Heron Island is one of twenty-odd cays in the Capricornia Cays Marine Park, and home to the world’s largest coral reef research station in the Southern Great Barrier Reef, where half of the coral cover has been lost in just the last three decades. This Fantasia, once existing in seeming perpetuity, is now rapidly disappearing, including the myriad micro and macro-organisms that together compose the living symphony that is a healthy coral reef. The ferry from the port of Gladstone, a markedly industrial town, is exclusive for Heron Island, which is just a tiny speck in a huge swath of reef the size of Japan, hosting a small village of resort workers, guests, researchers, and school groups. As we cut through cold, deep, indigo waters, with forested mountains on the landward horizon, I began to doubt that we would come upon the tropical paradise I had long imagined.
I also witnessed a dozen or so massive tankers, proof of the unprecedentedly numerous industrial operations neighboring the marine park. Tens of thousands of ships move through the GBR every year, with a 20% increase expected in the next twenty years, and three major groundings since 1996 have damaged around 5,000 square meters of coral, with a further 115,000 damaged by the five tons of oil that spilled from the Shen Neng I when it hit Douglas Shoal in April of 2010. Toxins, from anti-fouling hull paints, such as the banned but ever present tributylin (TBT) and copper, when not leaching gradually into the water column, are loosed in quantity upon groundings, interfering with the critical life functions of marine organisms and inhibiting the natural recovery of smashed reefs. A further impact of shipping traffic is the introduction of foreign invasive species in bilge and ballast water and attached to the massive hulls.
Then, what appeared to be the crest of a distant and endless tsunami stretching across the horizon was announced as the breakwater of the Great Barrier Reef, the greatest structure ever built by living things! Stretching 2,100km, this has been a reef, on and off, for millions of years, with most coral taxa being at least 10-20 million years old. Amazingly, during the last ice age it was not a reef at all, but a grassy plain across which indigenous Australians once walked. Out of this vast expanse, appeared Heron Island, a little white and green strip of land that you can walk around in under a half hour, and tiny but significant part of a network of 22 reefs that straddle the Tropic of Capricorn, at the Great Barrier Reef’s southern end. Heron is incredibly representative of the entire GBR, and its 27k square km of “platform reef” is “home to a majority of the vertebrate, invertebrate and algal species identified in the GBR, with a similar proportion of the species awaiting ‘discovery‘.”
Heron Island’s terrestrial environment, while small, supports large populations of migrating birds along with crucial nesting sites for green sea turtles (Chelonia mydas). It was birdwatchers and guano (bird-poop) miners that first came to the island, before a Mr. L. Marsh applied for a special lease to establish a turtle soup factory in 1925. Years ago, when I told my Mexican grandmother that I was working in sea turtle conservation she said, “oh that’s wonderful, they are so delicious.” The Australian Turtle Company’s run was brief, however, and in a short time turtle numbers dropped so dramatically that the business went bust. In the 1930’s, the lease was taken over by Captain Christian Poulsen who built the resort and eventually disappeared at sea, but not before hauling in the famous wreck which stands as a breakwater in the channel. Poulsen’s rusted shipwreck was the first thing I noticed as we pulled expertly alongside a busy dock with a blue-polo-wearing crew ready to take bags and greet resort guests. At the end of the dock the resort guests would go left and the researchers right, from which point we would be treated as second class citizens, and perhaps rightfully so considering the exorbitant prices paid by the guests.
