A seven-year study in the Bay of Banyuls (North Western Mediterranean Sea) shows that despite some fluctuating environmental conditions, many microbial taxa displayed significant yearly rhythms.
The ISME journal 13:388-40,
We used DNA metabarcoding of the 18S rRNA gene and particle interceptor traps (PITs) to characterize the taxonomic composition of particles sinking out of the photic layer in the California Current Ecosystem (CCE), a productive system with high export potential. Sequences affiliated with Radiolaria dominated the eukaryotic assemblage in fixed traps (90%), with Dinophyta and Metazoa making minor contributions. The prominence of Radiolaria decreased drastically in live traps, possibly due to selective consumption by copepods, heterotrophic nanoflagellates, and phaeodarians that were heavily enriched in these traps. Our findings identify Radiolaria as major actors in export fluxes in the CCE.
Bolidophyceae contains species with cells surrounded by 5 or 8 silica plates (Parmales) as well as naked flagellated species (formerly Bolidomonadales). Bolidophyceae share a common ancestor with diatoms. This review summarizes the current information on taxonomy, phylogeny, ecology, and physiology.
Frontiers in Marine Science, 5:370,
The analysis of the 18S V4 region OSD metabarcoding dataset reveals that Chlorophyta are ubiquitous and can be locally dominant in coastal waters. Chlorophyta represented 29% of the global photosynthetic reads (Dinoflagellates excluded) and their contribution was especially high at oligotrophic stations (up to 94%) and along the European Atlantic coast. Mamiellophyceae dominated most coastal stations.
Scientific reports, 8:14020,
We describe RCC1774, a strain isolated from the foreshore near Roscoff (France). It is phylogenetically related to members of the Acaryochloris genus but completely lacks Chl d. Instead, it possesses monovinyl-Chl a and b at a b/a molar ratio of 0.16, similar to that in Prochloron and Prochlorothrix. It differs from the latter by the presence of phycocyanin and a vestigial allophycocyanin energetically coupled to photosystems. Its very unusual pigment content compared to other Acaryochloris spp. is likely related to its specific lifestyle.
Scientific reports, 8: 9142,
We compared the composition of eukaryotic communities using two genetic markers (18S rRNA V4 and V9 regions) at 27 sites sampled during Ocean Sampling Day 2014. Globally, the V4 and V9 regions of the 18S rRNA gene provided similar images of alpha diversity and ecological patterns.
Dinoflagellates are a heterogeneous group of protists present in all aquatic ecosystems. They play a major role as primary producers, but many species are mixotrophic or heterotrophic. Environmental metabarcoding based on high-throughput sequencing is increasingly applied to assess diversity and abundance of planktonic organisms, and reference databases are definitely needed to taxonomically assign the huge number of sequences. We provide an updated 18S rRNA reference database of dinoflagellates: DINOREF.
Symbioses between eukaryotic algae and nitrogen-fixing cyanobacteria have been recognized in recent years as a key source of new nitrogen in the oceans. We investigated the composition of the small photosynthetic eukaryote communities associated with nitrogen-fixing cyanobacteria in the Brazilian South Atlantic Bight using a combination of flow cytometry sorting and high throughput sequencing of two genes: the V4 region of 18S rRNA and nifH.
We obtained phenotypic and genetic data on a large set of prasinophyte clade VII culture strains that allowed us to clarify the taxonomy of this important marine group. We describe two novel classes, the Picocystophyceae and the Chloropicophyceae, the latter containing two novel genera, Chloropicon and Chloroparvula, and eight new species of marine picoplanktonic green algae.