Mixotrophic dinoflagellate species with low or moderate growth rates but diverse prey cause red tides globally.

Total annual net primary productions in marine and terrestrial ecosystems are similar. However, a large portion of the newly produced marine phytoplankton biomass is converted to carbon dioxide because of predation. Which food web structure retains high carbon biomass in the plankton community in the global ocean? In 6954 individual samples or locations containing phytoplankton, unicellular protozooplankton, and multicellular metazooplankton in the global ocean, phytoplankton-dominated bottom-heavy pyramids held higher carbon biomass than protozooplankton-dominated middle-heavy diamonds or metazooplankton-dominated top-heavy inverted pyramids. Bottom-heavy pyramids predominated, but the high predation impact by protozooplankton on phytoplankton or the vertical migration of metazooplankton temporarily changed bottom-heavy pyramids to middle-heavy diamonds or top-heavy inverted pyramids but returned to bottom-heavy pyramids shortly. This finding has profound implications for carbon retention by plankton communities in the global ocean.

A novel bacterium, strain SJAQ100^T, was isolated from a freshwater aquarium and was characterized taxonomically and phylogenetically. Strain SJAQ100^T was a Gram-stain-negative, aerobic, rod-shaped and non-motile bacterium. The strain grew optimally with 0 % NaCl and at 25–37 °C on Reasoner's 2A agar. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the strain SJAQ100^T clustered with members of Burkholderiales incertae sedis in the order Burkholderiales , but sequence similarities to known species were less than 96.5 %. The genomic DNA G+C content of strain SJAQ100^T was 71.2 mol%. Genomic comparisons of strain SJAQ100^T with species in the order Burkholderiales were made using the Genome-to-Genome Distance Calculator, average nucleotide identity and average amino acid identity analyses (values indicated ≤22.1, ≤78.1, and ≤68.1 % respectively). Strain SJAQ100^T contained C_16 : 0 and C_16 : 1  ω7c/C_16 : 1  ω6c as major fatty acids and Q-8 as the major quinone. The major polyamines were putrescine and cadaverine. Strain SJAQ100^T contained phosphatidylethanolamine and diphosphatidylglycerol as major polar lipids. Based on the genotypic, chemotaxonomic and phenotypic results, strain SJAQ100^T represents a novel genus and species, Aquariibacter albus gen. nov., sp. nov., which belongs to order Burkholderiales and the class Betaproteobacteria . The type strain is SJAQ100^T (=KCTC 72203^T=CGMCC 1.18869^T=MCC 4385^T).

Microcystis aeruginosa is a major cyanobacterium that can secrete toxins, such as microcystin, and causes harmful algal blooms. Despite extensive research on the effects of microcystins on other organisms, research on how introduced M. aeruginosa into estuaries affects marine phytoplankton is scarce. In this study, the effect of M. aeruginosa on the growth of seven representative marine phytoplankton species that inhabit estuaries was determined. The marine phytoplankton species differed in their responses to M. aeruginosa ; of the seven species, the growth rate of Akashiwo sanguinea was the most affected by M. aeruginosa cells and filtrate. Moreover, our results revealed that M. aeruginosa affected the growth rate and photosynthetic efficiency of A. sanguinea in a density‐ and time‐dependent manner. Our findings suggest that M. aeruginosa may alter the phytoplankton community structure in estuarine ecosystems.