Doctoral Thesis
Effects of experimental disturbance on stream invertebrates and their traits
Doctor of Philosophy (PhD), Murdoch University
2024
Abstract
Ecosystems are increasingly subject to multiple disturbances, but the influence of large-scale, long-term disturbances on smaller-scale, shorter-term disturbances is poorly understood. I used field manipulation of a short-term flow disturbance, within the context of large-scale, long-term disturbance (agricultural clearing) to determine whether ecosystem responses to short-term disturbances were impaired by long-term disturbances. This thesis investigated the distribution of invertebrates and their functional and flow-related traits between two levels of agricultural clearing, the effect of long-term agricultural clearing on the responses of invertebrates to short-term flow disturbance, and the role flow-related and functional traits play in mediating these responses. Initially, invertebrates and physicochemical conditions were collected from 16 streams in southwestern Australia (SWA) across a gradient of landscape clearing to describe the distributions of invertebrates and their flow- and functional traits. A multiple control-impact and recovery experiment was then created in eight of these streams, four with < and four with >30% catchment clearing using temporary half-weirs and the responses of environmental and ecosystem variables and species were quantified. Catchment clearing increased similarity of invertebrate communities, favouring taxa adapted to sedimentation and higher temperatures. Trait distributions also differed with catchment clearing but not in ways predicted by existing literature. During weir operation, clearing impaired responses to flow disturbance by reducing invertebrate α-diversity, minimum DO concentrations, and microbial activity. Some patterns in trait distributions among flow treatments, mediated by level of catchment clearing, were detected. However, these patterns were temporally complex and obscured by other variation within and among streams. Functional traits did not effectively predict responses to flow manipulation nor the influence of agricultural clearing on these responses. Historic land-use and climate driven habitat fragmentation have increased β-diversity leading to context-dependent trait responses to short-term flow disturbances, calling into question the effectiveness of traits in predicting responses to disturbance.
Details
- Title
- Effects of experimental disturbance on stream invertebrates and their traits
- Authors/Creators
- Sean T Atkinson
- Contributors
- Belinda Robson (Supervisor) - Murdoch University, Centre for Sustainable Aquatic EcosystemsEdwin T Chester (Supervisor) - Murdoch University
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005691069407891
- Murdoch Affiliation
- Centre for Sustainable Aquatic Ecosystems
- Resource Type
- Doctoral Thesis
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