As we walked along the long dock, we pointed excitedly as a brown shadow belonging to a four-foot shovelnose shark scooted slowly along the shallows and passed under the dock. Half an hour later this would seem trivial as we snorkeled under the sunset, surrounded by gliding five-foot lemon and black tipped reef sharks. At one point, I had my masked face out of the water and put it back down to see a lemon shark directly under my feet, causing me to whoop loudly despite myself. Shortly after we glided away from the dock we were also guided by a massive, 1.5-meter, ancient patriarch of a loggerhead named Ben, with great big barnacles on his head. The massive turtle was in the channel most nights, sleeping on the sand and hiding his head under the reef ledge. The beauty of the reef during the day is unsurpassable, and my favorite sights were the schools of small cerulean fish and the blue and red crown of thorns sea star (Acanthaster planci), a pest species spread by water quality loss and currently the reef’s number one bane, oozing its belly over the corals and digesting them while alive. One species of coral hosts a symbiotic crab (Trapezia spp.) that, like Goliath’s David, pinches at the giant echinoderm’s tube feet and breaks off its spines, repelling the beasties that would otherwise consume six square meters of coral in a single meal. While the Pacific Sea Star (Asterias amurensis), is an introduced exotic, Acanthaster is a native organism that is prone to five-year outbreaks, three major ones having been recorded on the reef thus far. It is probable that overfishing the Sea Star’s main predators has contributed to these booms.
As I floated through this ancient wonderland, I couldn’t stop picturing the British-Australian illustrator Greame Base’s watercolors in “The Sign of the Seahorse” and thinking that he was not stretching his imagination after all when he drew a sea of multicolored sea horses floating amidst the crystalline turquoise water. I’m sure this seahorse garden must exist in another less frequented spot and having been a fan of Mr. Base’s children’s books since “Animalia” was published in 1986, you can imagine I was excited to learn that our professor from the University of Queensland, Selena Ward, was a family friend of his! Dr. Ward came with us on all the snorkeling trips and reef flat excursions, always wearing a pair of ray bans, loose cloths, and fashionable jewelry near as bright as her eyes, which sparkle with enthusiasm for this veritable paradise on Earth. With long, wavy black hair, a full physique, and the wisdom of a matriarch, Ward gave me some hope for the reef’s future, which lies in the shadow of anti-environmental, right wing Australian patriarchs, who like Donald Trump claim that climate change is a hoax. In addition to being a scientist, Dr. Ward’s job can be very political and she devotes much of her time to the tireless advocacy of the Great Barrier Reef Marine Park (GBRMP), which was established in earnest with the Great Barrier Reef Marine Park Authority in 1976.
In 1981, UNESCO (the United Nations Educational Scientific and Cultural Organization) added the Great Barrier Reef to the World Heritage List. Nonetheless, Australians need to be constantly reminded that their world treasure is something worth protecting, and that it is not simply an obstruction to Australian jobs and dollars. A Queensland Premier politician, Campbell Newman, once responded to a critical UNESCO report by saying that “we are in the coal business.” But Queensland is also in the fisheries and tourism business, and if we look after the Reef, tourism will persist as a vibrant industry long after burning coal has followed the dinosaurs into oblivion. According to Access Economics, the Great Barrier Reef “contributes over $5 billion to the Australian economy each year, and it supports more than 50,000 jobs, overwhelmingly in tourism.” At the University of Queensland research station on Heron Island, understanding the vastly complex ecosystem is a long-term mission. It is a world-class facility, but surprisingly it is run by aggressive, chicken-sized birds called buff-banded rails (Gallirallus philippensis). Being a protected species, they are not afraid to jump into your lap to snatch your lunch out of your hand or rip a scab off your leg as happened to one of our hosts. During the wet season, in the Southern Hemisphere’s summer, sea birds take control of the island, namely two species of terns called White-Capped and Black Noddys (Anous minutus), along with wedge tailed shearwaters, which make burrows during an overlapping nesting season. Together they make it a challenge to sleep over a true cacophony.
