Search results for "coccolith"

First data on oceanography, phytoplankton density and nutrient distribution of the western Libyan sea area (August, 2006)

2008

Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean

2023

Funding: Funding was provided by NSF Grants OCE1220600 and OCE1220302 awarded to JA and WB, respectively, MINECO PID2020-113526RB-I00, the Generalitat de Catalunya MERS (#2017 SGR-1588) awarded to PZ and NERC grant NE/N011716/1 awarded to JR. Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO2. Surprisingly, references to the absolute and relative contribution of these organisms to calcium carbonate production are lacking. Here we report quantification of pelagic calcium carbonate production in the North Pacific, providing new insights on the contribution of the three main planktonic calcifying groups. Our results show that coccolithop…

Holocene climate variability of the Western Mediterranean: Surface water dynamics inferred from calcareous plankton assemblages

2020

A high-resolution study (centennial scale) has been performed on the calcareous plankton assemblage of the Holocene portion of the Ocean Drilling Program Site 976 (Alboran Sea) with the aim to identify the main changes in the surface water dynamic. The dataset also provided a seasonal foraminiferal sea surface water temperatures (SSTs), estimated using the modern analog technique SIMMAX 28, and it was compared with available geochemical and pollen data at the site. Three main climate shifts were identified as (1) the increase in abundance of Syracosphaera spp. and Turborotalita quinqueloba marks the early Holocene humid phase, during maximum summer insolation and enhanced river runoff. It i…

Integrated micropaleontological and stratigraphical study of the Late Quaternary Arcose C_33 core (offshore SW Sardinia)

2012

Calcareous Nannofossil Assemblages from the Central Mediterranean over the last Four Centuries.

2009

Calcifying zooplankton standing stocks and in the North Pacific from the R/V Kilo Moana cruise KM1712

2022

This dataset compiles the standing stocks (ind/m³), the integrated standing stocks (ind/m²) and the integrated CaCO3 standing stocks (mg/m²) for three groups of zooplanktonic calcifying organisms: pteropods, heteropods and foraminifers. The organisms were collected by oblique towing (Ø 0.5 m, 90 μm mesh size, SeaGear mechanical flowmeter) in the North Pacific between Hawaii and the Gulf of Alaska during the R/V Kilo Moana cruise KM1712 in August 2017. The sampling strategy was designed to capture an integrated sample of all foraminifers, pteropods and heteropods from juveniles to adults living throughout the upper water column. Pteropods and heteropods were quantified and shell diameter mea…

Conflicting coccolithophore and geochemical evidence for productivity levels in the Eastern Mediterranean sapropel S1

2011

Abstract The cyclic development of anoxic conditions in the eastern Mediterranean deep sea waters is one of the most fascinating research topics in paleoceanographic studies. In combination with bottom water stagnation, enhanced primary production is a common explanation for the deposition of organic-rich layers (sapropels). This is supported by extensive evidence from both geochemical and micropaleontological studies. The correspondence of recent sapropel layers with peaks of the lower photic zone coccolithophore species Florisphaera profunda has been interpreted as a proxy for the development of a deep chlorophyll maximum (DCM), due to the pycnocline/nutricline shallowing into the lower p…

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…

Living Coccolithophores from the Gulf of Sirte (Southern Mediterranean Sea) during the summer of 2008

2012

The Gulf of Sirte is a largely unexplored area in the southernmost Mediterranean Sea.We are presenting here 2008 summer data on the distribution pattern of living coccolithophores, a main phytoplankton calcifying group, in 105 samples from 20 stations. The survey includes coastal and offshore stations, enabling us to provide indications on the dynamics of phytoplankton productivity in relation to oceanographic processes. The total coccosphere concentrations show higher values in the offshore stations and lower ones for coastal sites. Umbellosphaera tenuis, Emiliania huxleyi, Florisphaera profunda, Syracosphaera pulchra HOL (Calyptrosphaera oblonga) and Rhabdosphaera spp. dominate the assemb…