The Trails and Trials of Dugong Research
Floating at the sea’s surface, equipped with just my mask, snorkel and flippers, I was engrossed in the lush seagrass meadow eight metres below. There were distinct, cleared, serpentine paths between the thread-like blades of seagrass, and I was hoping they were the signs I was looking for. The rest of my team, in an attempt to maximize our chances, were several metres away, breaching the vital buddy-system rule of the sea (always stay in a pair or group). We had been at this for almost a week without luck, and I was beginning to despair. I stared hard at the serpent paths below, as though I could will the creature to appear.
My focus was suddenly interrupted by a large brown object moving less than four feet away from me. At this distance, it seemed impossibly large. It looked strange, with a body like a dolphin and a head like a pig. With a creature so big, the first human instinct is to freeze, and then attempt to run. I knew that this made no sense in that vast, deep, turquoise sea. There was no place to hide. My best bet was to stay calm and focus on the lurking danger. I gave the encounter a few minutes to sink in and for my heart rate to settle. I soon realized that my new ‘swim buddy’ was not dangerous – it was a six-foot-long male dugong. I knew in my head that it was a gentle creature, but its sheer size was intimidating. It was focused on plucking as much seagrass it could in the six minutes it had been holding its breath, all the while keeping a watchful eye on me. I watched as it leisurely mowed down the seagrass meadow, leaving behind a maze of criss-cross trails completely devoid of seagrass. I was ecstatic. We could finally claim to have seen a dugong in its natural habitat. On that first day in February 2007, we swam with Alpha (our first dugong) for almost seven hours. When we finally got out of the water, it felt like we had emerged from a dream. Over the next two months, we encountered Alpha several times. He seemed to recognize us each time we met. He would cock an eye in our direction, then peacefully continue doing what he was doing while we swum alongside him.
Sighting a dugong in Indian waters is near-impossible. At some other locations around the tropics, dugongs can form large herds of tens to hundreds. Not so in India. All our large herds are long gone. The population in all three regions (Gulf of Kutch, Gulf of Mannar and the Andaman and Nicobar archipelago) have been reduced to such low numbers that they are on the verge of local extinction. To sight an animal swimming on the surface is rare. Seeing a live animal underwater is virtually unheard of. And for the animal to allow us to observe it as it went about its daily life was a privilege indeed. Our luck did not end with this lone sighting. By the end of the year, we chanced upon two more male dugongs whom we christened Lunar and Dugong 3 (the 10 minutes we spent with the last one was not enough to name him). We realized how rare an opportunity this was and our team spent months swimming with these majestic creatures – spending as many hours as we could in the water, getting to know these animals, making precious, basic behavioural observations that later went on to form the foundation of our future research. For me, this was a small vindication of a journey that started several years earlier…
The sun had just begun to reveal itself behind the small flat island of Aves, at the eastern entrance to the Mayabunder Bay. It was a calm clear day in March 2010… In the distance, we heard a rhythmic chug, as a ten-metre-long, two-metre-wide, motorized dugout dinghy, cutting through the water, approached the jetty… For the next 10 days, this would be our mode of transport and our home while we traversed up the west coast of the north Andaman Islands to survey some of the remotest and undiscovered dugong habitats. Our agenda for the expedition was simple but ambitious. Visit every location that dugongs had ever been spotted at over the last 50 years. Explore the area for seagrass meadows and check for signs that dugongs were still using those areas.
Over the last decade, our team had made several such voyages across the Andaman and Nicobar archipelago, covering most of the coastline, except for the Jarawa reserve. These revealed the presence of several seagrass meadows, some located in the intertidal zone, exposed during the ebb tide, some in the shallows, often murky and inhabited by saltwater crocodiles and some in deep waters, up to depths of almost 20 metres. A typical day would pack in four to five hours of snorkeling… Dugong grazing leaves a characteristic, meandering path in the meadow called a feeding trail, which lasts for almost 10 days after an animal has fed. This was a certain way to confirm that a dugong had visited this meadow in the last few days. Most of my terrestrial colleagues studying rare elusive animals could rely on technology… Being in a marine environment… There was no substitute for the painstaking drudgery of examining every meadow closely in the off chance that a dugong had been there in the recent past, and had left signs of its passing. Several years of these surveys and a grim picture began to emerge. In the last five decades, dugongs had disappeared from more than half of the sites where they were once common. According to our estimates, the number of dugongs based on sightings from a robust network of informants covering most of the coastal waters was less than 50, in small pockets and at low densities, clinging on to a few seagrass meadows where they could feed undisturbed.
