Finding coral species on Curaçao becomes increasingly difficult for UvA master’s students
Every year, students of the UvA master’s in marine biology go diving on Curaçao to identify coral species and to learn techniques for underwater research. But that is becoming increasingly difficult with the decline of coral reefs. “It’s shocking to see.”
One of the spots UvA PhD student Esmeralda Alcantar always visits when doing fieldwork on Curaçao is a reef with a huge colony of brain coral (Colpophyllia natans) in the middle. The domed coral, as its name suggests, is shaped like a brain and is common in the Caribbean. By last January, this brain coral had completely died off.
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Students of the UvA’s master’s program in Coral Reef Ecology saw a the progressive decline of Caribbean coral reefs in early January. In addition to climate change and overfishing, Curaçao’s reefs have recently been affected by a new disease from Florida that has been spreading through the Caribbean from Florida since 2014 and has also been rampaging Curaçao since last August. “It’s shocking to see.”
Last year, the reefs were hit extra hard by bleaching. Coral bleaching is caused by temperature increases and sunlight, among other things. Corals are bleached every year and usually recover, but last year’s summer was so hot that the sea surface rose to for just above 30° C, resulting in a fair amount of coral mortality.
In addition, an infectious disease has also been circulating in the Curaçao since August called stony coral tissue loss disease. It was first discovered in Florida in 2014 and has already affected more than 20 species of corals in the Caribbean since April. The disease is identifiable by leopard-like spots that quickly spread across the coral.
A centimeter a day
This happens incredibly quickly. Master’s students already showed in a small study that the disease can spread across the surface of a coral colony at a rate of one centimetre a day. In a matter of weeks, a coral colony can die from the disease.
When the disease first appears on a coral, it can help to treat the coral with an antibiotic paste. “Last summer all the diving stores in Curaçao helped apply that paste,” says UvA PhD student Kelly Latijnhouwers, who lives in Curaçao and works with the corals every day. “That helped, but because coral bleaching was so extreme last year, we still have to wait and see how much effect this treatment will have over time.”
UvA researchers mainly work on reef recovery by breeding and releasing new corals. “But that doesn’t solve the cause of death,” Latijnhouwers sighs. “We are developing tools to examine corals, breed them, and find out what is going wrong. That’s all we can do. In the end, we can’t solve climate change; policies must change to save the reefs.”
Years away
Seeing this decline is depressing for the PhD’s. Also master’s students who come to Curaçao mainly to see the coral species they want to study. Alcantar says: “We are now reaching a point where it becomes difficult for students to do determination assignments properly. Some coral species that used to be common here before, are hardly found in some places anymore.”
The PhD students hope for a less intense heat wave in the area next summer. Latijnhouwers says: “One bright spot is that not all coral species are affected by the disease, and the young corals we have released in recent years have survived the bleaching and the disease because they were shaded by larger reefs. But before these young corals grow into a coral the size of an adult brain coral, we are years away.”
