Wednesday 1st October

12 — 1 pm

Rm 312.222

WAMSI/Curtin Coral Reef Geomorphology and Growth History Project

Curtin University

Geomorphology and Growth History of the Kimberley Coral Reefs

The Kimberley in Northwest Australia is one of the last marine wilderness areas, and the coral reefs of the Kimberley Bioregion lie within a “biodiversity hotspot”. Situated along a subsiding complex Ria coast of 400 km length (thousands of kilometres long if the coastal complexity is considered) the Kimberley reefs are subject to macrotidal (11 m tides) conditions, frequent cyclones, high turbidity from active river systems, warm conditions, and frequent exposure for long periods. The reefs are poorly known, of recognised international significance, and in need of study. It has been argued from preliminary surveys that some of the reefs are veneers over rock platforms rather than true reefs.

The WAMSI/Curtin Coral Reef Geomorphology and Growth History project, one of the  first geoscientific reef studies of the Kimberley Biozone, has as its objectives the establishment of a regional geodatabase of coral reefs based on remote sensing; determination of a Holocene record of reef growth; and establishment of internal reef architecture and growth history from shallow seismic (Boomer) surveys.

The seminar will consist of a series of short presentations by research team members, as follows:

1) Introduction and objectives: Lindsay Collins.

2) Title: A Large Scale Geomorphological and Surficial Cover Map of Nearshore Reefs in the Kimberley Coast, WA

Authors: Moataz Kordi1,2, Lindsay Collins1,2 and Alexandra Stevens1,2

1 Department of Applied Geology, Curtin University, WA

2The Western Australian Marine Science Institution, Floreat, Australia, 6014

Abstract

Coral reefs occur extensively along the north-western coast of Australia in the Kimberley Bioregion (KIM), forming major geomorphic features (landforms) along and just off the coast. These reefs have not been studied in as much detail as the offshore reefs and are poorly known. Geomorphological and surficial cover substrates and habitats maps of coral reefs provide significant information to both researchers and managers about the distribution and extent of reef landforms. This study aims to produce a large scale dynamic map in order to study reef spatial distribution patterns and to provide more information on geomorphological and surficial cover on reefs. Also other multiple data sources were integrated using Remote Sensing and Geographic Information System (GIS) to construct a geodatabase of the Kimberley reefs (ReefKIM) based on data fusion to verify results as well as to add value to the data in order to produce consistent, accurate, and useful geomorphic maps. The outcomes will facilitate better understanding of reefs in this region to develop a reef geomorphic classification scheme which describes reef evolution, classification and distribution of reefs by type. Moreover, they will provide a robust foundation to foster further studies in various disciplines beyond the scope of this study.

3) Title: Reef Geomorphology and Holocene Growth History of Cockatoo Island, Inshore Kimberley Bioregion, Northwest Australia.

Authors: Tubagus Solihuddin1,4, Lindsay. B. Collins1,4, D. Blakeway2, Michael J. O’ Leary3,4

1Department of Applied Geology, Curtin University, Bentley, WA 6102

2Fathom 5 Marine Research, 17 Staines Street, Lathlain, WA 6100

3Department of Environment and Agriculture, Curtin University, Bentley, WA 6102

4The Western Australian Marine Science Institution, Floreat, Australia, 6014

Abstract

This study describes reef geomorphology and Holocene (last 12,000 years) growth history in a macrotidal, high turbidity setting at Cockatoo Island, in the inshore Kimberley Bioregion, including geomorphic and associated habitat, chronology, Holocene and modern reef communities, nature of foundations, and type of reef accretion. The Holloway current, driven by the Indonesian throughflow, plays a major role in delivering nutrients and planktic biota for reef development. Preliminary study using aerial photography delineated, moving seaward across the reef flat, substrate of sediment, low and medium density intertidal coral cover. Towed camera observations confirm that live Porites and Faviids along with Sargassum sparsely colonise the intertidal coral zone, whilst branching Millepora and Porites cylindrical, which increase seaward, are present in the medium density intertidal coral zone. The Holocene reef unit investigated is ~13 m thick and of two distinct facies; domal and branching coral framestone units. Coral clasts are visually dominated by branching corals especially of the genus Acropora and massive corals including Porites. The contemporary live corals are not very common in the measured Holocene sections, suggesting that the Holocene reef communities lack reef flat habitat. The Holocene reflects mostly subtidal growth whereas the present reef is largely intertidal or very shallow subtidal. Compared to the same muddy-rich environment of the Great Barrier Reef (GBR), Cockatoo turbid reefs show broad similarities in terms of coral cover and accretion rates, but a contrast is between palaeoecological and contemporary reef communities, which are similar in the GBR but distinctly different at Cockatoo Island.

