Coral reefs are the rainforests of the sea floor, providing some of the most biologically diverse habitats in the world to a multitude of marine species. Fisheries across the tropics are supported by reef fish which find a safe haven to live, lay eggs and raise their young among the intricate three-dimensional structures of the coral. Reefs also protect coastlines from erosion by high energy waves. A 2015 assessment of the value of natural assets found coral reefs to be worth six trillion pounds a year in services they provide for people (almost four times as much as the UK economy). Since his youth, Jahson Alemu I has both loved nature and felt deep affinity for the ocean. Now, as a marine biologist, he has combined these interests, bringing this passion and his experiences in the Indian Ocean, on the far-off island of Rodrigues back to his home country, and turning them toward the mission of preservation. Jahson’s research involves studying the health and resilience of Tobago’s reefs and demonstrating the benefits of conservation. His ultimate goal is to generate precise data so that leaders can make informed, practical decisions in the best interests of both the island’s ecosystem and its people.

NIHERST interviews Jahson Alemu I

Q: What were the early influences that fuelled your interest in science?
A: I was born and bred in Chaguanas. My mum was a seamstress and my dad was a craftsman working with materials such as calabash and leather. I spent a lot of time at my grandmother’s home in Mamoral, in Central, at the base of the Central Range which was heavily forested at the time. I used to hike through trails and play in ponds with my cousins. I went to Montrose Government Primary School, then St Mary’s College, where I joined the Sixth Trinidad Sea Scouts. They taught me how to swim, kayak, snorkel, sail and row and gave me this love for the ocean. In 2002, I entered The University of the West Indies, to do a first degree in Biology with minors in Zoology and Environmental Biology. In my second year, I visited Tobago for a week with friends and learned to scuba dive. I was studying ecology before, but after that the ocean was my niche.

Q: What would you count among your most rewarding research to date?
A: One of my proudest achievements has been the work I did at Shoals Rodrigues – an NGO on Rodrigues Island in the Indian Ocean. It’s part of Mauritius – same size and population as Tobago and even has a governmental system modelled after Tobago’s. I went there to study reef fish populations and connectivity among different habitats. By the time I left, we were working towards the establishment of a Marine Protected Area Network of four MPAs for Rodrigues. Other research included coral reef resilience to ocean warming and the impact of the invasive lionfish to Trinidad and Tobago and even amphibian health.

Q: What is an MPA Network?
A: An MPA refers to a marine protected area. This is an imaginary box in the ocean, managed to protect all within it. However, fish and the other animals living in the ocean don’t know that the box is there so they move in and out freely to neighbouring habitats. An MPA Network is a series of MPAs spread over a large area in such a way that they not only protect areas of high biodiversity (such as coral reefs) but also protect the connectivity of animals to other habitats. Wrecks are similar. When a ship sinks, this is a blank slate habitat and a whole bunch of organisms can live on it away from the competition of the existing ecosystem. Marine Protected Areas protect organisms from fishing so they can feed, reproduce and survive, but extra organisms can spill outside of the protected area, so people who need to fish aren’t left with nothing. But if we want to spread our reef and increase the viability for fisheries, we put artificial reefs outside (similar to sinking a wreck) so we provide more living space and facilitate greater reef growths. So for example, fish live and forage in coral reefs but might find mates and reproduce on a distant reef or habitat. By protecting both areas, the connectivity is maintained ensuring the protection to the entire life cycle of the fish. Overfishing was a major issue in Rodrigues and unfortunately the livelihood of most of the island’s population was directly or indirectly connected to fishing, especially sea cucumbers and octopuses for commerce. Through a community-driven process that had started before my arrival there, the communities identified what they wanted to protect and we helped them identify where would be the best locations that might encourage the rehabilitation of the reef populations.

Q: How did this experience impact your later studies?
A: This was my foundation for marine research and working with communities. Honestly, while I knew we had an MPA in Buccoo, I didn’t know much about it. On returning home, I couldn’t help but compare and contrast Mauritius and Rodrigues to Trinidad and Tobago and we were three MPAs behind. Since then, my vision has expanded and focused on ecosystem conservation, so whereas in my formative years in research I was more interested in species level research, I am now interested in ecosystems and the conservation of the services they provide (such as fisheries and coastal protection). As a result, as part of my doctoral programme at the UWI, I am linking the continued provision of coral reef goods and services to human well-being and disaster risk reduction in Tobago.

Q: How does Tobago’s reef compare to Rodrigues’?
A: It’s not comparable at all. The diversity of the Indian and Pacific oceans dwarfs anything I have seen in the Caribbean, although the reef in Bonaire comes close. There is so much diversity there in terms of number of species, forms, function and colour. Corals in the Caribbean are not as diverse or as colourful but they are equally interesting. At one point, mean coral cover (coral cover is an index by which reef scientists measure reef health) in the Caribbean measured over 60 per cent and were dominated by large elaborate “antlers” of elkhorns and staghorns. Today, coral cover is much lower and averages around 20 to 25 per cent. Caribbean reefs are on a general downward trajectory but I don’t believe all is lost. On a coral reef optimism scale with -5 being Caribbean corals are doomed and +5 being Caribbean coral reefs have a chance, I’d put it as a +3. It is unlikely our reefs will look like those in the Indo-Pacific, but the uniqueness of what we have here is undeniable and a lot of effort is being put into protecting it.

