Fewer fish species but more sharks at Saba Bank

The Daily Herald reports that a  team of international researchers, which completed a one-week scientific expedition to the Saba Bank over the weekend, has noted a reduction of several fish species and an increase in sharks. The expedition from October 19 to 27, organised by marine ecology institute IMARES of Wageningen University and Research Centre, resulted in more than 2,000 images of the reef, and more than 5,000 fish counts of almost 100 fish species. The team worked with 33 transects of 50 metres each. A preliminary comparison with data of the previous survey in 2011 showed a reduction in snappers, groupers and grunts, while there were noticeably more sharks. There were fewer algae on the bank than in 2011. This might indicate a healthier reef. However, there appeared to be a gradient in increased algae cover towards Saba.

The international team of marine biologists led by Erik Meesters of IMARES investigated the coral reef structure, as well as the spatial variation in species assemblages and population genetic connectivity of corals, fish and sponges on Saba Bank. Corals, algae and sponges form essential components of the biodiversity of the Bank. Together they create and maintain the coral reef ecosystem which forms Saba Bank, one of the major hotspots of biodiversity in the Caribbean. Great numbers of fish species inhabit the reefs and algal plains of Saba Bank. These fish communities, which have shown a decline since 2011, provide important information on the status of the ecosystem.

The data from the fish survey, benthic images and population connectivity study will be further analysed in the Netherlands with the final results expected by mid-2014. The work of the researchers, above the water, on the Caribbean Explorer II and under water, was recorded on film as part of the series Marine Life for National Geographic TV. The expedition, a followup of the 2011 survey, was part of the Saba Bank Research Programme 2011-2016 of the Dutch Ministry of Economic Affairs.

Saba Bank is a marine protected area and acknowledged as an ecological and biological significant area. The research was part of the implementation of the Exclusive Economic Zone management plan for the Dutch Caribbean. The expedition brought together a wide range of marine specialists, mainly from the Netherlands, France and the Caribbean. Besides a number of representatives from IMARES, there were also researchers from institutes like OMMM Martinique, DÉAL Guadeloupe, CRIOBE France, Royal Netherlands Institute for Sea Research (NIOZ) CAH Vilentum University of Applied Sciences, Naturalis Biodiversity Centre, University of Amsterdam, Van Hall Larenstein University of Applied Sciences. The last four are from the Netherlands. The expedition also included two scientists from St. Eustatius: Steve Pointek of STENAPA and Erik Boman of Statia’s Department of Agriculture, Husbandry and Fishery LVV.

Saba Bank is the largest submarine atoll in the Caribbean Sea, spanning an area of 2000 square kilometres. It houses an expansive coral reef ecosystem with a rich diversity of species and as such is also an important source of commercial fish for the nearby islands. Saba Bank is the largest protected area of the Kingdom of the Netherlands after the Dutch part of the Wadden Sea in Europe. Saba Bank can be considered as relatively pristine. Environmental threats, such as climate change, sea surface temperature increase and acidification, however, also threaten the bank’s coral reefs.