Mitigation of urbanisation effects on aquatic ecosystems by synchronous ecological restoration

Ecosystem degradation and biodiversity loss have been caused by economic
booms in developing countries over recent decades. In response, ecosystem
restoration projects have been advanced in some countries but the
effectiveness of different approaches and indicators at large
spatio-temporal scales (i.e., whole catchments) remains poorly understood.
Our datasets with a diverse array of 440 aquatic restoration projects
including wastewater treatment, constructed wetlands, plant/algae salvage,
and dredging of contaminated sediments implemented and maintained from
2007 to 2017 across more than 2000km2 of the northwest Taihu basin
(Yixing, China). Synchronized investigations of water quality and
invertebrate communities were conducted before and after restoration. Our
datasets showed that even though there was rapid urbanization at this
time, nutrient concentrations (NH4+-N, TN, TP) and biological indices of
benthic invertebrates (taxonomic richness, Shannon diversity, sensitive
taxon density) improved significantly across most of the study area.
Improvements were associated with the type of restoration project, with
projects targeting pollution sources leading to the clearest ecosystem
responses compared with those remediating pollution sinks. However, in
some locations, the recovery of biotic communities appears to lag behind
nutrients (e.g. nitrogen and phosphorus), likely reflecting long-distance
re-colonization routes for invertebrates given the level of
pre-restoration degradation of the catchment.