Experimental studies of wetland systems

Spartina anglica, an intertital grass species, has been introduced to estuaries all around the world. We found a population of this estuarine plant, introduced to Puget Sound, Washington, to be highly vulnerable to two insect species of the genus Prokelisia from California. More than 90% of plants died in greenhouse culture with high insect densities, while <1% died at the very low insect densities of the control. This result suggests that Prokelisia spp. have the potential to be biological control agents to limit the growth and spread of S. anglica plants.; Spartina pectinata, is native and wide spread in North America. The ability of plant oxygen root release of this aquatic macrophyte species was examined in an anaerobic buffer. The nitrification performances of subsurface flow constructed wetlands containing S. pectinata plants were also investigated. More oxygen was observed being released from roots of S. pectinata compared with a common wetland species, Typha latifolia. Also, higher nitrogen removal rates were calculated from wetlands containing S. pectinata plants. We conclude that S. pectinata has excellent potential for use in constructed treatment wetland systems.; The major pathway of oxygen in constructed treatment wetlands is atmospheric oxygen diffusion. We quantified the oxygen diffusion rates in both subsurface flow and free water surface constructed treatment wetland systems. Higher oxygen diffusion rates were observed in lab scale subsurface flow constructed treatment wetlands than that in free water surface systems. We found that there is no significant difference in atmospheric oxygen diffusion rates between wetlands containing plants and wetlands with no plant growth.