RV Investigator ship-time: Project HALO – Halimeda bioherm Origins, function and fate in the northern Great Barrier Reef

The offshore HALO science team Aug-Sep 2022 (image credit: Luke Nothdurft)

7/11/2022

Important HALO update: Following our recent CSIRO RV Investigator voyage to investigate the Halimeda bioherms in the northern Great Barrier Reef, I wanted to acknowledge the amazing contributions from entire HALO science team – both offshore & shore-based – that contributed to it’s great success. The entire team looks forward now to diving into the post cruise science objectives. To the wider scientific community, if you’re interested in being part of this collaborative project please don’t hesitate to reach out.

Jody

#MarineScienceSydneyUni

HALO Science team members

Name Institution Offshore/Shore-based
Jody Webster USYD Offshore
Maria Byrne USYD Offshore
Matthew Clements USYD Offshore
Monique Webb USYD Offshore
Luke Nothdurft QUT Offshore
Zsanett Szilagyi QUT Offshore
Trevor Graham QUT Offshore
Robin Beaman JCU Shore-based
Stefano Borghi JCU Offshore
Tom Bridge JCU/Qld Museum Shore-based
Helen Bostock UQ Offshore
Kimberley Chua UQ Offshore
Molly Husdell UQ Offshore
Patrick Moss UQ Shore-based
Darren Skene Quaternary Resources Offshore
Mardi McNeil Geosciences Australia Offshore
Juan Carlos Braga Universidad de Granada Offshore
Angel Puga-Bernabeu Universidad de Granada Shore-based
Bethany Behrens University of Tokyo Offshore
Yuning Zeng University of Tokyo Offshore
Yusuke Yokoyama University of Tokyo Shore-based
Dirk Erler Southern Cross University Shore-based
Willem Renema Naturalis, Biodiversity Center Shore-based
Pat Hutchings Australian National Museum Shore-based
Matthew Kosnik Macquarie University Shore-based
Carra Williams USYD Shore-based
Victorien Paumard UWA Shore-based
Juliet Sefton Monash University Shore-based

Jun 23, 2018 

Hi all, it gives me great pleasure to announce that we have been officially awarded an RV Investigator voyage to study the Halimeda (green calcareous algae) build-ups in the Great Barrier Reef (project details below).

After McNeil, M. A., Webster, J. M., Beaman, R. J., and Graham, T. L., 2016, New constraints on the spatial distribution and morphology of the Halimeda bioherms of the Great Barrier Reef, Australia: Coral Reefs.

With colleagues from JCU, QUT, UQ, Queensland Museum and overseas, we have been awarded 33 days of shiptime in 2020 from the Marine National Facility.

Important update: Due to COVID-19 the Marine National Facility has now rescheduled this voyage for ~Aug-Sep 2022. This is positive news and voyage planning is well advanced and on track for this new schedule.

Project summary:

Calcareous green alga Halimeda is a major contributor to coral reef shelf sediments and is found along the entire GBR. Previous studies of extensive Halimeda deposits, or bioherms, show they represent important inter-reef habitats and potential carbon sinks in the GBR Marine Park, covering about 26% of the northern shelf area, at least equal to the modern coral reef system. Pioneering work in 70-80s using widely-spaced, singlebeam and seismic profiles indicate the bioherms are in depths of ~20-40 m and form linear ridges and flat-topped mounds up to 20 m thick. However, new bathymetry data reveals a completely different picture of their surface morphology; characterised by complex reticulate (honeycomb-like) shapes and cyclical internal reflectors continuous over 100s of m. These new findings suggest Halimeda bioherms are more complex than previously thought – challenging existing paradigms describing their origin, development and significance.

Day Reef bioherm (Credit: Emma Kennedy)

We will conduct high-resolution multibeam swath mapping and sub-bottom profiling, in conjunction with autonomous and remotely operated underwater vehicles (AUVs, ASV, ROV) seabed imaging, and sediment coring at strategic locations. Key scientific objectives of HALO are to:

1) Define the spatial distribution and morphological variation of the Halimeda bioherms;

2) Explore the relationship of the bioherms to the undersea landscape (channels, passages and submarine canyons) and key oceanographic processes;

3) Develop new 3D models explaining their origin and development, generate Holocene paleo-climate data, including novel archives of upwelling, paleo-flooding and water quality;

4) Quantify their total volume/area as a regional geological carbon sink within the context of the global carbon budget; and

5) Assess the importance of the bioherms as modern, inter-reef benthic habitats.

This research will increase our fundamental understanding of the processes that control bioherm development, and have direct implications for environmental managers tasked with predicting how these poorly studied inter-reef environments might respond to future climate change.

Exciting times ahead.

Cheers

Jody

#MarineScienceSydneyUni

4 responses to “RV Investigator ship-time: Project HALO – Halimeda bioherm Origins, function and fate in the northern Great Barrier Reef

  1. Pingback: Fully funded PhD projects now available with the Geocoastal Research Group!! | Geocoastal Research Group·

  2. Pingback: Fully funded PhD projects now available with the Geocoastal Research Group!! | Geocoastal Research Group·

  3. Pingback: Hot off the press! Variations in Mid‐ to Late Holocene Nitrogen Supply to Northern Great Barrier Reef Halimeda Macroalgal Bioherms | Geocoastal Research Group·

  4. Pingback: Hot off the press! Evolution of the inter-reef Halimeda carbonate factory in response to Holocene sea-level and environmental change in the Great Barrier Reef | Geocoastal Research Group·

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