Atrazine is in the news again (e.g. ABC 7.30 Report Thursday 25^th March, 60 Minutes, 21^st March) and is being found in more and more water bodies in Australia, and notably Queensland in recent times.  Here is where it has been found so far:

1. Rainwater at a few ng/l (unpublished data from Atherton, Qld), in streams in almost all of eastern Queensland at concentrations of between one and 50 ug/l (Lewis et al 2009; Packett et al 2009),
2. Great Barrier Reef lagoon waters as far offshore as we have looked (outer reef waters) at ng/l concentrations (passive sampler work, Shaw et al 2010)
3. Wet season discharge conditions in the lagoon at ug/l concentrations (Lewis et al 2009),
4. Groundwater of the lower Burdekin at a few ug/l (as far back as 1976 (Brodie et al 1984) and
5. Tap water in Rockhampton, Mackay, Ayr, Home Hill, Innisfail at 1 ug/l (unpublished and suppressed data)
6. Noosa River associated with the infamous ‘two headed fish’, fish kills and human health problems (along with other pesticides) (Matt Landos’s work),
7. Victorian tap water and in streams in Tasmania.

You might say this isn’t ‘everywhere’ but that’s only because we haven’t looked ‘everywhere’. Everywhere we have looked we have found it.

All I can say is that obviously current management (i.e. APVMA federally) is not working. Given this failure of management the only solution left is to ban atrazine. This is unfortunate for farmers as atrazine is a valuable product and possibly could be kept in use if there was a competent management regime. The part on the 7.30 Report story where APVMA notes that atrazine use was banned along watercourses says it all. This will have no effect in losses from sugar application where atrazine leaks from sugarcane via drainage (sugarcane is always drained due to dislike of wet roots) and is not used in watercourses anyhow!

This is the telling point against APVMA as their review (2008) does nothing whatsoever to reduce loss of atrazine from sugarcane crops. So a review that took 13 years produced no actions which had any effect on losses from sugarcane (and I suspect other crops as well), yet the problems of loss from sugarcane were well known by then and published in the open scientific literature.

Meanwhile APVMA continues to ignore the evidence and cannot provide a satisfactory management regime for these pesticides to keep them out of our waterways. Currently the role and scope for action of APVMA is being reviewed but it unlikely any major changes to make APVMA more effective will occur.

An example of a healthy reef (Princes Charlotte Bay, Far Northern GBR)

There is a large body of published results from hundreds of studies  showing that (with just a few of the possible references):

1. Water discharged from rivers to the GBR continues to be of poor quality in many locations. The main source of pollutants is agriculture (cropping and grazing) e.g Packett et al (2009),  Bainbridge et al (2009).

2. Land derived pollutants, including suspended sediments, nutrients and pesticides are present in the GBR at concentrations likely to cause environmental harm e.g. Lewis et al (2009) and  De’ath and Fabricius (in press).

3. Coral cover on the GBR is generally much lower (about 25%) now than 40 years ago (cover about 50%) e.g. Bruno and Selig 2007. Macroalgal cover appears to be greatly increased e.g. De’ath and Fabricius (in press) Wismer et al (2009)

4. This loss in coral cover has been caused by a combination of  factors – poor water quality (see references above), crown of thorns starfish damage also associated with poor water quality (Brodie et al 2005), bleaching associated with climate change, loss of calcification associated with increased carbon dioxide in the surface water (De’ath et al 2008) and some minor damage from fishing activities.

Most of these results up till 2008 are summarised in the following document (click through for a link to the site and pdf download)

On the other hand there are few published results of research showing that agricultural pollution is having no effect on the Great Barrier Reef – none that I can find. What can be found are unsupported (by research results) opinions. Now we all have opinions and I think mine are as good as anybodies but I don’t pass them off as facts when they are not supported by research results.

An example of a degraded macroalgal dominated reef (Russell Island, Wet Tropics, Northern GBR)

I make no statements about the recently introduced Queensland Government legislation or its likely effectiveness, which remain to be tested, but do claim that there is ample well-founded evidence that agricultural pollution of the GBR is occurring, the effects are severe and that management of this pollution is a necessity.

Jon Brodie
Catchment to Reef Research Group
Australian Centre for Tropical Freshwater Research
James Cook University, Townsville.

