Adam Kerezsy

Climate change and its implications for Australia's freshwater fish

Freshwater environments and their fishes are particularly vulnerable to climate change because the persistence and quality of aquatic habitat depend heavily on climatic and hydrologic regimes. In Australia, projections indicate that the rate and magnitude of climate change will vary across the continent. We review the likely effects of these changes on Australian freshwater fishes across geographic regions encompassing a diversity of habitats and climatic variability. Commonalities in the predicted implications of climate change on fish included habitat loss and fragmentation, surpassing of physiological tolerances and spread of alien species. Existing anthropogenic stressors in more developed regions are likely to compound these impacts because of the already reduced resilience of fish assemblages. Many Australian freshwater fish species are adapted to variable or unpredictable flow conditions and, in some cases, this evolutionary history may confer resistance or resilience to the impacts of climate change. However, the rate and magnitude of projected change will outpace the adaptive capacities of many species. Climate change therefore seriously threatens the persistence of many of Australia’s freshwater fish species, especially of those with limited ranges or specific habitat requirements, or of those that are already occurring close to physiological tolerance limits. Human responses to climate change should be proactive and focus on maintaining population resilience through the protection of habitat, mitigation of current anthropogenic stressors, adequate planning and provisioning of environmental flows and the consideration of more interventionist options such as managed translocations.

Continuous recruitment underpins fish persistence in the arid rivers of far-western Queensland, Australia

Fish living in highly variable and unpredictable environments need to possess life-history strategies that enablethemtosurviveenvironmentalextremessuchasfloodsanddrought.Weusedthelength-frequencydistributionsof multiple fish species in multiple seasons and highly variable hydrological conditions to infer antecedent breeding behaviourinriversoffar-westernQueensland,Australia.Hypothesestestedwereasfollows:(1)recruitmentofsomeorall speciesoffishwouldoccurwithinwaterholesduringno-flowperiods;(2)therewouldbeseasonalrecruitmentresponsesin some fish species; (3) recruitment of some species would be enhanced by channel flows and/or flooding. Hydrology and the incidence of flooding were highly variable across the study area during 2006-2008. Flood-influenced recruitment was evident for Hyrtls tandan, Barcoo grunter and Welchs grunter. Silver tandan, golden goby, Cooper Creek catfish and Australian smelt showed evidence of seasonal recruitment unrelated to antecedent hydrology. However, most species demonstrated continual recruitment in isolated waterholes, irrespective of antecedent flow conditions and season. Continual and seasonal recruitment capabilities have obvious advantages over flood-pulse recruitment in rivers with highly unpredictable flood regimes and underpin the persistence of many fish species in arid and semiarid rivers. Additional keywords: ephemeral rivers, fish life-history variation, flood pulse concept, Lake Eyre Basin, no-flow recruitment hypothesis.

Conservation of the endangered red-finned blue-eye, Scaturiginichthys vermeilipinnis, and control of alien eastern gambusia, Gambusia holbrooki, in a spring wetland complex

The red-finned blue-eye is the only pseudomugilid fish known from inland Australia and it is found only within an isolated cluster of Great Artesian Basin springs on Edgbaston Reserve in central-western Queensland. Surveys conducted in early 2009 revealed that red-finned blue-eye was present in four individual springs and that invasion of the spring complex by alien eastern gambusia was the most likely factor contributing to local extirpations. A three-year project commenced in the same year, with the twin aims of investigating methods for removing gambusia from springs and relocating small populations of red-finned blue-eye to fish-free springs. Gambusia removal with rotenone has been successful in a trial spring at Edgbaston and aquatic invertebrates have not been adversely affected. From a total of seven relocation events conducted in the same period, red-finned blue-eye populations have persisted in three. The results indicate that gambusia removal and red-finned blue-eye relocation are both suitable methods for red-finned blue-eye conservation, and as the fish is both endangered and declining, these methods and other strategies such as captive breeding should be implemented to prevent species extinction.

The Biota of Intermittent Rivers and Ephemeral Streams: Fishes

Despite their often temporary nature, intermittent rivers and ephemeral streams (IRES) provide important habitat, resource advantages, and nurseries for a range of fish species throughout the world. Fishes have adapted to the variable nature of these environments. A small subset of species using IRES has evolved specific traits such as air-breathing that make living in extreme habitats possible, but the majority relies on opportunistic dispersal to colonize such areas. Fish existence in IRES is precarious but when conditions are favorable, fishes play major roles in ecosystem functioning (e.g., trophic links in food webs). Habitat fragmentation of IRES by water extraction, river regulation, and climate change is the biggest threat to their ecological integrity and has major implications for the distribution and abundance of fishes in IRES.