DISTRIBUTION, SIZE AND BACTERIAL-COLONIZATION OF TRANSPARENT EXOPOLYMER PARTICLES (TEP) IN THE OCEAN

The distribution, abundance, and size spectra of transparent exopolymer particles (TEP) generated from excretion products of phytoplankton were investigated. TEP was found at all stations studied, but abundance and total quantity of TEP varied by 4 orders of magnitude among coastal, slope and oceanic environments. Abundance and size distributions of TEP appeared to be related to plankton composition. Abundance tended to be higher in coastal and shallow waters compared to oceanic and deep waters respectively. The average size of TEP was appreciably larger at stations where diatoms dominated phytoplankton. Size distributions of TEP generally followed a power-law function, except when aggregation dominated interaction of particles. The type of size distribution of TEP may allow us to predict the tendency of a plankton community to aggregate. General differences in the shape of size spectra of TEP indicate TEP generated by diatoms to be stickier and more fractal compared to TEP generated by non-diatom plankton. All TEP were colonized by bacteria, but no correlation was found between numbers of attached bacteria on individual TEP and the respective size of TEP. Bacteria density on TEP, however, decreased with increasing size of TEP exponentially. Between 2 and 25% of the total bacterial population were attached to TEP. Total number of bacteria were not correlated with total quantity of TEP, suggesting that no simple overall relationship exists between TEP and bacteria.