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Eastern boundary upwelling systems (EBUS) host very productive marine ecosystems that provide services to many surrounding countries. The impact of global warming on their functioning is debated due to limited long-term observations, climate model uncertainties, and significant natural variability. This study utilizes the usefulness of a machine learning technique to document long-term variability in upwelling systems from 1993 to 2019, focusing on high-frequency synoptic upwelling events. Because the latter are modulated by the general atmospheric and oceanic circulation, it is hypothesized that changes in their statistics can reflect fluctuations and provide insights into the long-term variability of EBUS. A two-step approach using Self-Organizing Maps (SOM) and Hierarchical Agglomerative Clustering (HAC) algorithms was employed. These algorithms were applied to sets of upwelling events to characterize signatures in sea-level pressure, meridional wind, shortwave radiation, sea-surface temperature (SST), and Ekman pumping based on dominant spatial patterns. Results indicated that the dominant spatial pattern, accounting for 56%-75% of total variance, representing the seasonal pattern, due to the marked seasonality in along-shore wind activity. Findings showed that, except for the Canary-Iberian region, upwelling events have become longer in spring and more intense in summer. Southern Hemisphere systems (Humboldt and Benguela) had a higher occurrence of upwelling events in summer (up to 0.022 Events/km²) compared to spring (<0.016 Events/km²), contrasting with Northern Hemisphere systems (<0.012 Events/km²). Furthermore, long-term changes in dominant spatial patterns were examined by dividing the time period in approximately two equally periods, to compare past changes (1993-2006) with relatively new changes (2007-2019), revealing shifts in key variables. These included poleward shifts in subtropical high-pressure systems (SHPS), increased upwelling-favorable winds, and SST drops towards higher latitudes. The Humboldt Current System (HumCS) exhibited a distinctive spring-to-summer pattern, with mid-latitude meridional wind weakening and concurrent SST decreases. Finally, a comparison of upwelling centers within EBUS, focusing on changes in pressure and temperature gradients, meridional wind, mixed-layer depth, zonal Ekman transport, and Ekman pumping, found no evidence supporting Bakun’s hypothesis. Temporal changes in these metrics varied within and across EBUS, suggesting differential impacts and responses in different locations. [ABSTRACT FROM AUTHOR]

Knowledge of the tropical terrestrial cyanobacterial flora from the African continent is still limited. Of 31 strains isolated from soil and subaerial samples collected in Lagos State, Nigeria, three were found to be in the Oculatellaceae, including two species in a new genus. Subsequently, isolates from microbial mats in White Sands National Park in New Mexico, United States, and from a rock near the ocean in Puerto Rico, United States, were found to belong to the new genus as well. Cyanobacterial isolates were characterized microscopically, sequenced for the 16S rRNA gene and associated ITS region, and phylogenetically analyzed. Egbenema gen. nov., with three new species, as well as two new species of Albertania were differentiated from all other Oculatellaceae. Both genera belong to a supported clade within the Oculatellaceae that includes Trichotorquatus and Komarkovaea. The two new species of Albertania, A. egbensis and A. latericola, were from the same sample, but were evolutionarily separate based on 16S rRNA gene phylogenies, percent identity below the 98.7% threshold, and ITS rRNA percent dissimilarity >7.0%. Egbenema aeruginosum gen. et sp. nov. was phylogenetically separated from Trichotorquatus and Albertania but was in a clade with other strains belonging to Egbenema. The two Egbenema strains from the United States are here named Egbenema epilithicum sp. nov. and Egbenema gypsiphilum sp. nov. Our results support the hypothesis that further species discoveries of novel cyanobacteria will likely be made in soils and subaerial habitats, as these habitats continue to be studied, both in tropical and temperate biomes. [ABSTRACT FROM AUTHOR]