Production and calcification variations of the key coccolithophore species Gephyrocapsa during the Late Pleistocene (MIS 14 to MIS 7)

2021 ◽  
Author(s):  
Alba González-Lanchas ◽  
José-Abel Flores ◽  
Francisco J. Sierro
Keyword(s):  
Sediment Cores ◽  
Western Mediterranean ◽  
Community Culture ◽  
Carbonate Production ◽  
The North ◽  
Western Mediterranean Sea ◽  
Global Environmental ◽  
Seawater Carbonate Chemistry ◽  
Ocean Chemistry

<p>There is an increasing interest in understanding the role of coccolithophores, a group of major calcifying phytoplankton, in the marine carbon cycle: they have a dual contribution to the operation of the carbonate and biological pumps during their lifecycle. How the recent changes in seawater carbonate chemistry are affecting their production and calcification is a matter of debate in the scientific community. Culture experiments suggest that modern coccolithophore species (<em>Emiliania huxleyi</em>) is sensitive to such variations. Conversely, could past evolutionary or adaptative changes in the most important coccolithophore species have an impact on ocean chemistry?  </p><p>We focus on the interval comprising the MIS 14 to 7 (Mid-Brunhes, Pleistocene) when a remarkable increase in the amplitude of glacial/interglacial atmospheric CO<sub>2</sub> was recorded. We analyzed (i) the composition of the dominant coccolithophore <em>Gephyrocapsa</em> assemblages and (ii) the morphometric parameters (length, mass, and thickness) of its coccoliths (carbonated scales) <span>in samples from a set of sediment cores (Sites IODP U1314, U1385and ODP 925 and 977) located in a north-south transect in the North Atlantic and the western Mediterranean Sea. We estimated the primary productivity conditions at the different regions and explore methodological approaches to measure the calcification of <em>Gephyrocapsa</em> coccoliths.</span></p><p>Preliminary results show a correlation between the abundance of coccoliths, assemblage composition, and coccolith morphology at different regions. A comparison with geochemical and sedimentological records suggests a significant role of <em>Gephyrocapsa</em> coccolithophore in marine organic and carbonate production throughout the interval. These observations open the discussion about the existence of a global environmental relationship between coccolithophore assemblages and coccolith morphometrical variations, but also, a possible impact of the changes in the <em>Gephyrocapsa</em> production and calcification on the ocean chemistry.</p>

scholarly journals Dynamical Downscaling of ERA5 Data on the North-Western Mediterranean Sea: From Atmosphere to High-Resolution Coastal Wave Climate

2021 ◽  
Vol 9 (2) ◽  
pp. 208
Author(s):  
Valentina Vannucchi ◽  
Stefano Taddei ◽  
Valerio Capecchi ◽  
Michele Bendoni ◽  
Carlo Brandini
Keyword(s):  
Mediterranean Sea ◽  
Wind Wave ◽  
Dynamical Downscaling ◽  
Wave Climate ◽  
Western Mediterranean ◽  
Limited Area ◽  
Computational Domain ◽  
Wave Hindcast ◽  
The North ◽  
Western Mediterranean Sea

A 29-year wind/wave hindcast is produced over the Mediterranean Sea for the period 1990–2018. The dataset is obtained by downscaling the ERA5 global atmospheric reanalyses, which provide the initial and boundary conditions for a numerical chain based on limited-area weather and wave models: the BOLAM, MOLOCH and WaveWatch III (WW3) models. In the WW3 computational domain, an unstructured mesh is used. The variable resolutions reach up to 500 m along the coasts of the Ligurian and Tyrrhenian seas (Italy), the main objects of the study. The wind/wave hindcast is validated using observations from coastal weather stations and buoys. The wind validation provides velocity correlations between 0.45 and 0.76, while significant wave height correlations are much higher—between 0.89 and 0.96. The results are also compared to the original low-resolution ERA5 dataset, based on assimilated models. The comparison shows that the downscaling improves the hindcast reliability, particularly in the coastal regions, and especially with regard to wind and wave directions.

scholarly journals Foraging dives of sperm whales in the north-western Mediterranean Sea

2012 ◽  
Vol 92 (8) ◽  
pp. 1799-1808 ◽  
Author(s):  
Alexandre Gannier ◽  
Estelle Petiau ◽  
Violaine Dulau ◽  
Luke Rendell
Keyword(s):  
Prey Capture ◽  
Sperm Whale ◽  
Western Mediterranean ◽  
Sperm Whales ◽  
The North ◽  
Western Mediterranean Sea ◽  
Single Animal ◽  
Components Analysis ◽  
Passive Acoustic ◽  
North Western

