Carbon uptake in surface water food webs fed by paleogroundwater

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American Geophysical Union
The use of 14C to elucidate sources of carbon within freshwater aquatic ecosystems is challenging the assumption that modern autochthonous carbon dominates energy flows. We measured the uptake of old carbon through several trophic levels of a wetland fed by groundwater of the Great Artesian Basin, Australia, the largest artesian basin in the world. Stable isotopes (δ13C and δ15N) and radiocarbon (14C) were used to quantify food chain links and connection between groundwater and surface water food webs. Our results suggest that old groundwater was the dominant carbon source even at the highest trophic levels, with predatory fish returning apparent carbon ages of up to 11 ka. Stable isotope analysis (δ13C and δ15N) identified trophic links between fish, aquatic insects, and algae with smaller contributions from particulate organic matter to the food webs. As natural mound springs and associated wetlands are the only source of reliable water during dry periods over vast areas of the western Great Artesian Basin, the result has potential implications for the interpretation of archaeological artefacts associated with indigenous passage within the interior. ©2019. ANSTO, Macquarie University, Commonwealth of Australia.
Carbon 14, Aquatic ecosystems, Carbon, Artesian basins, Australia, Stable isotopes, Aquaculture, Wetlands, Insects, Algae
Mazumder, D., Saintilan, N., Hollins, S., Meredith, K., Jacobsen, G., Kobayashi, T., & Wen, L. (2019). Carbon uptake in surface water food webs fed by palaeogroundwater. Journal of Geophysical Research: Biogeosciences, 124(5), 1171-1180. doi:10.1029/2018JG004925