The construction of wetlands has an important role to play in strategies to offset the loss of natural wetlands and treat wastewater. Typically, the effectiveness of constructed wetlands is assessed by comparing their levels of species abundance and diversity with those in natural wetlands. However, these structural indicators aren’t necessarily good measures of ecosystem function. In a study of riparian locations on the Ebro River in Spain, net ecosystem production (NEP, the balance between primary production and community respiration) was measured in matched sets of natural and constructed wetlands. Analysis revealed that water column NEP was significantly higher in natural than constructed wetlands. In the natural wetlands, NEP was highest in unvegetated habitats,while in the constructed wetlands NEP tended to be greatest in habitats dominated by submerged plants, particularly the branching alga Chara. Because previous work showed that invertebrate communities recovered rapidly in the same constructed wetlands, the new results suggested that ecosystem function recovered more slowly than ecosystem structure. Therefore, useful insights may be gained by including ecosystem function in the design and evaluation of new wetlands.
Reference: Espanol, C. et al. 2013. Is net ecosystem production higher in natural relative to constructed wetlands? Aquatic Sciences 75, 385–397. http://link.springer.com/article/10.1007/s00027-012-0284-1#page-1
Freshwater Research News 
Posted on March 10, 2014