Little is known about the role of microbial biofilms in nutrient cycling and ecosystem
processes within desert springs. Furthermore, the difference between nutrient limitation of
biofilms in desert springs and other ecosystems is unknown. Biofilms produce micro-scale
physicochemical variation important to ecosystem function. We measured the variation in microscale
physicochemical heterogeneity in biofilms of Devils Hole, Nevada. Microelectrodes were
used to measure micro-scale chemical gradients of temperature, pH, O2, and H2S in addition to
water column and pore water nutrient measurements in Spirogyra, cyanobacteria, and Beggiatoa
biofilms over one year. Biofilm physicochemical gradients were used to calculate diffusion and
metabolic rates. The rate of O2 and H2S diffusion ranged over two orders of magnitude. Biofilm
production and respiration were influenced by biofilm type, light exposure, and sample month.
Maximum O2 production occurred in spring and summer during direct light exposure. Oxygen
production and consumption varied with light exposure and season. The H2S production and
consumption varied with biofilm type. Higher concentrations of SO4 in Beggiatoa suggested that
H2S production in Beggiatoa was quickly oxidized in the ecosystem. Spirogyra and
cyanobacteria followed similar physicochemical trends; however, Spirogyra had more
pronounced diurnal and seasonal variation. The differences between cyanobacteria and
Spirogyra have implications on the ecosystem function of Devils Hole as well as other ecosystems with diverse biofilm communities. The heterogeneous physicochemistry of microbial
biofilms and the differences in biofilm nutrient limitation suggests that a change in microbial
biofilms or nutrient concentrations could alter ecosystem biogeochemical dynamics.
Additionally, we assessed the nutrient limitation of two desert springs in comparison with a
temperate stream. A nutrient diffusing substrata experiment was used to measure chlorophyll a,
respiration, and biomass with phosphorus, nitrogen, and sulfide treatments. Autotrophic and
heterotrophic biofilms responded differently to treatments and the temperate stream had higher
chlorophyll a biofilm accrual but lower respiration relative to the desert springs. / Spatial and temporal variation of microbial biofilm biogeochemistry in a desert spring, Devils Hole, Nevada -- Autotrophic and heterotrophic nutrient limitation across biomes. / Department of Biology
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:123456789/197438 |
| Date | 20 July 2013 |
| Creators | Madinger, Hilary L. |
| Contributors | Bernot, Melody J. |
| Source Sets | Ball State University |
| Detected Language | English |
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