Abundance of Pelagia noctiluca early life stages in the western Mediterranean Sea scales with surface chlorophyll

Este artículo contiene 12 páginas, 6 figuras, 1 tabla.Pelagia noctiluca is the most successful and well-studied jellyfish in the Mediterranean Sea. This species tolerates a wide range of water temperatures and succeeds in low to medium food regimes, but factors driving its distribution and population dynamics remain poorly understood. Here we applied a multiscale analytical approach using survey data and a physical−biochemical coupled model to assess how environmental factors affect the 3-dimensional distribution and seasonal abundance of P. noctiluca early life stages. The surveys took place after the spring bloom, when warm water favors fecundity and growth, but food shortage limits the reproductive investment and early survival. We found that most early life stages of P. noctiluca remained above the shallow thermocline and upper mixed layer where temperature is warm. Their spatial distribution was positively correlated with surface chlorophyll concentration, and over 90% of the variation in interannual abundance was explained by basin-scale productivity in June. Warmer water during winter and spring seasons coupled with protracted spring blooms increase the population of P. noctiluca, and this explains the trend of increasing outbreaks observed in the western Mediterranean Sea over the past decades.This work was co-founded by the European Union through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy (survey TUNIBAL 2019), the European Union’s Horizon 2020 research and innovation program under grant agreement No 773713 (project PANDORA), the Spanish Ministry of Economy and Competitiveness under grant agreements CTM2011-29525- C04 (project ATAME) and CTM-2015-68473-R (project ECOLATUN) and the joint research initiative between the Spanish Institute of Oceanography and the Balearic Islands Coastal Observing and Forecasting System (project BLUE - FIN). D.O. was supported by an FPI Fellowship from Vice - presidència i Conselleria d’Innovació, Recerca i Turisme of the regional Government of the Balearic Islands co-financed by the 2014−2020 European Social Fund program and re - ceived additional funds from the Cátedra de la Mar- Iberostar foundation.Peer reviewe