Dissolved organic matter (DOM) in the ocean represents approximately 662 billion tons of carbon, about 200 times more than the living biomass. It is produced mainly by microbial primary production. The largest fraction of this DOM is old (>weeks to months) and both chemically and biologically recalcitrant. The remaining fraction is young (seconds to weeks), more labile, surface-active, and powerfully changes the rheological properties in the bulk water and bordering interfaces, including the sea surface microlayer. Correlations have been observed between in situ phytoplankton concentrations and rheological thickening, with the greatest viscosity increases measured in blooms of harmful algae such as Phaeocystis spp., Karenia mikimotoi, K. selliformis, and Margalefidinium polykrikoides. Surface foams and increased viscosity and elasticity also occur in blooms of other microalgae and cyanobacteria. Living microplankton genomes (PGs) control the production and release of the main DOM molecules, largely polymeric complexes. The properties of ocean water and its interfaces and its biogeochemical fluxes may thus be engineered by PGs. These fluxes influence ocean and atmospheric climate. Viral infection may modify prokaryotic and eukaryotic genes and their expression. Therefore, these ocean PGs and the fluxes and microclimates they influence may be subject to Darwinian-type selection. Research programs need to integrate ocean ecology, rheology, biogeochemistry and genomics, to find the associations among them. High-biomass harmful algal blooms may be notable eco-engineers, where the effects of eco-engineering, exopolymers and causative DNA are likely to be spatially associated and thus easy to study.
Jenkinson et al. (Fri,) studied this question.