Species-specific transparent exopolymer particle (TEP) during three harmful algal blooms (2022–2024) in an upwelling-influenced coastal bay

Le résumé fourni par la source

Transparent exopolymer particles (TEP) are key components of the marine carbon cycle, coupling biological productivity with biogeochemical and operational processes in coastal environments. This study quantified ex-situ surface TEP concentrations during three harmful algal blooms (HABs) in Todos Santos Bay (Mexico) between 2022 and 2024, each representing a different bloom stage and dominated by a distinct species: Prorocentrum micans (2022), Pseudo-nitzschia cf. australis (2023), and Lingulaulax polyedra (2024). Surface TEP concentrations increased from 163 μg XG eq·L −1 in 2022 to 693 μg XG eq·L −1 in 2023 and 778 μg XG eq·L −1 in 2024. The highest TEP-to-biomass ratio occurred during the P. australis bloom, coinciding with low nutrients levels (PO₄ 3− = 0.4 μM; NN = 2.4 μM) and moderate upwelling conditions (BEUTI = 1.0 mmol m −3 s −1 ). The L . polyedra bloom developed under stratified, warm conditions (SST ≈ 18.5 °C), with high PO₄ 3− concentration (0.8 μM) and operational impacts including filter clogging at a desalination plant. In contrast, P. micans occurred under higher nutrient availability (PO₄ 3− = 2.46 μM; NN = 6.9 μM) and lower TEP levels. TEP-C contributed up to 87 % of the particulate carbon pool during the P. australis event, suggesting species-specific physiological control on exopolymer formation. Overall, each event represented a different bloom stage, underscoring how bloom progression, species dominance, and environmental forcing together shape TEP dynamics in coastal upwelling systems. • First quantification of TEP during three HABs in an upwelling-influenced bay. • TEP-C reached 87 % of particulate carbon during the Pseudo-nitzschia cf. australis bloom . • Distinct bloom stages and nutrient regimes shaped species-specific TEP dynamics.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.