Bonaire deep reef expedition I

The deep reef of Bonaire, Caribbean Netherlands, was explored with the aid of the “Curasub” submarine of Substation Curaçao. The shallow reefs of the Caribbean are considered a biodiversity hotspot, an area with exceptional diversity of plants, animals and ecosystems, yet surprisingly little is known about the flora and fauna of the deeper reefs.

Dives were made to depths of three locations on the Southern coast of Bonaire: Kralendijk,Cargill, and Statoil. Distinct depth zonations in substrate features were visible. Coral reef was observed until approximately 45m, then followed a zone of sand mixed with varying amounts of stones. At each site a wide layer of cyanobacteria mats covering sand were found spanning the depths of 90m.

The depth from 90-100m was typically dominated by sand with occasional small rocks on which fan corals and sponges resided. From 100-

150m depth fossil barrier reef and rodolith beds were observed, either in long stretches or in patches within a barren sandscape. By providing hard substrate, these fossil reefs displayed heightened biodiversity in a desert landscape of sand. Below 150m the substrate was generally dominated by fine sand. The cause of the cyanobacterial mats remains unclear. These mats are generally believed to indicate nutrient enriched (disturbed) environmental conditions, and should therefore be further studied to elucidate the cause. Trash was observed at all depths. High biodiversity was observed on the sporadic hard substrate below 100m, presumably fossil reef. In total 72 species were recorded, of which at least 15 species are new to science (shrimp, sponges, fish). The major focus was on sponges due to their importance in the deep reef in terms of diversity, filtering activities, biomass, and source of pharmaceutical compounds. A species list and picture gallery are provided in this report. This is just of subset of the true biodiversity of Bonaire’s deep reef. With the description of new species also comes a better understanding of ecosystems.

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