Biology subjects

Blanco-Bercial, L.

Publications and source records attributed to Blanco-Bercial, L..

4 recordsLinked to original sources

bioRxiv2025

Complementary assessment of fish biodiversity across the upper/lower mesophotic interface in a subtropical coral reef using eDNA metabarcoding and baited cameras

Mesophotic Coral Ecosystems (MCEs) occur in the middle to lower photic zone ([~]30-150 m) of tropical and subtropical regions, are often extensions of shallow reef communities, and generally hold great importance for local commercial fisheries. Compared to their shallower counterpart, MCEs have been traditionally understudied, primarily due to their inaccessibility with traditional monitoring methodologies. In this study, we aim to provide an interdisciplinary assessment of the biodiversity of Bermudan reef fish communities from the upper/lower mesophotic interface (60 m) by utilising a combination of environmental DNA (eDNA) metabarcoding and baited remote underwater videos (BRUVs). In total, 155 species from 137 genera were detected by eDNA metabarcoding whilst a total of 85 species from 53 genera were detected by BRUVs. The combined species detections totalled 182 species with approximately half of those detections unique to this study when compared to previous studies. Both methodologies found differences in -diversity between study locations, with each method independently detecting the highest species richness at the same location. The species assemblage at each location was dominated ([~]80%) by species known to occur throughout the shallow reef system and the upper mesophotic, whilst species only known to inhabit mesophotic ecosystems accounted for [~]6% at each location. These findings suggest a high level of species continuity with the adjacent shallower reef systems. The complementary nature of eDNA metabarcoding and BRUVs allows for a more accurate characterisation of fish biodiversity at the upper/lower mesophotic interface, which can lead to a more comprehensive understanding of ecosystem structure and more informed management decisions.

ecology↗

bioRxiv2024

Rhizaria in the oligotrophic ocean exhibit clear temporal and vertical variability

Recently studies have shown that Rhizaria, a super-group of marine protists, have a large role in pelagic ecosystems. They are unique in that they construct mineral tests out of silica, calcium carbonate, or strontium sulfate. As a consequence, Rhizaria can have large impacts on the oceans cycling of carbon and other elements. However, less is known about Rhizaria ecology or their role in the pelagic food-web. Some taxa, like certain Radiolaria, are mixotrophic, hosting algal symbionts. While other taxa are flux-feeders or even predatory carnivores. Some prior research has suggested that Rhizaria will partition vertically in the water column, likely due to different trophic strategies. However, very few studies have investigated their populations over extended periods of time. In this study, we present data investigating Rhizaria abundance and vertical distribution from over a year of monthly cruises in the Sargasso Sea. This study represents the first quantification of Rhizaria throughout the mesopelagic zone in an oligotrophic system for an extended period of time. We use this data to investigate the hypothesis that Rhizaria taxonomic groups will partition due to trophic mode. We also investigate how their abundance varies in accordance with environmental parameters. Rhizaria abundance was quantified using an Underwater Vision Profiler (UVP5), an in-situ imaging device. Ultimately, we show that different Rhizaria taxa will have unique vertical distribution patterns. Models relating their abundance to environmental parameters have mixed results, yet particle concentration is a common predictive variable, supporting the importance of heterotrophy amongst many taxa.

ecology↗

bioRxiv2023

Syndiniales parasites drive species networks and are a biomarker for carbon export in the oligotrophic ocean

Microbial associations that result in phytoplankton mortality are important for carbon transport in the ocean. This includes parasitism, which in microbial food webs, is dominated by the marine alveolate group, Syndiniales. Parasites are expected to contribute to carbon recycling via host lysis; however, knowledge on host dynamics and correlation to carbon export remain unclear and limit the inclusion of parasitism in biogeochemical models. We analyzed a 4-year 18S rRNA metabarcoding dataset (2016-2019), performing network analysis for twelve discrete depths (1- 1000 m) to determine Syndiniales-host associations in the seasonally oligotrophic Sargasso Sea. Analogous water column and sediment trap data were included to define environmental drivers of Syndiniales and their correlation with particulate carbon flux (150 m). Syndiniales accounted for 48-74% of network edges, most often associated with Dinophyceae and Arthropoda (mainly copepods) at the surface and Rhizaria (Polycystinea, Acantharea, and RAD-B) in the aphotic zone. Unlike other major groups, Syndiniales were significantly (and negatively) correlated with particulate carbon flux, suggesting parasites may drive flux attenuation through remineralization. Examination of Syndiniales amplicons revealed a range of depth patterns, including specific ecological niches and vertical connection among a subset (19%) of the community, the latter implying sinking of parasites (infected hosts or spores) on particles. Our findings point to the use of Syndiniales as biomarkers of carbon export, highlighting their importance for marine food webs and biogeochemistry. Significance StatementSyndiniales parasites are widespread in the ocean and represent a potentially important, albeit poorly resolved, source of carbon recycling. Here, we assess Syndiniales population dynamics, trophic relationships, and links to carbon export in the Sargasso Sea. Species networks at all depths were driven by Syndiniales, with parasite-host relationships varying with depth based on shifts in host composition. Syndiniales were the only eukaryote group to be significantly (and negatively) correlated with particulate carbon flux, indicating their contribution to flux attenuation via remineralization. Yet, a subset of parasites was vertically connected between photic and aphotic zones, suggesting continued export. Our findings elevate the critical role of Syndiniales in marine microbial systems and reveal their potential use as biomarkers for carbon export.

microbiology↗

bioRxiv2023

Ecological genomics in the Northern krill uncovers loci for local adaptation across ocean basins

Krill is a vital food source for many marine animals but also strongly impacted by climate change. Genetic adaptation could support populations, but remains uncharacterized. We assembled the 19 Gb Northern krill genome and compared genome-scale variation among 74 specimens from the colder Atlantic Ocean and warmer Mediterranean Sea. The genome is dominated by methylated transposable elements and contains many duplicated genes implied in molting and vision. Analysis of 760 million SNPs indicates extensive homogenizing gene-flow among populations. Nevertheless, we detect extreme divergence across hundreds of genes, governing ecophysiological functions like photoreception, circadian regulation, reproduction and thermal tolerance. Such standing variation may be essential for resilience in zooplankton, necessitating insight into adaptive variation to forecast their roles in future marine ecosystems and support ocean conservation. One-Sentence SummaryGenome-scans of Northern krill link genes for photoreception, reproduction and thermal tolerance to ecological adaptation.

evolutionary biology↗