During the Deep Reef expedition in 2013 extensive cyanobacteria fields were discovered on Bonaire between 45 and 90 m depth stretching out over hundreds of meters (see picture). These fields were found at three locations on Bonaire that cover a total distance of 7km. Cyanobacteria are considered harmfull bacteria and are often an indication of nutrient enrichment. They are cause for concern as they are also found on shallow reefs where they are viewed as a sign of nutrient pollution.
Cyanobacteria can cover large parts of the bottom. They can be toxic to organisms that come in contact with them. Also they use oxygen during the night and can produce an anoxic layer where only few organisms can survive. Normally, cyanobacteria need a nitrogen rich environment. One of the questions therefore is if there is a source of nitrogen that can be detected. Potentially, there are two sources, upwelling of cold deeper and nutrient rich water or down-welling of heavy nutrient rich water from Bonaire.
Are the deep cyanobacteria fields reason for concern? Are they a threat to the coral reef? The most urgent research questions are basically where are they, who are they, are they a danger, why are they there and what are they doing there? A consortium of researchers from IMARES, NIOZ, UvA and Perpignan will study the deep fields of cyanobacteria.