Postgraduate Research Opportunity

INFLUENTIAL, but seriously flawed research suggesting agricultural pesticides killed mature stands of mangroves at Mackay in Queensland was based on experiments with mangrove seedlings that were dosed with concentrations of Diuron orders of magnitude higher than anything found in waterways.

Seedling were used because it was claimed that it was impossible to grow mature mangrove plants under controlled conditions, and because of the urgency of proving a causal connection between agriculture and damage to the Great Barrier Reef high concentrations were applied.

In April 2011, with funding from the B. Macfie Family Foundation, and a permit from the Department of Fisheries, John Abbot and I oversaw the excavation (with a 10 tonne excavator) of 10 mature mangrove plants from the Koorana Crocodile Park on the Capricorn Coast. Eight of the 10 plants survived. In fact the eight have thrived under our cultivation system that includes an irrigation system that simulates diurnal tidal inundation of the large containers with the mangroves.

One of the plants is now nearly four metres tall. All of the plants have just started flowering for a second year.

mangrove flowering

If anyone is interested in postgraduate research, in particular there is a potential project using these potted mangroves to analysis their physiological response to concentrations of Diuron likely to be experienced under flood conditions, and chemical analysis of the breakdown components of Diuron in solution and sorbed to sediment.

Email me at jennifermarohasy at or telephone 041 887 32 22. The mangroves are growing in Rockhampton and the project would be based at Central Queensland University.


Key Reference:

Abbot J., Marohasy J. 2011. Has the herbicide Diuron caused mangrove dieback? A re-examination of the evidence. Human and Ecological Risk Assessment. Volume 17, Pages 1077- 1094.

Background reading:
Saving the Great Barrier Reef

Picture of the flowering Avicennia marina taken by me earlier today with my iphone.


14 Responses to Postgraduate Research Opportunity

  1. Larry Fields November 10, 2013 at 6:35 am #

    It’s always interesting to read about your research projects. The mangrove studies remind me of an old saying from Paracelsus, which should apply to plants, as well as animals:
    “The dose makes the poison.”

  2. bazza November 10, 2013 at 11:49 am #

    Is it ethical for advocates to do such research?

  3. Debbie November 10, 2013 at 12:12 pm #

    You seriously need to get over yourself.
    It is incredibly, incredibly easy to question the ethics of just about anybody doing just about any sort of research if we use your rather blatantly obvious criteria.
    Your attempted sneer is a joke and says more about you than anything else.
    Jen has NEVER made a secret of her past employment etc….

    The point. . .in case you missed it. . .is clearly made by Larry.
    Too much of anything can ultimately be and/or act like a poison.
    Even too much water or too much air or too much food can poison you.

  4. Dennis Webb November 10, 2013 at 12:21 pm #

    I’ve noticed that Jennifer Marohasy has been a ruthless advocate for evidence based science. We need more such advocates in our Universities.

    I gather she is a fan of Thomas Huxley who was a great advocate for Charles Darwin’s evolutionary theories and also perhaps the finest comparative anatomist of the 19th century.

    There is no lack of advocacy in the modern university, but it is usually by way of propaganda. Huxley and Marohasy prefer debate.

  5. spangled drongo November 10, 2013 at 1:53 pm #

    Jen, was there a test done of the mud where the mangroves died?

  6. Luke November 10, 2013 at 3:19 pm #

    Well Bazza – things have changed significantly since Jen’s sugar days.

    All I can say is there are significant number of people out there well versed in herbicide eco-toxicology. Get networked and get up to date would be sage advice for any prospective student. Wouldn’t have thought mangroves would be the main focus myself but that’s OK. Hope any analytical labs being used are up to spec and NATA accredited. Wouldn’t want any crappy analyte work.

    And there’s always endocrine disruptors if you wanted to be trendy.

  7. Luke November 10, 2013 at 3:20 pm #

    Dennis – but you still need to be right !

  8. Koala Bear November 10, 2013 at 5:07 pm #

    Don’t worry Luke, there is something much better available to help out that all the NATA nonsense- people from institutions like Imperial College , London who have a good education in chemistry. All they seem to be capable of in Australia is “sending their samples away” for analysis.

    No wonder the CSIRO is currently sacking all those people – most of them have no idea what they are doing anyway.

