2022-11-08 Planning & Environment Meeting Agenda

PLANNING & ENVIRONMENT COMMITTEE MEETING AGENDA                               8 NOVEMBER 2022


5    SUMMARY OF CURRENT AND HISTORICAL DISTRIBUTION OF SEAGRASS IN THE
     NOOSA ESTUARY

Author           Environment Officer - Rivers and Coast, Sophie Blond
                 Environment and Sustainable Development Department

Index            ECM/ Environmental Management/ Waterways/ 21.34

Attachments      1.    Current and Historical Distribution of Seagrass in the Noosa Estuary
                       Report (40 page attachment provided separately to this agenda)
                 2.    Noosa River Estuary: Seagrass Distribution Study


EXECUTIVE SUMMARY
This report provides a summary of an assessment undertaken by The Nature Conservancy in
November 2020 to determine the current and historical distribution, coverage, and condition of
seagrass in the Noosa Estuary. This report was undertaken in accordance the strategic partnership
Council has with the Nature Conservancy. The assessment found that approximately 80% of
seagrass has declined in the past 20 years due to a range of influences including flooding,
sedimentation and mobilisation of sandbars, changes to the hydrodynamic regime, flooding, boat
wash and anchoring. Further assessment and consideration is necessary to determine future
management actions for seagrass.
RECOMMENDATION
That Council note the report by the Environment Officer, Rivers & Coast to the Planning &
Environment Committee Meeting dated 8 November 2022, and note:
A.   The reports titled ‘Current and Historical Distribution of Seagrass in the Noosa Estuary’ and
     ‘Seagrass Distribution Study’ as Attachment 1 & 2 prepared by Ecological Service
     Professionals for The Nature Conservancy and Council;
B.   That Council’s integrated water quality monitoring program will identify options for future
     management strategies and factors influencing seagrass decline; and
C.   That seagrass monitoring and restoration will be considered as part of the final Noosa River
     Plan, and funding needs for this will form part of upcoming budget deliberations.

REPORT
In 2020, The Nature Conservancy engaged Ecological Service Professionals to conduct an
assessment of the distribution, coverage and condition of seagrass within the Noosa River Estuary,
downstream of Lake Cooroibah and in the Weyba Creek catchment. The most recent comparable
comprehensive and detailed mapping study of seagrass was undertaken in 1987, with several
small-scale studies and monitoring programs completed in more recent years.
The study area included both intertidal and subtidal zones, with the most upstream extent in Lake
Cooroibah to the mouth of the estuary; and upstream in Weyba Creek to Lake Weyba. The study
separated the estuary into seven reaches, including Lake Cooroibah (and the main Noosa River
channel upstream of the vehicle ferry), Noosa River from Tewantin to the vehicle ferry, Noosa River
around Goat Island and downstream, Noosa River mouth and Noosa Sound, Lake Doonella,
Weyba Creek and Lake Weyba.
A desktop review and gap analysis of historical data were performed and used to prioritise specific
focal areas for more detailed field validation and seagrass characterisation. Field surveys were
completed over four days, using a combination of techniques including direct visual assessment,
underwater tow and drop cameras, and visual assessments on foot at low tide, and a grapple hook
for targeted confirmation of seagrass species present to identify the condition and presence of

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