Science Education News (SEN) Journal 2017 Volume 66 Number 4 December 2017 | Page 42

GENERAL ARTICLES
Swimming in Sand – Frogs and Sand-Mining at Smiths Lake (continued)
How did the frogs React to Sand Mining?
Both the dune pond and the swamp had a sudden and relatively
short (5 to 10 year duration) "shock" period when mining
commenced in the area in 1983/84. Some frog species did not
reappear ever again. Some frog species disappeared, but have
returned at some later point. Furthermore, some new frog species
turned up to inhabit the altered ecosystems.
In the dune pond the three frog species that disappeared entirely
were (Tusked Frog Adelotus brevis, Green and Golden Bell frog
Litoria aurea and the Broad-palmed Frog Litoria latopalmata). In
the swamp, the species that disappeared entirely were the Tusked
Frogs again, Spotted Grass Frogs Limnodynastes tasmaniensis
and the Brown Toadle Pseudophryne bibroni.
Figure 8: Changes in the Numbers of Spotted Grass frogs in the
Dune Pond over time.
Litoria aurea was present in the dune pond at the start of the
study, actually exhibited an increase in abundance during and
immediately after mining, but declined steadily throughout the
later post-mining period before disappearing altogether from the
area in 1989 (Fig. 7).
Bibrons Toadlet Pseudophryne bibroni was present in the Swamp
Site in the pre-mining phase in relatively high numbers, up to 10
frog detected per transect. However their numbers decreased
rapidly during the mining phase and immediate post-mining
phase (Fig. 9). The species was not found in the swamp transect
between 1985 and 1997. The species was eventually redetected
in the swamp site in May 1999 and remained in the site until
2003 before finally disappearing altogether from the site. Bibrons
Toadlet was never present in the Dune Pond Site.
Figure 7: Changes in the Numbers of Green and Golden Bell
frogs in the Dune Pond over time.
The Spotted Grass Frog Limnodynastes tasmaniensis was
present in the Swamp Site during th e pre-mining and mining
phases but disappeared in the early post-mining phase. It was
last detected in May 1982 (Fig. 8). Opportunistic surveys of the
Lake Swamp over the ensuing thirty years have failed to relocate
the species in the local area.
Figure 9. Changes in the Numbers of Pseudophryne bibroni in
the Swamp Site over Time.
Tusked Frogs were present both in the Dune Pond and Swamp
Site during the pre-mining phase of the study. This species
was present in reasonably high numbers (up to 10 individuals
recorded per transect) at both the Dune Pond Site and Swamp
Site before mining but quickly declined once mining commenced
(Figure 10, 11). It disappeared completely from the swamp site
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SCIENCE EDUCATIONAL NEWS VOL 66 NO 4