Biodiversity assessments are critical for setting conservation priorities, understanding ecosystem function and establishing a baseline to monitor change. Surveys of marine biodiversity that rely almost entirely on sampling adult organisms underestimate diversity because they tend to be limited to habitat types and individuals that can be easily surveyed. Many marine animals have planktonic larvae that can be sampled from the water column at shallow depths. This life stage often is overlooked in surveys but can be used to relatively rapidly document diversity, especially for the many species that are rare or live cryptically as adults. Using DNA barcode data from samples of nemertean worms collected in three biogeographical regions—Northeastern Pacific, the Caribbean Sea and Eastern Tropical Pacific—we found that most species were collected as either benthic adults or planktonic larvae but seldom in both stages. Randomization tests show that this deficit of operational taxonomic units collected as both adults and larvae is extremely unlikely if larvae and adults were drawn from the same pool of species. This effect persists even in well-studied faunas. These results suggest that sampling planktonic larvae offers access to a different subset of species and thus significantly increases estimates of biodiversity compared to sampling adults alone. Spanish abstract is available in the electronic supplementary material.

The democratisation of next‐generation sequencing has vastly increased the availability of sequencing data from metabarcoding. However, to effectively prepare these metabarcoding data for subsequent analysis, researchers must consistently apply several different bioinformatic tools—including those which denoise reads, cluster sequences and assign taxonomic identities. This often creates a bioinformatics bottleneck in workflows for non‐specialists due to obstacles around: (a) integrating different tools, (b) the inability to easily modify and rerun bioinformatic pipelines involving non‐scripted (‘point‐and‐click’) elements and (c) the multiple outputs that may be required of a single dataset (e.g. amplicon sequence variants [ASVs] and operational taxonomic units [OTUs]), which often results in users running pipelines multiple times. Here, we introduce SimpleMetaPipeline, an open‐source bioinformatics pipeline implemented in R, which addresses these obstacles. SimpleMetaPipeline integrates the most robust and commonly used existing bioinformatic tools in a single reproducible pipeline, with a streamlined choice of parameters, to generate a sequence data table containing alternative clustering and assignment options. SimpleMetaPipeline accepts demultiplexed paired‐end and single reads from multiple sequencing runs. We describe the pipeline and demonstrate how alternative annotations enable the easy implementation of multi‐algorithm agreement tests to strengthen inferences. SimpleMetaPipeline represents a valuable addition to the existing library of pipelines, providing easy and reproducible bioinformatics, including a range of commonly desired clustering and assignment options, such as OTUs and ASVs.

Lingulids and discinids are the only brachiopods that exhibit life histories that include a feeding planktonic stage usually referred to as a “larva”. We collected planktotrophic brachiopod larvae from the Pacific and Caribbean coasts of Panama and took a DNA barcoding approach with mitochondrial cytochrome c oxidase subunit I (COI), mitochondrial ribosomal 16S, and nuclear ribosomal 18S genes to identify those larvae and to estimate their diversity in the region. We observed specimens from both coasts with distinct morphologies typical of lingulid and discinid larvae. COI and 16S were sequenced successfully for the lingulid larvae but failed consistently for all discinid larvae. 18S was sequenced successfully for larvae from both families. Sequence data from each gene revealed one lingulid operational taxonomic unit (OTU) from Bocas del Toro on the Caribbean coast, and one lingulid OTU from the Bay of Panama on the Pacific coast. These OTUs differed by >20% for COI, >10% for 16S and ~0.5% for 18S. Both OTUs clustered with GenBank sequences of Glottidia species, the only genus of lingulids in the Americas, but were distinct from G. pyramidata the only species reported for the Caribbean. Analysis of 18S sequence data for discinid larvae recovered 2 OTUs, one exclusively from the Pacific and one with a mixture of Pacific and Caribbean larvae. The 18S marker does not provide enough resolution to distinguish between species, and comparisons with GenBank sequences suggest that one OTU includes Pelagodiscus species, while the other may include Discradisca species. When compared with other marine invertebrates, our surveys of brachiopod larvae through DNA barcoding show relatively low levels of diversity for Panama.