Mining in focus
in the different representative ecosystems in
the Limpopo River Valley, which included
the Limpopo Ridge Bushveld where Venetia
is currently operating and in the surrounding
habitat type referred to as the Musina
Mopanie Bushveld. Once completed, the
research will indicate whether bats are a viable
option in South Africa as ecosystem bio-
indicators in open cast diamond mining and in
the areas adjacent to these operations.
Another question is which bat species
should be considered as bio-indicators and
how to determine that, but lastly, and probably
the most important for mining companies,
would be to determine the mitigation
strategies mines can adopt to prevent
significant environmental degradation, and to
conserve biodiversity in their footprint and the
surrounding areas, using bats as a reference.
Acoustic sampling at control sites
Rusty bats were recorded in the vicinity of the open pit.
[20] MINING MIRROR AUGUST 2019
can thus be monitored. They are top predators
and bats have high metabolic rates, which
makes them susceptible to bioaccumulation.
Objectives of research
The objectives of Cory-Toussaint’s research are
to determine the physiological and population
impacts of open cast mining on bats, and the
ecosystem services these bats provide. One of
her aims is to establish the bat species diversity
fragmentation of habitats. In some places
the developers will leave small patches of
vegetation, which creates serious issues for
biodiversity.
“Another severe impact is contamination
during extraction. Chemicals used during
this process results in certain elements
being elevated in the water, which might be
detrimental to animals, and ultimately leads to
a loss of biodiversity. These impacts are often
irreversible and are very difficult to rehabilitate
successfully,” said Cory-Toussaint.
The two major effects of open cast mining
on animal populations are thus a decrease
in population size of different species, and a
decrease in species diversity. Cory-Toussaint
explained that she will look at how three
impacts at the Venetia open cast mine will
affect the bat population in the vicinity of the
mine. “The first is the stripping of vegetation,
and what happens with the land that’s left
vulnerable. The second factor that I will
look at is the increase of certain elements in
the water of the surrounding areas, and the
bioaccumulation within the bat species. I will
then also determine how the bat populations
are affected by light pollution,” she said.
A 24-hour a day mining operation uses
lights at night, which attracts food in the form
of insects. Studies in Europe have proven
that some bats completely avoid lit areas and
permanently leave the area. Others, however,
move in to prey on the great swarms of insects
the lights attract, so it does benefit some
species. There is a big trade-off between the
two, and that is why, Cory-Toussaint said, she
looked at bats as bio-indicators.
Cory-Toussaint explained that a bio-
indicator has to show a measurable response to
an environmental change, which bats do. They
are also taxonomically stable, and they have
a very low reproductive output, so any major
disturbance in the environment will reflect in
their breeding success. Furthermore, they have
a long life expectancy and population trends
When I spoke to her in October 2018, Cory-
Toussaint had already conducted 81 nights
of acoustic sampling (identifying bat species
from eco-location calls) at Venetia during the
winter period. She used a number of different
control sites to determine the species diversity
on these sites and then compare them to the
open pit site. In the natural vegetation on the
Venetia Game Reserve to the east of the mine,
the dominant species (60%) recorded were
Free-Tailed bats, the majority being Ansorge’s
free-tail bats and Egyptian Free-Tailed bats.
Clutter foragers like Horseshoe bats were
also recorded. Clutter foragers need a specific
habitat structure to feed, ideally where there is
thick bush. They don’t forage in open areas and
need rocky areas and caves to roost. According
In the natural vegetation on the Venetia Game Reserve to the east of the mine, the dominant species (60%)
recorded were Free Tail Bats, the majority being Egyptian Free Tail bats.
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