4) Title: Sub-bottom profiling and growth patterns of Kimberley coral reefs, North West Australia

Authors: Giada Bufarale1,3, Lindsay B. Collins1,3, Michael O’Leary2,3, Moataz Kordi1,3, Tubagus Solihuddin1,3, Alexandra Stevens1,3

1Department of Applied Geology, Curtin University, Bentley, WA 6102

2Department of Environment and Agriculture, Curtin University, Bentley, WA 6102

3The Western Australian Marine Science Institution, Floreat, Australia, 6014

Abstract

The Kimberley region is located on the north western continental margin of Australia and is characterised by unique and complex geology and geomorphology, significantly influenced by the macrotidal range systems (up to 11 m), which result in expansive intertidal zones.

A total of 300 km of high-resolution shallow imaging data were acquired during a sub‐bottom profiling (SBP) study of various southern Kimberley reef settings. Acoustic datasets were collected with a Boomer SBP system covering reefs where remotely sensed images were previously used to produce geomorphic and substrate classification maps.

A classification diagram has been developed on the basis of imaging of internal structures. Vertical and lateral differences were identified and categorised according to their shape and acoustic reflection characteristics along the hiatuses and internal reflectors.

These new datasets have provided a better understanding of Quaternary reef growth. The pre-existing substrate has influenced the successive morphology of fringing reefs, intertidal platforms and platform reefs. Global sea-level change, controlled by ice age fluctuation events, provides a signal which is recorded in successive stages of the reef growth separated by hiatuses. Two acoustic reflectors can be consistently distinguished across the inner shelf reefs (Sundays Group, Buccaneer Archipelago and Montgomery Reef), marking the boundaries between Holocene reef (Marine Isotope Stage 1, MIS1, last 12,000 years) commonly 10-15 m thick, and MIS 5 (last 125,000 years) and an ancient Neoproterozoic rock foundation over which Quaternary reef growth occurred. Three acoustic reef units characterise the Adele Group offshore.

5) Collecting shallow sediment cores in macrotidal reef terrains: issues and techniques.

Michael O’Leary.

Biographical Details

Lindsay Collins is a marine sedimentologist who has completed projects on continental shelf mapping of Australian shelves, and coral reef studies at the Abrolhos, Ningaloo, Scott Reef and the Rowley Shoals prior to establishing the Kimberley Coral Reef Study, with sponsorship from the WA Marine Science Institute (WAMSI).

Mick O’Leary research interests include reef geomorphology and palaeoclimate. He completed his PhD in Earth and Environmental Sciences at James Cook University, undertook post doc positions at Manchester Metropolitan and Boston Universities and now lectures in Coastal and Marine Science in The Department of Environment and Agriculture, Curtin University.

Giada Bufarale gained her MSC in Geology (University of Milano-Bicocca, Italy) and subsequently, started working as a marine geologist/geophysicist in a marine consultancy. In 2009 she joined the Applied Sedimentology, Coastal and Marine Geosciences group at Curtin University as a research assistant. She has carried out research on the stratigraphy and geomorphology of Shark Bay, the Swan River and Kimberley coast. In March 2014 she has started her PhD.

Moataz Kordi is a researcher in GIScience and remote sensing at KACST, Riyadh, SA. Currently he is a PhD candidate in the Department of Applied Geology, Curtin University. His study aims to construct a Geodatabase of the Kimberley reefs (ReefKIM) based on data fusion utilising GIS.

Tubagus Solihuddin is a 3rd year-PhD Candidate in Department of Applied Geology, Curtin University in which he is studying “Holocene Reef Growth of the Inshore Kimberley Bioregion and Response to Sea-level Changes and Climate Impact. He has been working in Centre for Research and Development of Marine and Coastal Resources, The Republic of Indonesia since 2004 as a marine geologist.

Alexandra Stevens is a GIS Analyst with research interests in Coastal Management and Marine and Coastal Geoscience. She joined the Applied Sedimentology, Coastal and Marine Geosciences group in late 2005 as a research assistant and has completed projects in the Northern Agricultural Region, Ningaloo Reef, Scott Reef and Shark Bay.