HR: 14:30h
AN: NB23D-05    [Abstracts]
TI: Standing Out From the Crowd: New Fish Recruits Have Unique δ¹⁵N Signatures in a Heavily Polluted Intermittently Open Estuary.
AU: * Hadwen, W L
EM: w.hadwen@griffith.edu.au
AF: Centre for Riverine Landscapes, Griffith University, Centre for Riverine Landscapes, Faculty of Environmental Sciences, Griffith University, Nathan Campus, Brisbane, QLD 4111 Australia
AU: Arthington, A H
EM: a.arthington@griffith.edu.au
AF: Centre for Riverine Landscapes, Griffith University, Centre for Riverine Landscapes, Faculty of Environmental Sciences, Griffith University, Nathan Campus, Brisbane, QLD 4111 Australia
AB: Intermittently open estuaries (IOEs) are the dominant coastal ecosystems of the Australian coastline. Conditions in IOEs range from freshwater when closed, to marine when open to the ocean, during which time marine fish often migrate into these systems. Many IOEs are facing increasing pressure from coastal development and ongoing nutrient inputs from industrial and urban sources have been shown to increase the δ¹⁵N isotope signatures of biota in receiving waters. In this study, we examined the food web structure of Tallows Creek, a relatively small IOE in northern NSW, Australia, which receives ongoing sewage treatment plant inputs. We first sampled Tallows Creek when it was closed to the ocean and found that all components of the food web had enriched δ¹⁵N signatures relative to biota sampled from a relatively undisturbed neighbouring system. However, samples collected immediately following an entrance opening event revealed some individuals of highly mobile taxa with δ¹⁵N signatures more typical of unpolluted estuaries. We suggest that these isotopically light individuals were recent migrants into Tallows Creek and that δ¹⁵N signatures can act as a guide to the importance of heavily polluted systems as nursery grounds for mobile taxa, owing to the distinction between resident and migrant signatures.
DE: 1803 Anthropogenic effects
DE: 4235 Estuarine processes
DE: 4815 Ecosystems, structure and dynamics
DE: 4817 Food chains
DE: 4870 Stable isotopes
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly