Great Barrier Reef coral fights for survival


This December 2014 video says about itself:

In what has been described as the “world’s biggest orgy”, coral on Australia’s Great Barrier Reef has spawned in one of nature’s most amazing and rarely-seen shows. In an even rarer occurrence, the coral put on an encore performance, re-producing – or spawning – for the second time in two months, releasing millions of eggs and sperm into the waters of the Great Barrier Reef to fertilise. This almost unseen “split-spawning” event had marine scientists and tourists marvelling in delight.

From the University of Queensland in Australia:

Strange coral spawning improving Great Barrier Reef’s resilience

August 6, 2019

A phenomenon that makes coral spawn more than once a year is improving the resilience of the Great Barrier Reef.

The discovery was made by University of Queensland and CSIRO researchers investigating whether corals that split their spawning over multiple months are more successful at spreading their offspring across different reefs.

Dr Karlo Hock, from UQ’s School of Biological Sciences, said coral mass spawning events are one of the most spectacular events in the oceans.

“They’re incredibly beautiful,” Dr Hock said.

“On Australia’s Great Barrier Reef, all coral colonies typically spawn only once per year, over several nights after the full moon, as the water warms up in late spring.”

Study co-author Dr Christopher Doropoulos from the CSIRO Oceans & Atmosphere said sometimes however, coral split their spawning over two successive months.

“This helps them synchronise their reproduction to the best environmental conditions and moon phases,” he said.

“While reproductive success during split spawning may be lower than usual because it can lead to reduced fertilisation, we found that the release of eggs in two separate smaller events gives the corals a second and improved chance of finding a new home reef.”

The research team brought together multi-disciplinary skills in modelling, coral biology, ecology, and oceanography, simulating the dispersal of coral larvae during these split spawning events, among the more than 3800 reefs that make up the Great Barrier Reef.

They looked at whether the split spawning events more reliably supply larvae to the reefs, as well as whether the ability to exchange larvae among the reefs is enhanced by them.

UQ’s Professor Peter J. Mumby said split spawning events can increase the reliability of larval supply as the reefs tend to be better connected and have more numerous, as well as more frequent, larval exchanges.

“This means that split spawning can increase the recovery potential for reefs in the region.

“A more reliable supply of coral larvae could particularly benefit reefs that have recently suffered disturbances, when coral populations need new coral recruits the most.

“This will become more important as coral reefs face increasingly unpredictable environmental conditions and disturbances.”

Dr Hock said the research also revealed that the natural processes of recovery can sometimes be more resilient than originally thought.

“However, even with such mechanisms in place, coral populations can only withstand so much pressure,” he said.

“It all ends up being the matter of scale: any potential benefits from split spawning might be irrelevant if we don’t have enough coral on these reefs to reproduce successfully.

“Mitigating well-established local and global threats to coral reefs — like river runoffs and carbon dioxide emissions — is essential for their continued survival.”

The study between UQ, CSIRO and ARC Centre of Excellence for Coral Reef Studies was published in Nature Communications.

Scientists have completed a landmark study on how to save coral reefs in the Indian and Pacific Oceans: here.

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Great Barrier Reef coral trout babies study


This video says about itself:

Coral trout, Plectropomus leopardus, gather to spawn at dusk around the new moon in spring and early summer at Lizard Island on the northern Great Barrier Reef. Substantial research into the biology and ecology of this highly sought-after table fish has been conducted at the Australian Museum’s Lizard Island Research Station.

This video was shot just before sunset on 27 September 2011 at about 6 metres depth. Males wear spawning colours – very pale with a black outline – that are quite different to their normal colouration. They shimmy up to smaller females as an invitation to join a spawning rush towards the surface.

In this video, a male shimmies at several females and chases off a rival male before making a really fast spawning rush with a female at about 1 minute into the clip. Each fish emitted a puff of spawn at the apex of the rush.

This 4 December 2018 video says about itself:

Can you identify the fish swimming over the acropora coral?

Here are the fish to look our for:

Scarus ghobban – Blue-barred Parrotfish
Plectropomus maculatus – Bar-cheeked Coral Trout
Acanthurus grammoptilus – Finelined Surgeonfish
Lutjanus lemniscatus – Darktail Snapper
Labroides dimidiatus – Bluestreak Cleaner Wrasse

This video was recorded on the 9th of August 2018 at 9:08am AEST in Pioneer Bay, Orpheus Island, Australia.

From the ARC Centre of Excellence for Coral Reef Studies in Australia:

Tracking baby fish for better reef management

August 1, 2019

Summary: Scientists have created the world’s first computer model to predict the movements of baby coral trout across the Great Barrier Reef. The models are validated by in-depth fieldwork and genetic tracking, and will help managers decide which areas need the most protection to ensure future adult populations of coral trout.

