The diversity and biogeography of abundant and rare intertidal marine microeukaryotes explained by environment and dispersal limitation

Abstract

SummaryBenthic microeukaryotes are key ecosystem drivers in marine sandy beaches, an important and dynamic environment; however, little is known about their diversity and biogeography on a large spatial scale. Here, we investigated the community composition and geographical distributions of benthic microeukaryotes using high-throughput sequencing of the 18S rRNA gene and quantified the contributions of environmental factors and spatial separation on the distribution patterns of both rare and abundant taxa. We collected 36 intertidal samples at 12 sandy beaches from four regions that spanned distances from 0.001 to 12,000 km. We found 12,890 operational taxonomic units (OTUs; 97% sequence identity level) including members of all eukaryotic super-groups and several phyla of uncertain position. Arthropoda and Diatomeae dominated the sequence reads in abundance, but Ciliophora and Discoba were the most diverse groups across all samples. About onethird of the OTUs could not be definitively classified at a similarity level of 80%, supporting the view that a large number of rare and minute marine species may have escaped previous characterization. We found generally similar geographical patterns for abundant and rare microeukaryotic sub-communities, and both showed a significant distance-decay similarity trend. Variation partitioning showed that both rare and abundant sub-communities exhibited a slightly stronger response to environmental factors than spatial (distance) factors. However, the abundant subcommunity was strongly correlated with variations in spatial, environmental and sediment grain size factors (66% of variance explained), but the rare assemblage was not (16%). This suggests that different or more complex mechanisms generate and maintain diversity in the rare biosphere in this habitat.

Abundant and Rare Bacterioplankton in Freshwater Lakes Subjected to Different Levels of Tourism Disturbances

“…Consistent with our present study, some recent studies revealed that abundant and rare bacterioplankton in freshwater lakes and reservoirs were also significantly correlated with different environmental factors [31,35]. Interestingly, similar observations have also been reported in activated sludge bioreactor [30], soil [50], and intertidal marine ecosystem [72]. Recent work has confirmed that abundant and rare bacterial taxa had discrepant ecological niches and different roles in oil-contaminated soils [50].…”

Insights into protist diversity and biogeography in intertidal sediments sampled across a range of spatial scales

“…They are an important part of marine food webs, supplying organic carbon to higher trophic levels in both plankton and benthos, and are an important component of the vertical flux of organic carbon in the sea (Tirichine et al ). A previous study demonstrated that diatoms are the dominating group (by sequence number) among the 43 deep‐branching lineages of microeukaryotes (Zhang et al ), indicating their important role in ecosystems. In total, 439 Bacillariophyta OTUs were detected in this study which was higher than previous work focusing on diatoms in intertidal sediments that was based on microscopy and/or PCR‐DGGE methods (Sahan et al ; Ribeiro et al ; Siqueiros‐Beltrones et al ).…”

“…This study provides the first detailed insights into the diversity and biogeography of Cercozoa in intertidal sandy ecosystems. In total, 661 Cercozoa OTUs were recovered, comprising 5.1% of the total microeukaryote OTUs (Zhang et al ). A previous study found that Cercozoa comprised between 9% and 24% of all assigned eukaryotic OTUs on the ocean floor of the Arctic and Southern Oceans (Pawlowski et al ).…”

“…Thirty‐six benthic samples were collected from 12 intertidal stations located in four regions (Connecticut [CT]; and Qingdao [QD], Zhoushan [ZS] and Xiamen [XM] in China). Detailed sampling strategy and methodology have been described in a previous study (Zhang et al ). In short, samples of intertidal sands were transported to the laboratory and immersed in 5 L of filtered, sterile seawater and shaken to extract the microbes.…”

“…These variables included water temperature, salinity, pH, total carbon (TC), total organic carbon (TOC), total nitrogen (TN), nitrite and nitrate nitrogen (NO X ‐N), total phosphorus (TP), phosphate phosphorus (PO 4 ‐P), sedimentary organic matter content (ORG), and grain size. Detailed methods have been described in a previous study (Zhang et al ).…”