Life in the Great Barrier Reef

Archival image of a potato cod (Epinephelus tukula) with a diver to scale, taken in the famous much dived Cod Hole. Used to divers, many big cheeky Potato cods follow divers to check them out. The Cod Hole is the very reef where the Great Barrier Reef Marine Park originated.

Diving with 15 coral, fish, and shark scientists to survey the GBR for the Khaled bin Sultan Living Oceans Foundation we visited reefs no dive tourist will ever get to see. In stark contrast to the highly visited reefs, the fish were often alarmed by the vibrations of exhaling bubbles from the divers. And as they do, they swam away.

On one interesting dive, there was a curious pelagic floating blob in the water with blue and yellow fusiliers feeding on it! I could go near and not spook the fish away as they were engrossed in eating.

School of blue and yellow fusiliers (Caesio teres) eating the gossamer netting egg ribbon of a large squid in the family Thysanoteuthidae.

Here are some more obliging critters that didn’t swim away from my monster camera…

Tawny nurse shark (Nebrius ferrugineus) swimming above the sandy area.

We were diving within some of the zones that have been set aside for greater protection. What was really wonderful to see in the marine protected areas was the number of sea cucumbers littering the sea floor.   Sea cucumber is a high value, high demand Chinese delicacy sought after by Chinese traders buying dried sea cucumbers from all over the world, especially in Asia and the Pacific. They are collected from the ocean floor and processed into a dry food product called bêche-de-mer and exported to Asian markets. Sea cucumbers were harvested and processed into bêche-de-mer as early as the eighteenth century, continuing and becoming increasingly exploited throughout the nineteenth and twentieth centuries as the Chinese population, appetite, and buying power increased in China and in Chinatowns worldwide. It is a common story of woe heard amongst fishermen that they are catching smaller and smaller, lower value sea cucumbers, since many high value species have been depleted from their fishing grounds.

Sea cucumbers are flexible, elongated echinoderms belonging to the class Holothuroidea. They live on the sea floor in reefs, lagoons and coastal shallows, with some species living in deeper waters. They move about slowly over the sea bottom like scavengers, feeding on debris found in the sand and sediment. Sea cucumbers are ecologically important in the marine environment – acting like the sea floor vacuum cleaners.

Sticky threads of a sea cucumber secreted when the animal feels threatened.

There were some stunning reefs that we saw and it was only in the top few meters at the outer edge of the Great Barrier Reef that I photographed these unusually shaped corals.

Coral growth is forced into interesting elongated and stunted shapes in the surge and surf zone on top of the outer Great Barrier Reef.

On April 2014 category 5 Cyclone ‘Ita‘ developed in Papua New Guinea, headed south-southwest, making landfall near Cape Flattery and moved offshore past Lizard Island – devastating reefs all along its path. LOF Chief Scientist Dr. Andy Bruckner said “During today’s dive, at the south-western end of Hicks Reef, we witnessed considerable storm damage. Thickets of staghorn coral had been crushed and their skeletons littered the bottom. Large massive corals and entire chunks of reef rock had tumbled down the reef accumulating at the base of the reef slope.  We measured rubble piles that were more than 70 cm deep.” 

Giant clam’s (Tridacna gigas) heart shaped siphon in the reef surrounded by algae covered dead corals.

Andy also said “While the damage was alarming, reefs have weathered storms throughout their history and in absence of other stressors they demonstrate remarkable resilience, rebounding in a matter of years.  Given the high survival of coral fragments we observed among the rubble piles, we expect similar rates of recovery on Hicks Reef.”

Then one of the bad guys of the reef was seen in many areas – the crown-of-thorns starfish. Otherwise known as COTS, this animal is a large, multiple-armed starfish (or seastar) that usually preys upon hard, or stony, coral polyps (Scleractinia). The crown-of-thorns receives its name from venomous thorn-like spines that cover its upper surface, or the crown of thorns. It is one of the largest sea stars in the world and is very destructive as it voraciously feeds on healthy corals.

Crown of thorns starfish beside a dead coral it had digested to death.

The Khaled bin Sultan Living Oceans Foundation conducts scientific surveys on coral reefs around the world to determine the health and resilience of the reef. The primary scientific goals of the Expedition are to map and characterize coral reef ecosystems, identify their current status and major threats, and examine factors that enhance their ability to resist, survive and recover from major disturbance events like bleaching, cyclone damage, or Crown of Thorns outbreaks.

At each site LOF brings an international multi-disciplinary team of scientific divers as well as teaming-up with the local scientific community to conduct these surveys and get the most scientifically accurate data possible. The scientific results are shared freely with participating countries and scientific and regulatory organizations. This helps governments, environmental managers, and local residents gain a better understanding of their local coral reefs so they can better manage and protect them. They combine the power of education and outreach with scientific information to help inform and persuade people to take action.

And although it will take some time to analyze all the scientific results here are some breathtaking scenes to enjoy from under the waves of the Great Barrier Reef.