Periphyton wetland

Floodwater pH in wetlands is usually regulated by the photosynthetic activity of periphyton communities and submerged macrophytes. Depending on the alkalinity of water, the pH values can increase to about 9 during the day and decrease to near neutral levels during the night. These diel changes are directly linked to the absence or presence of carbon dioxide. The possible sources of carbon dioxide in floodwater are as follows ... 

Similar interactions (described above) can occur in the water column of wetlands dominated by periphyton or microbial mat communities, and detrital matter prodnced from emergent macrophytes. 

Pathway 6 shows dinitrogen fixation, which is the reduction of atmospheric, inert nitrogen to ammonia that plants and microbes can then use. It occurs in the water column, soil-floodwater interface, root zone, and anaerobic soil in wetlands. It is carried out by free-living bacteria (Clostridium), bacteria living in symbiotic association with plants (Rhizobium), cyanobacteria (Anabaena), and periphyton. 

Floodwater depth (Figure 8.33b) Periphyton activity is higher in wetlands with shallow water depth and decreases with an increase in water depth. In shallow water depths, mixing and currents increase the rate of exchange of ammonia between the water column and the... 

FIGURE 8.50 Biological nitrogen fixation in periphyton mats along eutrophic gradient in northern Everglades wetland. (From Inglett et al., 2004.)... 

Phosphorus accumulation in wetlands is regulated by vegetation, periphyton and plankton, plant litter and detrital accumulation, soil physicochemical properties, water flow velocity, water depth, hydraulic retention time, length-to-width ratio of the wetland, phosphorus loading, and hydrologic fluctuations. In evaluating wetlands for phosphorus accumulation, it is necessary to consider the following ... 

FIGURE 9.60 A schematic showing phosphorus cycling in periphyton mats of a wetland. 

The sources of organic sulfur in wetlands include detrital matter from vegetation and periphyton and soil organic matter. Organic sulfur constitutes 93% of the total sulfur in the organic matter. 

Discuss how hydrology, vegetation, periphyton, and microbial communities, and associated biogeochemical processes regulate long-term retention of phosphorus in the Everglades wetlands. 

DeBusk, T. A., K. A. Grace, F. E. Dierberg, S. D. Jackson, M. J. Chimney, and B. Gu. 2004. An investigation of the limits of phosphorous removal in wetlands amesocosm study of a shallow periphyton-dominated treatment system. Ecol. Eng. 23 1-14. 

J. E. Haky, andC. Carraher. 1997. Shading of periphyton communities by wetland emergent macrophytes decoupling of algal photosynthesis from microbial nutrient retention. Arch. Hydrobiol. 139 17-27. 

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