation of the mechanisms by which microbial communities are replaced during temporal resource partitioning.…”

Autumnal Biomass and Potential Productivity of Salt Marsh Fungi from 29° to 43° North Latitude along the United States Atlantic Coast

“…The lower 11.5-cm piece of each blade was cut free, and the tips were discarded. The 11.5-cm pieces were rinsed in running tap water to remove any clay present (39), and the widths 1 and 10 cm from the ligule were measured. The pieces were then air dried again at a relative humidity of approximately 50% and 23 to 25°C.…”