Substrate-Controlled Succession of Marine Bacterioplankton Populations Induced by a Phytoplankton Bloom

TLDR

Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea, observing a dynamic genus‑level succession. Distinct carbohydrate‑active enzyme expression and phosphate acquisition strategies showed that Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria specialize in successive decomposition of algal‑derived organic matter, creating ecological niches that allow specialized populations to bloom and avoid extinction by direct competition.

Abstract

Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea and observed a dynamic succession of populations at genus-level resolution. Taxonomically distinct expressions of carbohydrate-active enzymes (transporters; in particular, TonB-dependent transporters) and phosphate acquisition strategies were found, indicating that distinct populations of Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria are specialized for successive decomposition of algal-derived organic matter. Our results suggest that algal substrate availability provided a series of ecological niches in which specialized populations could bloom. This reveals how planktonic species, despite their seemingly homogeneous habitat, can evade extinction by direct competition.