Karenia mikimotoi #2

The contention from Professor Paul McShane and others (Letters, The Advertiser, 23/5) that the recent reactivation of the Lonsdale desalination plant may have been a contributing factor to the devastating marine algal bloom in South Australia is rightly challenged in “Salt idea debunked” (The Advertiser, 26/5). 

Evidence that has been provided to date by citizen scientists around the state and from daily satellite chlorophyll-A readings indicates the origin of the bloom was likely hundreds of kilometres away off the southeast of the state in summer, before progressing in a north-westerly direction. 

This bloom was fuelled principally by a stronger than usual upwelling event providing high nutrient levels as well as exceptionally calm seas and warmer than average air and water temperatures. The particular micro algae involved here (Karenia mikimotoi and related species) bloom in normal seawater salinity or salinities reduced slightly by ooding. 

The toxic effects are also enhanced in lower salinity water, rather than the higher salinities that would be encountered near desalination plant outflows. While thousands of marine animals were dying in other parts of the state due to a toxic, oceanic algal bloom, Lonsdale was operating unrelatedly, providing much needed fresh water for South Australians during the worst drought on record.

It is clear to us the reactivation of this plant was not a contributing factor to the current algal bloom.

David Hall, former SA & NT director of fisheries and Janine Baker, marine ecologist