Meiofauna metabarcoding in Lima estuary (Portugal) suggests high taxon replacement within a background of network stability

Abstract

Meiofauna organisms play an important role in ecological and sedimentary processes in estuarine ecosystems. Recently, the application of environmental DNA (eDNA) for investigating meiofauna in different environments, improved the accessibility to its diversity and composition in a scale, frequency and depth previously unattainable. Nevertheless, little attention has been given to the description of baseline patterns of coupled spatial and temporal dynamics of meiobenthic communities. In an earlier study conducted in Lima estuary (NW Portugal), using eDNA metabarcoding of sediment samples, high levels of meiofauna Operational Taxonomic Units (OTUs) turnover were recorded, between sampling points only a few metres apart, and among sampling stations along the estuary. In order to verify the consistency of these patterns, in the current study we re-assessed Lima estuary's meiofauna communities approximately 1 year after, applying the same methodological approach (targeting segments of the COI and 18S rRNA genes), and expanding HTS-data analyses through the use of association networks. A high degree of spatial turnover was found both within and between sampling stations and this was consistent for both markers and years. As a consequence, most of the betadiversity was accounted by OTU replacement with only a minor contribution from OTU richness. Despite the high levels of OTU replacement, relatively stable network properties were found in meiofaunal communities, irrespective of the sampled year. Network properties appear to shift sharply from the downstream/high salinity area of the estuary to the mesohaline medium-upstream areas, suggesting high resilience and redundancy of meiofaunal communities along the estuarine gradient. The recognition of meiofauna's networks features may improve the understanding of the ecology and dynamics of these communities that apparently hold large portions of variable elements, thereby making difficult their analyses solely based on the OTU/species composition.

The spatial network structure of intertidal meiofaunal communities derived from environmental DNA metabarcoding surveys in Northwest Iberia

“…Although our study focused on a limited part of community diversity, sample diversity within each station was successfully recovered, as confirmed by previous studies on meiofauna in Lima estuary (Fais et al, 2020a; 2020b). The present study not only re-captured the high turnover within and between the sampling stations in Lima estuary (Fais et al, 2020a; 2020b), but highlighted a similar situation in two other distinct estuarine systems in the region, spanning approx. 300 km maximum distance (Fig.…”

“…In particular, several genetically divergent species with a limited geographical distribution were discovered through the use of DNA-based approaches (Guardiola et al, 2016; Fonseca et al, 2017; Mills et al, 2017; Faria et al, 2018; Worsaae et al, 2019). Moreover, evidence on the patchy distribution of meiofauna has been found through the application of DNA metabarcoding and ecological network analysis, highlighting high levels of both α and β -diversity (Fais et al, 2020b).…”

Environmental filtering along a bathymetric gradient: A metabarcoding meta‐analysis of free‐living nematodes

“…Overall, phylogenetic clustering in PD and MNTD suggests that contemporary assemblages are predominantly shaped by environmental filtering of conserved traits, while competitive interactions with conspecifics are of lesser importance. Although this aspect of deep‐sea communities has seldom been investigated, environmental filtering has been documented in macroinvertebrates (Judge & Barry, 2016), octocorals (Quattrini et al., 2017) and nematodes (Macheriotou et al., 2020, 2021); our results show that this seems to be a common feature of assemblages inhabiting different soft sediment habitats irrespective of depth (Fais et al., 2020; Hauquier et al., 2018).…”

Comparing species detection success between molecular markers in DNA metabarcoding of coastal macroinvertebrates

“…After COI, the nuclear small subunit rRNA gene (18S) is among the most widely used markers in marine biodiversity studies (e.g. Lejzerowicz et al 2015;Wangensteen et al 2018;Zhang et al 2018;Fais et al 2020a;Duarte et al 2021).…”