Regime shifts between free-floating plants and phytoplankton: a review.

DE TEZANOS PINTO, PAULA; O'FARRELL, INES

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2014

0018-8158

Field studies evidence shifts between phytoplankton and free-floating plant regimes; yet, it is unclear what drives these shifts and if they are critical transitions (alternative stable states). In this review, we synthesized field and experimental data on free-floating plants (of varying size and phylogenies) and phytoplankton regimes, to assess the effects of these producers on the environment. Nutrient rich environments promote free-floating plants dominance ?regardless of life form?, which causes dark, and anoxic environments, and nutrient release from sediments. This reinforces free-floating plants dominance, but controls phytoplankton biomass by strong shading (despite high nutrients and low grazing). Phytoplankton dominance renders turbid and oxygen rich (when producing) environments. We also searched for case studies of regime shifts for free-floating plants and phytoplankton dominance. Most studies showed that when free-floating plants dominance was interrupted, phytoplankton biomass (usually Cyanobacteria) rose steeply. Likewise, when phytoplankton-dominated, the development of dense mats of free-floating plants cover usually controlled phytoplankton. Field evidence that suggest critical transitions include abrupt regime transitions in time and space; yet, evidence including indoor controlled experiments and mathematical models are needed for conclusive evidence of alternative stable states to be drawn.