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Triazine herbicides alter growth competition to promote cyanobacteria blooms


Al Qasmi, AM and Seen, AJ and Bolch, CJS, Triazine herbicides alter growth competition to promote cyanobacteria blooms, Abstract Book of the Annual Conference of the Australasian Society for Phycology and Aquatic Botany, 27-29 November 2013, Brisbane, Queensland, pp. 17. (2013) [Conference Extract]

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Pesticides and herbicides applied during intensive agriculture can contaminate aquatic environments where they have selective effects on phytoplankton, alter community structure and have been hypothesized as a mechanism promoting cyanobacteria blooms. We used two-species competition cultures with different relative starting concentrations of the chlorophyte Oesmodesmus asymmetricus and the cyanobacterium Anabaena circinalis to determine whether outcomes of growth competition could be reversed by the triazine herbicide atrazine. In 10 day competition experiments, 0. asymmetricus out-competed A. circinalis in the absence of atrazine, except when starting species dominance was 4 to 1 in favour of A. circinalis. In contrast, environmentally relevant concentrations of atrazine resulted in A. circinalis out-competing 0. asymmetricus even when starting dominance favoured 0. asymmetricus by 4 to 1. Atrazine inhibited both species during exponential growth, and was more severe for 0. asymmetricus. However during the latter half of experiments A. circinalis suppressed 0 . asymmetricus by release of an allelopathic factor. Our findings show triazine herbicides can favour A. circinalis, reverse competition outcomes even from a position of sub-dominance, and shift temperate community structure toward cyanobacterial dominance.

Item Details

Item Type:Conference Extract
Keywords:herbicides, atrazine, cyanobacteria, algae blooms
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Phycology (incl. marine grasses)
Objective Division:Environmental Management
Objective Group:Fresh, ground and surface water systems and management
Objective Field:Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water)
UTAS Author:Al Qasmi, AM (Dr Adil Al Qasmi)
UTAS Author:Seen, AJ (Associate Professor Andrew Seen)
UTAS Author:Bolch, CJS (Associate Professor Christopher Bolch)
ID Code:87920
Year Published:2013
Deposited By:NC Marine Conservation and Resource Sustainability
Deposited On:2013-12-17
Last Modified:2014-08-07

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