DOI: 10.5061/dryad.wh70rxwk6
title: Data from: Large scale patterns of marine diatom richness: drivers and trends in a changing ocean.

description: Aim Plankton diversity is a pivotal element of marine ecosystem stability
 and functioning. A major obstacle in the assessment of diversity is the
 lack of consistency between patterns assessed by molecular and
 morphological data. This work aims to reconcile the two in a single
 richness measure, to investigate the environmental drivers affecting such
 measure, and finally to predict its spatio-temporal patterns. Location
 & Time period This is a global-scale study, based on data
 collected within the 2009-2013 interval during the Tara Oceans expedition.
 Major taxa studied The focus of this study is diatoms. They play an
 important role in several biogeochemical cycles and within marine food
 webs, while displaying a high taxonomic and functional richness. Methods
 We integrate measures of diatom richness across the global ocean using
 molecular and morphological approaches, giving particular attention to the
 rare biosphere. We then perform a machine-learning-based analysis of these
 reconciled patterns to extrapolate diatom richness at the global scale and
 to identify the main environmental processes governing it. Finally, we
 model the response of diatom richness to climate change. Results By
 filtering out 0.3% of the rarest operational taxonomic units,
 molecular-based richness patterns show the best possible match with the
 morphological approach. Temperature, phosphate, chlorophyll a and the
 Lyapunov exponent are the major explainers of these reconciled patterns.
 Global scale predictions provide a first approximation of the global
 geography of diatom richness and of the possible impacts of climate
 change. Main conclusion Our models suggest that diatom richness is
 controlled by different processes characteristic of distinct environmental
 scenarios: lateral mixing in highly dynamic regions, and both nutrient
 availability and temperature elsewhere. We present herein the implications
 of these processes on richness and how these same implications differ from
 other diversity indices because of the main component of richness: the
 rare biosphere.
description: Supplementary data 1: Diatoms ribotypes
 validated by the taxonomic and phylogenetic check, their total abundance
 and their count in every <i>Tara</i> Oceans sample.
 Supplementary data 2: Morphology-based
 diatom richness estimated by light microscopy analysis of
 <i>Tara</i> Oceans net samples
 Supplementary data 3: Relative abundance
 matrix of identified diatom genera in the size fraction 20-180
 <i>μ</i>m. The first sheet shows the relative abundances at
 the genus level in each station obtained by the <i>Tara</i>
 Oceans metabarcoding samples (filtered Swarm d1). OTUs representatives
 have been annotated to Genebank and later aggregated by genus. The second
 sheet specifies the coordinates and sampling depth of every sample id
 present in the first matrix. Supplementary data
 4: Abundance matrix of the Swarm (d1) metabarcode of
 <i>Tara</i> Oceans as resulting from the filtering process.
 Each row corresponds to a Swarm OTU and represents its abundance in the
 20-180 <i>μ</i>m <i>Tara</i> Oceans
 samples.