Impacts of watercress farming on stream ecosystem functioning and community structure. Cotter, Shaun The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author For additional information about this publication click this link. http://qmro.qmul.ac.uk/jspui/handle/123456789/8385 Information about this research object was correct at the time of download; we occasionally make corrections to records, please therefore check the published record when citing. For more information contact
[email protected] Impacts of watercress farming on stream ecosystem functioning and community structure Shaun Cotter School of Biological and Chemical Sciences Queen Mary, University of London Submitted for the degree of Doctor of Philosophy of the University of London September 2012 1 Abstract. Despite the increased prominence of ecological measurement in fresh waters within recent national regulatory and legislative instruments, their assessment is still almost exclusively based on taxonomic structure. Integrated metrics of structure and function, though widely advocated, to date have not been incorporated into these bioassessment programmes. We sought to address this, by assessing community structure (macroinvertebrate assemblage composition) and ecosystem functioning (decomposition, primary production, and herbivory rates), in a series of replicated field experiments, at watercress farms on the headwaters of chalk streams, in southern England. The outfalls from watercress farms are typically of the highest chemical quality, however surveys have revealed long-term (30 years) impacts on key macroinvertebrate taxa, in particular the freshwater shrimp Gammarus pulex (L.), yet the ecosystem-level consequences remain unknown.