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Solihuddin T.,Curtin University Australia | Solihuddin T.,The Western Australian Marine Science Institution | Collins L.,Curtin University Australia | Collins L.,The Western Australian Marine Science Institution | And 3 more authors.
Marine Geology | Year: 2015

The inshore Kimberley Bioregion of northwest Australia is a macrotidal, low wave energy, frequent cyclones, and high turbidity setting with abundant fringing coral reefs. Here we describe the Holocene development of a sheltered fringing reef at Cockatoo Island in the Kimberley, using data from reef cross-sections subaerially exposed in an iron ore mining pit, seismic profiles across the adjacent contemporary reef, and GIS and ground truth mapping of contemporary reef habitats. Subsidence since the Last Interglacial has provided accommodation for ~. 13-20. m of Holocene reef accretion upon an older, probably Last Interglacial, reef. In the pit cross-sections, the reef initiated at ~. 9000. cal y BP and accreted in a catch-up mode, reaching sea level at ~. 3000. cal y BP, and reef accretion rates varied from 26.8. mm/year to 0.8. mm/year, averaging ~. 2. mm/year. The catch-up interpretation is supported by the predominance of branching Acropora throughout the Holocene section and the absence of contemporary intertidal indicators such as Porites cylindrica and Millepora intricata. This pattern differs from the otherwise similar mud-rich but mostly microtidal inshore fringing reefs of the Great Barrier Reef, which initiated in the late Holocene on shallow substrates under a stable sea level. The study provides the first Holocene reef growth history for an inshore Kimberley reef within a biodiversity "hotspot". © 2014 Elsevier B.V.

Kordi M.N.,Curtin University Australia | Kordi M.N.,The Western Australian Marine Science Institution | Collins L.B.,Curtin University Australia | Collins L.B.,The Western Australian Marine Science Institution | And 4 more authors.
Ocean and Coastal Management | Year: 2016

Coral reefs of the Kimberley Bioregion are seldom studied due to limited accessibility and extreme water conditions, which make management of these vital ecosystems a challenging task. Managing reef resources requires a considerable amount of credible, consistent and continual information. We identified the geographic information system (GIS) approach to be useful in developing an integrated geodatabase by acquiring information from different sources relating to the Kimberley reefs. Based on this approach, the study aimed to create a foundation for the first comprehensive geodatabase of the Kimberley reefs, called ReefKIM. The work included compiling existing spatial and non-spatial data, as well as collecting new data to complete information gaps. The study demonstrates how new technologies can be harnessed to crowdsource data from a wide range of people though a web-based platform. ReefKIM will provide a practical tool for scientists and managers to facilitate better monitoring and sustainable management of these vital natural resources. Moreover, it will support further studies in various disciplines leading to a more detailed understanding of the Kimberley Bioregion reefs. © 2015 Published by Elsevier Ltd.

Bufarale G.,Curtin University Australia | Bufarale G.,The Western Australian Marine Science Institution | Collins L.B.,Curtin University Australia | Collins L.B.,The Western Australian Marine Science Institution | And 8 more authors.
Continental Shelf Research | Year: 2016

The inner shelf Kimberley Bioregion of Northwest Australia is characterised by a macrotidal setting where prolific coral reefs growth as developed around a complex drowned landscape and is considered a biodiversity "hotspot". High-resolution shallow seismic studies were conducted across various reef settings in the Kimberley (Buccaneer Archipelago, north of Dampier Peninsula, latitude: between 16°40'S and 16°00'S) to evaluate stratigraphic evolution, interaction with different substrates, morphological patterns and distribution. Reef sites were chosen to assess most of the reef types present, particularly high intertidal planar reefs and fringing reefs. Reef internal acoustic reflectors were identified according to their shape, stratigraphic position and characteristics. Two main seismic horizons were identified marking the boundaries between Holocene reef (Marine Isotope Stage 1, MIS 1, last 12 ky), commonly 10-20 m thick, and MIS 5 (Last Interglacial, LIG, ~120 ky, up to 12 m thick) and Proterozoic rock foundation over which Quaternary reef growth occurred. Within the Holocene Reef unit, at least three minor internal reflectors, generally discontinuous, subparallel to the reef flat were recognised and interpreted as either growth hiatuses or a change of the coral framework or sediment matrix. The LIG reefs represent a new northernmost occurrence along the Western Australian coast. The research presented here achieved the first regional geophysical study of the Kimberley reefs. Subbottom profiles demonstrated that the surveyed reefs are characterised by a multi-stage reef buildup, indicating that coral growth occurred in the Kimberley during previous sea level highstands. The data show also that antecedent substrate and regional subsidence have contributed, too, in determining the amount of accommodation available for reef growth and controlling the morphology of the successive reef building stages. Moreover, the study showed that in spite of macrotidal conditions, high-turbidity and frequent high-energy cyclonic events, corals have exhibited prolific reef growth during the Holocene developing significant reef accretionary structures. As a result coral reefs have generating habitat complexity and species diversity in what is a biodiversity hotspot. © 2016 Elsevier Ltd.

Dandan S.S.,University of Western Australia | Dandan S.S.,The Western Australian Marine Science Institution | Falter J.L.,University of Western Australia | Falter J.L.,The Western Australian Marine Science Institution | And 4 more authors.
Coral Reefs | Year: 2015

We report seasonal changes in coral calcification within the highly dynamic intertidal and subtidal zones of Cygnet Bay (16.5°S, 123.0°E) in the Kimberley region of northwest Australia, where the tidal range can reach nearly 8 m and the temperature of nearshore waters ranges seasonally by ~9 °C from a minimum monthly mean of ~22 °C to a maximum of over 31 °C. Corals growing within the more isolated intertidal sites experienced maximum temperatures of up to ~35 °C during spring low tides in addition to being routinely subjected to high levels of irradiance (>1500 µmol m−2 s−1) under near stagnant conditions. Mixed model analysis revealed a significant effect of tidal exposure on the growth of Acropora aspera, Dipsastraea favus, and Trachyphyllia geoffroyi (p ≤ 0.04), as well as a significant effect of season on A. aspera and T. geoffroyi (p ≤ 0.01, no effect on D. favus); however, the growth of both D. favus and T. geoffroyi appeared to be better suited to the warm summer conditions of the intertidal compared to A. aspera. Through an additional comparative study, we found that Acropora from Cygnet Bay calcified at a rate 69 % faster than a species from the same genus living in a backreef environment of a more typical tropical reef located 1200 km southwest of Cygnet Bay (0.59 ± 0.02 vs. 0.34 ± 0.02 g cm−2 yr−1 for A. muricata from Coral Bay, Ningaloo Reef; p < 0.001, df = 28.9). The opposite behaviour was found for D. favus from the same environments, with colonies from Cygnet Bay calcifying at rates that were 33 % slower than the same species from Ningaloo Reef (0.29 ± 0.02 vs. 0.44 ± 0.03 g cm−2 yr−1, p < 0.001, df = 37.9). Our findings suggest that adaption and/or acclimatization of coral to the more thermally extreme environments at Cygnet Bay is strongly taxon dependent. © 2015 The Author(s)

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