New project aims to restore sea urchins in Saba, Statia waters

The new RAAK PRO Diadema project aims to restore the pop­ulation of the long-spined sea urchin populations (Diadem antillanim) on the coral reefs around Saba and St. Eustatius. This particular urchin was once the most important herbi­vore on Caribbean coral reefs until more than 95 per cent of the sea urchins died in 1983 due to an unknown disease.

Without their grazing the algae flourished, which then smothered the corals as well as prevented baby corals from finding clear surfaces to start growing on. This changed the coral reefs to algal beds.

More than 35 years later, these long-spined sea urchins are still very rare and only sometimes abundant in shal­low waters such as harbours.
They are seldom seen on the deeper coral reef. Worldwide, coral reefs face many threats that are difficult to tackle locally, such as global warming and ocean water be­coming more and more acidic due to absorption of carbon di­oxide. This makes it even more urgent to remove as many local threats as possible.

Increasing the number of sea urchins to numbers that existed before the die-off will success­fully remove the overgrowing algae and will make the reefs more resilient to the other threats they face.

To do this, University of Ap­plied Sciences Van Hall Lar­enstein, St. Eustatius National Parks STENAPA Foundation, Saba Conservation Founda­tion, Wageningen Marine Re­search, Wageningen Univer­sity, Caribbean Netherlands Science Institute (CNSI), Uni­versity of Applied Sciences HZ, Institute for Socio-Eco­logical Research ISER Ca­ribe, Wortel Product Design and Golden Rock Dive Cen­ter are working together in the new RAAK PRO Diadema project. The project is partly funded by the Dutch Organi­zation for Scientific Research NWO and will run for four years starting this month.

The first step to be taken by this team will be to find out why the populations on most reefs have not recovered. Ini­tial tests have found a high abundance of very small juve­nile sea urchins. Adult long­spined sea urchins were, how­ever, absent on the reefs.

The presence of these juve­niles makes one thing clear — that there is potential for the population to recover as needed. Therefore, the re­search will focus on the early stages in the lifecycle of these sea urchins.

The ultimate goal is to de­velop a new method to maxi­mize settlement and survival of larvae and juveniles and, by doing this, restore the popula­tions of this important herbi­vore, so that the sea urchins will, once more, graze away the algae and aid in the recov­ery of Saba’s and Statia’s coral reefs.

The Daily Herald.