Noddy’s form nesting colonies in the low Pisonia grandis trees, a species of flowering tree in the Bougainvillea family. Like something out of “The Life of Pi,” this dominant species only forms forests on small, largely uninhabited islands where there is abundant sea bird guano to fertilize them – a unique example of convergent evolution. Because of the huge amounts of energy that it requires to catch food at sea, and bring it back to the nests, all the local sea birds have only one chick per pair. In contrast to their elegant physique, Noddy nests are crude piles of spit, poo, and leaves, and eggs and chicks often fall to their deaths. If the fall doesn’t kill them, the pisonia seeds, notorious for their ability to stick to bird feathers, sometimes rendering them helpless to scavengers. The national park service does not allow interference with natural processes, but you would have to be heartless to stand by and not help a baby bird in these conditions. The foraging success of the birds, and their ability to feed the single chick, is affected by sea surface temperatures (SST’s), and not just in El Niño years. SST’s impact the schools of small baitfish, commonly known as hardy-heads, and excesses of 28oC for extended periods will result in chicks starving, as occurred in 2002, when there was a total reproductive collapse in the Noddy colony. This was, by no coincidence, also the year of the worst coral bleaching event that was ever occurred on the GBR, proving that sea birds are sensitive indicators of climate change at the higher levels of the food chain. Studying them is thus worth a coral scientist’s time and effort. The other few, undesirable realities of the island include bird-ticks and nocturnal centipedes that live in the easily broken and rotting pisonia branches, and that will happily curl inside of your shoes or wetsuit. After all, it wouldn’t be Australia without such invertebrate pleasantries.
The best learning is always experiential, done hands-on, and we all enjoyed visiting the reef flat. This environment is just what it sounds like, a very flat expanse of sand and coral covered by shallow water and with parts completely exposed at low tide. Being on the reef flat is a little unnerving as there are stonefish that can poke through your shoe and kill you within minutes, not to mention sharks circling with the approaching tide, but once you let go of your fear it is like taking a stroll through a saltwater aquarium. Some of us used plastic cones with open tops and glass bottoms to see into the shallow water, but I preferred to simply adjust my eyes to the rippled water and refracted light to experience the life beneath. Corals must survive the relentless sun for hours, and they have adapted the capacity to repair their DNA along with producing their own microbial sunscreen in the form of mycosporine-like Amino Acids, or MAA’s. These photo-protective compounds absorb UV light and are found in coral mucus as well as on other reef organisms like in the mucus of the pallid damselfish (Pomacentrus amboinensis) – incidentally, the first fish to be tested positively for color vision. When I noticed that I was getting badly sunburnt during our transect studies of coral bleaching, I lay down in the knee deep water that was flowing strongly with the incoming tide and let the coral mucus cover my body. For the next hour I felt gross but greatly protected from the Sun’s harmful rays. MAA’s may also increase photosynthetic capacity for the coral’s symbiotic algae and buffer against oxygen, salt, desiccation, and thermal stress. These amazing compounds are a reminder of the potential assets to medicine that are yet undisclosed in these endangered coral ecosystems.
Being so close to the corals that you must tip toe around them, or step on them unwillingly, also allows you to appreciate their vibrant colors, which are due to a combination of pigments in the coral tissue and in the symbiotic zooxanthellae that live within. For this reason, the tops of the Acropora corals, stripped of algae by exposure and bleaching, are a bright purple color belonging to the more visible coral tissue. They are also identifiable by terminal polyps on the tips of each branch. Acropora is an endangered genus that forms highly three-dimensional habitats, like calcium bushes or “tables,” and small fish, like the blue green chromis (Chromis viridis), can hide very effectively in and underneath the horny structures, effectively disappearing and making it exceedingly frustrating for predators or humans trying to photograph them. It has been shown that ocean acidification causes behavioral changes in coral reef fish, inciting them to leave already depleted shelters more often and exposing them to higher rates of predation. I was also introduced to “soft corals,” with their amorphous, rounded forms that look like a wet clay pot on a pottery wheel that is spinning too fast. These are surrounded by a wide diversity of algae, with one bright green species forming little tufts on the eroded reef, that when submerged looked like trees drawn by Dr. Seuss. Calcareous algae, meanwhile, has the appearance of ornate pink lace, and is responsible for literally cementing the reef together, while fleshy macro-algae are missing entirely from the scene as it competes directly with the corals for much needed sunlight and nutrients.
