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April 2022
Research highlights edition  

Authored by: Luke Thomas, Shannon Duffy, & Josh Bonesso

 

Director's Note

 

Dear Oceans Institute Community,

Welcome to another special Research Highlights edition of the Oceans Institute's eNewsletter. 

This month we feature the research of OI Adjunct Research Fellow and AIMS@UWA Science Lead Dr Luke Thomas, who presents some of his recent research carried out in Exmouth, Western Australia, during the latest coral spawning event. 

The OI will be providing a number of Research Highlights editions throughout the year, showcasing examples of the outstanding research across the Institute, and demonstrating the diversity and impactful work of OI members.

 
We invite OI members to contact oceans@uwa.edu.au to have your research  featured. We are keen to share your successes with our extensive ocean community!

 
 

Dr Julian Partridge
Associate Professor
Director, Oceans Institute

 

Corals in a Changing World 

Oceans Institute Adjunct Research Fellow in Molecular Ecology and AIMS@UWA lead scientist Dr Luke Thomas’ research has been focusing on how increasing ocean temperatures associated with global climate change is among the greatest threats to the health of coral reef ecosystems. 


(Photo credit: Josh Bonesso, UWA)

Oceans Institute member and AIMS@UWA PhD candidate Shannon Duffy's research utilises advanced molecular techniques to elucidate the standing variation to thermal stress in tropical reef-building corals across fine-scale habitats. 

(Photo credit: Josh Bonesso, UWA)
The coral bleaching response 
 
Thermal stress outside a coral’s normal range of exposure triggers the breakdown of the obligate symbiosis between the cnidarian coral animal host and the photosynthetic dinoflagellate (of family Symbiodiniaceae). As corals expel their dinoflagellates, they lose colour and appear white, often termed ‘coral bleaching’. Corals rely on energy from their dinoflagellate symbionts to meet daily metabolic demands and prolonged periods of bleaching often lead to mortality. The result is a loss of important habitats and ecosystem services provided by healthy coral reef ecosystems.  

There have been three major global bleaching events since the 1980s, with the most recent and severe occurring during the strong El Niño years of 2015 – 2017.  More than one-third of the world’s coral reefs were impacted, and unprecedented bleaching was seen throughout Australia. Events like these highlight the fragility of these iconic and important ecosystems to climate induced thermal stress, and have triggered a paradigm shift towards actively managing coral reefs for resilience in the face of anthropogenic climate change.  

Naturally heat adapted, climate-ready, coral populations represent an important reservoir of genetic diversity and are a natural asset for reef management. Yet, we have a very limited understanding of the patterns and mechanisms of thermal adaptation in corals, impeding our ability to take proactive steps towards effectively managing coral reefs for resilience against climate change.  
 
Parent coral colonies under observation for coral spawning at the Minderoo Exmouth Research Lab (MERL), Exmouth, Western Australia (Photo credit: Shannon Duffy, AIMS@UWA PhD student).  
 
Coral Spawning on WA's Ningaloo Coast

The coral spawning research carried out at the Minderoo Exmouth Research Lab (MERL) in March 2022 was focused on understanding the core genetic pathways through which elevated thermal tolerance is achieved in Ningaloo Reef corals. This research is an AIMS@UWA funded project lead by PhD student Shannon Duffy in collaboration with the UWA Oceans Institute, AIMS and The Minderoo Foundation.  
 
Spawning of Acropora (branching) corals underway in MERL isolation tanks (Photo credit: Declan Stick, AIMS@UWA PhD Student). 
 

Minderoo Exmouth Research Lab Spawning 2022 

Work conducted at the Minderoo Exmouth Research Lab involved spawning corals in tanks, collecting and fertilizing gametes, rearing larvae for several days, and then exposing replicate larval cultures to experimental heat stress. The cultures were sampled when approximately 50% of the culture had crashed, and preserved in liquid nitrogen for whole genome sequencing analyses. The goal is to identify genetic loci that show significant allele frequency shifts in response to heat stress.   

A Delicate Process

Parent coral colonies were collected from Tantabiddi Lagoon on March 18, following the full moon. These colonies were transported to the Minderoo Exmouth Research Lab. Once in holding tanks, the corals were kept at temperature and light conditions similar to that of the reef.

Prior to sampling, the lagoon from which parent colonies were taken had been under mild heat stress during the month prior to spawning. While there was no visible bleaching in the area, on average, temperatures were at least 1 degree Celsius above historical average temperatures for this time of year. To reduce their stress and ensure the success of the experiment the holding tanks temperature was reduced to the historical average for March (27 degrees).   

Each night post collection, corals were observed for signs of spawning. On March 21, eleven of the twenty colonies began to show signs of setting (where the coral polyps bring egg/sperm bundles to the tips of their mouths and hold them there until the colony is ready to release) at 6:40pm and were isolated from the holding tank into individual containers. By 7:45pm all eleven were spawning, and spawning was over by 8pm.  

Gamete bundles (bundles of egg/sperm) were gently removed from containers holding parent colonies, and eggs and sperm were measured. Once eggs were all counted, equal amounts of sperm and eggs from all parent colonies were mixed, from where fertilisation occurred at 9:30pm. Once fertilisation was confirmed through visual assessment of embryo cleavage, fertilised eggs were washed with filtered seawater and equally distributed between holding tanks stocked at 400 eggs per litre. These were then left to sit for 12 hours without flow and aeration for development into coral larvae.  

