Journal Article
Groundwater estuaries of salt lakes: buried pools of endemic biodiversity on the western plateau, Australia
Humphreys, W.F., Watts, C.H.S., Cooper, S.J.B. and Leijs, R.
Record Number:
5587
Year:
2009
Journal:
Hydrobiologia
Pages:
79-95
Volume:
626
Abstract:
Abstract Subterranean or groundwater estuaries
occur in porous and cavernous substrates where
groundwater abuts the ocean. Like surface estuaries,
they are strongly stratified, temporally and hydrochemically
heterogeneous environments that support
complex hydrogeochemical and biological processes
and ecological communities. Here, we contend that
groundwater estuaries also occur where groundwater
flow approaches salt lakes and provide evidence in the
context of groundwater (valley or phreatic) calcretes
in palaeovalleys of the arid western plateau of
Australia. The calcrete groundwater estuaries display
marked and complex physico-chemical gradients
along, across and through the groundwater flow path.
From the first principles and the density differences
between water bodies, we may expect the form and
dynamics of the saltwater front to mimic that of
marine estuaries but with the dynamic and temporal
response to changing hydrology heavily dampened,
and driven by the episodic groundwater recharge and
lake filling typical of arid regions. The calcrete
aquifers support diverse biological communities of
obligate groundwater animals, largely endemic to a
given calcrete body. These communities comprise
both macro and microinvertebrates, predominantly a
suite of crustacean higher taxa, and a great diversity of
diving beetles (Dytiscidae) isolated in the calcrete
aquifers between ca. 5 and 8 million years ago.
Keywords Groundwater, Anchialine, Calcrete, Stygofauna, Estuary, Biodiversity
Times Cited:
3