Project Leader and Host
Organisation
Associate Professor Jian-xin Zhao (The University of
Queensland)
Project Description and Objectives
For detailed descriptions of the outputs for
this project for Year 4 (2009/2010) of the MTSRF Research
Programme, see the Annual Research
Plan.
A large number of dead branching corals and
massive coral heads, representing individual life spans up to
hundreds of years, exist among the coral communities of coastal
reefs. Modern dating methods using the TIMS Uranium-series
allow us to know the age of dead coral colonies in situ on
the GBR at a resolution of 1-3 years over several hundred years of
history. This allows temporal bracketing of significant mortality
events back to the time of early European settlement of Queensland
and beyond. Knowledge of the age structure of the death assemblages
can be related to major human developmental events and recent mass
bleaching events related to global warming, so that the sources of
the mortality can be identified; management can be directed toward
ameliorating those sources. If the coral mortality has resulted in
substantial changes in reef coral community structure, then
management is in a position to understand what the previous state
of the reef was, so we can overcome the 'shifting baseline
syndrome' whereby each new generation of managers and scientists
has a different view of what constitutes 'natural'. GBRMPA
has already invested in this historical perspective through its
'Historical Photographs' initiative, and we intend to expand this
perspective to inform the Authority about the natural state of the
coral reef.
Project 1.1.4 has seven main objectives:
-
To refine a specially designed sample preparation and analytical
protocol to improve the precision and accuracy of U-series dates of
the death assemblages.
-
To determine the decadal death rate of both massive and
branching corals over the last 200 years (since European
settlement);
-
To determine the variation in coral community structure over the
past 200 years;
-
To correlate rates of coral mortality with major human
development and recent El Niño events;
-
To reconstruct coral mortality rates and community change over
the past millennium leading up to European settlement using short
cores from back reef environment;
-
To reconstruct cyclone history and frequency over the past
millennium through precise dating of transported reef blocks and
lagoon sediment cores; and
-
To distinguish the impact of human developmental events and
anthropogenically-induced global warming from natural
variability.
