Historical records of terrestrial sediment and flood plume inputs to the Whitsunday Island region from coral skeletons: 1861-2017 Neal Cantin, Yang Wu, Stewart Fallon and Janice Lough Project Milestone Report prepared for CSIRO and DOEE May 2019 Australian Institute of Marine Science PMB No 3 PO Box 41775 The UWA Oceans Institute Townsville MC Qld 4810 Casuarina NT 0811 (M096) Crawley WA 6009 This report should be cited as: Cantin NE, Wu Y, Fallon S and Lough JM (2019) Historical records of terrestrial sediment and flood plume inputs to the Whitsunday Island region from coral skeletons: 1861-2017. Australian Institute of Marine Science, Townsville, Qld. (30pp). © Copyright: Australian Institute of Marine Science (AIMS) [2019] All rights are reserved and no part of this document may be reproduced, stored or copied in any form or by any means whatsoever except with the prior written permission of AIMS DISCLAIMER While reasonable efforts have been made to ensure that the contents of this document are factually correct, AIMS does not make any representation or give any warranty regarding the accuracy, completeness, currency or suitability for any particular purpose of the information or statements contained in this document. To the extent permitted by law AIMS shall not be liable for any loss, damage, cost or expense that may be occasioned directly or indirectly through the use of or reliance on the contents of this document. Vendor shall ensure that documents have been fully checked and approved prior to submittal to client Revision History: Name Date Comments Prepared by: Neal Cantin & Janice Lough 2 May 2019 1 Approved by: Britta Schaffelke 7 May 2019 Reviewed by: Mark Baird 13 May 2019 2 Revised Final draft Neal Cantin 16 May 2019 CONTENTS 1 EXECUTIVE SUMMARY ............................................................................................................................. 6 1.1 PURPOSE ................................................................................................................................................... 6 1.2 PROJECT SUMMARY ............................................................................................................................. 6 1.2.1 KEY FINDINGS .................................................................................................................................... 7 2 INTRODUCTION........................................................................................................................................ 8 2.1 Massive corals as historical archives of growth rates and the marine environment ................ 8 2.2 Coral luminescence as a recorder of freshwater impacts .............................................................. 8 2.3 Geochemical proxies of river discharge and terrestrial sediment inputs to the reef ............. 9 3 MATERIALS and METHODS ..................................................................................................................... 9 3.1 Coral core collection .................................................................................................................................... 9 3.2 Preparation of core slices and measurement of coral growth rates and luminescence ............. 10 3.3 Data Quality .................................................................................................................................................. 12 3.4 Geochemical trace element analysis ........................................................................................................ 12 3.4 Environmental data ...................................................................................................................................... 13 3.5 Analyses .......................................................................................................................................................... 14 4 RESULTS ....................................................................................................................................................... 14 4.1 Climate variation and change: sea surface temperatures, tropical cyclones and river flows ..... 14 4.2 Coral growth rates ...................................................................................................................................... 17 4.3 Coral luminescence as a recorders of freshwater flood plumes ...................................................... 19 4.4 Geochemical tracers of terrestrial input ................................................................................................ 19 5 References .................................................................................................................................................... 