The Amazon River estuary is a highly dynamic system characterized by the world’s largest freshwater discharge (~200,000 m³ s⁻¹) and a strong mesotidal regime, with a tidal range of 2–4 m. Hydrodynamic conditions strongly influence microplastic transport, redistribution, and fate. This study characterized microplastics in surface water, mid-depth water, and bottom sediments collected from five sampling stations in the northern sector of the Amazon River mouth, totaling 15 independent field samples. Particle morphology, color, size distribution (0.063–5 mm), polymer composition, and screening-level ecological hazard were assessed. Fibers (49.4–51.8%) and fragments (47.4–50.6%) predominated across all environmental compartments, whereas films were rare or absent. Blue particles were the most frequent (49.6–53.0%), and the 0.1–0.3 mm size class was dominant (32.3–33.7%). Microplastic composition showed no significant differences among compartments or stations, although the limited number of samples per compartment warrants caution in interpreting the absence of a compartment effect. The observed overlap among samples is consistent with similar particle composition within the sampled northern sector, although it does not establish estuary-wide compositional homogeneity or particle redistribution. The observed cross-compartment pattern may reflect the dynamic hydrodynamic setting of the Amazon River mouth, although the relevant hydrodynamic processes were not directly measured. Screening-level indices indicated a high polymer-hazard score (PHI = 575) and a PERI score of 3552, corresponding to the formal extreme-danger screening category, despite the comparatively low pollution load indicated by the PLI (4.17). Overall, microplastics were detected across all sampled compartments in the northern sector, with no detectable compartment-level compositional differences under the present design and a contrasting screening profile characterized by low pollution load but elevated polymer-hazard and PERI scores during the 2023 rainy season.
Offshore wind farms (OWF) play a major role in addressing the climate change crisis. Large-scale OWF are currently planned in many parts of the global oceans, and thorough investigations of their effects on the marine environment are therefore needed. The aim of this work was to identify the OWF effects on the density of five abundant seabird species across 21 OWF in the German North Sea through a large-scale before-after-control-impact analysis using ship-based and aerial surveys. Densities of northern fulmars (Fulmarus glacialis), northern gannets (Morus bassanus), and razorbills (Alca torda) declined by 55 % to 91 % inside the OWF (+1 km), with response radii of 1.5–4.5 km. For black-legged kittiwakes (Rissa tridactyla) and lesser black-backed gulls (Larus fuscus) a mixed and scale-dependent pattern was detected, indicating avoidance of OWF in spring and summer up to 1.5 and 13.5 km, respectively, and attraction to OWFs in winter and autumn. The current approach and representative selection of focus species provide a comprehensive large-scale and multi-site investigation into the OWF effects, with relevance beyond German waters, while complementary fine-scale studies may help clarify underlying local mechanisms. The findings highlight the importance of considering seabird occurrence and sensitivity when planning and developing large-scale OWF.
