Mixotrophy in the Marine Plankton

Abstract

Mixotrophs are important components of the bacterioplankton, phytoplankton, microzooplankton, and (sometimes) zooplankton in coastal and oceanic waters. Bacterivory among the phytoplankton may be important for alleviating inorganic nutrient stress and may increase primary production in oligotrophic waters. Mixotrophic phytoflagellates and dinoflagellates are often dominant components of the plankton during seasonal stratification. Many of the microzooplankton grazers, including ciliates and Rhizaria, are mixotrophic owing to their retention of functional algal organelles or maintenance of algal endosymbionts. Phototrophy among the microzooplankton may increase gross growth efficiency and carbon transfer through the microzooplankton to higher trophic levels. Characteristic assemblages of mixotrophs are associated with warm, temperate, and cold seas and with stratification, fronts, and upwelling zones. Modeling has indicated that mixotrophy has a profound impact on marine planktonic ecosystems and may enhance primary production, biomass transfer to higher trophic levels, and the functioning of the biological carbon pump.

Coccolithoviruses: A Review of Cross-Kingdom Genomic Thievery and Metabolic Thuggery

“…HGT could have occurred in situations where the genetic material of EhVs and bacteria co-occurred during virus replication. It is possible that EhVs and bacteria share, at moments, the same intracellular environment within E. huxleyi , particularly in light of recent data highlighting the importance of mixotrophy in phytoplankton [88]. For instance, in another NCLDV (i.e., Cafeteria roenbergensis virus), a 38-kb genomic region was suggested to be bacterial in origin and possibly acquired during an infection of its microflagellated grazer host that often contains a phagocytosed bacteria in its cytoplasm [89].…”

Microbial Eukaryote Diversity and Activity in the Water Column of the South China Sea Based on DNA and RNA High Throughput Sequencing

“…If fast-sinking is the reason for the presence of photoautotrophic cells in the deep sea, their sinking rates must either be much faster than expected (some of these cells were within the pico-sized fraction), or they can survive in the dark for much longer than previously realized. Furthermore, we cannot rule out the possibility that some of these photoautotrophic microbial eukaryotes are facultative heterotrophs because mixotrophy in protists is well documented and such forms are thought to contribute significantly to biogeochemical cycles in the oceans globally (Mitra et al, 2014; Worden et al, 2015; Stoecker et al, 2016). If the latter is the case, there are at least two possibilities that need to be investigated in further studies: (1) that these cells come from the surface layers sink to the deep sea and survive by phagotrophy (e.g., grazing on prokaryotes), or; (2) they are endemic in the deep sea and act as grazers in the microbial loop.…”

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

“…The competitive advantage of phagotrophic species when dissolved nutrients are low has been shown in experimental studies (Isaksson et al, 1999;Katechakis & Stibor, 2006;Palsson, 2004) as well as in studies comparing aquatic systems of differing trophic status (Saad, Unrein, Tribelli, L opez, & Izaguirre, 2016;Stoecker, Hansen, Caron, & Mitra, 2017). The competitive advantage of phagotrophic species when dissolved nutrients are low has been shown in experimental studies (Isaksson et al, 1999;Katechakis & Stibor, 2006;Palsson, 2004) as well as in studies comparing aquatic systems of differing trophic status (Saad, Unrein, Tribelli, L opez, & Izaguirre, 2016;Stoecker, Hansen, Caron, & Mitra, 2017).…”