2022-02-08 Planning and Environment Committee Meeting Agenda

PLANNING & ENVIRONMENT COMMITTEE MEETING AGENDA   8 FEBRUARY 2022




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PLANNING & ENVIRONMENT COMMITTEE MEETING AGENDA                                         8 FEBRUARY 2022

           Algae in general are found in most aquatic environments including rivers, lakes, estuaries, oceans,
           hot springs and glaciers. They have specific nutrient, light, salinity and pH requirements for growth;
           however,under favorable conditions, some algal species have the potential to ‘bloom’ grow rapidly
           and dominate the aquatic environment (Healthy Waterways 2005, Phillips 2006).

           The duration of an algal bloom depends on the availability of nutrients, flow conditions and the
           weather. Under optimal environmental conditions, the biomass of bloom forming macroalgal species
           doubles approximately every 14 days with bloom development to ‘nuisance’ levels generally
           requiring approximately 1-2 months (Phillips 2006).
           In Noosa, notably from 2002 to 2005, a non-toxic, brown filamentous alga identified as Hincksia
           sordida has periodically  bloomed in Laguna Bay during spring / early summer, coinciding with
           popular holiday periods and recreational use of Noosa’s Main Beach in particular..
           These blooms lasting several months, form dense accumulations of stringy, brown alga within the
           surf zone of Laguna Bay which affect people’s enjoyment of the water. The algae stranded on Main
           Beach by outgoing tides emits a nauseating sulphurous odor as it decomposes and affects people’s
           enjoyment of the beach, as well as dining at adjacent restaurants and cafes.
           It was estimated by consultants at the time that the impact of the bloom on the local tourism industry
           was a loss in tourism revenue of between $ 4.5 to $5.8M.

           At this time, Council engaged Healthy Waterways and a consortium of scientists to investigate the
           cause of the Hincksia sordida bloom, however the results of these investigations were relatively
           broad and inconclusive.

               Phase 1 investigated the regional distribution and duration of blooms in southern Queensland
               and the physical transport and dispersion processes related to the blooms. The basic premise
               was the blooms at Noosa were a product (at least in part) of changes in regional circulations
               drivers, leading to an unusual accumulation of material at this point and other comparable points
               along the coastline. This investigation also proposed three plausible source populations of the
               alga and persistence in surf zone:
                  e   Local, near shore source.
                  e   Estuarine source.
                  e   Offshore, northern source.
               Phase 2 monitored algal blooms and water quality, assessed the regional movement of algae to
               determine sources and associated factors, characterised the growth dynamics of Hincksia
               sordida and proposed management recommendations which included two key factors critical to
               understanding the occurrence of the Hincksia sordida bloom at Main Beach:
                  e   The source of the algal material, i.e. where is it growing and is it growing in greater
                      abundance now than it has in the past, hence contributing to the problem.
                  e   The key physical processes that are involved in the removal of the algae from its place
                      of origin and transportation onto the beach and how these processes might have changed
                      in the years leading to a greater accumulation of material.
           During this time, Noosa Council staff undertook random algae sampling of the river and observed
           two small populations of brown, filamentous algae growing on rocks in the Noosa River estuary at
           Noosa Sound. These samples were identified as Hincksia sordida.

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