The Story of the Lost Brain Coral

Professor Charles Sheppard, a wonderful On the third day’s sail, the vessel arrived at Ile character known to many at CCT and in my Diamant to anchor for a day or two, whilst we romantic mind, a passionate marine scientist used the inflatable boats to survey the reefs straight out of the rumpled pages of my copy of the islands nearby. At the seaward sites of of The Lost World. Ile de la Passe and Ile Diamant, I continued to search for and sample the abundant Acropora As the warm winds tugged at our hair (well, and Porites species which form the focus of certainly mine, at any rate), Charles was our research into reef health at Oxford, whilst regaling me with glorious and nostalgic always keeping half an eye out for Ctenella. chronicles of his time diving in the Chagos Archipelago in the 1970s, and the tragic The occasional surge of hope was more demise of one of its most iconic denizens, often than not a false one, colonies of similar- the Chagos brain coral (Ctenella chagius), looking brain corals Goniastrea and Leptoria Figure 1 © Amelia Rose/University of Oxford an endemic to this region of the world. easy to mistake at depth. That afternoon, buffeted by a slight swell, we skipped As he eloquently described in his article across the waves to anchor just off Moresby for CCT several years ago (‘The Chagos Island, named after the eighteenth century brain coral Ctenella chagius: falling into cartographer who surveyed these islands. the red’; Chagos News, No. 52 July 2018), The Story of the this beautiful hemispherical coral (Figure 1) The site comprised a wide terrace at six was once one of the most common in the metres depth, sloping down to 11 metres and Lost Brain Coral archipelago. then dropping off–it was a wonderful place, Dr Bryan Wilson, Department of Zoology, and with hindsight, one of my favourite on However, recent warming events in the Indian that expedition, with high coral cover and University of Oxford Ocean have disproportionately decimated diversity. And yet also a challenging dive, its once abundant populations, such that the subsurface current increasing steadily on a previous expedition to BIOT in 2017, throughout the hour underwater. Employing As a child, I was entranced by the world and conserve the species for posterity not a single live colony was found and there my usual survey tactic of heading upcurrent to fantastical fictional tales of Conan Doyle’s and eventual reintroduction back into its were fears that it had become extinct. Upon begin and then drift-diving back to the anchor, The Lost World, and later, by its real-life jungle home. their return to the archipelago the following my research associate (Amelia Rose) and I (and admittedly slightly less exotic but year however, a small number of diminished finned across the reef looking for corals to nonetheless enthralling) counterpart, the Despite it being the 1980s, those dreams extant living fragments were discovered in the sample and tag. telling of Marjorie Courtney-Latimer’s always seemed to be illuminated by Victorian northern atolls of Salomon and Peros Banhos, rediscovery of the long thought extinct flash photography, possibly in tribute to the and with it, the chance that the species was And within the first ten minutes, we spotted coelacanth, amongst a rotting waste tall tales of that time, who knows. Of course, not lost to science after all. our first glimpse of the enigmatic Ctenella, pile of landed fish on the docks of East that was some decades ago and whilst my albeit a very pale and sorry-looking fragment, After hearing this and forever being the London, South Africa in 1938. dreams have become slightly jaded by the a small surviving part of what was once a realisation of the hundreds of extinctions that optimist, I had on something of a whim much larger colony (Figure 2) and likely one In my frequent young flights of fancy, I often have happened since my childhood, I have included a permit for Ctenella when applying of the specimens that Charles had spotted the imagined myself some great explorer of old, always held on to that same bookwormish to the BIOT Administration to sample for a year before. Six more similarly sorry-looking pushing through dense undergrowth into a fantasy. And then, several decades later, I number of other more commonly-occurring findings followed and I couldn’t help but be jungle clearing, only to see the merest flash finally took that flight of fancy... coral species, on the off chance (nay, the slightly underwhelmed–and terribly sad. of something disappearing into the thicket–the inspired hope!) that I would stumble upon one striped tail of a thylacine, the flecked breast Early in April 2019 and having only just joined on my upcoming dives. The photos Charles had showed me were of a Mauritius kestrel, or possibly even the the Bertarelli Program in Marine Science of pink-hued and beachball-sized giant As luck would have it, our expedition began comedically portly rump of a dodo. (BPMS) several months before, I found underwater brains and these fragments myself on their annual expedition to the in the south-west corner of Peros Banhos were mere shadows of those. Still, where I And then the furious chase that followed British Indian Ocean Territory (BIOT), aboard Atoll, surveying Ile du Coin, and as we sailed could, I tagged the colonies and gently took (possibly more of a clumsy lunge in the case the Patrol Vessel Grampian Frontier, forcing steadily northwards and clockwise in the thumbnail-sized tissue samples for which of the dodo). The capture! And the return its way through an unseasonable Indian coming days, my anticipation to dive the I’d so optimistically applied for a permit home a hero, to share my discovery with the Ocean surge and chatting up on deck with northern islands of the atoll grew. those months before, in the hope that some

