Temporal changes in fish abundance in response to hydrological variability in a dryland floodplain river

Abstract

Riverine fish living in unpredictable flow environments tend to be ecological generalists with traits that allow them to persist under highly variable and often harsh conditions associated with hydrological variation. Cooper Creek, an Australian dryland river, is characterised by extreme flow variability, especially in the magnitude, timing and duration of channel flows and floods, which, if they occur, do so mainly in summer. The present study examined the influence of hydrological variability on fish assemblages and abundance in four waterholes in the Windorah reach of Cooper Creek over eight occasions between 2001 and 2004. Antecedent flows had marked influences on fish species richness and assemblage structure. Following high summer flows, all waterholes supported a rich and abundant fish fauna, whereas fewer species and lower numbers were recorded following periods of zero channel flow. Recruitment of three of the four most common and abundant species was enhanced when intermittent flows inundated backwater and floodplain habitats that provide a food-rich environment. Opportunistic responses to rising channel flows and occasional large floods in Cooper Creek help to explain the prominent ‘boom’ patterns of fish production in this arid-zone river, whereas low-level recruitment during periods of low or no flow maintains populations of some species through the ‘bust’.

Fish Distribution in Far Western Queensland, Australia: The Importance of Habitat, Connectivity and Natural Flows

“…The low number of species detected in winter supports the findings of previous studies [26,47] and also demonstrates that population peaks and increases in species diversity following flooding are most likely to occur during the warmer months [24,27]. Results demonstrating a preference for ephemeral habitats by certain fish species are also supported by data from this study, however it should be noted that the number of species declined dramatically in the ephemeral Mulligan catchment as it dried throughout 2007, a result not replicated in the Mulligan's parent river, the Georgina.…”

“…Stephen also has extensive experience working in the river systems that were studied and in other arid and semi-arid Australian systems [28,39,47].…”

Climate change and its implications for Australia's freshwater fish

“…In the major catchments, such as the Diamantina/Warburton, Georgina and Cooper, flow and flood events generally occur in summer and occasionally fill large terminal lakes, such as Lake Eyre. The 23 native and 2 alien fish species present in central Australian rivers often have life-history characteristics adapted for these variable habitats (Pusey et al 2004;Balcombe et al 2006;Kerezsy 2010), with the majority of species reproducing throughout the year in permanent waterholes (Balcombe and Arthington 2009). Many fish species from central Australian waterways are also capable of migrating long distances (at least 300 km in the case of L. unicolor) in ephemeral desert systems when flow and connection pathways are re-instated (Kerezsy 2010).…”

Climate-change threats to native fish in degraded rivers and floodplains of the Murray–Darling Basin, Australia

“…However, where the impact of climate change interacts with the effects of barriers on fish migration (such as low flows), the fish species that migrate as part of their breeding cycle (e.g. Hyrtl's tandan, Balcombe and Arthington 2009;Kerezsy et al 2011) could be affected in some rivers. There are likely to be some localised impacts of less flow reaching terminal wetlands (climate change added to waterresource development), affecting floodplain and wetland vegetation, especially encroachment from lignum.…”