Distribution of coccoliths in surface sediments from the southwest Atlantic Ocean in relation to environmental gradients

• Published in: Lethaia Vol. 57; no. 1; pp. 1 - 14
• Main Authors: Rivas, Lucía, Alperin, Marta I., Pérez Panera, Juan P., Cusminsky, Gabriela C.
• Format: Journal Article
• Language: English; Norwegian
• Published: Universitetsforlaget 01.03.2024
• Subjects: assemblage distribution; compositional data; Nannoplankton; redundancy analysis; southwest Atlantic Ocean; surface sediments
• ISSN: 0024-1164; 1502-3931
• DOI: 10.18261/let.57.1.8

Coccolith compositions of surface sediment samples from the Southwestern Atlantic Ocean were analysed in relation with present-day surface-water environmental parameters (temperature, salinity, phosphate, and nitrate). This work is based on surface sediment data sets obtained from the Argentinean Continental Margin (40 – 55°S and 55 – 65°W). A multivariate ordination technique, Redundancy Analysis, was applied on the relative abundances of the most abundant taxa (Emiliania huxleyi, Gephyrocapsa muellerae, Calcidiscus leptoporus and Gephyrocapsa spp. small). The results of the analysis revealed the affinities of G. muellerae and Gephyrocapsa spp. small for high nutrient conditions. In contrast, E. huxleyi and C. leptoporus seem to be associated with high salinity and high temperature. Statistical analysis results revealed three Groups (I–III), nutrient content controlled. Group I lies within northern sites, is dominated by E. huxleyi and has a positive correlation with salinity and temperature. Conversely, Group II, located in Sloggett Canyon, is dominated by E. huxleyi and is not correlated to any environmental variables. Group III, is composed by E. huxleyi and G. muellerae, is geographically confined to the southeast area and has a positive correlation with phosphate and nitrate. There would be a moderate association of certain groups of coccolithophores (as Gephyrocapsa spp.) with nutrient-rich waters from the Malvinas Current, and Emiliania huxleyi strains more associated with relatively low nutrient content of waters from the northernmost part of Argentinean Continental Margin.