Raw taxonomic and abundances data

• Main Authors: Vereshchaka, Alexander L., Eteri I. Musaeva, Lunina, Anastasiia A.
• Format: Dataset
• Language: unknown
• Published: Zenodo 2021
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://dx.doi.org/10.5281/zenodo.4561887; https://zenodo.org/record/4561887

BIOGEOGRAPHY OF THE SOUTHERN OCEAN: ENVIRONMENTAL FACTORS DRIVING MESOPLANKTON DISTRIBUTION SOUTH OF AFRICA Spatial distribution of zooplankton communities depends on numerous factors, especially temperature and salinity conditions (hydrological factor), sampled depth, trophic factor, and dial cycle. We analyzed and compared the impact of these factors on abundance, biodiversity, quantitative (QNT-structure based on proportion of taxa) and qualitative (QUAL-structure based on presence/absence of taxa) structure of mesoplankton in the Southern Ocean. Samples (43 stations, three vertical strata sampled at each station, 163 taxa identified) were collected with a Juday net along the SR02 transect in December 2009. Mesoplankton abundance in discrete vertical layers ranged from 0.2 to 13743.6 ind. m -3 (five orders of magnitude), maximal and minimal values were recorded in the upper mixed and in the deepest layer, respectively. Within the combined 300-m layer, abundances ranged from 16.0 to 1455.0 ind. m -3 (five orders of magnitude) suggesting that integral samples provide little information about actual variations of mesoplankton abundances. A set of analyses (CCAs, ANOSIM, clustering) showed that depth was the major driver of mesoplankton distribution (abundance, biodiversity, QNT-structure), hydrological factors influenced two of them (QNT-structure and QUAL-structure), trophic factor (surface chlorophyll as a proxy) strongly affected one parameter (QNT-structure), and dial cycle had an insignificant effect on mesoplankton distribution. Using our current knowledge of the fine structure of the Antarctic Circumpolar Current, we compared effects of four hydrological fronts (boundaries between different water-masses with distinct environmental characteristics) and eight dynamic jets (narrow yet very intense currents) on mesoplankton distribution. Three hydrological fronts (Subtropical, Polar, Subantarctic) drove QNT-structure and QUAL-structure of mesoplankton assemblages (decreasing in order of influence), while the fourth front (Southern Boundary) affected only QUAL-structure. Effects of dynamic jets were insignificant. We suggest that mesoplankton composition is driven by hydrological parameters and further maintained through compartmentalization by fronts. Impact of local eddies and meanders on biodiversity, abundance, QUAL and QNT-structure of mesoplankton is comparable to that of hydrological fronts. QUAL-structure of mesoplankton assemblages mirrors hydrological structure of the Southern Ocean better than QNT-structure and is therefore greatly worth for solution of biogeographic tasks. We compared results of our survey and a survey conducted along the same transect within the same 0-300 m layer in 1992/1993 (17 years before). No significant changes in mesoplankton distribution were found. In spite of different sampling methods, spatial variations in abundance, distribution, and taxa richness were similar in both surveys.