Q: What exactly is coral?
A: Coral is like a jellyfish that doesn’t move and is attached to the sea floor. It as an animal closely related to jellyfish and sea anemones and the individual coral organism is called a polyp. The coral polyp secretes calcium carbonate (basically chalk but in the marine environment it’s called aragonite) which becomes its outer protection or exoskeleton which is what most people think of when they talk about “coral”, not the polyp inside. The polyps reproduce asexually and then we get a coral colony which is what we see on the reef. Within the polyps are tiny
single-celled plants called zooxanthellae, which have a symbiotic relationship with the coral polyps so they produce food for the corals and the coral provide shelter and raw materials for photosynthesis.

Q: Why are reefs important in marine ecology?
A: Over 25 per cent of the world’s fish diversity and over 10 per cent of the world fisheries are associated with coral reefs, and over 500 million people are dependent on this tiny bit of the sea floor for food, income and other goods and services. Coral reefs are essential habitats for a wide range of organisms such as fish, turtles, corals and sponges for breeding, feeding and protection from predators. The diversity in coral reefs is so high that they
are referred to as the rainforests of the sea. However, they are quite vulnerable to the negative impacts of environmental change. Recognising this, many marine scientists spend a lot of time researching and advising management actions, trying to conserve, protect or build resilience within coral reefs.

Q: You mentioned threats to reefs in Tobago. What are some?
A: Overfishing, coastal development and climate change stand out. Important to the survival of any coral reef is the maintenance of key ecosystem functions such as herbivory- by animals such as parrotfish and sea urchin which is important in preventing corals from being overgrown by algae. (Think of it as lawn grass over growing your prized rose bush, and regularly mowing the lawn prevents the overgrowth). However, the over-harvesting of reef fish over the decades has resulted in fewer and less effective grazers (herbivores), in turn reducing the resilience of coral reefs. Coastal development is critical to the economic and developmental demands of Tobago. However, in some cases, poor coastal development practices such as hillside slash-and-burn and incompatible coastal development uses have resulted in large amounts of sediment and nutrients washing over reefs, both physically smothering corals in some cases and inhibiting sunlight from reaching corals which is needed for their survival.

Climate change presents two problems, ocean warming and ocean acidification which exacerbate the other threats. Corals in this region have a narrow upper temperature tolerance of 28 to 29 degrees F. If water temperatures are maintained above this upper threshold for a prolonged period, coral bleaching events can occur. Coral bleaching refers to the whitening of corals as a result of the temperature induced expulsion of the symbiotic algae from the coral. The algae give most corals their colour and without the algae what we see is the white exoskeleton through the transparent polyp. While corals can survive in a bleached state where they catch food in the water, they will eventually die if the bleaching is prolonged. As much as 90 percent of the coral’s food can come from the algae, so if that bleaching is prolonged, the polyps starve. If cooling occurs in sufficient time, the algae can re-enter the corals. Already we’ve noted in Tobago, that some species die within weeks of prolonged and severe ocean warming, whereas others are more resilient and can survive for much longer and recover.

The second major issue associated with climate change is ocean acidification. This is more a long-term concern which results in most shell animals or animals which require calcium carbonate having less available, resulting in weaker shells and skeletons. Climate change is probably the greatest threat facing our reefs as the resolution to this problem requires global action whereas the other can be resolved through local management.

Q: And in terms of those areas that are within our reach, are we managing well?
A: I don’t think so, at least not in a meaningful way. The threats are complex and the management solutions are equally challenging to implement. But in a small country like ours, socio-economic development needs often take priority. Consider that 55,000 to 60,000 people live in Tobago, most of who live and work in the southwest. Housing, industry, commerce, trade and education are all developmental needs required in that area. Development of the coastline has a real impact on marine ecosystems, removal of mangrove for housing can increase the amount of sediment getting onto reefs, and the removal of mangroves destroys the necessary habitat for juvenile fish and shellfish populations such as grouper, snapper, parrotfish, shrimp and lobster. It is a difficult job reconciling developmental needs with environmental protections. However, the general well-being
of everyone rests upon the sustainability or the health of the environment. The biggest house can’t replace clean air.

Q: What are you currently working on?
A: For the last four years I’ve been monitoring the health of reefs and studying resilience characteristics− which species seem better able to survive or adapt to climate change impacts and which won’t. We may lose some and keep others. We don’t see elkhorns and staghorns as much but other species may become equally as important.

I’ve also been studying an invasive alien species of Pterois commonly known as lionfish. Lionfish are a new threat to Caribbean reef. With no natural predators or natural disease in this region, a voracious appetite, prolific reproduction and of course, venomous spine, they have an ominous presence on our reefs. They aren’t aggressive and won’t attack and chances are if you get stung by one, it would be accidental. Most people experience intense
pain at the site of puncture and, in a worst case scenario, some persons may be allergic to the lionfish venom and go into anaphylactic shock, much like from a bee sting. Regardless of the reaction, you should always seek professional medical attention. We’ve been educating the public through workshops, news articles, outreach programmes and culling events. In the wider Caribbean, researchers have been trying to encourage other predator
species to start hunting lionfish, but with limited success so far.

Lastly, I’m working on linking coral reef ecosystem services to coastal zone planning. This is a bit complicated, but the idea is to model and quantify the services that coral reefs provide, such as coastal protection from storm surge, and weigh that against the short-term benefits we derive from coral reefs such as tourism and fisheries under different management and climate change scenarios.

Q: Would you recommend a career in your field to a young person?
A: Definitely. Everyone asks what they need to study, which is great, and it would include biology, geology and chemistry. But beyond that, they need to get as much practical experience as they can. Volunteer at local research institutes or at universities or with NGOs and visiting researchers. There are lots of internship programmes, some of them you pay for, others pay you. Invest in yourself. Learn to scuba dive or swim. You know people are serious when they volunteer and they come to you knowing what they are about. We definitely see the world differently from underwater.