African dust plumes carry microbes across the Atlantic into the Amazon rainforest

Biological particles are an important but poorly understood component of Amazonian aerosols, with implications for ecosystems, climate and human health. A new study at the Amazon Tall Tower Observatory shows that African dust plumes transport microbial communities across the Atlantic into the Amazon rainforest, adding a biological dimension to a dust pathway usually discussed in terms of mineral nutrients.

The researchers characterized bacterial, fungal and archaeal communities in air sampled at 42 and 323 meters above ground, comparing background conditions with a five-day North African dust intrusion. This paired design allowed them to separate locally produced bioaerosols from microorganisms arriving with long-range transported dust.

Under background conditions, the two height levels told different stories. Bacterial communities varied with height and over time, reflecting a mixture of diverse local and transported sources. Fungal communities, by contrast, remained stable and were dominated by locally produced fungi, suggesting that fungal aerosol in the rainforest boundary layer is largely of local origin.

The dust intrusion changed that picture sharply for bacteria but not for fungi. During the five-day event, bacterial communities shifted strongly toward microorganisms associated with dryland soils, biological soil crusts and marine environments, a signature consistent with airborne transport from North African source regions and the marine atmosphere crossed en route.

Fungal communities remained unchanged throughout the intrusion, indicating that the intercontinental microbial transfer recorded at the tower was selective rather than general. The stability of the local fungal assemblage against a five-day dust pulse suggests that fungal spores in the Amazon air are replenished or controlled by local processes even when mineral dust loads rise.

The intrusion also had a measurable biochemical effect: airborne endotoxin concentrations increased threefold during the dust event. Notably, the team found no enrichment of obligate pathogens in the dust-influenced air, so the transported community was dominated by environmental microorganisms rather than disease-causing species.

The findings demonstrate that African dust is not only a mineral nutrient source for Amazonian ecosystems but also a vector of intercontinental microbial transport.

The study, published open access in Communications Earth & Environment, carries potential consequences for ecosystem functioning, atmospheric processes and human health, though the authors frame these as possibilities arising from the observed transport rather than demonstrated impacts. The measurements were limited to one observatory, two sampling heights and a single five-day intrusion event, so the findings characterize one well-documented episode against background conditions rather than a long-term climatology of dust-borne microbes over the basin.

Subject of Research: Intercontinental microbial transport by African dust intrusions into Amazonian rainforest air

Article Title: Amazonian rainforest bioaerosol influenced by African dust intrusion

Article References: Weber, J., Hrabe de Angelis, I., Brill, S., Barbosa, C. G. G., Chilinski, M. T., Violaki, K., Maier, S., Yordanova, P., Alves, R. P., Dias-Junior, C. Q., Araújo, A., Fröhlich-Nowoisky, J., Artaxo, P., Godoi, R. H. M., Pöschl, U., Pöhlker, C., & Weber, B. (2026). Amazonian rainforest bioaerosol influenced by African dust intrusion. Communications Earth & Environment. https://doi.org/10.1038/s43247-026-04119-1

Image Credits: AI Generated

DOI: 10.1038/s43247-026-04119-1

Keywords: Amazon rainforest, bioaerosols, African dust, microbial transport, bacteria, fungi, endotoxin, Amazon Tall Tower Observatory, biological soil crusts, atmospheric aerosols, Amazonian, rainforest