A Lagrangian approach to the Atlantic Jet entering the Mediterranean Sea: Physical and biogeochemical characterization

The temporal evolution of the physical and biogeochemical properties Atlantic Jet (AJ) along first ∼ 75 m water column during a 4-day journey was analysed by following trajectory drifter dragged jet from Strait Gibraltar towards Alborán Sea. Three stages were differentiated based on several variables (e.g., velocity, temperature, nutrients, fluorescence). (i) Within Gibraltar, primarily influenced tidal cycle, leading to nutrient-enrichment surface waters. However, due short residence time, phytoplankton community that mainly dominated diatoms, did not demonstrate significant changes. (ii) Once outside Strait, frontal dynamics associated with AJ. moved forward but also laterally across it continuously attracted mainstream (maximum current speed) or detached its southern edge (minimum speed). Due upwelling processes induced intensification mainstream, characterized colder, nutrient-richer lower fluorescence values. Conversely, jet, higher low nutrient concentration, fluorescence. Along stations this stage, diatom total abundance biovolume increased, reaching values 12-times than initial concentrations. (iii) In last parcel still less intensity. Additionally, colder denser AJ subducted progressively as into region surrounded warmer Concomitantly, diatoms decreased decline availability increase mesozooplankton. Our results reveal coupled entrance in Sea highlight strong control environment over ecological region.