A group of Australian scientists has created the world’s first computer model that can accurately predict the movements of baby coral trout across the Great Barrier Reef. The study confirms the importance of fish larvae produced in no-take zones for the health of fish populations within nearby fishing zones.

Tracking the lives of thousands of tiny baby fish is no easy task. But knowing where they’ll settle and spend their lives as adults is invaluable data for the fishing industry and reef managers.

The accuracy of the model was tested in a recent study — led by Dr Michael Bode from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU) — that validates the computer predictions with field data.

This is a world-first achievement, combining the movement of ocean currents in and around the Great Barrier Reef with the genetic and behavioural data of fish.

“The study is a unique conservation collaboration between marine biologists, geneticists, and recreational fishers,” Dr Bode said.

“This was a major field effort combined with some clever genetic work that involved matching baby fish to their parents to understand their movement,” co-author Dr Hugo Harrison, also from Coral CoE at JCU, said. “The behaviour of fish in their first few weeks after hatching can really influence where they eventually settle.”

The study focussed on coral trout, Plectropomus maculatus, which is one of the most valuable species of fish regularly caught on the Great Barrier Reef.

To test the computer model’s predictions 1,190 juvenile and 880 adult fish were tracked — from spawning locations to settlement — across the reef for two years.

The computer model recreates the movements of baby fish across space and time by considering what depth the coral trout swim at, how fast they swim, and how they orient themselves as they grow older.

The results highlighted the interconnectedness of reefs, and how important no-take zones are when considering future adult fish populations.

“Our results prove that the Great Barrier Reef’s no-take zones are connected with invisible threads,” Dr Bode said.

“Knowing how reefs are connected to one another means fishers and managers alike can identify which areas are likely to be most productive and need protecting,” Dr Harrison said. “It’s the babies from these protected areas that will continue to restock fish populations on neighbouring reefs where fishing is allowed.”

Dr Bode said establishing the accuracy of these models is an important breakthrough.

“Our match between models and data provides reassuring support for using them as decision-support tools, but also directions for future improvement.”

Great Barrief Reef fish and snakes


This video says about itself:

Deadly Predators of the Reef: the Queensland Grouper and the Sea Snake | BBC Earth

30 June 2018

The reef is full of dangerous predators, including the giant Queensland grouper and the deadly sea snake.

Stretching a full 2000 kilometres in length and made up of 3000 individual reef systems and hundreds of islands, Australia’s Great Barrier Reef is breathtakingly beautiful. Given world heritage status in 1981 it is one of the wonders of the natural world.

Crab fights coral-eating starfish


This video, recorded in Australia, says about itself:

This Crab Doesn’t Take Kindly to Home Intruders

23 jan. 2018

The crown-of-thorns starfish eats coral reefs; coral reefs happen to be the home of the guard crab. This puts these two tenacious aquatic creatures on a direct collision course.

From the series: David Attenborough’s Great Barrier Reef

Manta rays helped by small fish


This video says about itself:

Manta Rays Use Tiny Fish to Help Them Stay Clean

12 January 2018

Wrasse perform a vital cleaning function for other fish, by ridding their bodies of dead cells and parasites. Their biggest customers–literally and figuratively–are the massive manta rays. From the series: David Attenborough’s Great Barrier Reef: Visitors.

Manta rays have an unusual mouth filter that resists clogging. Instead of snagging in the filter, plankton ricochets toward the manta’s throat. By Laurel Hamers, 2:05pm, September 26, 2018.

Mantis shrimp mating dance


This video says about itself:

Watch This Male Mantis Shrimp Dance to Attract a Mate

9 January 2018

Mantis shrimp have a reputation as fighters and it’s well deserved. But they also have a romantic side to them, which they show off with a well-choreographed mating dance. From the series: David Attenborough’s Great Barrier Reef: Builders.

Great Barrier Reef coral reproduction


This 9 January 2018 video says about itself:

See ‘Underwater Snowstorm’ of Coral Reproducing | National Geographic

This is what it looks like when coral spawns in the Great Barrier Reef.

REEF REPAIR Australia will spend $379 million trying to save the Great Barrier Reef — the largest single investment ever made toward protecting the fading ecosystem. [HuffPost]

Scientists reveal global warming’s impact on Great Barrier Reef: here.

Nearly 200 Great Barrier Reef coral species also live in the deep sea. The unexpected coral bounty means deep reefs have a richer biodiversity than thought. By Cassie Martin, 7:05pm, December 11, 2018.

CLIMATE CHANGE DRIVES CORAL COLLAPSE The deadly back-to-back bleaching events that hammered Australia’s Great Barrier Reef in 2016 and 2017 led to a collapse in the recruitment of new corals, severely affecting the ecosystem’s ability to recover from the devastation. [HuffPost]