Palaeolimnological evidence for the independent evolution of neighbouring terminal lakes, the Murray Darling Basin, Australia

被引:58
作者
Fluin, Jennie [1 ]
Gell, Peter
Haynes, Deborah
Tibby, John
Hancock, Gary
机构
[1] Univ Adelaide, Adelaide, SA 5005, Australia
[2] Univ Adelaide, Sch Earth & Environm Sci, Adelaide, SA 5005, Australia
[3] CSIRO Land Water, Canberra, ACT 2601, Australia
关键词
river regulation; estuaries; diatoms; salinisation; sedimentation; eutrophication; ramsar;
D O I
10.1007/s10750-007-0799-y
中图分类号
Q17 [水生生物学];
学科分类号
071004 ;
摘要
The estuary of the lower River Murray features a complex mosaic of lakes, coastal lagoons and interconnecting channels. The waters of these wetlands are degraded as a result of river regulation, water abstraction, salinisation, sedimentation and the recent constriction of the River mouth. Palaeolimnologial analysis of sediment cores in two wetlands reveals that salinity in the large terminal Lake Alexandrina was only moderately influenced by tidal inflow, particularly over the past ca. 2000 years. It is now largely fresh as a result of isolation by a series of barriers completed by 1940 AD. In contrast, the seaward portion of the Coorong, a back barrier coastal lagoon, was determined to be a subsaline estuary strongly influenced by marine inflows. These findings contrast somewhat with the Coorong's current Ramsar classification as a saline lagoon. Riverine diatoms, typical of the fossil flora of Lake Alexandrina, are rare or absent in the Holocene sediments of the Coorong, other than for a short period in the late Holocene in the northernmost end of the lagoon. The palaeolimnological evidence for independent evolution of these wetlands is consistent with geomorphic evidence of a stranded, last interglacial shoreline that acted as a sill limiting the exchange of flows between Lake Alexandrina and the Coorong lagoon.
引用
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页码:117 / 134
页数:18
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