Professor Alex David Rogers, Ernest Cook Fellow
Operation Wallacea (OpWall) is an education and conservation organisation providing rich learning experiences for school and university students whilst also working to conserve some of the most bio-diverse ecosystems on Earth. Oxford biologists have been working with OpWall for many years, providing our students with opportunities to work in tropical marine and terrestrial ecosystems, mainly towards their final year projects.
When OpWall began to work in Honduras just a few years ago, the Ocean Research and Conservation Group of which I am Principal Investigator, took up the opportunity to collaborate on studying the coral reefs of the region. Honduras has the dubious reputation of having the highest per-capita murder rate in the world. However, parts of the country are relatively safe to work in and with careful planning care of OpWall’s experience we have managed to establish several new research sites that we can return to year on year. Thus it was that in July, following a busy year’s teaching I left the U.K. to go to Utila, a small island in the Bay Islands group, previously a part of British Honduras (now Belize).
After two flights, a long bus journey from San Pedro Sula, the regional capital, to the coastal town of La Ceiba, and then a very rough ferry journey on the Utila Princess I arrived on the island. However, at Utila we were met by the friendly faces of the diving team and the formidable Ms Tonia, a delightful Caribbean lady who owns the Coral View Beach Resort and Dive Centre where I was to spend the next few weeks. Bags were offloaded from the ferry directly to one of the dive boats and we sped over to the quay at Coral View, set in a lagoon surrounded by mangrove forest with brown pelicans at rest on any pile or other object sticking up out of the water.
Because much of my recent work has been in the deep ocean, based on large ships, I had taken a fifteen year break from diving. My first task at Utila, therefore, was to get back in the water and complete my PADI Rescue Diver course (Professional Association of Diving Instructors). Richard and Sarah, who run the Coral-View Diving Centre, had arranged for me to take the course led by Instructor Matthew Norman and I was joined by three students: Dylan, Ellen, and Michelle. It was quite a challenge in the heat of the Bay Islands, especially after such a protracted journey, but it was extremely rewarding to cover everything from basic first aid to dealing with diver-related emergencies and practical exercises on rescuing non-breathing or otherwise incapacitated divers from the surface or the seabed. I could then turn my attention to the main purpose of the visit, which was to familiarise myself with local coral reefs and to look in detail at the work several of my students were undertaking in collaboration with Dr Dan Exton from OpWall.
Divers swim past elk horn coral, Honduras
Copyright: Alex Rogers
The Caribbean, unfortunately, has become an icon for the destruction humankind has wrought on marine ecosystems. Several centuries ago a rapacious plundering of the biological resources of what must have been a marine paradise began the extreme overexploitation of Caribbean marine life. Whales, manatees, turtles, sharks, and other fish species (including predators such as groupers and herbivores) successively disappeared. Shellfish, such as conches, also disappeared from many parts of the Caribbean as important components of reef ecosystems were disassembled by human predation.
Then, in the 1970s a less obvious reef killer appeared in the form of a disease that near wiped out the dominant shallow-water reef forming corals of the region, elkhorn and staghorn corals (Acropora palmata and Acropora cervicornis) to the point where they are now regarded as endangered species. White-band disease, as it became known, completely altered the appearance of Caribbean coral reefs but the unravelling of these ecosystems did not stop there. In 1983-4 another epidemic killed most of the population of a long-spined sea urchin called Diadema antillarum. Most people know of urchins from holidays as a menace hiding in shallow rocks that can cause painful wounds if stepped upon. Urchins, however, are efficient grazers of marine algae that prevent coral larvae from settling and growing into adult colonies. When the urchins largely disappeared – almost overnight – the last effective algal grazer was removed from many parts of the Caribbean.
Coral reefs underwent further degradation as algae came to further dominate Caribbean coastal ecosystems. Finally, in the 1990s the effects of global climate change came to bite in the form of mass coral bleaching caused by the sea becoming too warm, which further destroyed the reef ecosystems. These problems were exacerbated by the release of untreated sewage and the use of agricultural fertilisers in the Caribbean, which encouraged the growth of algae. Hurricanes have also increased the rate of reef devastation. Average coral cover declined from around 55% in 1977 to 5% by 2001.
