Importance of freshwater flow in terrestrial–aquatic energetic connectivity in intermittently connected estuaries of tropical Australia

Abrantes, Kátya Gisela, and Sheaves, Marcus (2010) Importance of freshwater flow in terrestrial–aquatic energetic connectivity in intermittently connected estuaries of tropical Australia. Marine Biology, 157 (9). pp. 2071-2086.

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δ13C was used to identify seasonal variations in the importance of autochthonous and allochthonous sources of productivity for fish communities in intermittently connected estuarine areas of Australia’s dry tropics. A total of 224 fish from 38 species were collected from six intermittently connected estuarine pools, three in central Queensland (two dominated by C3 forest and one by C4 pasture) and three in north Queensland (one dominated by C3 and two by C4 vegetation). Samples were collected before and after the wet season. Fish collected in the two forested areas in central Queensland had the lowest δ13C, suggesting a greater incorporation of C3 terrestrial material. A seasonal variation in δ13C was also detected for these areas, with mean δ13C varying from −20 to −23‰ from the pre- to the post-wet season, indicating a greater incorporation of terrestrial carbon after the wet season. Negative seasonal shifts in fish δ13C were also present at the pasture site, suggesting a greater dependence on carbon of riparian vegetation (C3 Juncus sp.) in the post-wet season. In north Queensland, terrestrial carbon seemed to be incorporated by fish in the two C4 areas, as δ13C of most species shifted towards slightly heavier values in the post-wet season. A two-source, one-isotope mixing model also indicated a greater incorporation of carbon of terrestrial origin in the post-wet season. However, no seasonal differences in δ13C were detected for fish from the forested area of north Queensland. Overall, hydrologic connectivity seemed to be a key factor in regulating the ultimate sources of carbon in these areas. It is therefore important to preserve the surrounding habitats and to maintain the hydrologic regimes as close to natural conditions as possible, for the conservation of the ecological functioning of these areas.

Item ID: 15209
Item Type: Article (Research - C1)
ISSN: 1432-1793
Keywords: Oceania; Australia; tropical zone; estuaries; energy balance; terrestrial environment; fresh water
Date Deposited: 14 Jan 2011 04:51
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 90%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 10%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 80%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960305 Ecosystem Adaptation to Climate Change @ 20%
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