Controls on Phytoplankton Community Change in a Redeveloped Freshwater Dock: A Case Study of Salford Quays

  • Robert Mansfield

    Student thesis: Unknown


    Salford Quays were created from the highly polluted Manchester docks after their closure in 1984. In order to make use of the potential for an attractive waterside location in the centre of Greater Manchester, it was decided to redevelop the area for commercial, recreational and residential use. This involved isolating and artificially mixing the docks and instigating a series of management interventions, including the introduction of fish, macrophytes and the invasive filter-feeding bivalve Dreissena polymorpha. The positive results of these interventions are clearly visible in modern day Salford Quays (SQ) which now provides a home to several thousand people, office and retail space, a site for water sports activities and the location of the new BBC Media City. Despite this success the precise drivers of environmental improvements and the extent to which each intervention has contributed to restoration has proven elusive. Therefore further investigation is warranted, not only to inform future water quality management but also to determine the ecosystem processes involved and to increase our understanding of how lentic ecosystems function. Restoration of SQ has been accompanied by intensive monitoring of water quality and ecology from 1984 to the present day. The resulting dataset has been analysed to examine the relationships between the physiochemical environment, management and phytoplankton community structure using a combination of non-linear regression and ordination techniques. This has explained the patterns behind the change from Planktothrix agardhii dominated eutrophy to the clear waters of the present day and indicated the importance of nutrient control and D. polymorpha filtration on past and present ecosystem function. This study has demonstrated how useful non-linear approaches are to the study of ecology and a strong case has been made for their incorporation into future analysis. To quantify the effects of the introduced D. polymorpha population, further data were collected on their spread and effects on the SQs ecosystem. Using the limited past data available, plus a full scuba dive survey in 2010 and ex situ lab experiments on filtration rate it has been possible to quantify their effect on the phytoplankton communities and show that mussels are likely a significant controlling factor in all basins except the larger, Huron basin where populations remain inexplicably low. In parallel a new molecular method has been developed to chart the spread of D. polymorpha both around SQ and in new areas via a 9 loci microsatellite multiplex to assess both historic effects and the potential for future dispersal. Finally, a high resolution, multi-parameter dataset was collected over 2010/2011 to determine the current seasonal patterns in biological and physiochemical environment in SQ. It has shown the overwhelming influence of D. polymorpha to the annual and inter-annual variation in water quality and plankton ecology and, when combined with molecular analysis, shows the possible implications of their use in water management. This thesis will serve to broaden our understanding of freshwater ecology and will prove especially useful in future management projects, especially in relation to other artificial waterways and lake systems.
    Date of Award1 Aug 2014
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorKeith White (Supervisor) & Richard Preziosi (Supervisor)

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