Science Education News (SEN) Journal 2017 Volume 66 Number 4 December 2017 | Page 43

GENERAL ARTICLES
Swimming in Sand – Frogs and Sand-Mining at Smiths Lake (continued)
with the last individuals being detected in late 1980 (Fig. 11).
They persisted at the Dune Pond Site in low numbers until 1989
when they disappeared, returning in 1992 for a period of two
years before disappearing again (Fig. 10).
Figure 12: Changes in the Numbers of Crinia tinnula in the
Swamp Site over Time.
Figure 10: Changes in the Numbers of Adelotus brevis in the
Dune Pond Site over Time
Changes in Habitat Parameters in the Dune
Pond Site
Many changes in pond habitat features occurred during the
course of this study; the most apparent changes to the pond
itself were the gradual reduction in pond depth and reduction of
open water area. Concurrent with these changes were increases
in the relative spread of emergent plants, particularly Typha
orientalis. At the same time, there was a measured reduction
in the relative abundance of Baumea juncae, B. articularis and
Schoenus brevifolius. Other less dominant plants also appeared
in the dunal pond after mining, such as
Triglochin striatum and Crotula coronopifolia. Changes in water
parameters also occurred, particularly a transient increase in pH
and salinity associated with mining.
Changes in Habitat Parameters in the Dune
Swamp Site
Figure 11: Changes in the Numbers of Adelotus brevis in the
Swamp Site over Time
The habitat parameters associated with the dune swamp site
also changed over time. The most abrupt changes to the swamp
site occurred during the mining phase with sudden changes in
water parameters; in particular, there was a short-lived (3-year
duration) but sudden elevation of water pH to alkaline levels.
Concurrent with this was a surge in salinity and conductivity
levels of the swamp water.
The Wallum Froglet Crinia tinnula was not detected in the Swamp
Site until May 1982. This species has been consistently detected
in surveys since then and has become one of the more common
species in the Swamp Site (Fig. 12).
The swamp also had an increase in open water area available
during the mining phase and the first ten years post mining. Open
water levels have since returned to pre-mining levels. Plants in
the swamp site also changed with Leptospermum liversidgei,
Selaginella uliginosa and Xanthorrhoea minor becoming more
abundant post-mining. Species such as Gahnia sieberi and
Restio tetraphyllus have become less abundant in the swamp
site.
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SCIENCE EDUCATIONAL NEWS VOL 66 NO 4