Engineered ponds as environmental and ecological solutions in the urban water cycle: A case study in Patagonia

MANZO, L.M.; EPELE, L.B.; HORAK, C.N.; KUTSCHKER, A.M.; MISERENDINO, M.L.

ECOLOGICAL ENGINEERING

ELSEVIER SCIENCE BV

Año: 2020 vol. 154

0925-8574

Environmentally sound solutions such as engineered ponds haveprimarily been established for waste water treatment and flood control inurban areas. However, there is a lack of comprehensive understanding ofthe factors that influence the aquatic biodiversity of these artificialwater bodies, and it has been questioned whether ponds that are designedfor water treatment are also able to enhance or support regionalbiodiversity. The present study (1) examined the water managementfunction of two constructed wetland systems in the urban water cycle:flood prevention ponds (FP) and waste water treatment ponds (WT); (2)analysed their role to enhance local and regional biodiversity(macrophytes and invertebrates); and (3) assessed the functioning of awaste water treatment plant (WTP) in view of regional regulations. Asexpected, strong differences were found in water quality conditionsbetween FPs and WTs, mostly in terms of nutrients, conductivity,suspended solids and oxygen levels. FPs created optimal environmentsharboring several species of macrophytes and supporting diverseinvertebrate assemblages, comparable to those recorded at natural ponds.On the contrary, WTs sustained three times less taxa, with Psychoda sp.and Chironomus sp., (dipterans indicators of poor ecological conditions)dominating the assemblage. The waste water treatment plant was partiallysuccessful with regards to domestic effluent processing. Nutrient valuesfor treated effluents exceeded the permissible standards for receivingsurface waters in the region. Constructed ponds offer an opportunity formanagers and environmental regulators to conserve and enhance aquaticbiodiversity in ecologically poor environments. In addition to otherecosystem services (sociocultural), FPs also promoted bioticbiodiversity. WTs functioned as nutrient sinks rather than asbiodiversity spots, but their biodiversity and functioning could beenhanced through proper design and management. Some feasible solutions toimprove WTP functioning are itemized and discussed.