HR: 09:30h
AN: NB51E-04 INVITED     [Abstracts]
TI: Influence of Flow Regime on the Food web of a Dryland River System
AU: * Bunn, S E
EM: S.Bunn@griffith.edu.au
AF: CRC for Freshwater Ecology, Centre for Riverine Landscapes, Griffith University, Nathan, Qld 4111 Australia
AU: Balcombe, S R
EM: S.Balcombe@griffith.edu.au
AF: CRC for Freshwater Ecology, Centre for Riverine Landscapes, Griffith University, Nathan, Qld 4111 Australia
AU: Fellows, C S
EM: C.Fellows@griffith.edu.au
AF: CRC for Freshwater Ecology, Centre for Riverine Landscapes, Griffith University, Nathan, Qld 4111 Australia
AU: McKenzie-Smith, F J
EM: fmckenzie-smith@seqwater.com.au
AF: CRC for Freshwater Ecology, Centre for Riverine Landscapes, Griffith University, Nathan, Qld 4111 Australia
AB: Australian dryland rivers are among the most variable and unpredictable in the world in terms of their flow regimes. Although renowned for their spectacular floods over vast floodplains, rivers exist for much of the time as discrete waterholes, which are important refugia for aquatic biota. During these dry spells, aquatic food webs in waterholes are clearly supported by algal production, despite the high natural turbidity and significant terrestrial carbon inputs. However, the relative importance of pelagic and benthic sources is less clear. Although fish rarely have stable isotope signatures consistent with a phytoplankton diet, gut contents analysis suggests that zooplankton can be a significant component of diets. Planktonic sources of carbon appear to be important during and immediately after flood events, where aquatic production on inundated floodplains provides an immense food resource. As waterholes become isolated post-flood, we predict that benthic sources of production become increasingly important as algae develop along the relatively stable shoreline. More frequent flow pulses connect waterholes and enhance their physical persistence, but may disrupt the formation of these productive algal mats. We propose that the relative importance of benthic and pelagic algal production to dryland river food webs varies in response to recent flow history.
DE: 9330 Australia
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly