Reproductive biology and ecology of the boreoatlantic armhook squid Gonatus fabricii (Cephalopoda: Gonatidae)

2019 ◽  
Vol 85 (3) ◽  
pp. 287-299 ◽  
Author(s):  
Alexey V Golikov ◽  
Martin E Blicher ◽  
Lis L Jørgensen ◽  
Wojciech Walkusz ◽  
Denis V Zakharov ◽  
...  
Keyword(s):  
Reproductive Biology ◽  
Deep Water ◽  
The Arctic ◽  
Male Size ◽  
Breeding Area ◽  
Attachment Structures ◽  
Special Attachment ◽  
Length Width ◽  
Spermatophore Size ◽  
Oocyte Resorption

Abstract The squid Gonatus fabricii (Lichtenstein, 1818) is the most abundant pelagic cephalopod in the Arctic and the only squid to spend all of its life cycle in this region. Despite being highly abundant, its reproductive biology remains poorly known, and data on large maturing and mature specimens are especially rare. This study, based on extensive material (51 large specimens and >35,000 specimens in all), fills major gaps in the knowledge of the reproductive biology and ecology of G. fabricii. The fecundity of females ranged from 8,862 to 16,200 oocytes, with mature and late maturing specimens having between 8,862 to c. 10,000 and 11,402 oocytes, respectively. Oogenesis was synchronous, and oocyte resorption was observed; resorbed oocytes constituted up to 23.5% of fecundity. Between two to five ripe oocytes were observed, and these were 4.0–5.5 mm in diameter (maximum dimension). Males possessed between 77 and 257 spermatophores (length = 5.8–10.8 mm). Spermatophores were characterized by a cement body with well-developed collar and discs at the oral end, an ejaculatory apparatus longer than the cement body and the lack of a tapered, sharp tip to the cement body. Spermatophore size showed a uniform increase in relation to increasing male size. In newer spermatophores, the length, width and volume of the seminal reservoir also increased. Females possessed between 62 and 84 spermatangia (length = 1.8–2.6 mm); the spermatangia were present on the buccal membranes and lacked special attachment structures. Seminal receptacles were not found on the buccal membranes of females. Our findings are consistent with the hypothesis of geographically restricted spawning in G. fabricii. The study found evidence for one new breeding area in south-eastern Greenland. No differences in sizes at maturity were found between the breeding areas. Such geographically localized reproduction is relatively common in non-deep-water squids, but is much less common in deep-water squids. Localized reproduction may be especially important for G. fabricii because increased food availability in the epipelagic layers would likely increase the survival of epipelagic juveniles, with surface currents potentially aiding in their dispersal.

The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

1982 ◽  
Vol 62 (1) ◽  
pp. 45-55 ◽  
Author(s):  
P. A. Tyler ◽  
J. D. Gage
Keyword(s):  
Reproductive Biology ◽  
Deep Water ◽  
Larval Stage ◽  
North Pacific ◽  
Deep Sea ◽  
Direct Development ◽  
The Arctic ◽  
Shallow Waters ◽  
Arctic Seas ◽  
Rockall Trough

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

Reproductive biology of deep-water calanoid copepods from the Arctic Ocean

2006 ◽  
Vol 151 (3) ◽  
pp. 919-934 ◽  
Author(s):  
K. N. Kosobokova ◽  
H.-J. Hirche ◽  
R. R. Hopcroft
Keyword(s):  
Arctic Ocean ◽  
Reproductive Biology ◽  
Deep Water ◽  
The Arctic ◽  
Calanoid Copepods ◽  
The Arctic Ocean

scholarly journals Autogenic influence on the morphology of submarine fans: an approach from 3D physical modelling of turbidity currents

2017 ◽  
Vol 47 (3) ◽  
pp. 345-368
Author(s):  
Cristiano Fick ◽  
Rafael Manica ◽  
Elírio Ernestino Toldo Junior
Keyword(s):  
Deep Water ◽  
Physical Modelling ◽  
Sediment Concentration ◽  
Experimental Series ◽  
Turbidity Currents ◽  
Geometrical Parameters ◽  
Submarine Fans ◽  
Relative Standard ◽  
Length Width ◽  
Depositional Evolution

ABSTRACT: Autogenic controls have significant influence on deep-water fans and depositional lobes morphology. In this work, we aim to investigate autogenic controls on the topography and geometry of deep-water fans. The influence of the sediment concentration of turbidity currents on deep-water fans morphology was also investigated. From the repeatability of 3D physical modeling of turbidity currents, two series of ten experiments were made, one of high-density turbidity currents (HDTC) and another of low-density turbidity currents (LDTC). All other input parameters (discharge, sediment volumetric concentration and grain size median) were kept constant. Each deposit was analyzed from qualitative and quantitative approaches and statistical analysis. In each experimental series, the variability of the morphological parameters (length, width, L/W ratio, centroid, area, topography) of the simulated deep-water fans was observed. Depositional evolution of the HDTC fans was more complex, showing four evolutionary steps and characterized by the self-channelizing of the turbidity current, while LDTC fans neither present self-channelizing, nor evolutionary steps. High disparities on the geometrical parameters of the fans, as characterized by the elevated relative standard deviation, suggest that autogenic controls induced a stochastic morphological behaviour on the simulated fans of the two experimental series.

