Diuron and mangrove dieback : a comment on the analyses

From about the early 1990s to at least 2002 there was considerable dieback of the grey mangrove Avicennia marina (Forsk.) Vierh. along more than 50 km of coastline around Mackay in central Queensland. This led to an extensive study by Duke and others to examine the extent and characteristics of the dieback. Their findings, published as a report to the Queensland Department of Primary Industries (Duke et al., 2003) and in Marine Pollution Bulletin (Duke et al., 2005), were interpreted as suggesting the herbicide diuron might be a likely cause. Evidence for this hypothesisis summarised in three graphs in Duke et al. (2003, 2005). Their finding is of considerable importance since it suggests a way of reducing the likelihood of such environmental impacts in the future.On reading Duke et al. (2005) I was intrigued by some results of their statistical analyses. This led to (unpublished) correspondence with Marine Pollution Bulletin and a reply from Duke with an explanation that included alerting me to a list of errata on his website see Duke (2005), which has been revised since our correspondence), applying to the 2003 report. Considering, however, that websites can be ephemeral (e.g. the link to the electronic copy of the 2003 report (http://www.marine.uq.edu.au/marbot/significantfindings/mangrove dieback.htm) in the reference list of Duke et al.(2005) is no longer extant), and that some analyses and data presented in the 2005 Marine Pollution Bulletin paper appear to need clarification, I suggest the following points for discussion. They are important since uncorrected mistakes in presentation of data and analyses may detract from the impact and adoption of any research findings.