References:

Bainbridge, Z.T., Brodie, J.E., Faithful, J.W., Sydes, D.A. & *Lewis*, S.E. (2009). Identifying the land-based sources of suspended sediments, nutrients and pesticides discharged to the Great Barrier Reef from the Tully-Murray Basin, Queensland, Australia. Marine and
Freshwater Research, 60, 1081-1090

Brodie, J.E., Fabricius, K., De’ath, G. & Okaji, K. (2005). Are increased nutrient inputs responsible for more outbreaks of crown-of-thorns starfish? An appraisal of the evidence.
Marine Pollution Bulletin, 51:266-278

Bruno JF, Selig ER (2007) Regional Decline of Coral Cover in the Indo-Pacific: Timing, Extent, and Subregional Comparisons. PLoS ONE 2(8): e711

De’ath G. and Fabricius K. in press. Water quality as a regional driver of coral biodiversity
and macroalgae on the Great Barrier Reef. Ecological Applications

De’ath G, Lough JM, Fabricius KE, (2008) Declining Coral Calcification on the Great Barrier Reef, Science, 323, 116-119

Lewis, S.E. Brodie,  J.E. Bainbridge, Z.T. Rohde, K. Davis, A. Masters, B. Maughan, M.
Devlin, M. Mueller, J. Schaffelke, B. ( 2009) Pesticides: A new threat to the Great Barrier Reef. Environmental Pollution 157, 2470-2484

Packett, R. Dougall, C. Rohde, K. Noble, R. 2009. Agricultural lands are hot-spots for annual runoff polluting the southern Great Barrier Reef lagoon. Marine Pollution Bulletin 58, 976-985.

Wismer S, Hoey AS, Bellwood DR (2009) Cross-shelf benthic community structure on the Great Barrier Reef: relationships between macroalgal cover and herbivore biomass. Marine
Ecology Progress Series 376:45-54.

Image 1: Satellite image from 15 January 2009. Image courtesy of Lachlan McKinna, JCU.

Heavy rainfall has been occurring in northern Queensland since December causing widespread flooding of coastal rivers (Burdekin, Haughton, Bohle, Herbert, Tully, O’Connell and others) as well as inland catchments. In some places all-time records were broken, especially around Townsville, and the flows in the Herbert and Burdekin were both far above average (more rain may occur as well).

The river discharge events are being tracked by satellite imagery in collaboration with Arnold Dekker’s group, CSIRO, Canberra and Lachlan McKinna in Michelle Devlin’s flood plume project at JCU. The plumes are noticeable as sediment rich in the early stages (January – image1) and extending out to near Dunk Island but colour rich (chlorophyll and coloured dissolved organic matter) in the latter stages (February – image 2) extending completely across the main reef and into the Coral Sea.

The plumes are being sampled via the GBRMPA – Reef and Rainforest Research Centre, Marine Monitoring Program run by the Catchment to Reef Group, ACTFR, JCU (Michelle Devlin coordinator) and AIMS (Britta Schaffelke). Sampling from both fixed installations and vessel surveys have been going since December.

Image 2: from 18 February 2009. Image courtesy of Arnold Dekker, CSIRO.

Incidentally to the plume monitoring, reports from many scientists working on the reef in the area between Mackay and Cooktown have been coming in of coral ‘bleaching’ and mortality, ‘fresh’ water layers, turbid water layers, green water and stratified water. Corals in poor condition have been reported by Katharina Fabricius (Dunk Island and surrounds), Sheriden Morris (Frankland group), Angus Thompson (Pandora, Palms, Whitsundays), Michelle Devlin, Jane Waterhouse and David Haynes (Dunk and surrounds), Britta Schaffelke (Franklands, High, Fitzroy, Pandora and others), Ray Berkelmans (Magnetic Island), Stephen Lewis and Brett Baker (Burdekin plume).

Image 3: Coral mortality at Russell Island (Franklands group) 24 February 2009. Photo: Britta Schaffelke, AIMS.

Images of white/dead coral from Franklands can be seen in image 3 and white bommies from surface near Dunk Island and the Family Group in image 4. Ongoing monitoring is being coordinated by David Wachenfeld and his team at GBRMPA.

Coral mortality and ‘bleaching’ is widespread on inner-shelf reefs in the above region. I put ‘bleaching’ in commas as this event is probably not mostly normal bleaching i.e. expulsion of zooxanthellae, but rather actual death of the coral organism. This is obviously somewhat speculative but consistent with observations of coral mortality in low salinity water by van Woesik and others after similar events in 1991 in the Keppel Islands.

Image 4: White coral bommies at Coombe Island (Family Group) 5 March 2009. Photo: Jane Waterhouse, ACTFR.

The coral mortality is no doubt associated with the long period (more than 8 weeks) of low salinity flood water but other factors such as elevated suspended sediment, nutrients and pesticides may also be important. Water temperatures were also above average in the period before the floods and an element of combined stress may also be important. Disentangling the separate and combined effects of the multiple stresses and their role in the coral mortality will be a major challenge.