Approximate size ranges of particulates in coastal waters. Particles in coastal seas encompass a wide range of particle types, both organic and inorganic, which are not necessarily restricted to any defined filter cut-off points (e.g., 0.45 µm) as indicated by the grey transition zone. Organic particles include organisms such as viruses, bacteria, phytoplankton and zooplankton, which can also aggregate to form larger particles such as macroaggregates. These organisms are also producers of macromolecules such as proteins and carbohydrates, which can anneal to larger microgels and subsequently macrogels, including, for example, transparent exopolymeric particles (TEP). Today, microplastics and nanoparticles are additional particulate components found in coastal waters. DOI: https://doi.org/10.1525/elementa.149.f1