  9. Luke November 10, 2013 at 6:04 pm #

    Sounds like doing a runner from scrutiny. If one wants to skip accreditation and quality control I guess that’s the standard sceptic modus operandi. Sort of like publishing in E&E or an on-line journal. Of course to know if you had “better” you’d need some inter-lab comparisons – hahahahahahahhahahahhaaaa …..

    “All they seem to be capable of in Australia is “sending their samples away” for analysis.” Wreally – well you’re telling the yarn mate.

    And as for CSIRO – at least more honest than free range poncing around in universities – at least there is a derived strategic direction which doesn’t suit non-conformist mavericks I guess. Don’t worry – just reducing us to a bogan backwater by flushing out all the young talent which I’m sure is what our tea party libs love. The anti-science party party. Just back from a watching the footy on the tax payers dime.

  10. jennifer November 10, 2013 at 7:22 pm #

    Thanks Spangled.

    Short answer is yes.

    Long answer…

    Judith Wake developed a stress index for mangrove health status representing a composite of five factors including leaf colour, canopy density, and the proportion of the tree that was dead or alive. Each factor was expressed as a percentage and the composite stress index expressed as a sum of these values ranging between 0 and 500. Correlating this index with Diuron concentration, Wake found no consistency of association: Diuron concentrations varied from 0 to more than 0.10 μg/L but the stress index fell anywhere in a range between 100 and 260.

    Norman Duke and coworkers established a biological gradient, also known as a dose-response curve, for Diuron and the incidence of dieback in A. marina, based on the assumption that the concentration of Diuron bound to sediment, also known as sorbed Diuron, constitutes a measure of herbicide availability. Diuron molecules can penetrate membranes.However, Diuron sorbed on the surfaces of sediment particles must first desorb into aqueous phase before crossing membrane barriers.

    There is a significant technical literature dating from the 1950s explaining that once herbicides like Diuron become bound to sediment they are no longer available for uptake by plants.

    Duke et al. report measured concentration ranges of 0.004 to 0.014 μg/L and a corresponding wide variation in mangrove health status with the percentage of healthy trees varying between 10% and 85%. We tested the correlation between the values reported by Duke et al. (2003) and the status of mangrove health (represented by percentage healthy trees) and found it was not statistically significant (Pearson correlation coefficient, r = −0.401).

    There is widespread community concern about the potential impact of pesticides in environmentally sensitive areas. Duke et al. corroborate this concern by providing a value for the amount of Diuron applied to mangroves expressed as the amount of Diuron applied in a particular catchment divided by the area of mangrove in that catchment. The relatively high application rates calculated were then reported for the Pioneer and Plane catchments compared to much lower application rates for the Burdekin, Herbert, and Tully catchments and reference made to the catchments with higher rates also having mangrove dieback.

    However, the analogy falters when also considering the high application rates for the Noosa and Mary catchments, where dieback was not reported. But given Diuron was not applied directly to the mangroves there is no justification for this analogy as only a fraction of the applied herbicide will be transported to the vicinity of the mangroves and numbers of mangroves will not affect concentration levels (Simpson 2002). To illustrate the inapplicability of the application rate concept, consider a situation where mangroves are growing on opposite sides of a river carrying a fixed concentration of Diuron. If all the mangroves growing on one side of the river were removed, this would not change the concentration of the herbicide affecting the remaining mangroves.

  11. jennifer November 10, 2013 at 7:37 pm #


    Following on from the comment from Koala Bear, as important as the chemical analysis, is the correct interpretation of the result.

  12. spangled drongo November 10, 2013 at 8:30 pm #

    Jen, with all those scientists being paid a fortune to live in paradise at Cape Ferguson to tell us if we have a problem, we always know what the answer will be.

    “Houston! we have a problem!”

    The most likely solution of an extended term burial of the pneumatophores due to flood runoff is not gonna get them their required fame and fortune.

  13. jennifer November 10, 2013 at 11:04 pm #

    If we can please restrict further comments at this thread to the postgraduate opportunity or Great Barrier Reef research relating to pesticides and water quality. If you want to make further general comment or undertake chit-chat please post at the Open Thread.

  14. Ian Thomson November 11, 2013 at 6:27 pm #

    Passed it on .

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