Drivers of change in a redeveloped urban lake: long term trends in a simplified system
Mansfield, R.; Williams, A.; Hendry, K.; White, K.
published: Oct 1, 2014
ArtNo. ESP141018501008, Price: 29.00 €
Shallow urban lakes are inherently variable due to their unpredictable mixing regime and often rapid response to the external environment. They therefore present a number of challenges to water managers seeking to improve water quality. Salford Quays (8.14 ha, depth = 6.6 m), Greater Manchester, UK is an example of a managed artificial shallow urban water body that provides a number of ecosystem services but in the past was one of the most polluted areas of water in the UK. Here we examine the long-term dataset (1985–2010) associated with restoration and document changes of several orders of magnitude in both phosphorus and chlorophyll-a. Three distinct phases of phytoplankton community succession were identified over the restoration period: cyanobacterial dominance, an abundance of larger chlorophytes and finally a preponderance of r-selected taxa such as nanoplankters and cryptomonads. We show that these phases relate to changes in limitation from photolimitation to increased zooplankton grazing and, finally, the combined effects of low nutrients and filter feeding by the invasive bivalve Dreissena polymorpha. Owing to water column mixing and the lack of a littoral zone in the main basins, Salford Quays will be relatively unaffected by confounding variables such as stratification and therefore offers an insight into the processes of community change in similar artificial and heavily modified natural systems elsewhere. In addition the Quays offer an excellent case study of urban water management and serves as an example both of best practice and a target ecosystem to direct the restoration of other urban waterways.