SeaSim coral spawning activities

Coral mass spawning is a natural phenomenon where corals of multiple species synchronise the release of sperm and eggs over several days following the full moon, which occurs only once or twice a year. The coral sperm and eggs float to the surface of the ocean and fertilise to form larvae which eventually settle on the reef to form new coral colonies. The spawning and larval phase of corals is a key event for the production of future coral generations and the replenishment of coral ecosystems. Read more about sexual reproduction in corals on our coral facts sheet webpage.
On the Great Barrier Reef (GBR), coral spawning is an annual event which takes place in spring, usually after the October/November full moon. In contrast, the corals in Western Australia spawn during autumn.
It is during this very narrow window of opportunity lasting only days that researchers can study how broad-cast spawning corals reproduce and collect samples of coral larvae for study. 
Along with AIMS researchers and students, SeaSim has attracted national and international collaborators (e.g. from the Smithsonian Institute, University of Texas and the New York University - Abu Dhabi) to AIMS during GBR coral spawning seasons for a number of high profile projects to:
  • understand natural variation and the inheritance of temperature tolerance
  • extend the GBR coral cryo-repository 
  • attempt to enhance coral resilience
  • conduct experiments that examine the effects of dredging sediments, water quality and climate change on coral reproduction and their early life stages. 
Details of some of these projects can be found below:

2015 spawning activities

Assisted evolution - juvenile corals growing in SeaSim. Photo: K. Green

Assisted evolution 

AIMS, University of Melbourne, Hawaii Institute of Marine Biology, Swinburne University of Technology, ARC Centre of Excellence for Coral Reef Studies

Prof Madeleine van Oppen
Prof Ruth Gates
Dr Victor Beltran
Ms Lesa Peplow
Ms Wing Chan
Ms Katarina Damjanovic
Ms Leela Chakravarti
Prof Ary Hoffman
Prof Linda Blackall
Prof Bette Willis
Dr Bill Leggat

This project will use 'assisted evolution' -  the active genetic manipulation of native coral populations - to increase the rate of naturally occurring evolutionary processes in order to enhance certain traits such as environmental stress resistance and growth rate. During this year's spawning event, three approaches will be followed:

  1. Different coral species are crossed in order to create new genetic combinations on which selection can act to enhance stress tolerance. This component of the research has linkages to Paul Allen foundation/Vulcan funding to Gates and van Oppen.
  2. Early coral life stages are inoculated with a wide range of species of algal symbionts to assess whether new coral-algal combinations can be formed; stability and the environmental stress tolerance of these associations will be assessed. This component of the research has linkages to Paul Allen foundation/Vulcan funding to Gates and van Oppen.
  3. Early coral life stages are inoculated with bacteria isolated from stress susceptible and stress tolerant coral species; stability and the environmental stress tolerance of these associations will be assessed. This component of the research has linkages to the Australian Research Council Discovery grant to van Oppen and Blackall.


Dr Line Bay and team examine their study corals before spawning, 2014 Photo: S. Clarke

Genetic markers of climate change adaptation in corals

AIMS, James Cook University, University of Texas - Austin, USA

Dr Line Bay
Dr Carly Kenkel
Prof. Bette Willis
Maria Nayfa (PhD student) and others

Climate change brings about three well-documented coral stressors: rising sea surface temperatures, that lead to coral bleaching; ocean acidification that affects calcification processes and skeletal growth, and increased bacterial loads resulting in a greater incidence of coral disease. Persistence of coral species into the future will require adaptation to each of these stressors and their combined effects.

Our project examines the potential for corals to adapt to increased temperatures, acidification and bacterial loads and the physiological and genetic mechanisms by which this process occurs. We will measure variation in coral fitness traits in response to single and compound climate stressors in coral families with known relatedness. We will then estimate trait heritabilities and use genomic analyses to identify the genetic basis of these traits. Using SeaSim facilities, this team will rear a large number of coral larvae from controlled crosses through to settlement. During the larval period, metamorphosis and juvenile stage the team will measure a range of physiological attributes to test whether performance under singular climate change conditions predicts performance when stressors are combined. The team will also develop genetic markers of stress tolerance and analyse the distribution of tolerant gene variants in coral populations across natural environmental gradients.



An Acropora coral releasing eggs during spawning Photo: Mickaela Nordborg

Dredging and coral reproduction 

AIMS, Western Australian Marine Science Institute, University of Western Australia

Dr Andrew Negri
Gerad Ricardo (PhD student)
Dr Ross Jones and others

Sediments released from dredging activities can reduce or block light, clog feeding and smother coral. The sediments can also affect many aspects of coral reproduction and recruitment processes and this project aims to understand the impact of dredging sedimentation on early life history stages of coral.



Researchers collecting eggs after corals have spawned Photo:AIMS

Cumulative effects of climate change and water quality early life history stages of corals 

AIMS, NERP, James Cook University

Dr Andrew Negri
Adriana Humanes (PhD student)
Dr Katharina Fabricius and others

Monsoonal flood plumes deliver organically-enriched sediment into the GBR Lagoon, often coinciding with mass coral spawning and high summer temperatures.  This research project investigates the combined impacts of organically enriched sediments and temperature on the coral reproduction, from fertilisation to the survival of coral recruits.



Coral larvae that have settled Photo:AIMS

Coal dust and coral spawning

AIMS, James Cook University

Dr Andrew Negri
Dr Mia Hoogenboom 
Kathryn Berry (PhD student) and others

Coal particles from loading facilities and shipping accidents may interact with coral in a variety of ways.  During coral spawning floating eggs and coal dust may mingle at the ocean surface, while juvenile corals may experience larger sinking particles. This project aims to determine if any of the various life stages of coral are vulnerable to accidental encounters with coal.



Eggs are carefully collected from the surface of the water Photo: AIMS

Oil spills and coral spawning


Dr Andrew Negri
Diane Brinkman
Florita Flores and others

Oil from spills and leaks can interact with corals at the water surface and under the ocean.  Millimetre long coral will be exposed to oils under controlled conditions to measure the sensitivity of this critical stage in the corals life history.  These results can be used by industry and regulators to assess the risks posed to corals by spills and leaks.



Eggs are collected under red light so as to not disturb colonies yet to spawn Photo: AIMS

Toxicity of pesticides, their formulations and breakdown products

AIMS, University of Queensland, NERP

Dr Andrew Negri
Dr Frederieke Kroon 
Prof. Jochen Mueller 
Philip Mercurio (PhD Student) and others

Pesticides from agricultural runoff have been detected in waters of the GBR but little is known of the potential toxicity of their breakdown products and formulations that may contain industrial detergents.  A series of experiments will expose coral larvae to these contaminants to assess their sensitivity vs priority pesticides that are currently measured and managed.