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Title: The impact of organic enrichment on invertebrate community structure and micromorphology of sediments in the Ythan estuary
Author: Maloney, Joanna Louise
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1993
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A combination of laboratory and field experiments were used to assess the effects of a natural source of organic enrichment, the opportunistic green macroalgae Enteromorpha, on the ecology and sediment physico-chemistry of intertidal mudflat communities. An organic enrichment gradient was established and monitored by recording redox potentials. As expected, the results indicated a significant reduction in Eh as organic enrichment increased. The impact of this gradient or organic enrichment on the biology of the system was assessed in terms of community parameters such as abundance, biomass and species richness. To explore enrichment-size correlates further, benthic biomass size spectrum in sediments experimentally treated with different levels of organic material were constructed. Schwinghamer's (1981) suggestion that the conservative properties of the biomass spectrum could have potential in biomonitoring environmental perturbations was assessed. It is concluded that the benthic biomass spectrum is conservative despite the dramatic changes observed in species biomass, abundance and diversity. Changes in the spectrum were only apparent in the very high organic enrichment treatment. However, due to a lack of a clear dose-dependent response and to the time intensive data manipulation involved for its construction, the potential of the benthic biomass spectrum as a tool for biomonitoring is probably not great. Caging artifacts were investigated and were not detected in terms of silt and organic carbon. However, caution is advised in interpreting these non-significant effects as evidence of no caging artifacts. Clearly other caging artifacts had occurred to account for significant biological differences between ambient and cage controls, evident by Eh. Biological interactions between species were investigated to determine if the changes in community structure observed in previous experiments were the direct result or organic enrichment or due in part to biological interactions occurring within a disturbed community. It was concluded that biological interactions may be as significant as organic enrichment effects per se in affecting benthic community structure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available