Summary of Abstract Submission

Abstract Submission No. IO50-04-0023PresentationPoster


Benjamin Kürten*1, Ali M. Al-Aidaroos2, Saskia Kürten1, Ulrich Struck3, Thomas Hansen4, Mohsen M. El-Sherbiny2, Reny Devassy2, Ulrich Sommer4, Nikolaos Zarokanellos1, Burton Harold Jones1

1 King Abdullah University of Science and Technology, Kingdom of Saudi Arabia
2 King Abdulaziz University, Kingdom of Saudi Arabia
3 Leibniz Institute for Research on Evolution and Biodiversity, Germany
4 GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany


The Red Sea (RS) offers a basin-wide study system of biogeography and biogeochemistry. Its ecohydrography is governed by atmospheric, oceanographic, and biological processes, due to monsoon-driven intrusions of Indian Ocean water, thermohaline and eddy-induced up-welling, and fixation of nitrogen (N). This study assessed isotopic compositions of zooplankton, POM and relationships with salinity, temperature, chl a, nutrient stoichiometry, phytoplankton composition, and remote sensing information. Samples were collected from 16°28¿N to 26°57¿N following the axial trough. We predicted that nutrient richness across the latitudinal gradient alters the configuration of zooplankton food webs, wherein the contribution of atmospheric and diazotroph N end members with depleted δ15N signatures in the diet of zooplankton decreases towards the South where Indian Ocean water contributes N sources with a higher δ15N. As predicted, the δ15N of POM and zooplankton generally increased from North to South. Bayesian mixing models indicated that contributions by NO3-fuelled phytoplankton, POM, and diazotrophs (including Trichodesmium) to the diet of zooplankton varied among sites; with larger contributions from diazotrophs in the North, POM in the South, but phytoplankton in the central RS. Remote sensing corroborated the presence of a dipole eddy in the central RS supplying deep water macronutrients to the euphotic zone. Consistency among most zooplankton taxa with patterns of nutrients and phytoplankton composition highlighted that ecohydrographic features relate to isoscape patterns at macroecological scale.