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

           5.     Summary of Algae Monitoring Points
           The most dominant algae species Hincksia mitchelliae was identified in Noosa Woods Bay with
           points G, H, | and J showing the highest growth rates of this long brown filamentous algae. The
           highest growth rates of algae for the monitoring program to date were observed in July and August
           2020, the usual high growth periods (Phillips 2006, Healthy Land and Water 2005). Stinking mats
           of algae and diatoms were observed at various points in November 2020, but these decreased or
           disappeared by the December monitoring round. The reason for this is unsure, but could be due to
           increased flushing from rainfall events.

           High growth rates of algae were also observed at in Noosa Waters Points L, M, N, O, and P in the
           canal system, including Laurencia spp, Padina australis, Cladophora spp, and assorted diatoms. but
           no Hincksia spp. to date.

           However, species of the diatom (Genus Melosira) have been found in high numbers in the Noosa
           Waters canal system and these are known to be an indicator of eutrophic conditions (Phillips, Eco
           Algae Report 2018). This could just be a case of sampling occurring when flushing was minimal. In
           in August 2021 long strands of algae looked like they were breaking to form rafts at Point O in the
           Noosa Waters canal system. However, none of the samples sent back contained Hincksia spp.
           although Rhizocionium spp. was present (Figure 5).

           In Figure 5 below the rafts are almost entirely comprised of diatoms, and the green alga
           Rhizoclonium spp. and Cladophora spp. Although these algae species have the potential to form
           blooms none have been associated with blooms that have washed up on Main Beach. In, one month
           later in September 2021 it was observed that this same patch of algae and diatoms had almost
           completely disappeared (Figure 6 below). It seems the algae patches in the estuary tend to grow
           prolifically in late winter spring but disappear or decrease in size when flushing from seasonal rainfall
           events occurs.

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