2018-07-10 P&E Agenda Attachment 1 to Item 8 - Draft Noosa River Plan

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3.6
Coastal algal blooms
Since 2002, Hincksia sordida, a naturally occurring non-toxic brown alga has periodically ‘bloomed’ in
Laguna Bay to form dense patches within the surf zone of Noosa’s Main Beach, with large quantities of
Hincksia becoming stranded on the beach by the receding tides.
These algal blooms have occurred during spring or early summer and coincided with popular holiday
periods and recreational use of the beach and ocean. The duration of the bloom depends on the
availability of nutrients, flow conditions and the weather.
The presence of Hincksia is visually unappealing to swimmers and decomposing algae on the beach can
emit a sulphurous odour which also deters beach goers. Council removes the washed up Hincksia to
landfill which helps to keep the beach free of the algae so it remains enjoyable for residents and tourists.
All other beaches south of Main Beach are not affected by Hincksia.

Why is Hincksia here?
Algae in general are found in most aquatic environments including rivers, lakes, estuaries, oceans, hot
springs and glaciers. They are vital components of aquatic ecosystems as they are producers of oxygen
and carbohydrates.
When conditions are favourable, some algae species (including Hincksia) have the potential to ‘bloom’ and
they can grow rapidly to dominate the aquatic environment. Coastal algal blooms can persist for several
weeks or even months. The bloom ‘collapses’ once the algae have consumed all available nutrients, or
conditions (e.g. flow, weather) are no longer conducive to rapid growth (Healthy Waterways, 2005).


Page 54 l Noosa River Plan