Metabarcoding Analyses and Seasonality of the Zooplankton Community at BATS

Leocadio Blanco-Bercial

doi:10.3389/fmars.2020.00173

Leocadio Blanco-Bercial

Open Access

https://doi.org/10.3389/fmars.2020.00173

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Abstract

The diversity and specific composition of zooplankton communities have a direct effect on the ecosystem services (e.g. carbon export) and structure of ocean food webs. In areas where diversity is high, a detailed characterization of the whole community can represent a hurdle that prevents a complete understanding of those processes and interactions. One such region is the Sargasso Sea, where zooplankton diversity is among the highest in the world oceans. As a consequence, at the Bermuda Atlantic Time-series Study location, most research has focused on zooplankton biomass or on particular groups. To provide new insight into the total community composition at the BATS site, in this study the zooplankton community is investigated by means of metabarcoding of the 18S V9 hypervariable region. Day and night samples from a full year (2015) show the signature of diel vertical migration, driven by those groups with a higher representation in the metabarcoding reads. Seasonal ordination was detected after square-root transformation and, similarly to temperate regions, four seasons could be differentiated based on community composition (post-spring bloom, summer stratification, fall mixing event and winter mixing), with no correspondence with the zooplankton biomass patterns. This community ordination showed correlation with the measured vertical flux, highlighting the need of understanding community regimes, even in theoretically stable regions such as the oligotrophic ocean, to advance in our understanding of zooplankton-mediated processes

Highlights

The zooplankton community is a key component of the ocean ecosystem
Seasonal succession in the zooplankton community has an effect on its functional profile, including, the zooplankton trophic role, both as predators and as prey (Pomerleau et al, 2015) or their influence in the carbon cycle (Mayzaud and Pakhomov, 2014)
The observed seasonality of the water column has been previously described for the Bermuda Atlantic Timeseries Study (BATS) station in several publications (e.g., Steinberg et al, 2001; and references therein; Lomas et al, 2013)

Summary

Introduction

The zooplankton community is a key component of the ocean ecosystem. Considering both their direct grazing on primary producers and their grazing of other consumers, zooplankton channel 15 to > 50% of the ocean production toward upper trophic levels (Steinberg and Landry, 2017), key for sustaining ecosystems and fisheries. To properly understand the processes affecting or driven by the zooplankton community, a truly knowledge of their taxonomic composition (i.e., biodiversity) is needed (Chiba et al, 2018). Seasonal succession in the zooplankton community has an effect on its functional profile, including, the zooplankton trophic role, both as predators and as prey (Pomerleau et al, 2015) or their influence in the carbon cycle (Mayzaud and Pakhomov, 2014)

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