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




4.7 Influential Environmental Factors
Several factors may have contributed to the decline in the extent of seagrass in Noosa
Estuary. In particular, flooding has resulted in substantial declines in seagrass elsewhere in
the region at a similar time as observed here (Preen et al 1995; Campbell & McKenzie 2004).
An assessment of available rainfall and riverine flow data was completed to determine if
similar events contributed to the substantial declines observed in the Noosa Estuary.
The Noosa River flooded in 1992 (approximately 757 mm of rain fell over a two-day period in
February 1992 recorded at Kiamba) (Figure 4.6), which may have been a trigger for
substantial loss in seagrass extent due to mobilisation of sediment. This corresponds to a
period of substantial loss of seagrass in several key areas, particularly in Lake Cooroibah
and along the Main Noosa River channel. The impact of flooding on seagrass distribution is
likely to differ depending on the reach, as the flood plume did not extend substantially up the
Weyba Creek (Figure 4.5) and may have lessened the potential impact on light attenuation
(duration and magnitude) and therefore seagrass survival.




    Figure 4.5 Aerial image of the mouth of Noosa River on 24 February 1992 showing the majority
               of the flood plume bypassing Weyba Creek and Noosa Sound, and extending out into
               Laguna Bay (Source QLD Government 2021a)




Assessing Distribution of Seagrass in the Noosa Estuary                                               A-21