Paleolimological investigation of the use of stable isotopes of carbon and nitrogen in bulk sediment and cladoceran zooplankton to reveal ecosystem changes in Kings Billaong Northwest Victoria, Australia
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Date
2013-07-10
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University of Western Australia
Abstract
Northwest Victoria hosts a large number of shallow floodplain wetlands along the
Murray River system. One of these, Kings Billabong, is known for its high conservation
values. However, the naturally occurring flood pulses, which maintain ecological
connectivity between river and wetlands, have been altered impacting the ecology of Kings
Billabong. The human-induced river regulation in the Murray River following the arrival of
Europeans, and increased farming activities around Mildura for irrigation, has switched
Kings Billabong to a permanent water regime resulting in accelerated sedimentation rates and
changed sources of carbon and, subsequently, altered ecological character. This study focuses
on a 90 cm long sediment core taken from Kings Billabong in 2011, where the 210Pb dating
detected sediments at c. 60 cm depth to be c. 65 years old. Around this time (c. 1940-1945
AD), a systemic change occurred in the billabong. The enrichment of carbon substantially
declined, while, in the meantime, nitrogen enrichment increased. Coincidently, the subfossil
cladoceran zooplankton assemblages revealed changes in the limnological conditions of the
wetland ecosystem. Among the littoral species, the Chydorus sphaericus group, which prefers
eutrophic water, became dominant. Since the early 2000s, the abundance of Biapertura
affinis, a pioneer plant dwelling species, has declined. Before the assemblage of B. affinis
began to decline, a large number of cladoceran ephippia were recorded in sediment samples
indicating the elevated stress in the wetland. This study suggests that paleolimnological
investigations, together with the use of stable isotopes of carbon and nitrogen in sediment
samples, provides an opportunity to reveal the impacts of anthropogenic disturbances on the
floodplain wetlands of the Murray River system across northwest Victoria, and potentially
more widely across Australia. © The Authors.
Description
Keywords
Stable isotopes, Limnology, Aquatic ecosystems, Carbon, Nitrogen, Sediments, Zooplankton, Victoria, Australia, Wetlands, Rivers, Irrigation
Citation
Kattel, G., Gell, P., Zawadski, A., & Barry, L. (2013). Paleolimological investigation of the use of stable isotopes of carbon and nitrogen in bulk sediment and cladoceran zooplankton to reveal ecosystem changes in Kings Billaong Northwest Victoria, Australia. Paper presented at the 12th Australian Environmental Isotope Conference, University of Western Australia, Perth, Australia, 10th-12th July 2013.