The joys and challenges of working on a biodiversity paradise - Part One

Nature Seychelles works to protect and understand the marine ecosystem around Cousin Island Special Reserve. Two large projects have been underway in the marine reserve. Researcher, Tove Jorgensen, together with her team is investigating herbivore fish movement around Cousin Island using the latest technology in acoustic methods by tracking fish and mapping the seascape. 

"The Seychelles, and especially Cousin Island marine reserve, offer a fantastic opportunity to study this kind of science topic, since the marine protected area has been implemented for a long time and is very well protected." Says Tove.

The project is tracking the movements of rabbitfish which leave the safety of the marine reserve each full moon to spawn at a granitic offshore reef. The granitic reefs are a unique feature of the inner Seychelles and create a stable substrate for coral to attach. I have been lucky enough to visit the spawning site to assist in survey work and it really is a spectacular scene.

Of course the local fishermen also make the most of these spawning events where it is easy for them to catch a lot of fish. One of the conservation objectives is to discover where these fish- an important food source in the area but also a vital player in ecosystem health-travel and whether the current level of protection they have is enough to ensure they are harvested sustainably.

I have also been working alongside the ‘Reef Rescuers’ a team of scientific divers who have for the last three years been harvesting healthy coral fragments, rearing them in a net nursery and finally transplanting them to a degraded reef within the Cousin Special Reserve. This is the only coral transplantation project of this magnitude worldwide and the team has transplanted thousands of corals.

I have been monitoring the success of this transplant site over the past two years in comparison to two close-by control sites but you don’t need to be a scientist to see the results of the project. Over time the corals have attached naturally to the substrate and grown, providing a complex habitat for juvenile fish to shelter, securing the bases of what all reef ecosystems require, protection from predators and nutrients providing food for the complex food web.

Part of my role includes coordinating the Seychelles Seabird Group (SSG) and the Seychelles Magpie Robin Recovery Team (SMART) for various islands. The collaboration between islands is essential for maintaining a standard monitoring protocol, ensuring that population trends and breeding success can be compared on a nationwide level. Seabirds are particularly vulnerable to changes in climate patterns and can be used as indicators of ocean and fisheries health; low breeding success often reflects a lack of food availability.

Twice yearly on all the main seabird nesting islands full censuses are carried out as well as breeding success studies. This entails following a number of breeding attempts from egg laying through to fledging. This study can be tricky when nests are high or when parent birds are present. The long-term collection of data on Cousin for seabirds, land birds, reptiles and marine life is a very important tool when tackling conservation management issues, providing vital information on individual species ability to cope with environmental changes and anthropogenic impacts.

By April Burt
Conservation Manager, Cousin Island

Photos: 1) Tove inserting a tag on rabibit fish 2) taking measurements in order to assess gonad (reproductive organ) size 3) Seabird monitoring on Cousin Island