Isotopic and trophic structure of mesozooplankton communities across a volcanic archipelago (Canary Islands, Central East Atlantic)

Mesozooplankton play a key role in the transfer of energy and organic matter through marine food webs, yet their trophic structure and spatial variability remain poorly resolved in oceanic archipelagos influenced by contrasting oceanographic regimes. Here, we studied mesozooplankton community composition, abundance, biomass, and trophic position along a longitudinal environmental gradient across the Canary Islands (Central Eastern Atlantic). Zooplankton samples were collected during the ATLANTIS 2024 research cruise and were analysed using stable isotopes (δ 13 C, δ 15 N, δ 34 S), combined with physical–biogeochemical satellite data and multivariate statistical analyses. Sea surface temperature increased westward (15–24 °C), while chlorophyll- a concentration showed the opposite trend (1.0 to < 0.1 mg m −3 ), consistent with a shift from productive upwelling-influenced waters in the east to oligotrophic conditions in the west. Zooplankton abundance and biomass generally tended to be higher at nutrient-rich eastern stations. Stable isotope data revealed spatial variation in isotopic composition and resource use across the archipelago, with higher δ 15 N values observed in the more productive eastern sector, although part of this variation may reflect regional differences in isotopic baseline conditions. These results demonstrate that the mesoscale oceanographic variability around the archipelago shapes the trophic structure of mesozooplankton communities. This study provides the first integrated isotopic (δ 13 C–δ 15 N–δ 34 S) characterization of zooplankton in the Canary Islands, contributing new insights into carbon and sulfur trophic pathways in subtropical oceanic systems.