Phytotoxicity of four photosystem II herbicides to tropical seagrasses

Flores, Florita, Collier, Catherine J., Mercurio, Philip and Negri, Andrew P. (2013) Phytotoxicity of four photosystem II herbicides to tropical seagrasses. PLoS One, 8 9: e75798.1-e75798.12. doi:10.1371/journal.pone.0075798


Author Flores, Florita
Collier, Catherine J.
Mercurio, Philip
Negri, Andrew P.
Title Phytotoxicity of four photosystem II herbicides to tropical seagrasses
Journal name PLoS One   Check publisher's open access policy
ISSN 1932-6203
Publication date 2013-09-01
Sub-type Article (original research)
DOI 10.1371/journal.pone.0075798
Open Access Status DOI
Volume 8
Issue 9
Start page e75798.1
End page e75798.12
Total pages 12
Place of publication San Francisco, CA, United States
Publisher Public Library of Science
Language eng
Formatted abstract
Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zostera muelleri and Halodule uninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield ({increment}F/Fm′), indicating reduced photosynthesis and maximum effective yields (Fv/Fm) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of the GBR from further decline.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Medicine Publications
 
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