Improving the sampling of red Noctiluca scintillans to understand its impact on coastal ecosystem dynamics

Recently, natural and anthropogenic pressures caused an apparent increase in the frequency and spread of red Noctiluca scintillans (RNS) blooms. Here, we describe this potential expansion and the associated environmental factors based on an extensive literature review (1857–2023). Our analysis suggests that Noctiluca increased over time in several Australian, Chinese and European coastal regions. We point to eutrophication, ocean warming and deoxygenation as possible drivers of these intensifications. Moreover, we demonstrate Noctiluca’s importance for coastal ecosystems: with competitive advantages causing fast and intense blooms, Noctiluca has the potential to alter plankton communities, influencing productivity in affected areas. Throughout our analysis, we identified major knowledge gaps that are relevant to assess Noctiluca: (i) challenges in determining its spatiotemporal evolution; (ii) limited knowledge about drivers triggering and ending blooms; (iii) scarce information about feeding, reproduction and interaction in situ and (iv) uncertainty regarding its contribution to carbon export. We hypothesize that these gaps are related to limitations in traditional sampling techniques, and we highlight the need for a holistic approach combining traditional with novel techniques like remote sensing and underwater cameras. Our suggested approach could help filling the identified gaps and facilitate predictions of bloom dynamics and impacts under future climate conditions.