POSTER SESSION 1
15:30–17:30, Monday, September 14
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1412 | POSTER 209
SATELLITE-DERIVED IDENTIFICATION OF CONTRASTING BIO-OPTICAL REGIMES IN THE GUINEA-BISSAU EXCLUSIVE ECONOMIC ZONE (2018–2023)
The Exclusive Economic Zone (EEZ) of Guinea-Bissau is among West Africa’s most productive marine regions, yet its seasonal bio-optical variability remains poorly documented. This study used MODIS-Aqua Level-2 observations at 1-km resolution from 2018 to 2023 to investigate the variability of Sea Surface Temperature (SST), Chlorophyll-a (Chl-a), Diffuse Attenuation Coefficient at 490 nm (Kd490), Photosynthetically Available Radiation (PAR), Particulate Organic Carbon (POC), and Particulate Inorganic Carbon (PIC). SST climatology identified two persistent oceanographic regimes: a Cooling Period (CP; Jan–May; mean SST ≈ 25.1°C) and a Warming Period (WP; Jun–Dec; mean SST ≈ 28.4°C). The WP was characterized by homogeneous thermal conditions and elevated biological concentrations restricted to coastal and shelf waters. In contrast, the CP exhibited an offshore cold-water intrusion across the EEZ, accompanied by an expansion of productive waters. Despite lower temperatures, the CP represented the most productive phase of the annual cycle. Relative to the WP, mean Chl-a, POC, and Kd490 increased by approximately 74%, 70%, and 100%, respectively, while PIC increased by 36%. Chl-a, POC, and Kd490 showed similar spatial patterns, with enhanced concentrations extending offshore during the CP, indicating strong coupling between phytoplankton biomass, particulate organic matter, and optical properties. In contrast, PIC remained confined to coastal and shelf environments, suggesting different controlling mechanisms. PAR varied little between seasons (<2%), indicating that ecosystem variability is driven by oceanographic forcing and nutrient supply rather than light availability. These findings demonstrate the value of satellite ocean-colour observations for characterizing bio-optical regimes in the eastern tropical Atlantic.
Tiago Serpa*, University of the Azores, [email protected], https://orcid.org/0000-0001-8176-6769
Diosnes Nonque, University of the Azores, [email protected]
Régis Santos, University of the Azores, [email protected], https://orcid.org/0000-0002-4167-3573
Ana Martins, University of the Azores, [email protected], https://orcid.org/0000-0002-4169-8201
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