28 Coral luminescence records freshwater impacts from the Fitzroy River Basin Page 3 LIST OF FIGURES Figure 1: Site map showing reef locations within the Mackay-Whitsunday Islands region where long cores have been collected for this study. Cores from South Molle Island (SMI01 and SMI81) were collected from the same colony in 1984 and for this project in 2018. Icons in purple are Porites colonies used for both geochemistry analyses, growth and luminescence, icons in green are cores that were collected and used for only growth and luminescence. Figure 2: a) average annual SST anomaly (from 1961-1990 mean) for Whitsundays (coloured bars) and global land and sea temperatures (grey line), 1871-2018, and b) Whitsundays maximum, annual and minimum SST, 1950-2018, with linear trend lines. Figure 3: Annual (October-September) river flows for a) Pioneer River 1917-2018, and b) Fitzroy River 1915-2018. Also shown (dashed lines) are 90th percentile, median and 10th percentile flows. Extreme high flow years (>90th percentile) are highlighted in green and extreme low flow years (<10th percentile) are highlighted in orange. The dark blue line is 10-year Gaussian filtered data emphasising decadal variability. Figure 4: a. observed Burdekin River flow (Oct-Sept) 1922-2018. b. reconstructed Burdekin River flow extended beyond the observational record from 1648-2011 using the calibration of luminescence intensity from coral cores against the instrumental record (Lough et al. 2015). Figure 5: (a) Annual average Ba/Ca ratios within the coral skeleton from South Molle Island (SMI01 and SMI81). Also shown (dashed lines) are 90th percentile, median and 10th percentile Ba/Ca ratios. Extreme Ba/Ca years (>95th percentile) are highlighted in red, high Ba/Ca years (>90th percentile) are highlighted in green and extreme low Ba/Ca years (<10th percentile) are highlighted in orange. (b) Scatterplot of annual average Ba/Ca ratios within the coral skeleton from South Molle Island (SMI01 and SMI81) vs Pioneer river flow 1917- 2017 showing positive trend in increased Ba/Ca with increasing river flow. Figure 6: Annual luminescence range for seven coral cores. Also shown (dashed lines) are 90th percentile, median and 10th percentile values. Extreme high years (>90th percentile) are highlighted in green and extreme low years (<10th percentile) are highlighted in orange. The dark blue line is 10-year Gaussian filtered data emphasising decadal variability. Note different y-axis scale for SMI01C. Figure 7: Annual average coral skeleton Ba/Ca (mol.mol-1) ratios throughout the Whitsunday Region to explore spatial patterns in sediment transport: a. Hook Island, b. Stonehaven, c. Whitsunday Island, d. Shaw Island, e. Scawfell Island. Also shown (dashed lines) are 90th percentile, median and 10th percentile values. Extreme high years (>95th percentile) are highlighted in red, high years (>90th percentile) are highlighted in green and extreme low years (<10th percentile) are highlighted in orange. Note: Start years of each record are different and a function of time available on ICPMS and the length of each individual core. Figure 8: Annual calcification anomalies (from 1959-1984 mean) for seven coral cores. Thick line is 10-year Gaussian filter emphasising decadal variability. Coral luminescence records freshwater impacts from the Fitzroy River Basin Page 4 Figure 9: Relationships between a) calcification rate, b) linear extension rate, and c) density for massive Porites spp. vs annual average SST. Grey symbols and regression line for 49 Indo- Pacific sites; coloured symbols for seven Whitsunday coral cores. LIST OF TABLES Table 1: Porites spp. coral cores used in Whitsunday water quality project. Table 2: Average annual skeletal growth and luminescence characteristics for the base period, 1959-1984 (growth) and 1960-1983 (luminescence), ± 1 sd. Table 3: (a) Correlations between annual luminescence range and Pioneer and Fitzroy River flows (October-September) for a) 7 coral cores, (1960-1983), (b) 5 coral cores (1949-2015) and (c) annual skeletal Ba/Ca concentrations with luminescence range, Pioneer, Fitzroy and Burdekin River observed flows. Shaded values are significant at 5% level, locations are in order of perceived distance from River mouth and inshore influence. Appendices Appendix 1: X-ray and UV images Whitsundays 2019 Appendix 2: Whitsunday data sets Appendix 3: density and extension time series Coral luminescence records freshwater impacts from the Fitzroy River Basin Page 5 1 EXECUTIVE SUMMARY 1.1 PURPOSE This technical report is the milestone report submitted to CSIRO for the Department of the Environment and Energy as part of the project “Scoping study to address poor water quality in the Whitsunday Region”. The AIMS contribution in this report seeks to provide indicative