Diatom resting stages can remain viable in sediments for decades and germinate when exposed to suitable environmental conditions, inoculating the water column and the surface sediments with new populations of cells. Classical methods, based on acid-cleaning of diatom frustules in sediment samples, do not discriminate between living and dead cells and may destroy the more fragile taxa. We used a metabarcoding dataset based on t...

Dinoflagellates constitute an abundant and diversified component of marine plankton, mostly associated with stratified conditions typical of late spring through autumn in temperate regions. Yet, difficulties with the identification of many species limit the knowledge of their composition and seasonal succession. Here we use a 3‐year V4‐18S rDNA metabarcoding dataset (4,366,007 reads, 4650 Amplicon Sequence Variants, ASVs) coll...

The presence of phytoplankton parasites along the water column was explored at the Long‐Term Ecological Station MareChiara (LTER‐MC) in the Gulf of Naples (Mediterranean Sea) in October 2019. Microscopy analyses showed diatoms dominating the phytoplankton community in the upper layers (0–20 m). Metabarcoding data from the water column showed the presence of Chytridiomycota predominantly in the upper layers coinciding with the...

Diatoms are photosynthetic microorganisms playing a key role in the functioning of aquatic ecosystems; they are at the base of the food web and are the main drivers of biogeochemical processes. These microalgae have a unique diplontic life cycle in which the vegetative phase entails a cell size reduction that would lead to the extinction of the cell population if the size was not restored, usually by sexual reproduction. The s...

Pseudo-nitzschia is a widespread genus of marine pennate diatoms comprising 58 species of which 28 can produce the neurotoxin domoic acid, causative of Amnesic Shellfish Poisoning (ASP). Species of the genus are found in both oceanic and coastal waters where they can form large blooms. The timing and magnitude of blooms is generally described based on water samples collected at the surface, while limited information is availab...

Summary High‐throughput sequencing (HTS) metabarcoding is commonly applied to assess phytoplankton diversity. Usually, haplotypes are grouped into operational taxonomic units (OTUs) through clustering, whereby the resulting number of OTUs depends on chosen similarity thresholds. We applied, instead, a phylogenetic approach to infer taxa among 18S rDNA V4‐metabarcode haplotypes gathered from 48 time‐series samples using the mar...

The internal organization of plankton communities plays a key role in biogeochemical cycles and in the functioning of aquatic ecosystems. In this study, the structure of a marine plankton community (including both unicellular and multicellular organisms) was inferred by applying an ecological network approach to species abundances observed weekly at the long‐term ecological research station M are C hiara ( LTER ‐ MC ) in the G...

Whereas it is accepted that the population dynamics of higher organisms is strongly grounded in life history processes, such as the time taken to mature and reproduce, regulation in the abundance of aquatic protists is generally attributed to proximate properties of the environment in which they grow. We used 10 yr of data from the Gulf of Naples to determine the life history of a planktonic diatom, Pseudo‐nitzschia multistria...