Salt lakes can be so salty that salt precipitates in
particles on the surface - or so fresh that tadpoles are
able to survive in them - and this can be in the same lake
(though not at the same time).
With underlying clay and gypsum layers registering high salt
levels small rainfall events produce shallow and highly saline
water on the lake's surface.
This water evaporates or drains away into the sediments of
the lake 'bottom' quite quickly, and is of little help in
establishing or supporting life.
Big rainfalls produce substantial inflows, giving the
salt lake a depth of up to a metre of basically fresh water.
This is 'sweet' enough and long lasting enough for many types of invertebrate
fauna to hatch out and go through their life cycles before the lake dries up
or becomes too salty to support life.
It is under these circumstances that whole food chains develop around the lakes,
supporting teeming flocks of waders and waterbirds.
Life on and around salt lakes is not only tough going
for fauna - flora too, has to be highly adapted to survive
these arduous conditions.
Plants that grow in salty environments have developed different
ways of dealing with the salt and the harsh conditions.
Samphires have salts in their cells to regulate their
osmotic balances.
When it is very hot and dry they 'shut down'- often turning
purple or red. Under these circumstances they do not produce
any new growth.
Often peripheral vegetation dies off and the plant will look
like a stick with just a couple of tiny 'branches' alive.
Yet when rain comes, the plant will turn green and will quickly
produce new growth and flower spikes as if to celebrate its
survival.
The various species of Frankenia have developed remarkably
long root systems and appear able to exude salt from their
leaves, which are very small and hard (to reduce moisture
loss).
Most salt bushes (Atriplex sp) have silvery grey and slightly
hairy leaves to reduce moisture loss - and do not live as
close to the salty water as the Samphires or Frankenias.
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