2022-04-12 Planning & Environment Meeting Agenda

PLANNING & ENVIRONMENT COMMITTEE MEETING AGENDA   12 APRIL 2022




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PLANNING & ENVIRONMENT COMMITTEE MEETING AGENDA                                                                 12 APRIL 2022

                                                                                              The Nature
                                                                                              Conservancy                     \P
                                                                                                            Australia

           Seagrass as habitat                                            Why seagrass changes
           Seagrass meadows provide food and shelter for a diverse        Seagrasses are highly sensitive to changes in
           range of marine fauna. They also support benthic               environmental conditions and declines in water quality
           macroinvertebrate communities, which in turn provide           (particularly high levels of suspended sediment in the
           food for many larger, commercially and recreationally         water) and are therefore considered indicators of
           important species of crustacean, mollusc and finfish.          environmental stress or degradation.
                                                                          As a result, the spatial distribution of seagrass can be
           Current seagrass extent                                        highly dynamic, with large interannual changes in the
                       .          .      ;               :                extent of seagrass habitats and community structure
           The Noosa River estuary is dominated by soft sedimentary            :                :
           habitats includi   tensive intertidal  dand    mud flat        resulting from natural disturbances. These natural
            Se oe ee ee                                ee    alee         disturbances however, do not typically result in a net loss
           with several seagrass meadows occurring in the lower            f                      ti
           atilary,                                                       of seagrass coverage over time.
           The seagrass meadows are dominated by Long Eelgrass            What is next for Noosa‘s seagrass
                                                                                   ‘                       '
           (Zostera muelleri sub sp.capricorni) with occasional sparse    Becaue of their importance for estuarine ecosystems, the
           patches of Halophila ovalis. Z. muelleri meadow are            precise drivers for the decline and lack of recovery of the
           predominantly found in dense, but patchy, beds along the       Noosa River Estuary seagrass meadows need urgent
           main channel and around several small islands.                 investigation. Better understanding of the Noosa River
          Ss             decli                                            system would advise river managers, who could advocate
             eagrass       aeciine                                        for resources to enable research and recovery action.
           Since 1989, the Noosa River estuary has lost 80 percent of
           its seagrass and is showing no signs of recovery (see Table    Final comment from the expert
           1). In 1989, seagrass covered 337.4 hectares of Noosa          “Recovery from impacts such as flooding in other similar
           estuary. By 2006, this coverage had fallen to just 53.7 ha.    seagrass meadows has occurred within a few years. This is
           The largest seagrass declines have been in the main            not the case in Noosa. “
           sisnnsiipl.sierGheyna and lake emnelieale                      Simon Walker (Director and Principal Ecologist -
           Studies in 2009 and 2020 confirmed that despite some           EcologicalService Professionals)
           minor seasonal fluctuations, Noosa’s seagrass meadows
           have not recovered. In other parts of Queensland,             Full report
           including the southeast, Zostera-dominated seagrass            Walker SJ, Hayes M, Watson E, Goodwin S & Thorburn L.
           meadows typically recover quickly from significant losses,     2021. Current and historical distribution of seagrass in the
           often within a few years. The lack of seagrass recovery in     Noosa   Estuary.  Report  prepared   for  The    Nature
           Noosa is therefore alarming.                                   Conservancy, September 2021. 37pp.
           What caused the seagrass loss
           Storms and flooding most likely caused the major loss of
           seagrass in the Noosa River estuary. The big question
           today is: What is preventing the recovery of the
           Noosa River estuary’s seagrass meadows?

             Table 1. Results of the Seagrass mapping comparison from 1987 to 2020.
              SX=r (040)                   Area (m2) of Seagrass                                Change 1989 to
                                              1987        1989      2006      2009       2020   2020(%)
              Lake Cooroibah                    NA     229,624    71,323     61,672         0               —100
              Noosa River — Tewantin       106,651     134541     39360      36,731    28540                 -79
              Lake Doonella                495,772     457,164   127,158   363,764    318,129                -30
              Noosa River — Goat Island     93,865     105,247    28831      23,539     9,313                -91
              Weyba Creek                       NA     647,065   270,366   239,551    205,510                —68
              Lake Weyba                        NA _ 1,800,445          0         0        20               -100
              Total Seagrass Area (m2)
              Noosa Estuary                     NA   3,374,086   537,038   725,258    561,512                -83
              Total Seagrass Area (Ha)
              Noosa Estuary                     NA       337.4       53.7      72.5      56.1                -83

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