“Darwin’s Paradox” refers to the famous naturalists’ bewilderment at how such a low nutrient environment could be so productive, and only by sitting down to rest in the shallow water, like a child in a kid-pool, can one come upon the answer. Before long, crabs begin to poke their heads out of crevices and tiny fish with upwards facing eyes and colorful fins crawl across the sand to get a closer look. You notice strands of mucus stretched across the landscape from one coral to the next, exploring and enforcing dominance over competing species and Spaghetti Worms connecting one colony to the next. These are all the sometimes obvious and other times illusive agents of symbiosis, the socio-cultural network of the reef. If an alien came to our planet and saw a single suburban man weeding his yard, it would be hard pressed to believe that humans could alter an entire planet. Nevertheless, if that alien first visited a bustling city where assembly lines of men were fabricating huge agricultural machines, it might have a different perspective. The reef, and for that matter, each coral colony, is like a city composed of thousands of polyps, each assigned a task such as feeding, or defense, and together they create a home for myriad other species. Through complex relationships, some of them mutualistic, some commensal, and others parasitic, an abundance of organism can co-exist and make the most of the limited bottom-up resources, constantly recycling them to a new trophic level.
Not all of what goes on in the reef is immediately available to a clumsy person wading around the reef flat, and it was usually the more visible animals that caught my eye. These included giant sea cucumbers, deposit feeders with hydro-vascular systems, known appetizingly as “sand fish” by the Indonesians who eat them. Some of these tubular echinoderms hide under coral heads or bask pompously in the open, and the sheer abundance of them makes it obvious that they play a crucial function in filtering the reef water and recycling nutrients and minerals through their digestive system, which they will eviscerate if molested. The black-fringed sea cucumber (Holothuria leucospilota) was impressively long and reacted quickly to prodding, while the mesmerizingly verdant Holothuria atra were stiffer and bolder. The massive, spotted, olive colored Stichopus variegatus, meanwhile, looked like something out of the book Dune. Less abundant but in equal variety were the sea stars, the most beautiful being the big, royal blue Linckia laevigata, which contrasted with the humbler and more patterned New Caledonian sea star, Nardoa novacaledoniae. I also saw many giant clams, whose eye-spotted-mantle comes in a variety of neon colors depending on the individual, and who can squirt a powerful jet of water several meters into the air when they feel threatened. I was not prepared to be impressed when my professor, Simon Davy, called me over to “come see a really big snail,” and was left awestruck when I saw a marine gastropod in an olive shaped shell the size of an American football!
The reef flat is like a patchwork quilt, constantly being torn, redesigned, and fixed by the forces of nature. Even our walking on the corals and hearing them crunch under our feet like cereal has an impact, but we comforted ourselves with the idea that this was after all an opportunity for us and other students of biology and conservation to become, for those few hours, a strange part of the ecosystem. The beach at night was just as thrilling, and on a solo-mission to recover my flip-flops, I encountered an epaulette shark (Hemiscyllium ocellatum), a skinny, leopard spotted beauty the length of my leg, swimming – no, crawling – in remarkably shallow water. The shark is known for its feet-like pectoral fins and for being able to survive in tide-pools with extremely anoxic conditions. On our last night at Heron, after drinking and dancing at the resort, a group of us followed Chloe, Ward’s friendly daughter, down the trail through the enchanted pisonia forest to Shark Bay. When we came out of the trees onto the beach it was a moment as surreal as any I have ever lived. By the soft moonlight, the beach was clearly visible in a pink and blue light that made it look essentially immaculate – like a beach on an unvisited planet. “Welcome to paradise,” Chloe chuckled with perfect timing, and indeed standing on the cold sand, in a place where man is not meant to be, I felt in awe of the world in which we are so fortunate to live, and which we must come together to protect.
