2022-04-12-P&E Agenda - Item 6 - Attachment 3- Appendix 2 - Current and Historical Distribution of Seagrass in the Noosa Estuary

                                                                 Ecological Service Professionals
                                                                                     Sustainable Science Solutions




3 Current Seagrass Distribution and Characteristics

3.1 Composition and Distribution
A total of 56 Ha of seagrass was recorded throughout the estuary in November 2020, with
the greatest extent of seagrass occurring in Lake Donnella and along Weyba Creek (Table
3.1). Seagrass species recorded in the intertidal and shallow subtidal included Zostera
muelleri subsp. capricorni and Halophila ovalis. Dense stands of Z. muelleri grew along the
edge of channels in Weyba Creek (particularly around the mouth of Lake Weyba (Figure 3.1)
and Keyser Island), and also along the main river channel at Tewantin (Figure 3.2). Several
sparse patches of H. ovalis were also recorded on the edges of and between patches of
dense Z. muelleri (Figure 3.6). Patches of dense H. ovalis were recorded in parts of Lake
Doonella (Figure 3.3).

    Table 3.1    Area (m2 and Ha) of seagrass mapped in Noosa Estuary in November 2020

 Reach                      Coverage Type           Area (m2) of Seagrass    Area (Ha) of Seagrass
 Lake Cooroibah             Dense                             0                       0
                            Sparse                            0                       0
                            Total                             0                       0
 Noosa River –              Dense                        25,037                     2.5
 Tewantin                   Moderate                      1,505                     0.2
                            Sparse                        3,503                     0.4
                            Total                        30,045                     3.0
 Lake Doonella              Dense                             0                     0.0
                            Sparse                     318,129                     31.8
                            Total                      318,129                     31.8
 Noosa River – Goat         Dense                           737                     0.1
 Island                     Sparse                        1,259                     0.1
                            Total                         9,313                     0.9
 Noosa River Mouth          Dense                             0                       0
                            Sparse                            0                       0
                            Total                             0                       0
 Weyba Creek                Dense                        18,365                     1.8
                            Sparse                        2,133                     0.2
                            Total                      205,510                     20.6
 Lake Weyba                 Dense                            20                     0.0
                            Sparse                            0                     0.0
                            Total                            20                     0.0
 Total Noosa Estuary                                   563,018                     56.2


The condition of seagrass was generally good to very good (>57% of seagrass surveyed) with patches
generally providing good to very good value for fisheries species (>65% of seagrass surveyed) (Table
3.2; Figure 3.1). The remaining patches generally remain well connected to other seagrass patches or
other structural habitat such as mangroves throughout the lower estuary. The least structurally diverse
seagrass beds were recorded in Lake Doonella, however due to good proximity to deeper water
channels and good connectivity to the mangrove fringe, these habitats still provide good potential
value for fisheries species (Table 3.2).




Assessing Distribution of Seagrass in the Noosa Estuary                                                         7