The abundance of CyanoBacterial Mats (CBMs) at a depth of 50-90m was mapped along the west coast of Bonaire. Simultaneously local conditions (i.e. nutrient concentrations, temperature, salinity, pH, and light intensity) were measured and compared with locations where CBMs were absent. Most CBMs were found near Kralendijk. Differences in temperature and salinity levels between sites with and without CBMs were found, but nutrient concentrations were similar. The species composition in samples of the deep water CBMs were compared with samples of CBMs at 15m depth. All CBMs had a rich species consortia of bacteria, averagely consisting out of 7821 different species (OTUs). The composition between shallow and deep CBMs was found to be significantly different. Moreover, a gradient was seen in the abundances of cyanobacterial genera between the different locations of deep CBMs, which suggests that all deep CBMs have a comparable species composition with different abundances adapted to the local conditions. Overall, the presence of the deep CBMs seems to be related to a combination of multiple parameters: sufficient nutrients which are likely caused by eutrophication events, a relatively flat sandy bottom and low wave energy.
keywords CyanoBacterial Mats, CBM, deep, genera, Illumina sequencing, species composition