There is an age-old battle taking place on coral reefs between slow growing corals and fast growing macroalgae. Historically corals have been victorious thanks to the combination of low nutrient concentrations in tropical coastal waters and the actions of herbivores. However, deterioration in water quality and the loss of herbivores have tipped the balance in favour of macroalgae, leading to phase shifts towards algal dominated systems, especially in the Caribbean. Damselfish have emerged as key players in this war. They kill patches of coral and use them to actively farm algae. But they are also highly aggressive, and will attack fish many times their own size who try to enter their territory. These fish that are usually only 10cm in size will even regularly attack SCUBA divers! This aggression impacts the activities of herbivores who provide a vital ecosystem service in clearing growth of macroalgae. In addition, damselfish are too small to be of value to fishers, meaning that while predators of damselfish such as groupers have been decimated by overfishing, damselfish have been able to thrive in many parts of the Caribbean. Students on this project will assess the population of damselfish in relation to herbivores and predators. They will also quantify the impacts of dense damselfish populations on nearby coral health, and could also study their aggressive behaviour towards other reef organisms. This will help improve our understanding of the disruptive role of damselfish on modern Caribbean coral reefs and explore its implications for conservation.
In the Caribbean, there are a number of core issues that have been affecting the biodiversity of coral reefs, including the mass mortality of keystone sea urchins that have allowed algal colonisation of reef areas, an invasive predator (lionfish) originally from the Indo-Pacific that has spread across the Caribbean, and overfishing of reef fish by local communities. Opwall has two marine research sites in Honduras where these issues and many more are studied: one is on the island reefs of Utila and the second on the coastal barrier reef of Tela. At both sites, teams of Opwall scientists and students collect annual monitoring data to assess temporal patterns in reef community health, alongside novel research to address key conservation priorities and gaps in our current understanding of these fragile ecosystems. Honduras is also home to Opwall’s pioneering efforts to integrate technological solutions into the monitoring and study of coral reefs, including our 3D computer modelling method. Opwall’s team of marine scientists in Honduras helps to support not only international academic research and new method development, but also supports local non-governmental organisations with their efforts to improve marine conservation in Honduras.
Climate
Our marine sites are hot and usually dry, but with occasional storms.
Fitness level required
Low. Some fitness is required if including in-water activities, but conditions are relatively easy.
Creature comforts
Facilities are comfortable but basic. There is phone signal and limited wifi that is often unreliable.
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