Stags horn coral, Honduras
Copyright: Alex Rogers
This tragedy, which has unfolded largely within the space of my lifetime, is understood in its broadest terms but many aspects remain mysterious. Why, for example, did elements of the reef ecosystem, such as Diadema, not return after the epidemics that killed them off? What do Caribbean reef ecosystems look like now, how diverse are they and how are they functioning? Do the deeper parts of Caribbean coral reefs act as refugia for some of the fish and corals that are threatened by human impacts?
All these questions are now being addressed through the Oxford-OpWall collaboration with our students Vanessa Lovenburg, Dominic Andradi-Brown, Max Bodmer and Alex Kolliari-Turner. Vanessa is studying the octocorals of the Utila coral reefs. She has found a tremendous diversity of these animals which are colloquially called sea fans, gorgonians or soft corals. Vanessa is also investigating the role these animals play as hosts for other animals, whether for shelter or food, and how the associated fauna affects the corals. I joined her during several surveys of the Utila reef as well as for underwater transplant experiments involving flamingo tongue snails to try and understand more about the behaviour of this coral predator.
Dominic has trained in technical diving techniques to undertake research into the fish communities of deep coral reefs, also known as mesophotic reef ecosystems, a project funded by the Fisheries Society of the British Isles. I joined Dominic, who was assisted by Erica, a young Mexican scientist, on a survey of seabed and fish communities at 15m depth on a submarine cliff face on the North Shore of Utila. This involves filming the seabed along a 50m line to describe the distribution of animals, as well as filming the fish communities with a stereo camera. The latter enables scientists to estimate the size of fish living on the coral reef so we can estimate their biomass as well as their diversity and abundance. Dominic also deployed baited camera traps to film what fish were living below the depths to which he can scuba dive. Alex is an undergraduate student planning to do a D.Phil. on deep-reef communities.
As well as helping Dominic out on the deep fish communities project, I also took part in several dives on which lionfish were being hunted with spear guns. These Indo-Pacific animals are invasive species in the Caribbean and are causing damage to reef communities by preying on native species. Divers, led by Cape Eleuthra Institute biologist Alicia Hendrix, are trying to eliminate lionfish from the Bay Islands, while OpWall is undertaking research into what they are eating and how they are impacting ecosystems around Utila.
Max Bodmer is working on the Honduran mainland at a delightful resort called Tela. This is based on miles of white sand beach lined with coconut trees, and backs onto a lagoon surrounded by mangroves at which I watched flocks of parrots flying into roost as the sun set – a magical experience. We joined Max for two dives on the Tela reefs. These involved a beach launch of the dive boat and an eight mile boat journey to the reefs which lie offshore. The water is turbid but a thriving coral reef survives here and Max is trying to find out why. He is also trying to understand why the Diadema have not returned to Caribbean coral reefs. We joined him carrying out seabed surveys and it was here we had a close encounter with a scorpion fish, a well-camouflaged but very poisonous member of the reef fish community. The team also saw sharks and a sailfish on the days we were at Tela – unfortunately we missed these.
After visiting Max we returned to Utila for a final day of diving. My final dive was with the Reef Ecology lecturers Chelsea and Derek from OpWall; we explored some shallow sea caves off of the airport in Utila. After exiting the caves I turned and saw Chelsea making flying motions with her arms, showing the number two on her fingers and pointing off to my right. From behind a rock came two spotted eagle rays which swam slowly and gracefully right past where I was hovering, a beautiful and breathtaking sight. It was the perfect end to my visit to the Caribbean and a reminder that the coral reefs of this region still have the power to strike awe into anyone who sees them, even a seasoned marine biologist.
We need to know more about these marvellous habitats and we should be doing everything to stop them from degrading further both at international and regional levels. Both our scientists who work with OpWall and some of the local Hondurans I met are working hard to gain in understanding and enact the measures necessary to achieve this. There is much to be positive about even though the overall picture could be taken as bleak. In future years we will keep you updated on our achievements in Honduras and what they mean for reef conservation in the region.