A Study of the Impact of Seismic Lines on Ant Communities in the
Cooper Basin and Potential Use as Bio-Indicators of Ecological
Recovery Rates
The Petroleum Geophysics Branch of the Department of Primary Industries and
Resources SA (PIRSA) has recently undergone the process of contracting a company
to undertake a study of the viability of the use of ants as indicators of ecological
damage. This study has been commissioned on recommendation from an independent
ecologist and will be conducted by the SA Museum and BiometricsSA.
The use of ants as bio-indicators is not a new process. From the tender process it was
revealed to PIRSA that a large volume of academic work has been conducted in
various educational and government institutions on the uses of ants to measure
environmental recovery after developments creating large scale environmental
impacts, such as mine sites, have been decommissioned.
We know the visual impact of seismic lines on the environment, but although the
fauna appears to recover in about 3-7 years, depending on environmental conditions,
the full impact of the seismic lines on the ecology may not be visibly discernible. So,
it is hoped that this group of invertebrates will be an effective indicator of impacts to
ecological systems and native fauna in general.
The objective of this project is to provide rigorous statistical evidence of the level of
impact on ant communities and their rate of recovery from such impacts.
Seismic Activities in the Cooper Basin
Since 1957 the Cooper/Eromanga Basin region in the North-East of South Australia
has seen over 100,000 kms of seismic data recorded as part of petroleum exploration
activities. Exploration activities have varied over this time in the way that lines are
prepared (eg roller, grader and bulldozer) and the types of seismic sources used (eg
dynamite and vibroseis). The most damaging form of line preparation is considered
the use of bulldozers. This took place mostly in the 1980’s, but in recent times
various studies have indicated the impacts of current exploration methods are not
significant. Most of these studies have only concentrated on the visual assessment of
plant and soil parameters. The use of small animals to measure impacts is nonconclusive, because of the low capture rates and large territorial ranges.
Ants have been chosen because of their good potential for sampling, being abundant
and diverse in terms of species and function.
Tender Process
Late February 1999, an invitation to tender was placed in the Advertiser looking for
expressions of interest for conducting an ant study in the Cooper Basin. Eight
expressions of interest were received and all eight were asked to submit a tender
proposal by 21st May 1999.
After careful deliberation, the tender panel selected the SA Museum/Biometrics team
to conduct this project.
Project
The project is expected to last for a duration of two years. The major focus area of the
study will be an area of approximately 20 km2 in the vicinity of Moomba, in the
Cooper Basin of South Australia. The project will be confined to seismic impacts on
the dunefield land unit (red, orange or yellow dunes), focusing on ants.
Field Work
The project will encompass three field studies to be conducted within a two year
period:
1) Pilot study of recent (1997-1999) lines – To make an assessment of the impact of
recent seismic line development, the focus of this study will be seismic lines
constructed within a two year period. This study will also test the veracity of the
sampling method. It would be expected that these lines will show minimal impact
on ant colonies.
2) A before and after line preparation study –The study will look at the real time
impact of a seismic survey on ant colonies. It is expected that the ants will be
sampled just prior to commencement of the survey (due to the possibility of
changes in to seismic line positions in the weeks prior to a survey it is not possible
to have any earlier sampling). The number of sampling periods post survey and
the timing of these sampling periods is yet to be decided. The results are hoped to
show that current seismic line preparation techniques have minimal impact on ant
communities. The timing of this study will depend on the scheduling of seismic
surveys in the Cooper Basin by Santos.
3) A vintage line study – this study will look at the condition of seismic lines in the
period 1982 to 1985. During this period seismic survey preparation methods are
considered the have had the greatest impact on the environment, with the main
method of line clearing utilising earth moving equipment.
PIRSA are going to have an active involvement in this part of the project, providing
field assistance and hence gaining valuable hands on knowledge of ecological field
sampling techniques.
Data Analysis and Ant Taxonomy
A major part of the project will be the analysis of samples gathered, taxonomic
grouping and statistical analysis.
Because of the amount of taxonomic interpretation required to be carried out in this
study, the level of expertise of the successful tenderer was considered a high priority
to the Petroleum Branch.
Expected Outcomes
The outcome of the study is to give the community confidence in the management of
seismic exploration activities, particularly relating to diligence in minimising the
environmental impact of such activities by:
(a) investigating the use and applicability of ants as indicators of impacts to
ecological systems and native fauna in general;
(b) providing rigorous statistical evidence of the level and rate of recovery from such
impacts;
(c) validating the observations of recent seismic audits which concluded that impacts
were primarily visual (rather than ecological);
(d) providing a check of the veracity of existing environmental objectives and criteria;
and
(e) indicating a revision of the existing environmental objectives and criteria (where
appropriate).
An added bonus will be the production of an illustrated identification manual of arid
zone ants in the sample region to assist in the future identification of ants in the
region.
Conclusion
With funding approval now gained, and with contract negotiations completed, the
project will be under way in mid November after an initial visit to Moomba in
October by the persons involved from the SA Museum and BiometricsSA.