Spatial and temporal variation in the prokaryotic community in the Australian Tropical Ocean

Prokaryotes play a vital role in marine food webs as primary producers. However, little is known about their ecology and physiology in oceanic waters surrounding Australia. We examined the distribution patterns of pico-phytoplankton collected in the Arafura Sea, Torres Strait and outside the Great Barrier Reef in the Coral Sea in 2012 across environmental gradients and estimated their contribution to photosynthetic biomass. Flow cytometry and petB amplicon sequencing revealed that Synechococcus ecotypes were abundant in the Arafura Sea and Torres Strait, while Prochlorococcus is the dominate phototroph in the Coral Sea. Principal component analysis and Multidimensional scaling analyses were undertaken to identify the main biotic and abiotic drivers affecting microbial community composition across the sampled marine environment.