Oceanic odontocetes rely on echolocation to forage on pelagic or benthic prey, but their feeding ecology is difficult to study. We studied sperm whale foraging dives during summer in the north-western Mediterranean, using visual and passive acoustic observations. Clicking and creaking activities were recorded during dives of focal whales, at distances <3000 m using a towed hydrophone and DAT recorder. A total of 52 sperm whales were recorded over at least one full dive cycle. Data were obtained for 156 complete dives in total, including sequences of up to nine consecutive dives. Various dive and environmental variables were entered in multiple linear regression and principal components analysis, as well as estimated mass of whales. Creak rate was 0.80 creak/minute on average, with moderate variance. Bigger whales tended to dive longer at greater depths (as suggested by ascent durations), and emitted more creaks during a dive: 20.2 creaks/dive on average for individuals <24 tons, compared to 25.6 creaks/dive for animals >24 tons of estimated mass. For individual whales, creak rates did not vary significantly with size (range 0.78–0.80 creak/minute), but decreased with time of the day, and increased for shorter foraging phases. For different dives, higher creak rates were also observed earlier in the day, and linked to shorter foraging phases and surface durations. Although the exact significance of creak emissions (i.e. foraging attempt or prey capture) is not precisely determined, creak rates may be reliably used to quantify sperm whale foraging when single animal dives can be followed acoustically.

scholarly journals The impact of Saharan dust on the particulate export in the water column of the North Western Mediterranean Sea

2010 ◽  
Vol 7 (3) ◽  
pp. 809-826 ◽  
Author(s):  
E. Ternon ◽  
C. Guieu ◽  
M.-D. Loÿe-Pilot ◽  
N. Leblond ◽  
E. Bosc ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Mass Flux ◽  
Total Mass ◽  
Spring Bloom ◽  
Western Mediterranean ◽  
Saharan Dust ◽  
The North ◽  
Western Mediterranean Sea ◽  
Total Mass Flux ◽  
North Western

Abstract. Simultaneous measurements of atmospheric deposition and of sinking particles at 200 and 1000 m depth, were performed in the Ligurian Sea (North-Western Mediterranean) between 2003 and 2007, along with phytoplanktonic activity derived from satellite images. Atmospheric deposition of Saharan dust particles was very irregular and confirmed the importance of sporadic high magnitude events over the annual average (11.4 g m−2 yr−1 for the 4 years). The average marine total mass flux was 31 g m−2 yr−1, the larger fraction being the lithogenic one (~37%). The marine total mass flux displayed a seasonal pattern with a maximum in winter, occurring before the onset of the spring bloom. The highest POC fluxes did not occur during the spring bloom nor could they be directly related to any noticeable increase in the surface phytoplanktonic biomass. Over the 4 years of the study, the strongest POC fluxes were concomitant with large increases of the lithogenic marine flux, which had originated from either recent Saharan fallout events (February 2004 and August 2005), from "old" Saharan dust "stored" in the upper water column layer (March 2003 and February 2005), or alternatively from lithogenic material originating from Ligurian riverine flooding (December 2003, Arno, Roya and Var rivers). Those associated export fluxes defined as "lithogenic events", are believed to result from a combination of forcing (winter mixing or Saharan events, in particular extreme ones), biological (zooplankton) activity, and also organic-mineral aggregation inducing a ballast effect. By fertilising the surface layer, mixed Saharan dust events were shown to be able to induce "lithogenic events" during the stratification period. These events would be more efficient in transferring POC to the deeper layers than the spring bloom itself. The extreme Saharan event of February 2004 exported ~45% of the total annual POC, compared to an average of ~25% for the bloom period. This emphasises the role played by these "lithogenic events", and in particular those that are induced by the more extreme Saharan events, in the carbon export efficiency in the North-western Mediterranean Sea.

scholarly journals Sea surface temperature variability in the central-western Mediterranean Sea during the last 2700 years: a multi-proxy and multi-record approach

2015 ◽  
Vol 11 (6) ◽  
pp. 5439-5508 ◽  
Author(s):  
M. Cisneros ◽  
I. Cacho ◽  
J. Frigola ◽  
M. Canals ◽  
P. Masqué ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sediment Cores ◽  
Atlantic Multidecadal Oscillation ◽  
Western Mediterranean ◽  
Sea Surface ◽  
Ice Age ◽  
Western Mediterranean Sea ◽  
General Cooling ◽  
Age Model ◽  
Cooling Trend

