WAMSI Node 3.4.2 - Characterisation of Geomorphology and Sedimentology of Ningaloo Reef

Brief description

The overall aim of this project was to determine the geomorphological and sedimentary characteristics (biological and physical) of the Ningaloo Reef and shelf, and to identify evolutionary characteristics relevant to the maintenance of marine biodiversity. This included characterising reef growth history, coastal and seabed geomorphology, surficial sediment facies and their influence on the distribution of benthic habitats. This research presents an interdisciplinary study that provides an important baseline for future habitat mapping, biodiversity assessments, spatial planning, and fisheries management. The characterisation and mapping of benthic habitats based on physical parameters is central for the ongoing monitoring, management and conservation of the NMP’s inshore and offshore resources, particularly during a time of increasing anthropogenic and environmental pressures.

Lineage

Statement: To achieve these objectives broadscale investigations were undertaken for the entire NMP and in detail for the northern Ningaloo Reef and shelf, to map and characterise bathymetry and seabed texture, geomorphology (reef and shelf zones/features), sedimentary bedform environments, surficial sediments (physical and biological components) and associated benthic communities. Both the inshore and offshore components of this research present an interdisciplinary study through the use of reef coring and dating, remote sensing mapping techniques, GIS modelling and interpretation, and ground-truthing data. The shallow inshore coral reef environment of the northern NMP was assessed through finescale surveys of habitats, coral community structure, surficial sediments, geomorphology and reef fish assemblages (a collaborative effort with UWA under WAMSI Project 3.2). Initial work by Cassata and Collins (2008) mapped the northern reef zones of NMP by manually delineating geomorphic and habitat boundaries from aerial photography. This study expanded on this research to investigate contemporary reef and coastal geomorphology using hyperspectral remote sensing imagery draped over 3D bathymetric models, to further characterise reef structure and geomorphic zonation. Diver-operated benthic video was used to survey specific lagoon habitats and these were supported by digital photo-quadrats to measure coral community structure and variability within major habitats. The offshore component of the project (seawards of the Ningaloo reef slope) focused on mapping the seafloor with acoustics (multibeam and single beam) and collecting towed-video data, sediment grabs and dredged samples to verify acoustic interpretations, and characterise the geomorphic, sedimentary and biological aspects of the seabed. Finescale investigations were undertaken in a section of the northern shelf to develop a robust methodology by which multibeam data could be transformed into classified map products. Classified maps were then draped over 3D bathymetric models to further characterise geomorphic and bedform environments, and their associated communities. Surficial sediment samples were collected spanning the entire inshore and offshore NMP using a widely spaced systematic grid of samples to provide broadscale map coverage. All sediment samples were analysed for grainsize statistics, textural parameters and descriptive terminology (such as fine gravelly sand) using standard classification schemes. Component analysis was undertaken on representative samples to examine the contribution of carbonate producing organisms to the sediments. The offshore component was run in collaboration with WAMSI Node 3.1.1 Further details on methodology can be found in Cassata and Collins (2008) and Twiggs et al. (2011) and final report.