Publications by authors named "Sdena Nunes"

Arabian Gulf ecosystems, particularly the phytoplankton communities, are influenced by natural and human activities. We analyzed coastal sediments chronology and pigment records to explore shifts in phytoplankton in the western Arabian Gulf, where long-term records are lacking. Our results revealed significant shifts in phytoplankton abundance over the past five decades.

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Phytoplankton-derived organic matter sustains heterotrophic marine life in regions away from terrestrial inputs such as the Southern Ocean. Fluorescence spectroscopy has long been used to characterize the fluorescent organic matter (FOM) pool. However, most studies focus only in the dissolved FOM fraction (FDOM) disregarding the contribution of particles.

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We explored how changes of viral abundance and community composition among four contrasting regions in the Southern Ocean relied on physicochemical and microbiological traits. During January-February 2015, we visited areas north and south of the South Orkney Islands (NSO and SSO) characterized by low temperature and salinity and high inorganic nutrient concentration, north of South Georgia Island (NSG) and west of Anvers Island (WA), which have relatively higher temperatures and lower inorganic nutrient concentrations. Surface viral abundance (VA) was highest in NSG (21.

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Article Synopsis
  • Transparent exopolymer particles (TEP), primarily made of polysaccharides, are important organic particles in ocean environments, influencing ecological processes.
  • A study in the Southern Ocean revealed that TEP concentrations peaked in surface waters, with chlorophyll a levels being a strong predictor of TEP variability both horizontally and vertically.
  • The highest TEP concentrations were linked to specific phytoplankton groups near the South Orkney Islands, and factors like light stress from sun exposure, sea ice melt, and water turbulence significantly affect TEP distribution.
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In oligotrophic regions, such as the Mediterranean Sea, atmospheric deposition has the potential to stimulate heterotrophic prokaryote growth and production in surface waters, especially during the summer stratification period. Previous studies focused on the role of leaching nutrients from mineral particles of Saharan (S) origin, and were restricted to single locations at given times of the year. In this study, we evaluate the effect of atmospheric particles from diverse sources and with a markedly different chemical composition [S dust and anthropogenic (A) aerosols] on marine planktonic communities from three locations of the northwestern Mediterranean with contrasted anthropogenic footprint.

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Climate warming affects the development and distribution of sea ice, but at present the evidence of polar ecosystem feedbacks on climate through changes in the atmosphere is sparse. By means of synergistic atmospheric and oceanic measurements in the Southern Ocean near Antarctica, we present evidence that the microbiota of sea ice and sea ice-influenced ocean are a previously unknown significant source of atmospheric organic nitrogen, including low molecular weight alkyl-amines. Given the keystone role of nitrogen compounds in aerosol formation, growth and neutralization, our findings call for greater chemical and source diversity in the modelling efforts linking the marine ecosystem to aerosol-mediated climate effects in the Southern Ocean.

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