History of The GBR - The Great Barrier Reef Library

The First Reefs Emerged

Earth’s original reefs were not made from corals, but Microbialites. These include photosynthesising cyano-bacteria, called Stromatolites.^10,11

3.5 Billion Years Ago

Corals Evolved

Coral polyps evolved from their jellyfish ancestors over 500 million years ago.^1,2,9

500 Million Years Ago.

The Ordovician-Silurian Extinction Event

The super-continent of Pangaea began to form, altering ocean currents. An Ice Age began as sea level temperatures decreased, leading to the extinction of corals and 60% of all marine life.²

435 Million Years Ago

Re-Emergence of Corals

Corals, re-appeared in the fossil record during The Devonian Period. This was the first time that they created extensive reefs and Scleractinian (Stony) Corals eveolved at the end of this period.²

410 Million Years Ago

2nd Coral Extinction

Although the reason is unclear, Corals once again disappeared from the fossil record, suggesting a second extinction event. It is possible that this was caused due to fluctuations in sea levels and a rapid reduction in atmospheric CO2.²

350 Million Years Ago

Corals Re-Emerge Once Again

Almost 100 million years after their extinction, corals reappeared once again.²

260 Million Years Ago

The Permian-Triassic Extinction Event

This was the largest extinction event in Earth’s history, wiping out 96% of all marine life. The cause of this event is thought to be a period of hypoxia (reduced O2) and hypercapnia (elevated CO2). This may have been due to a combination of factors, such as meteors, gas bubbling through Earth’s crust, reduced sea levels and volcanic activity.²

260 Million Years Ago

Corals Make A Comeback

Corals re-emerge once again! This time, modern day Scleractinian corals were in abundance, but this was short lived.²

230 Million Years Ago

A Period of Change

Pangaea began to break up, causing another extinction event that wiped out corals once again. This was followed by an extremely volatile period where corals frequently appeared and disappeared from records, with changing currents.²

205-75 Million Years Ago

Coral Benefits From Symbiotic Relationship With Zooxanthellae

The Zooxanthellae algae, Symbiodinium, first paired up with Coral about 160 million years ago, this important relationship is vital for the survival of modern day corals⁷

160 million years ago

Cretaceous-Tertiary Mass Extinction Event

This was the famous event responsible for wiping out The Dinosaurs. After the meteor impact, a dark period of about 1-10 years followed, as the sunlight was virtually blocked out. With little sunlight available, the symbiotic zooxanthellae algae within the coral began to starve and coral again became extinct. They made another shortlived comeback 55million years ago, before sufering extinction again, this time due to The Paleocene-Eocene Thermal Maximum.²

65 Million Years Ago

The Paleocene-Eocene Thermal Maximum Event

This was the most extreme period of global warming in History. Caused by the release of gases, such as Methane, that was previously held within the ice. These strong Greenhouse Gases caused a 6 degrees increase in temperature, which very nearly caused another extinction of Corals.²

55 Million Years Ago

Hopefully, The Final Coral Extinction

After emerging once more, 46 million years ago, corals were again wiped out only 6 Million years later.²

40 Million Years Ago

Creation of The Great Barrier Reef

The great barrier reef was created about 500,000 years ago, however it has not always looked the same and has changed and moved many times since.³

500,000 Years Ago.

Indigenous Arrival At The GBR

Indigenous and Torres Strait Island Clans arrived at The Great Barrier Reef and began to live with a strong connection between the land and sea.⁸

60,000 years ago

Creation of the Modern Day GBR

The current form of The Great Barrier Reef was created following the most recent ice age. Sea level rose quickly, pushing the coastline back 100s of meters every years^4,9

20,000 B.C.

Mass Bleaching Event

The first recorded mass bleaching event on The GBR was recorded, allowing us to make the initial connection between temperature and bleaching.^5,6

1981/82

Mass Bleaching Event

The second recorded mass bleaching event was the most widespread at the time, affecting many corals around the world. 74% of inshore reefs were bleached and 21% offshore.^5,6

1997/98

Mass Bleaching Event

This bleaching event helped us understand the links between bleaching and the La Nina / El Nino cycles. 72% of inshore reefs were bleached and 41% offshore.^5,6

2001/02

Small-Scale Bleaching Event

A localised bleaching event took place on the Southern reefs, particularly near Keppel Island, where 39% of mortality occurred on the reef flats.^5,6

2005/06

Mass Bleaching Event

Major bleaching events occurred each year due to extreme summers with lots of rainfall increasing the freshwater running into the ocean.^5,6

2008-2011

Mass Bleaching Event

This was the worst bleaching event on record, with widespread bleaching occurring, particularly in the northern sector. A 22% mortality rate was calculated over the entirety of The GBR.^5,6

2016

Mass Bleaching Event

More information needed.^5,6

2017

GBR Legacy Search for the Super Corals Expedition

An incredible expedition run by volunteers to get the world’s leading researchers out to the remote areas of the reef

15/11/2017

New Species of Coral Found

Charlie Veron discovered at least one new species of coral and about 7 species that are new to The Great Barrier Reef, at The Legacy Super Site

16/12/2017

Most Diverse Hard Coral Site on The GBR Identified

Charlie Veron returned to the location of his previous new species discovery to complete a full survey, with GBR Legacy. 208 species were found in a 200m section of reef, including the one unidentified species and 12 species new to the GBR

23/11/2018

Most Diverse Hard Coral Site Devastated By Cyclone Damage

GBR Legacy returned to their super site for further research, only to find it decimated by cyclone damage earlier in the year

Nov 2019

Most Widespread Coral Bleaching On Record

Early 2020 saw temperatures rise once more on The GBR causing widespread coral bleaching. Whilst mortality has not been as high as previous years, this was the most widespread coral bleaching event on record, affecting areas that escaped the 2016-2017 bleaching event.

2020

Report Claims 50% of Coral on The GBR has died since 1995

Australian Research Council (ARC) report that half of the coral on The Great Barrier Reef has been lost since 1995, largely due to coral bleaching events.

Oct 2020

Coral Bleaching Event

AIMS and GBRMPA confirm another mass coral bleaching event, although mortality appears to be low.

Mar 2022

Percentage Coral Cover at a Record High in Northern sections of Reef

AIMS report that the percentage coral cover on the central and Northern sections of the GBR are at its highest point for 36 years. The Southern section had decreased from 38% to 34%. This increase is largely due to fast growing Acropora species that are especially susceptible to coral bleaching, storm damage and crown of thorns starfish

Aug 2022