Structure of the zooplankton community and trophic interactions in a pelagic system influenced by internal island-trapped waves

Abstract

Zooplankton plays a crucial role in marine ecosystems, serving as an important link between primary producers and higher trophic levels. This study investigates zooplankton community structure and distribution in the area influenced by physical phenomena of internal island-trapped waves (ITWs) in the southern Adriatic. To assess the responses of the different zooplankton groups to ITWs, high-frequency sampling was carried out in July 2022. The results revealed pronounced shifts in zooplankton community composition, with taxa such as Evadne spinifera, Oithona spp., and Paracalanus parvus parvus exhibiting the most dynamic responses to nanophytoplankton availability. Centropages typicus and Temora stylifera showed depth-specific distribution patterns, reflecting their feeding preferences for microphytoplankton and adaptability in food sources. Organisms such as tintinnids, copepod nauplii, and radiolarians responded strongly to ITWs, while Oikopleura longicauda responded with a time lag, suggesting complex trophic interactions influenced by both biological and physical factors. These findings highlight the response of zooplankton community structure to specific physical dynamics, which likely influence trophic interactions and may affect the efficiency of energy transfer in the pelagic food web. The study emphasises the importance of high frequency sampling for capturing the fine-scale ecological processes that determine zooplankton dynamics in physically dynamic environments.