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Has the herbicide Diuron caused mangrove dieback? : a re-examination of the evidence

journal contribution
posted on 06.12.2017, 00:00 authored by John AbbotJohn Abbot, Jennifer MarohasyJennifer Marohasy
The claim that the herbicide Diuron in agricultural runoff caused dieback of the grey mangrove (Avicennia marina) in Central Queensland, Australia, has influenced government policies including programs to save the Great Barrier Reef. Several investigations on mangrove dieback in Central Queensland river estuaries have been published during the past decade. However, proof of a causal link between mangrove dieback and Diuron remains inconclusive. This study presents a systematic review of the evidence using Hill’s Criteria of Causation. Our review shows that using concentrations of the chemical bound to sediment as a measure for biological availability in either glasshouse or field studies is inappropriate. The appropriate measure is Diuron concentration in solution and this parameter bears no simple relationship to concentration bound to sediment, and is not strongly correlated with mangrove health. Only when the herbicide is applied in experimental investigations at many orders of magnitude higher than measured in rivers has an impact on A. marina been demonstrated. Evidence from field studies suggests burial of pneumatophores, the plant’s breathing roots, following flood events is a more likely causal factor in mangrove dieback, whereas any contribution from Diuron remains unproven.

Funding

Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)

History

Volume

17

Issue

5

Start Page

1077

End Page

1094

Number of Pages

18

eISSN

1549-7860

ISSN

1080-7039

Location

United States

Publisher

Taylor & Francis

Language

en-aus

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

Centre for Plant and Water Science; TBA Research Institute; University of Central Queensland;

Era Eligible

Yes

Journal

Human and ecological risk assessment.