Aeration was started 12 hours after fertilisation with gentle water flow beginning the following hour. For the next four days counts of the coral larvae in the holding tanks were completed using 12 by 10ml replicates and extrapolating stock densities from those counts.

After four days in the holding tank, settlement assays were conducted to assess if larvae were fully developed and healthy. This involved taking 6 replicates of 10 larvae and introducing them to coralline crustose algae to induce settlement. If approximately 40% settled this demonstrates larvae are actively searching for a place to settle indicating the heat stress assay could begin. 

Coral colonies being carefully prepared under strict light and temperature controls prior to coral spawning at the Minderoo Exmouth Research Lab (Photo credit: Dr Luke Thomas).  
 

Forecasting Future Resilience 

The 2022 coral spawning event has proven to be an important milestone in research at the Ningaloo Marine Park. Through determining the genetic variants that promote heat stress resilience in coral larvae, DNA probes can be developed to assess heat resilience in wild adult coral populations. 

Finding important genes associated with naturally heat tolerant coral species will allow targeted protection and restoration of those corals into the future, particularly under the threat of climate-induced changes.  

 

"We want to work out which coral species might survive climate change and foster and environment for which they can survive in" 
 
- Dr Luke Thomas

Project Partners

UWA Oceans Institute

Minderoo Foundation Flourishing Oceans Initiative

Australian Institute of Marine Science (AIMS)


A special thanks to Declan Stick (AIMS@UWA PhD Scholar) and the MERL operations team. 

PhD Supervisors

AIMS@UWA PhD Scholar Shannon Duffy is supervised by Professor Simon Jarman, Dr Luke Thomas, and Dr Jason Kennington
 

Seek Opportunities 

EOI are open! - Minderoo Exmouth Research Lab

Minderoo is looking for the next wave of researchers to conduct high-impact research, conservation, and educational projects at the Minderoo Exmouth Research Lab (MERL).

Do you have a project in mind, or do you know someone who does?

Submit your expression of interest today here

Minderoo Exmouth Research Lab (MERL), located in the town of Exmouth, Western Australia (Photo credit: Minderoo Foundation). 
 

Minderoo OceanOmics positions 

The Minderoo OceanOmics Centre based on the UWA Crawley campus is looking for two research officers:

  • Biostatistician - someone with a PhD aiming to use their quantitative skills to create a statistics research program to design and apply new observing and analytical strategies to complex datasets. 
  • Marine Cell Biology - a creative and organised individual interested in developing a program around cytometric and flow sorting tools, to address science questions concerning conservation and the genomics of ocean life.

About Minderoo OceanOmics
 
The Minderoo OceanOmics Centre is transforming how to measure biology in the ocean, to more accurately detect and understand biodiversity and fish populations using genomics tools and environmental DNA technologies
 
You’ll be able to develop and focus on your unique research questions in a well-resourced lab environment; you’ll be able to work both independently and as a team member, to achieve our mutual goals
 
 

Featured articles

'Bycatch' dolphin capture in WA, not sustainable

Past and ongoing levels of dolphin capture within 'bycatch' in the Pilbara, Western Australia, are not sustainable. Read more here

Why we should protect large female sea turtles!

Size does matter when it comes to nesting female turtles. Larger females found to have greater reproductive output. Find out more here

Preservation efforts of coral reefs not looking at the whole picture

An international team of researchers has quantified five critical ecological processes on more than 500 coral reefs worldwide to understand how these processes relate to each other. Read more here
 

Upcoming Events

May 12

6:30 pm - 7:30 pm

OI and City of Perth Library Series


Depths of the Ocean

Join Dr Todd Bond, Senior Postdoctoral Researcher in the Minderoo-UWA Deep-Sea Research Centre, as he reveals the mysteries of the depths of the ocean, the largest habitat for life on earth.
 

Little is known about the depths of the ocean, despite it being the largest habitat for life on earth. By deploying ocean landers equipped with high resolution cameras, animal traps and environmental monitoring sensors we can finally begin to see what lives at the bottom of the Indian Ocean.

Discovering new deep-sea species, assessing marine biodiversity, mapping the ocean floor, and charting deep-sea habitats is all part of exploring these exciting locations.

June 9

6:30 pm - 7:30 pm

OI and City of Perth Library Series 

Surf Tourism

What is the value of a wave? We know surfing can make places more desirable to live in and is good for the local community. Global surf tourism is worth up to $91 billion per year but surfing’s benefits to human well-being aren’t often studied in these economics terms.  

The value of surfing is only starting to be recognized among academics, policy-makers and coastal planners. Join Dr Ana Manero as she shares the real value of surfing and how it underpins local economy and lifestyle. 

July 14

6:30pm- 7:30pm

OI and City of Perth Library Series 

Feeding Bugs to Fish 

Growing aquaculture fish populations often relies on farmed sources such as poultry or soybean for feed. What if instead, we raised Black Soldier Fly larvae on food scraps, fattening them up to become a nutritional food source for farmed fish? 

PhD candidate Isobel Sewell shares how an insect diet can provide a massive amount of protein and has a much lower environmental impact. Is fly larvae the future for aquaculture?

August 11

6:30pm-7:30pm

OI and City of Perth Library Series

Kelp Restoration

Kelp forests used to dominate coastlines around the world, but an accelerated loss of kelp is happening globally.  How can we restore these crucial forests at the scales needed, whilst giving them the best chance to survive in a changing ocean? 

Postdoc researcher Georgina Wood is trialing restoration techniques using rocks seeded with baby kelp to find the solution. 
 
 
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