Doctoral Thesis
Effects of climate drying on endemic freshwater macrocrustacean persistence in south-western Australia
Doctor of Philosophy (PhD), Murdoch University
2023
Abstract
Global warming is causing the southwestern Australian climate to warm and dry, prolonging dry periods in wetlands and creating challenges for aquatic species persistence. Freshwater crustaceans perform important roles in wetland ecosystems, yet we know little about how they are affected by and respond to drying. This project investigated the drying responses of three endemic freshwater Crustacea: the gilgie (Cherax quinquecarinatus), isopod (Paramphisopus palustris) and amphipod (Chiltoniidae sp. nov.). Respirometry experiments showed no difference in metabolism between gilgies from a seasonal stream and those from a perennial stream. Surprisingly, intermittent stream gilgies showed limited burrowing ability, whereas perennial stream crayfish burrowed strongly in sediment with clay, that holds shape and moisture better than sand alone. Across the landscape, amphipod populations have persisted, but population sizes declined substantially due to warming and drying. Isopod populations have been lost since more wetlands became intermittent, mostly from perennial wetlands. Potentially, climate change prolongs stratification, causing deoxygenated bottom waters and hot surface water layers exceeding isopod tolerances, leading to extirpation. In comparison, seasonal wetlands dried during summer and isopods survived in microhabitat refuges. Isopods survived drying better in semi-perennial wetlands than seasonal wetlands, but always used microrefuges, posture and dormancy as drying responses. Although some crustaceans may be resistant to drying (e.g. crayfish), others (e.g. amphipods, isopods) are experiencing population and/or distribution reductions impacting their ability to provide critical ecosystem services, especially carbon-cycling and as prey. However, even resistant species may begin to decline as global warming continues, dry periods lengthen, temperatures rise, and perennial waterbodies become intermittent. Warmer waters may cause sub-lethal effects (e.g. reduced body size, which limits fecundity) in amphipods and isopods, limiting survival and investment in reproduction. Further research is needed to understand crustacean responses to drying and their effects on fitness.
Details
- Title
- Effects of climate drying on endemic freshwater macrocrustacean persistence in south-western Australia
- Authors/Creators
- Holly E Emery-Butcher
- Contributors
- Belinda Robson (Supervisor) - Murdoch University, Centre for Sustainable Aquatic EcosystemsStephen Beatty (Supervisor) - Murdoch University, Centre for Sustainable Aquatic Ecosystems
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005552669507891
- Murdoch Affiliation
- Centre for Sustainable Aquatic Ecosystems; College of Environmental and Life Sciences; Harry Butler Institute
- Resource Type
- Doctoral Thesis
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