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Ecology of acidification and recovery in Welsh upland streams

Frame, Jessica Laura (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

This study investigates the current impact of acid deposition on the structure and function of benthic communities in streams of contrasting pH in mid-Wales, UK, and examines barriers to biological recovery across the sites. The results of field surveys across 30 streams revealed sustained effects of acid stress on macroinvertebrate assemblages. Acid streams supported fewer grazers and filter-feeders than circumneutral waters but other functional groups were less affected by low pH. Field experiments tested the effects of acidification on two key processes in stream ecosystems, benthic algal grazing and leaf decomposition. Grazer impacts on algal abundance were generally feeble and largely unaffected by acid stress. Leaf litter decomposition was impaired by acidification, due largely to reduced microbial breakdown. Prospects for biological recovery in chemically restored streams are discussed, and field experiments were undertaken to test two hypotheses (biotic resistance and resource limitation) proposed to explain the observed delays in faunal recolonisation. A resident-colonist competition experiment revealed no evidence in support of biotic resistance as mediated through interspecific competition, whereas growth experiments revealed that the quality or palatability of algal resources in chemically ‘restored’ streams limits growth and survival of colonist mayfly nymphs (Baetis).

Type of Work:Ph.D. thesis.
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Geography, Earth & Environmental Sciences
Subjects:GB Physical geography
Institution:University of Birmingham
ID Code:605
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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