Understanding the gardener and the garden
It was little over an hour that we had been sitting on the cool white sands of Laxmanpur beach on the island of Shaheed Dweep (formerly called Neil Island). We were staring at the flat sea in front of us. This was usual in the morning hours, and the slightest movement on the surface does not go unnoticed for up to a kilometre. We waited and watched, hoping to see the brown back of a surfacing dugong. It was the fifteenth consecutive day that we were there and I was hoping to confirm some of my initial speculations. Suddenly, I thought I saw something from the corner of my eye and I turned around, but it was gone. I waited for about five minutes, the approximate time a dugong can stay underwater, and there it was again. The tide was high, perfect to cross the shallow intertidal stretch, filled with rubble, coral and a few hardy species of seagrass, to the deeper sandy areas, where more delicate seagrasses dominated the meadow. We swam quickly to the spot and there it was, feeding on the tiny blades of seagrass. It saw us but continued eating, unperturbed. It knew who we were by now. As it approached the edges where the sandy bottom changed to rubble, and the seagrasses changed to more fibrous species, the dugong stopped feeding and turned around, making sure it wasted no time and energy on those species. It was clearly making food choices. This seemingly small observation was a confirmation of something I long believed. Dugongs, the received wisdom goes, are more sea pigs than sea cows – they will eat anything and are not very selective. What we were observing in Shaheed Dweep showed otherwise. Dugongs are quite picky and will eat rougher species only when they have no choice.
We have come a long way since 2007. We now know that dugongs eat just four of the 12 seagrass species in the Andaman and Nicobar archipelago. They choose the smaller, tender varieties that are low in fibre and high in nutrients, and uproot them from the loose or compact sandy bottoms with their strong muzzles. This leaves behind meandering clear trails through the vegetation (what we were looking for before our first sighting). On occasion, they will crop the tops of short, thicker seagrasses as well, but we observed this only in areas that were close to a preferred seagrass meadow. I suspect the animal possibly chooses these when they feel the need for fibre or when there is a scarcity of their favourite grass. By their constant feeding, they promote the growth of newer, fresher and nutritious grasses, almost like one would do to the greens in a kitchen garden. This ensures a continuous supply for themselves and a whole lot of other small animals, especially those that use seagrasses as nurseries. In the absence of this feeding, the grasses age, their nutritional values reduce and over time they lose the battle for space to seagrasses that are fibrous, low in nutrients and avoided by smaller organisms. Our network of local informants kept a watch on a few seagrass meadows that were easily accessible throughout the year. They reported individual dugongs visiting these areas almost every week, each year, for a decade. We were able to confirm these reports by visiting these sites, peeking below and checking for fresh feeding signs. For an animal that eats almost 30 kilos of seagrass daily, one wonders how these meadows infinitely supply food to these hungry dugongs. Firstly, the dugongs we know in the islands use not just one, but a cluster of seagrass meadows that are usually within a radius of a kilometre. Secondly, there are not more than three animals using each of these spaces at any given time. We know this by measuring the width of the feeding trail – the individuals we have identified all have a different sized feeding width because of differently sized mouth parts. As a result, the quantity of seagrass consumed is always less than what the meadow produces and there is always food available for the animals. Lastly, these meadows grow back to their original cover within eight to 10 days after they are grazed. In the waters of Australia and the Arabian Gulf, dugongs graze in herds of 100 to 300. The mass feeding in these regions almost wipes out the meadow requiring the animals to move to greener pastures and return only when the meadow is lush again. I think that the feeding tactics of the dugongs in the Andaman and Nicobar archipelago may be an altered strategy of the remnants of a once large dugong herd or simply normal for small isolated populations, which had not been documented before…
The changing islands
Tucked away in the southern part of the Ritchie’s archipelago, the 13.7 square-kilometre island of Neil is truly breathtaking. My first impression of this small island in 2007 was of how quaint and peaceful it was… A few years later… The hundreds of tourists visiting the islands daily soon grew to thousands. While this surely benefited the local economy, it brought with it its own set of issues. By 2018, the once idyllic island had many problems… High-speed motorboats and jet-skis over seagrass habitats posed a threat to the three dugongs around Shaheed Dweep and coastal constructions almost completely destroyed some of the nearby seagrass meadows for the dugong. In April 2019, during my visit to this island, I found that the disturbances in the water were so high during the day that the dugongs were now feeding only during the quieter hours at night. They were obviously affected by the changes in their feeding grounds. With most of the feeding grounds in and around Shaheed Dweep now heavily disturbed, my fear is that they will abandon these meadows completely and travel several kilometres north or south to reach another meadow, surviving threats from boat traffic, hunting and fishing nets along the way. The islands have changed – and I just hope that the dugongs have the resilience to keep up with this change – as they have in the past.
…Searching, finding and observing dugongs in the wild have always been the most exciting parts of my research and have been the reasons that led to the initiation of this study on a rare and elusive creature… But somewhere early on, I realized that, unlike most other marine mammals, studying dugongs was very little about seeing the animal itself. In fact, most of the findings of this study were a result of a shift in focus from the animal to its habitat, that is, the seagrass meadows. By understanding seagrass ecology, I was able to better understand dugong ecology… More people know about dugongs today than they did when this work began, and that in itself is heartening.
Our research has come a long way since my first encounter with Alpha. Three years ago, I found out that he had passed on. His carcass had washed ashore on an island in the Ritchie’s archipelago, most likely after being hit by a propeller. The loss of every dugong is a huge setback to the remnant dugongs of the island, but I still see a silver lining for this population. Dugongs, I believe, are a more resilient lot than we give them credit. Every so often I see a dugong mother with a calf. Every youngling I see tells me that the population, low as it is, is still reproducing. Perhaps one of these calves was fathered by Alpha. I can only hope that it will grow to carry on his legacy.
Elrika D’Souza is a marine biologist with Nature Conservation Foundation.
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