DOI: 10.5061/dryad.n8pk0p2vf
title: Data from: Meroplankton diversity, seasonality and life-history traits across the Barents Sea Polar Front revealed by high-throughput DNA barcoding

description: In many species of marine benthic invertebrates, a planktonic larval phase
 plays a critical role in dispersal. Very little is known about the larval
 biology of most species, however, in part because species identification
 has historically been hindered by the microscopic size and morphological
 similarity among related taxa. This study aimed to determine the taxonomic
 composition and seasonal distribution of meroplankton in the Barents Sea,
 across the Polar Front. We collected meroplankton during five time points
 seasonally and used high-throughput DNA barcoding of individual larvae to
 obtain species-level information on larval seasonality. We found that
 meroplankton was highly diverse (72 taxa from eight phyla) and present in
 the Barents Sea year-round with a peak in abundance in August and
 November, defying the conventional wisdom that peak abundance would
 coincide with the spring phytoplankton bloom. Ophiuroids, bivalves and
 polychaetes dominated larval abundance while gastropods and polychaetes
 accounted for the bulk of the taxon diversity. Community structure varied
 seasonally and total abundance was generally higher south of the Polar
 Front while taxon richness was overall greater to the north. Of the
 species identified, most were known inhabitants of the Barents Sea.
 However, the nemertean Cephalothrix iwatai and the brittle star Ophiocten
 gracilis were abundant in the meroplankton despite never having been
 previously recorded in the northern Barents Sea. The new knowledge on
 seasonal patterns of individual meroplanktonic species has implications
 for understanding environment-biotic interactions in a changing Arctic and
 provides a framework for early detection of potential newcomers to the
 system.
description: See: Descôteaux R, Ershova E,
 Wangensteen OS, Præbel K, Renaud PE, Cottier F and Bluhm BA (2021)
 Meroplankton Diversity, Seasonality and Life-History Traits Across the
 Barents Sea Polar Front Revealed by High-Throughput DNA Barcoding. Front.
 Mar. Sci. 8:677732. doi: 10.3389/fmars.2021.677732
description: The FASTQ files are housed on NCBI Sequence Read Archive under
 BioProject name: PRJNA725248 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA725248). The FASTQ files combined with the <strong>ngsfilter_XXXX.csv</strong> files, the <strong>XXXX_metadata.csv</strong> files and the <strong>MeroInd_Rcode_Bioinformatics.R</strong> can be used to produce MOTU tables for all sequencing libraries. Note that R package Mjolnir and its parameterization presented here are equivalent to the OBITools software used in the article related to this dataset.  Data from the MOTU tables are shown in their processed form in the <strong>MeroInd_IndividualData.csv</strong> file (variables: Sample, Sequence, Highest.seq, Total.reads, Percent.highest.seq). Generally, the sequence with the highest number of reads in each sample was assumed to correspond to the individual of interest. Note that in a few cases, two individuals were combined into one sample for DNA extraction, amplification and sequencing, and therefore had to be added manually in the MeroInd_IndividualData.csv file. In this case, the two individuals would have different Ind.No but would share the same Sample number.  The <strong>MeroInd_IndividualData.csv, MeroInd_SequenceAssignments.csv, MeroInd_IDMatch.csv, MeroInd_Quantification.csv, MeroInd_Env_Summary.csv </strong>and the R code <strong>MeroInd_Rcode_DataAnalysis.Rmd</strong> are used together to produce the data analysis, figures and tables found in the related article. Note that, due to copyright issues, the temperature, salinity and chlorophyll <em>a</em> data cannot be included here. Most of the code can be run without these data. Please contact corresponding author for information on how to access these data if needed. The <strong>MeroInd_StationInfo.csv </strong>datasheet shows the latitude and longitude of each sampling station as well as the dates of collection.  All photos of individual plankton are included and are named according to Location (N vs S), Month (Nov, Jan, Apr, Jun, Aug), Depth.max, Depth.min, Photo #.  Example: <strong>N_Apr_120_80_003.jpg</strong> represents an individual collected between 120-80m at the northern location in April. Photo #3. Note that photo numbers are only unique within a sample.