Summary of presentations and key issues raised at the Biological Monitoring Review Workshop, October 2006, with status as of August 2010

Internal Report 580
Buckle D, Humphrey C & Turner K (eds)
Supervising Scientist Division
Department of the Environment, Water, Heritage and the Arts

About the report

Foreword

A review of the biological monitoring activities of the Environmental Research Institute of the Supervising Scientist (eriss) was conducted via a workshop that was held in October 2006. This report contains the presentations delivered at the workshop and the recommendations that were made for change. It documents the changes that were implemented over the following four years to August 2010, and provides a summary of the status of the stream biological monitoring program at that time.

Executive summary

Background

The Environmental Research Institute of the Supervising Scientist (eriss) has been conducting research into biological monitoring techniques for surface waters around Ranger mine since 1978 (Humphrey et al 1990, Humphrey & Dostine 1994). Initially eriss's role focused on the development and subsequent transfer of monitoring techniques to mining companies. However in 2000, additional resources were provided to the Supervising Scientist Division (SSD) to formalise a non-statutory independent monitoring program. A preliminary monitoring program was implemented during the 2000-01 wet season with the finalised program commencing during the 2001-02 wet season. eriss's biological monitoring techniques have been subject to a number of reviews in the lead up to implementation of the monitoring program that was formalised during the 2001-02 wet season. By 2006, over a decade of biological monitoring data had accrued and the opportunity was taken at this point to review the program in light of current 'best practice'. The biological monitoring review conducted in October 2006 took into account:

  1. Possible reduced sampling (frequency/effort) for components of the program, considering factors such as:
    1. sensitivity of monitoring organisms to mine-related, water quality changes
    2. adequacy of current datasets as a basis for monitoring during the operational and rehabilitation phase
    3. competing resources insofar as possible increased intensity of new monitoring approaches and rehabilitation research
  2. Optimisation of existing techniques (ie similar results with similar power, but with fewer samples/data)
  3. Wishes of stakeholders, including local landowners

With the delayed reporting of the results of this review, an update of current status as of August 2010 has been provided.

Early detection techniques

Creekside and in situ monitoring

Creekside monitoring (CSM) has been the mainstay of toxicity monitoring since the 1991-92 wet season. A two-year comparison of the CSM and an in situ snail egg production test procedure was conducted during the 2006-07 and 2007-08 wet seasons. In short, there was no significant difference in the response variable between the in situ and creekside methods over the two-year period of comparison. Consequently, the in situ 'once-only-feeding' regime has superseded the CSM method and was first implemented during the 2008-09 wet season, along with cessation of the creekside program. Advantages of the in situ monitoring include improved water flow-through the test containers, portable infrastructure and reduced resourcing compared to the creekside program.

Toxicity monitoring using the in situ reproduction test (egg number) for freshwater snails will continue to be conducted over the standard four-day exposure periods every other week in Magela Creek, and building towards a similar frequency of testing in Gulungul Creek. In a given wet season, testing will commence after deployment of continuous monitoring sondes in both creeks.

Based on the low sensitivity of larval black-banded rainbowfish to mine-derived contaminants, the large amount of staff resources required to maintain broodstock and poor fish survival using in situ testing conditions (akin to creekside monitoring conditions), toxicity monitoring using survival of black-banded rainbowfish larvae was removed from the Ranger mine stream monitoring program following the 2005-06 wet season.

Bioaccumulation in fishes and mussels

Monitoring of bioaccumulation in freshwater mussels will continue with annual sampling conducted in Mudginberri Billabong. Sampling effort has been substantially reduced from sampling individual age classes to collecting a bulk sample of mussels for re-assurance purposes. Collections using this approach was implemented in 2009 and is currently planned for the 2010 dry season. The option for analysing individual age classes in more detail every third year (commencing in 2011 and as per approach used to 2008) will be considered at a later date. The suitability of Sandy Billabong as a control site for this study remains to be assessed given that concentrations of most analytes in the tissues of mussels from this site are much lower than for mussels collected from Mudginberri Billabong. The results of a longitudinal study of mussels along Magela Creek in May 2007 showed that, like Sandy Billabong, analyte concentrations in mussels collected from sites in Magela Creek upstream of the mine are unlike those recorded in Mudginberri Billabong. Hence these upstream Magela sites may not serve as suitable control sites either. The identification of, or indeed necessity for, a suitable control site for this study remains under review.

Fish bioaccumulation has been removed from the routine monitoring program because measured concentrations are very low (ie fish do not bioaccumulate Ranger mine-derived contaminants) and so this measure is not sensitive to changes in mine-derived contaminant concentrations. In the event that local Aboriginal residents become concerned about fish in Mudginberri Billabong, or a significant mine-site influence is detected from other monitoring programs, a specific sampling program may be considered.

Biodiversity assessment techniques

Macroinvertebrate communities of seasonally-flowing streams

Macroinvertebrate sampling in seasonally-flowing streams will continue with the same sampling effort and design. A level of pooling of within-site replicates was investigated to explore reduced costs/time for macroinvertebrate sorting. However, during this investigation it was shown that utilisation of the replicate data in the statistical analysis has much greater statistical power and also provides the ability to assess impacts after a particular (typically preceding) wet season, which pooled data cannot provide.

Fish communities in channel billabongs

Refinements to the experimental design of fish community monitoring in channel billabongs have been implemented. The monitoring technique now has reduced observer counts per transect, ie from 5 to 4 counts. The reduction in observer counts has not altered the statistical power of the impact detection test.

Fish communities in shallow lowland billabongs

Fish community sampling in shallow billabongs has historically been conducted annually in up to nine billabongs. A refined experimental design has been implemented since the 2007 sampling. Sampling will only be conducted every other year (biennially) from three exposure-control paired sites (Coonjimba vs Buba; Georgetown vs Sandy Shallow; Gulungul vs Wirnymurr). Impact detection analysis now incorporates duplicate data from within each of five crocodile exclosure areas to increase statistical power.

Macroinvertebrate communities of shallow lowland billabongs

Macroinvertebrate sampling in shallow billabongs may be conducted every (say) 5 years or otherwise may be initiated if mine-derived contaminant concentrations in the relevant wet season have noticeably increased in Coonjimba, or Georgetown Billabongs compared with analyte values associated with previous sampling (1995, 1996 and 2006). This (relative infrequency) is due to the large work load involved in sampling and sorting macroinvertebrates from shallow billabongs that is in addition to the routine annual macroinvertebrate monitoring. Further work is being conducted to understand the impoverished benthic macroinvertebrate communities in Georgetown Billabong.

In the event that macroinvertebrate sampling in shallow billabongs is scheduled due to a deterioration in water quality conditions in a mine-site-influenced billabong, macroinvertebrate sampling will take precedence over the fish community monitoring. This is due to the increased sensitivity of macroinvertebrates to mine site contamination.