Effects of Photosystem II-inhibiting herbicides on mangroves: preliminary toxicology trials

Bell, Alicia M.;Duke, Norman C.

Abstract

Mangroves are sensitive to the root application of Photosystem-II inhibiting herbicides and Avicennia marina is more sensitive than other mangroves tested. Seedlings of four mangrove species, including two salt-excreting species (Avicennia marina and Aegiceras corniculatum) and two salt-excluding species (Rhizophora stylosa and Ceriops australis) were treated with a range of concentrations of the herbicides diuron, ametryn and atrazine. Assessment of responses required the separation of seedlings into two groups: those that had only their roots exposed to the herbicides through the water (Avicennia marina and Rhizophora stylosa) and those that had both roots and leaves exposed to herbicides through the water (Aegiceras corniculatum and Ceriops australis). Salt-excreting species in each group were more susceptible to all herbicide treatments than salt-excluding species, indicating that root physiology is a major factor in the uptake of toxic pollutants in mangroves. Submergence of leaves may facilitate herbicide uptake, having serious implications for seedling recruitment in the field. Each herbicide was ranked by its toxicity to the seedlings from most effective to least effective, with diuron>ametryn>atrazine. These preliminary trials support the idea that herbicides, particularly diuron, have contributed to the serious dieback of Avicennia marina in the Mackay region.

Journal

Marine Pollution Bulletin

Publication Name

Marine Pollution Bulletin

Volume

ISBN/ISSN

1879-3363

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Issue

1-4

Pages Count

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Publisher

Elsevier

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Date

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EISSN

N/A

DOI

10.1016/j.marpolbul.2004.10.051