4 5 contribution to the paucity of knowledge fortune, I was lucky enough to be awarded concerning this little coral could be made. a global research award to do just that by QIAGEN, one of the world’s leading The six or seven weeks that followed our biotechnology companies. And as I write this, return to the UK were nervous ones–far too I have received the first results back, and am many times in my career have samples gone currently delving into the first ever genome missing or spoiled during their inexorable data for this coral, hoping that the secrets of progress home around the globe–the its enigmatic and tenuous existence might sensation heightened by the thoughts that finally be revealed. given another unparalleled warming event in the central Indian Ocean, that these could be Buoyed up by last year’s finding, in the last samples of this coral ever taken. February of this year, I headed out once again on the annual BPMS expedition to But arrive they did and in unspoiled condition, BIOT, little knowing the global chaos that in a toughened-plastic trunk festooned with would soon ensue. permits and airline stickers, where they were immediately transferred to the -80C freezer in Arriving just before the main expedition our molecular lab at the University of Oxford’s team, our first week was to be based on John Krebs Field Station for safekeeping. the island of Diego Garcia (DG), assessing its feasibility to be an ecological study site So very little is known about Ctenella, and all representing the wider (and less easily that is comes from Charles’ sterling work in accessible) archipelago. recent decades, so almost anything that we learn will add to our knowledge of the coral. It was hoped that we might find Ctenella around DG, but that was tempered by the Therefore, with the tissue samples I had very real expectation that was it was highly collected, I fervently hoped I might be able to unlikely we would do so. Fortune however extract enough DNA to sequence its genome– favours the brave, and only our second and some months later, by incredible good dive of the expedition, at the seaward side

Figure 2 © Bryan Wilson/University of Oxford Figure 3 © Margaux Steyaert/University of Oxford/ZSL

6 7 of Barton Point at the northern end of the of the expedition joined us on the Grampian of Ctenella (Figure 5), dark-coloured and queer, my body tingled. I stood as if stricken island, we dropped over the boat’s side into a Frontier and we sailed northwards and up apparently healthy. to stone.”1 rough swell and literally on top of the largest through the archipelago. Ctenella colony I had yet seen, a full and As my heart began to race, Margaux spotted And on what was my first dry St Patricks beautifully coloured hemisphere likely five to My sombre mood was exacerbated by another–and then two more several metres Day in decades, as our inflatable made its ten years old, an incredible sight to behold. distressing reports that were beginning to further along. steady way back to the Grampian Frontier come in from around the globe that a novel for a journey home to a suddenly uncertain From one of the leading edges of the colony, coronavirus had taken hold in an increasing All in all we spotted some fifteen colonies world, I elatedly realised that I knew exactly I took a small tissue sample as before (Figure number of countries and that national borders in that hundred metre swim back to the boat, how he felt that day in 1938. And that I’d been 3), whilst warily looking over my shoulder at were suddenly springing shut worldwide. my depleted air supply diminishing faster awaiting that feeling my entire life. a large grey reef shark lurking almost out of still in the heady rush of my childlike sight some thirty metres behind in the gloom Two days before the expedition was excitement as we swam overhead just below Where there was none before, there is real (Figure 4). summarily aborted and we were ordered to the surface, in what to my mind was an tangible hope now borne that this lagoon– make for the Maldives with unseemly haste, Aladdin’s Cave of Ctenella richer than any I and others unexplored in the archipelago– My Reef0 team (comprising Margaux Steyaert the expedition team found themselves on could have imagined. might offer a last stronghold for the species, and Vivian Cumbo) and I enthusiastically what would unknowingly be one of our last a refugia for this critically endangered and searched for more colonies in the tens of dives in the Chagos Archipelago; Middle The very fact that this happened in the last iconic coral, especially given that these metres around this colony, but to no avail, Brother Island, one of the Three Brothers in minutes of our final dive here, low on air and colonies would predate the recent warming and the earlier nascent joy of the dive soon the centre of the Great Chagos Bank. knowing that we were steaming northwards events in the region. ebbed away. the following day, unsure as to when we Margaux and I had just completed a survey of would next return, made the surface swim Where we find viable populations, there exists For this coral to survive and reproduce, Middle Brother Lagoon, a wonderfully sandy back that much more bittersweet. a chance that the coral can be conserved teetering on the edge of extinction as it is, and protected basin replete with large puppy- and recovered, and whilst that chance might there needs be a biologically viable population like grey nurse sharks, and close to our safe J. L. B. Smith (the amateur ichthyologist indeed be slight, as Charles so optimistically of colonies within suitable spawning distance air limit for surfacing, were making our way who confirmed Marjorie Courtney-Latimer’s ended his 2018 article, “...we must still try!” of each other and this sadly was not it. back along a reef wall to the inflatable boats Coelacanth discovery) once wrote of his 1 anchored nearby. feelings that momentous day, when he Old Fourlegs: The Story of the Coelacanth by J.L.B. Smith. New Indeed, no further colonies were seen in the realised what lay before him: “Although I had York: Longmans, Green & Co., 1956 surveys around DG that week, nor in the And there, in the shadows of the base of come prepared, that first sight hit me like a coming days after the remaining members the wall, were two unmistakable colonies white-hot blast and made me feel shaky and

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