Search results for "A.Huxley"
showing 6 items of 6 documents
Decline in coccolithophore diversity and impact on coccolith morphogenesis along a natural CO2 gradient
2014
A natural pH gradient caused by marine CO2 seeps off Vulcano Island (Italy) was used to assess the effects of ocean acidification on coccolithophores, which are abundant planktonic unicellular calcifiers. Such seeps are used as natural laboratories to study the effects of ocean acidification on marine ecosystems, since they cause long-term changes in seawater carbonate chemistry and pH, exposing the organisms to elevated CO2 concentrations and therefore mimicking future scenarios. Previous work at CO2 seeps has focused exclusively on benthic organisms. Here we show progressive depletion of 27 coccolithophore species, in terms of cell concentrations and diversity, along a calcite saturation …
Lake zooplankton delta13C values are strongly correlated with the delta13C values of distinct phytoplankton taxa
2016
Article
Primary productivity variability on the Atlantic Iberian Margin over the last 70,000 years: Evidence from coccolithophores and fossil organic compoun…
2010
[1] This study analyzes coccolithophore abundance fluctuations (e.g., Emiliania huxleyi, Gephyrocapsa specimens, and Florisphaera profunda) in core MD01-2444 sediment strata retrieved at the Iberian Margin, northeastern Atlantic Ocean. Coccolithophores are calcareous nannofossils, a major component of the oceanic phytoplankton, which provide information about past ecological and climatological variability. Results are supported by data on fossil organic compounds (sea surface temperatures, alkenones, and n-hexacosan-1-ol index) and geochemical analyses (benthic δ13Ccc and planktonic δ18Occ isotopes). Three scenarios are taken into account for this location at centennial-scale resolution ove…
Utopijas un antiutopijas no T.Mora līdz S.Kolinsai
2015
Šajā darbā ir aprakstīta utopijas žanra attīstība gadsimtu gaitā, sākot no pirmajiem grieķu darbiem līdz antiutopijas daiļliteratūrai mūsdienās, iekļaujot vēl arī salīdzinošo analīzi trīs slaveniem utopijas un antiutopijas žanra darbiem, minot galvenās žanru iezīmes un analizējot tās attiecīgajās grāmatās. Šī darba mērķis ir izpētīt vēsturi un galvenos žanra autorus, svarīgākos notikumus un pagrieziena punktus tā attīstībā un esošo situāciju mūsdienās. Lai apkopotu nepieciešamo informāciju, tika pielietota literatūras pētījumu metode un visa iegūtā informācija par žanra attīstību ir atrodama šajā darbā, jo tēmas izpēte ir bijusi veiksmīga. Iegūtā informācija tiek izmantota arī, lai salīdzin…
Late Quaternary high uplift rates in northeastern Sicily: evidence from calcareous nannofossils and benthic and planktonic foraminifera
2011
The northeastern part of Sicily is characterized by intense seismic activity. Several systems of faults have been recognized in Pliocene and Pleistocene sediments in the area and, in fact, estimates of uplift rates are among the highest recorded in Sicily and south Italy. We examined calcareous nannofossil and benthic and planktonic foraminifera assemblages from pelitic sediments of the Contrada Zura section (Barcellona Pozzo di Gotto Basin, Furnari village, Messina). The occurrence of Emiliania huxleyi, a coccolithophore species which appeared in the oceanic record about 270,000 years ago, is witness to the uniqueness of this outcrop, while the planktonic/benthic foraminifera ratio indicat…
Mediterranean coccolith ecobiostratigraphy since the penultimate Glacial (the last 145,000years) and ecobioevent traceability
2015
The Mediterranean Sea is a miniature ocean ideal to test the response of marine ecosystems to amplified orbital and suborbital climate changes. Here we present coccolith data from a Sardinia Channel gravity core (Arcose C_33) analysed over the last 145,000 years, with a mean resolution of about 900 years. The study highlights that regional phytoplankton assemblages underwent significant modifications between the penultimate glacial and the last interglacial, as well as between the last glacial and the Holocene. The N ratio palaeoproductivity index suggests reduced productivity levels and the development of a deep nutricline during the last interglacial and the Holocene. Within the last glac…