Abstract. This study analyses the evolution of sea surface conditions during the last 2700 years in the central-western Mediterranean Sea based on six records as measured on five short sediment cores from two sites north of Minorca (cores MINMC06 and HER-MC-MR3). Sea Surface Temperatures (SSTs) were obtained from alkenones and Globigerina bulloides-Mg/Ca ratios combined with δ18O measurements to reconstruct changes in the regional Evaporation–Precipitation (E–P) balance. We reviewed the G. bulloides Mg/Ca-SST calibration and re-adjusted it based on a set of core top measurements from the western Mediterranean Sea. According to the regional oceanographic data, the estimated Mg/Ca-SSTs are interpreted to reflect spring seasonal conditions mainly related to the April–May primary productivity bloom. In contrast, the Alkenone-SSTs signal likely integrates the averaged annual signal. A combination of chronological tools allowed synchronizing the records in a common age model. Subsequently a single anomaly stack record was constructed for each proxy, thus easing to identify the most significant and robust patterns. The warmest SSTs occurred during the Roman Period (RP), which was followed by a general cooling trend interrupted by several centennial-scale oscillations. This general cooling trend could be controlled by changes in the annual mean insolation. Whereas some particularly warm SST intervals took place during the Medieval Climate Anomaly (MCA) the Little Ice Age (LIA) was markedly unstable with some very cold SST events mostly during its second half. The records of the last centuries suggest that relatively low E–P ratios and cold SSTs dominated during negative North Atlantic Oscillation (NAO) phases, although SST records seem to present a close positive connection with the Atlantic Multidecadal Oscillation index (AMO).

scholarly journals Further spreading of the non-indigenous bryozoan Celleporaria brunnea in the Mediterranean Sea: port to port morphological variations

2015 ◽  
Author(s):  
Jasmine Ferrario ◽  
Agnese Marchini ◽  
Martina Marić ◽  
Dan Minchin ◽  
Anna Occhipinti-Ambrogi
Keyword(s):  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Indigenous Species ◽  
Large Variability ◽  
Morphometric Characters ◽  
Morphological Variations ◽  
The North ◽  
Western Mediterranean Sea ◽  
The Pacific ◽  
The Mediterranean

The Pacific cheilostome bryozoan Celleporaria brunnea (Hincks, 1884), a non-indigenous species already known for the Mediterranean Sea, was recorded in 2013-2014 from nine Italian port localities (Genoa, Santa Margherita Ligure, La Spezia, Leghorn, Viareggio, Olbia, Porto Rotondo, Porto Torres and Castelsardo) in the North-western Mediterranean Sea; in 2014 it was also found for the first time in the Adriatic Sea, in the marina “Kornati”, Biograd na Moru (Croatia). In Italy, specimens of C. brunnea were found in 44 out of 105 samples (48% from harbour sites ad 52% from marinas). These data confirm and update the distribution of C. brunnea in the Mediterranean Sea, and provide evidence that recreational boating is a vector responsible for the successful spread of this species. Previous literature data have shown the existence of differences in orifice and interzooidal avicularia length and width among different localities of the invaded range of C. brunnea. Therefore, measurements of orifice and avicularia were assessed for respectively 30 zooids and 8 to 30 interzooidal avicularia for both Italian and Croatian localities, and compared with literature data, in order to verify the existence of differences in the populations of C. brunnea that could reflect the geographic pattern of its invasion range. Our data show high variability of orifice measures among and within localities: zooids with broader than long orifice coexisted with others displaying longer than broad orifice, or similar values for both length and width. The morphological variation of C. brunnea in these localities, and above all the large variability of samples within single localities or even within colonies poses questions on the reliability of such morphometric characters for inter and intraspecific evaluations.

scholarly journals A new species of Pista Malmgren, 1866 (Polychaeta, Terebellidae) from the north-western Mediterranean Sea

ZooKeys ◽  
2019 ◽  
Vol 838 ◽  
pp. 71-84
Author(s):  
Céline Labrune ◽  
Nicolas Lavesque ◽  
Paulo Bonifácio ◽  
Pat Hutchings
Keyword(s):  
New Species ◽  
Mediterranean Sea ◽  
Anterior Part ◽  
Posterior Part ◽  
Western Mediterranean ◽  
Single Pair ◽  
The North ◽  
Western Mediterranean Sea ◽  
North Western ◽  
A New Species

A new species of Terebellidae, Pistacolinisp. n., has been identified from the harbour of Banyuls-sur-Mer, north-western Mediterranean Sea. This new species was found in very high densities, exclusively in gravelly sand deposited manually, and was not found in the original source habitat of the gravel. This species is characterized by the colour of the ventral shields with pinkish anterior part and a blood red posterior part in live specimens, a pair of unequal-sized plumose branchiae inserted on segment II and anterior thoracic neuropodia with long-handled uncini. The presence of long-handled uncini even in the smallest specimens constitutes the major difference between Pistacolinisp. n. and other Pista species with a single pair of branchiae such as P.lornensis and P.bansei.

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