scholarly journals Tracking the Mediterranean Abyss

2016 ◽  
Author(s):  
Simona Aracri ◽  
Katrin Schroeder ◽  
Jacopo Chiggiato ◽  
Harry Bryden ◽  
Elaine McDonagh ◽  
...  
Keyword(s):  
Water Column ◽  
Seismic Waves ◽  
Western Mediterranean ◽  
The North ◽  
Deep Layers ◽  
Abyssal Circulation ◽  
Intense Activity ◽  
First Time ◽  
North Western ◽  
Northern Current

Abstract. The abyssal velocity of the Northern Current, in the north-western Mediterranean has been estimated using for the first time MERMAIDs, i.e. submarine drifting instruments that record seismic waves. In this study the Northern Current shows an intense activity even in deep layers of the water column. Through pseudo-eulerian statistics different components of the observed variability are analysed and described, revealing the turbulent nature of the Liguro-Provençal basin abyssal circulation.

Reproductive biology of the seastar Ceramaster grenadensis from the deep north-western Mediterranean Sea

2015 ◽  
Vol 95 (4) ◽  
pp. 805-815 ◽  
Author(s):  
A. Mecho ◽  
U. Fernandez-Arcaya ◽  
E. Ramirez-Llodra ◽  
J. Aguzzi ◽  
J.B. Company
Keyword(s):  
Mediterranean Sea ◽  
Population Distribution ◽  
Gonad Index ◽  
Western Mediterranean ◽  
The North ◽  
Western Mediterranean Sea ◽  
Continuous Reproduction ◽  
First Time ◽  
Wide Geographic Distribution ◽  
North Western

Ceramaster grenadensis is one of the most abundant bathyal seastars in the north-western Mediterranean Sea and also presents a wide geographic distribution in the Atlantic Ocean. As with other species in this genus, little information is available on the biology and reproductive strategy of C. grenadensis. In this context, we describe for the first time the reproductive cycle of this species from bathyal depths in the north-western Mediterranean Sea. Specimens (N = 141) were collected seasonally from 194 benthic trawls (141 Otter Trawls and 53 Agassiz trawls) conducted during 10 cruises from October 2008 to April 2013. Open slope and canyon systems were sampled at depths between 900 and 2250 m. The population distribution of C. grenadensis showed a depth-related structure, with the smaller adult specimens and juveniles present at greater depths. Sex ratio was 2:1 females per male, constant among seasons and depths. Histological analyses of the gonads showed an asynchronous ovarian organization, with previtellogenic and vitellogenic oocytes throughout the year. These oogenesis patterns suggest a continuous reproduction. However, the Pyloric Caeca Index (PCI) decreased in summer while the Gonad Index (GI) increased in autumn in males, suggesting a higher spawning capacity in autumn. In both sexes, an increasing GI and PCI trend was observed with increasing depth.

Comparative study of the Genus Isurus (Rafinesque, 1810), and description of a form (Marrajo Criollo) apparently endemic to the Azores

1992 ◽  
Vol 43 (1) ◽  
pp. 109 ◽  
Author(s):  
JA Moreno ◽  
JQ Moron
Keyword(s):  
Western Mediterranean ◽  
Distinctive Features ◽  
The North ◽  
Western Mediterranean Sea ◽  
Shortfin Mako ◽  
Eastern Atlantic Ocean ◽  
North Eastern ◽  
Western Morocco ◽  
First Time ◽  
North Western

Numerous captures of mako sharks (Isurus sp.) are made annually by the Spanish longline fishing fleet in the north-eastern Atlantic Ocean and the western Mediterranean Sea. Sampling of catches allowed us to compare the morphology of two species of Isurus (I. Oxyrinchus and I. Paucus) and to document the variations due to size or sex observed in populations exploited by the different fisheries. The distinctive features of a form apparently endemic to the Azores ('marrajo criollo') are defined, and the form's taxonomic identity is discussed. This form is possibly a distinct population of shortfin mako (I. Oxyrinchus). The presence of longfin mako (I. Paucus) is confirmed in waters off north-western Morocco, and this species is recorded for the first time off the Iberian peninsula.

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 Geodynamics and Oil and Gas Potential of the Yenisei-Khatanga Basin (Polar Siberia)

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 510 ◽  
Author(s):  
Valery Vernikovsky ◽  
Georgy Shemin ◽  
Evgeny Deev ◽  
Dmitry Metelkin ◽  
Nikolay Matushkin ◽  
...  
Keyword(s):  
Lower Cretaceous ◽  
Oil And Gas ◽  
Foreland Basin ◽  
Gas Reservoirs ◽  
The North ◽  
Western Arctic ◽  
Folded Structures ◽  
Gas Potential ◽  
First Time ◽  
North Western

The geodynamic development of the north–western (Arctic) margin of the Siberian craton is comprehensively analyzed for the first time based on our database as well as on the analysis of published material, from Precambrian-Paleozoic and Mesozoic folded structures to the formation of the Mesozoic-Cenozoic Yenisei-Khatanga sedimentary basin. We identify the main stages of the region’s tectonic evolution related to collision and accretion processes, mainly subduction and rifting. It is demonstrated that the prototype of the Yenisei-Khatanga basin was a wide late Paleozoic foreland basin that extended from Southern Taimyr to the Tunguska syneclise and deepened towards Taimyr. The formation of the Yenisei-Khatanga basin, as well as of the West-Siberian basin, was due to continental rifting in the Permian-Triassic. The study describes the main oil and gas generating deposits of the basin, which are mainly Jurassic and Lower Cretaceous mudstones. It is shown that the Lower Cretaceous deposits contain 90% of known hydrocarbon reserves. These are mostly stacked reservoirs with gas, gas condensate and condensate with rims. The study also presents data on oil and gas reservoirs, plays and seals in the Triassic, Jurassic and Cretaceous complexes.

scholarly journals New records of lichens and allied fungi from the Leningrad Region, Russia. VII

2016 ◽  
Vol 53 ◽  
pp. 25 ◽  
Author(s):  
Dmitry E. Himelbrant ◽  
Irina S. Stepanchikova ◽  
Jurga Motiejūnaitė ◽  
Ludmila V. Gagarina ◽  
Alexandra V. Dyomina
Keyword(s):  
New Records ◽  
European Russia ◽  
Leningrad Region ◽  
Lichenicolous Fungi ◽  
The North ◽  
Western European ◽  
First Time ◽  
North Western

Fourteen species of lichens, fifteen lichenicolous fungi and one saprobic fungus are reported for the first time for St. Petersburg, Western or Eastern Leningrad Region. The lichen Lecidella meiococca and the lichenicolous fungus Tremella phaeophysciae are reported as new to Russia, the lichen Lecania sambucina and the lichenicolous fungus Endococcus tricolorans are new for the European Russia, the lichens Buellia arborea, Chaenotheca cinerea, Bellemerea sanguinea, resinicolous calicioid fungus Chaenothecopsis mediarossica and lichenicolous fungi Arthonia molendoi, Lichenochora obscuroides, Pronectria leptaleae, Sphaerellothecium cladoniae are new for the North-Western European Russia. The most interesting records are briefly discussed. 

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