Biology subjects

Garcia-Cobo, M.

Publications and source records attributed to Garcia-Cobo, M..

3 recordsLinked to original sources

bioRxiv2026

Meiofaunal communities flourish in Antarctic marine sediments despite the harsh environmental conditions

While Antarctic terrestrial ecosystems support low metazoan diversity, the surrounding marine macrobenthos is rich. However, marine meiofauna remains historically neglected, leaving its diversity patterns unclear. In this study, we used 18S rRNA gene metabarcoding alongside an enhanced taxonomic annotation pipeline to characterize marine meiofauna diversity in the Ross Sea, comparing it to global datasets. We evaluated how depth, habitat type, and mesh size influence community structures to test if habitat heterogeneity drives diversity despite the harsh Southern Ocean conditions. Our results revealed exceptionally high diversity, with metazoans richness comparable to or higher than temperate regions. Although environmental variables had limited effects on taxonomic richness, they significantly shaped community composition, with habitat type explaining the highest proportion of variance. Interestingly, we detected several ASVs 100% identical to North Sea and North Atlantic sequences, likely reflecting the limited taxonomic resolution of the 18S marker rather than global dispersal (the "meiofaunal paradox"). Overall, these findings demonstrate that Antarctic marine sediments host rich meiofaunal communities where ecological processes operate similarly to other global regions, contrasting sharply with depauperate continental Antarctic ecosystems.

ecology↗

bioRxiv2025

Urbanisation reshapes community assembly differently across coastal beach and dune habitats

Urbanisation can reduce biodiversity through environmental filtering, but its effects may differ among neighbouring habitats within ecotones. Beach-dune systems provide a useful test because strong environmental gradients occur over short distances and overlap with gradients in human pressure. We collected 660 sediment samples from 55 transects along the Dutch North Sea coast, covering established dunes, incipient dunes, the upper intertidal zone, and the lower intertidal zone. Using environmental DNA metabarcoding and habitat-specific joint species distribution models, we tested how distance-to-city was associated with community composition, operational taxonomic unit (OTU) richness, and OTU-level occurrence. We found compositional differentiation along the urban-proximity gradient in both dune habitats, particularly in incipient dunes, but not in the intertidal habitats. Across all habitats, communities far from cities were more similar to one another than communities near cities, indicating greater among-site compositional variation near urban areas. OTU richness and mean OTU occurrence probabilities increased with distance-to-city in the lower intertidal, upper intertidal, and established dunes. Incipient dunes showed no clear richness gradient or directional OTU-level response despite the strong compositional turnover, suggesting that the main response was community replacement rather than loss of OTUs. Overall, habitat position within the beach-dune ecotone influenced whether biodiversity responses to urban proximity led to directional filtering, compositional turnover, or increased community heterogeneity. Our findings show that biodiversity and impact assessments based on a single habitat may miss important ecological change in coastal habitats.

ecology↗

bioRxiv2024

Enhancing metabarcoding efficiency and ecological insights through integrated taxonomy and DNA reference barcoding: a case study on beach meiofauna

Molecular techniques like metabarcoding, while promising for exploring diversity of communities, are often impeded by the lack of reference DNA sequences available for taxonomic annotation. Our study explores the benefits of combining targeted DNA barcoding and morphological taxonomy to improve metabarcoding efficiency, using beach meiofauna as a case study. Beaches are globally important ecosystems and are inhabited by meiofauna, microscopic animals living in the interstitial space between the sand grains, which play a key role in coastal biodiversity and ecosystem dynamics. However, research on meiofauna faces challenges due to limited taxonomic expertise and sparse sampling. We generated 775 new cytochrome c oxidase I DNA barcodes from meiofauna specimens collected along the Netherlands west coast and combined them with the NCBI GenBank database. We analysed alpha and beta diversity in 561 metabarcoding samples from 24 North Sea beaches, a region extensively studied for meiofauna, using both the enriched reference database and the NCBI database without the additional reference barcodes. Our results show a 2.5-fold increase in sequence annotation and a doubling of species-level Operational Taxonomic Units (OTUs) identification when annotating the metabarcoding data with the enhanced database. Additionally, our analyses revealed a bell-shaped curve of OTU richness across the intertidal zone, aligning more closely with morphological analysis patterns, and more defined community dissimilarity patterns between supralittoral and intertidal sites. Our research highlights the importance of expanding molecular reference databases and combining morphological taxonomy with molecular techniques for biodiversity assessments, ultimately improving our understanding of coastal ecosystems.

molecular biology↗