Seasonal dynamics of marine protist communities in tidally mixed coastal waters

Abstract

Major seasonal community reorganizations and associated biomass variations are landmarks of plankton ecology. However, the processes of plankton community turnover rates have not been fully elucidated so far. Here, we analyse patterns of planktonic protist community succession in temperate latitudes, based on quantitative taxonomic data from both microscopy counts (cells >10 μm) and ribosomal DNA metabarcoding (size fraction >3 μm, 18S rRNA gene) from plankton samples collected bimonthly over 8 years (2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) at the SOMLIT-Astan station (Roscoff, Western English Channel). Based on morphology, diatoms were clearly the dominating group all year round and over the study period. Metabarcoding uncovered a wider diversity spectrum and revealed the prevalence of Dinophyceae and diatoms but also of Cryptophyta, Chlorophyta, Cercozoa, Syndiniales and Ciliophora in terms of read counts and or richness. The use of morphological and molecular analyses in combination allowed improving the taxonomic resolution and to identify the sequence of the dominant species and OTUs (18S V4 rDNA-derived taxa) that drive annual planktonThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Insight into diatoms diversity at two European coastal sites (LTER-MC in the Mediterranean Sea and SOMLIT-Astan in the Western English Channel) using a DNA Metabarcoding approach

“…The LTER-MC and SOMLIT-Astan time-series stations are installed in 2 different pelagic habitats (permanently-mixed versus stratified half the year) and biogeographical regions (Atlantic versus Mediterranean). Long-term records of phytoplankton dynamics indicate that diatoms dominate at both sites but the species pools and typical annual sequences of taxa differ substantially (Ribera d’Alcalà et al, 2004; Guilloux et al, 2013; Piredda et al, 2017; Zingone et al, 2019; Caracciolo et al 2022). For example, the conspicuous late-spring/summer blooms in Naples are dominated by Leptocylindrus aporus, Chaetoceros tenuissimus and Skeletonema pseudocostatum (Zingone et al, 2019) while at Roscoff Guinardia delicatula is one of the greatest contributors to the blooms of that season (Sournia et al, 1995; Caracciolo et al, 2022).…”

“…Long-term records of phytoplankton dynamics indicate that diatoms dominate at both sites but the species pools and typical annual sequences of taxa differ substantially (Ribera d’Alcalà et al, 2004; Guilloux et al, 2013; Piredda et al, 2017; Zingone et al, 2019; Caracciolo et al 2022). For example, the conspicuous late-spring/summer blooms in Naples are dominated by Leptocylindrus aporus, Chaetoceros tenuissimus and Skeletonema pseudocostatum (Zingone et al, 2019) while at Roscoff Guinardia delicatula is one of the greatest contributors to the blooms of that season (Sournia et al, 1995; Caracciolo et al, 2022). The relative high contribution of benthic and tychopelagic species to winter communities is also a distinctive feature of the SOMLIT-Astan station (Guilloux et al, 2013, Caracciolo et al, 2022), and more generally of tidally-mixed coastal habitats (Hernandez-Farinas et al, 2017).…”

“…Today, HTS enables extensive ecological studies through spatial gradients across the global ocean (i.e. Malviya et al, 2016; Piredda et al, 2018) and offers new, high-resolution data that can be used to re-examine temporal patterns of diversity and hypotheses about the factors and processes involved (Piredda et al, 2017; Caracciolo et al, 2022).…”

“…Here, we used a HTS method based on the metabarcoding approach to report on the genetic diversity of diatoms in 2 coastal sites with contrasting hydrological features but recurring annual sequences of plankton species (Zingone et al, 2019; Caracciolo et al, 2022): the SOMLIT-Astan and LTER-MareChiara time-series stations, located respectively in Roscoff (France, Western English Channel) and Naples (Italy, Mediterranean Sea, Gulf of Naples). We then investigated whether or not diatoms with identical 18S V4 rDNA sequences that thrive in both habitats have similar temporal dynamics.…”

Beyond the limits of the unassigned protist microbiome: inferring large-scale spatio-temporal patterns of marine parasites

“…Our global dataset included 1 531 samples (ASTAN: 374, BBMO: 327, SOLA: 154, Malaspina: 289, MOOSE: 272) (Table S1). The metadata and environmental information associated with the studied samples were retrieved from the initial studies [60][61][62][63][64][65][66] ( mol/L), phosphate ( mol/L), silicate ( mol/L) and chlorophyll-a ( g/L). For ASTAN and BioMarKs datasets, when in situ environmental variables were missing, metadata were retrieved from public oceanographic databases (SOMLIT database (https://www.somlit.fr) ; World Ocean Database (https://www.ncei.noaa.gov/access/world-ocean-database-select/dbsearch.html), SeaDataNet (https://cdi.seadatanet.org/search)).…”