51²è¹Ý

Our team of researchers recently returned from Low Isles, where we walked over ten kilometres a day carrying, hammering and climbing through mangroves.  

Our visits to the northern Great Barrier Reef reveal that mangroves are expanding on many of the islands. We spent the week setting up stations to monitor an expanding forest of Rhizophora mangrove trees. At times we have joked about our ‘mangrove bootcamp’ as we carried 25-kilogram bags of cement and manoeuvred unwieldy aluminium planks through a dense climbing frame-like network of curved Rhizophora roots.  

Low Isles is an island with a lengthy history of mapping. Ninety years after the first scientific expedition, we have returned, armed with the long cartographic record to better understand how and why the mangrove forests are expanding. It is a good news story at a time when rising seas are driving dramatic change on reefs.  

The Great Barrier Reef has been variously imagined down the centuries as a mortal danger, an endless source of bountiful oceanic resources, a scientific mystery and a vulnerable ecosystem. People who picture the reef conjure idyllic white sands, rippling blue ocean and palm trees. But these islands are some of the most forlorn places I have visited. Often the only signs of human occupation are graves, tumbledown huts and worn plastics that have survived ocean crossings only to be thrown up onto the beach and pummelled by tides, waves and sun exposure. Human fates are closely aligned with the rest of the animals trying to survive in this unforgiving landscape. 

This is one of many mangrove islands I have walked around with fellow researchers on the northern Great Barrier Reef. Crocodiles have loomed large in our conversations and minds on each visit. On our first day of work, there was a sudden thrashing of water behind my back and my companion screamed. For a moment I stood unable to move, holding a heavy tube of steel rods across my shoulders with one leg on either side of a tall mangrove root. I was convinced that immediately behind me was the gaping mouth of a crocodile. It turned out to be a baby shark, surprised by our presence. I began to pay attention to the wealth of wildlife around us after the incident. Pelicans and masked boobies vied for fish in the shallows, whelks in conical shells dotted the mud surface and corals shimmered in the most unlikely mangrove swamps. 

Our visit to Low Isles follows in the footsteps of some well-known scientists. Maurice Yonge published A Year on the Great Barrier Reef about his time leading the 1928-29 Great Barrier Reef Expedition, which was based at Low Isles for 12 months. It was the first time scientists had stayed put on a coral reef so long. They built expedition huts, improvised scientific instruments and walked the reef daily collecting specimens, measurements and observations with thorny scientific questions at the forefront of their minds. Their intention was to unravel the mystery of how corals survive to build such large limestone reef structures by understanding the animals and plants living on the reefs, and answer some basic biological questions about how corals reproduce, develop, grow and feed. These were some of the first scientists to treat the reef as a natural laboratory and significant scientific advances were made on every front. 

In 1929, Sidnie Manton, a twenty-six-year-old female scientist, joined the Low Isles Expedition for four months to survey the marine creatures that lived above and underwater. She used a primitive dive helmet supplied by air pumped from the surface to make Australia’s first detailed underwater observations of coral along a reef front and establish how coral species change with depth. In doing so, Manton established records that would later become a baseline for evaluating long-term change, both in detailed coral reef communities and through mapping the islands and mangroves. Manton’s published diaries reveal that she rarely stopped, waking before sunrise to work sections of a traverse in the right tidal conditions and mapping on days when the sea was rough. Manton worked tirelessly and enjoyed life in the field, continually remarking on her health, ‘never have I flourished so exceedingly as here’ and describing a trip to the outer reef as the best day of her life. 

Philosophers, poets and nature writers have long championed the idea of walking as a means to think. To walk in a wilderness in which your fate is intertwined with the wildlife around you is a humbling experience. The nature philosopher Val Plumwood, who herself survived a crocodile attack in northern Australia, described how the experience shifted her perception of herself as a human in the world. Plumwood argued that by separating themselves from nature, humans get a false sense of our own character, distorting our perceptions of, impoverishing our relations with and making us insensitive to dependencies and interconnections in nature.  

Islands are attractive places to work. They are neat, self-contained landscapes where geography plays out in front of our eyes as we walk the full range of aspects from the windward to the leeward around their shorelines. Often, we carry the voices of those who have walked before us in our heads. The combination of hard physical graft, the feeling of being at one with the wildlife around us and the changing landscapes captured over time in maps is a recipe for developing ideas about nature. Time spent walking in wild places is a gift, precious to the mind and body. For all these reasons, Low Isles is a special place to visit. 

This is a diary extract by Sarah Hamylton from a fieldtrip undertaken in July 2022 with colleagues from the School of Earth, Atmospheric and Life Sciences, including Professor Kerrylee Rogers, Dr Jeff Kelleway, Dr Emma Asbridge and PhD candidate Brooke Conroy.  

Sarah Hamylton is an Associate Professor in the UOW School of Earth, Atmospheric and Life Sciences (SEALS). Her research explores how islands form and change over time and how humans engage with them.