Articles from Peter Ridd of James Cook University in newspapers and on blog sites and letters to the editor supporting his position (e.g. Tom Darlington, 9 February 2010 in the Townsville Bulletin) claim there is no scientific evidence agricultural pollution is damaging the Great Barrier Reef. As well, claims are made that there is a body of research available (specifically from Peter Ridd’s work) that shows that runoff from farming is having no effect (or very little effect) on the Great Barrier Reef (GBR). Neither of these claims is true.
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.
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.
Catchment to Reef Research Group
Australian Centre for Tropical Freshwater Research
James Cook University, Townsville.
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.