The use of Cs and Sr isotopes as tracers in the Arctic Mediterranean Seas

1988 ◽  
Vol 325 (1583) ◽  
pp. 161-176 ◽  
Keyword(s):  
Deep Water ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
The Arctic ◽  
Coastal Current ◽  
Intermediate Water ◽  
Sr Isotopes ◽  
Arctic Ice ◽  
Norwegian Coastal Current

The Arctic Mediterranean Seas constitute an oceanic region in which the thermohaline circulation has a strong advective component and deep ventilation processes are very active relative to other oceanic areas. Details of the nature of these circulation and ventilation processes have been revealed through use of Cs and Sr isotopes from bomb-fallout and nuclear-waste sources as ocean tracers. In both cases, their regional input is dominated by advective supply in the Norwegian Atlantic Current and Norwegian Coastal Current, respectively. The different temporal, spatial, and compositional input patterns of these tracers have been used to study different facets of the regional circulation. These input differences and some representative applications of the use of these tracers are reviewed. The data discussed derive from samples collected both from research vessels and from Arctic ice camps. The topics addressed include: ( a ) the role of Arctic Intermediate Water as source, supplying recent surface water to North Atlantic Deep Water via the Denmark Strait overflow; ( b ) deep convective mixing in the Greenland Sea; ( c ) circulation or recirculation of Atlantic water in the Arctic basins; and ( d ) the role of Arctic shelfwaters in the ventilation of intermediate and deep water in the Eurasian and Canadian basins.

scholarly journals Arctic–North Atlantic Interactions and Multidecadal Variability of the Meridional Overturning Circulation

2005 ◽  
Vol 18 (19) ◽  
pp. 4013-4031 ◽  
Author(s):  
Johann H. Jungclaus ◽  
Helmuth Haak ◽  
Mojib Latif ◽  
Uwe Mikolajewicz
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Ocean Model ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Deep Water Formation ◽  
Overturning Circulation ◽  
Multidecadal Variability ◽  
Water Formation ◽  
Meridional Overturning

Abstract Analyses of a 500-yr control integration with the non-flux-adjusted coupled atmosphere–sea ice–ocean model ECHAM5/Max-Planck-Institute Ocean Model (MPI-OM) show pronounced multidecadal fluctuations of the Atlantic overturning circulation and the associated meridional heat transport. The period of the oscillations is about 70–80 yr. The low-frequency variability of the meridional overturning circulation (MOC) contributes substantially to sea surface temperature and sea ice fluctuations in the North Atlantic. The strength of the overturning circulation is related to the convective activity in the deep-water formation regions, most notably the Labrador Sea, and the time-varying control on the freshwater export from the Arctic to the convection sites modulates the overturning circulation. The variability is sustained by an interplay between the storage and release of freshwater from the central Arctic and circulation changes in the Nordic Seas that are caused by variations in the Atlantic heat and salt transport. The relatively high resolution in the deep-water formation region and the Arctic Ocean suggests that a better representation of convective and frontal processes not only leads to an improvement in the mean state but also introduces new mechanisms determining multidecadal variability in large-scale ocean circulation.

scholarly journals North Atlantic deep water formation and AMOC in CMIP5 models

Ocean Science ◽  
2017 ◽  
Vol 13 (4) ◽  
pp. 609-622 ◽  
Author(s):  
Céline Heuzé
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Deep Water ◽  
Deep Convection ◽  
The Arctic ◽  
Subpolar Gyre ◽  
Deep Water Formation ◽  
Nordic Seas ◽  
Water Formation

Abstract. Deep water formation in climate models is indicative of their ability to simulate future ocean circulation, carbon and heat uptake, and sea level rise. Present-day temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5) models are compared with observations to assess the biases, causes and consequences of North Atlantic deep convection in models. The majority of models convect too deep, over too large an area, too often and too far south. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. Half of the models convect in response to local cooling or salinification of the surface waters; only a third have a dynamic relationship between freshwater coming from the Arctic and deep convection. The models with the most intense deep convection have the warmest deep waters, due to a redistribution of heat through the water column. For the majority of models, the variability of the Atlantic Meridional Overturning Circulation (AMOC) is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas up to 2 years before. In turn, models with the strongest AMOC have the largest heat export to the Arctic. Understanding the dynamical drivers of deep convection and AMOC in models is hence key to realistically forecasting Arctic oceanic warming and its consequences for the global ocean circulation, cryosphere and marine life.

Influence of Nordic Seas dynamics on the Atlantic Water propagation and its impacts on sea ice concentration.

2021 ◽  
Author(s):  
Sourav Chatterjee ◽  
Roshin P Raj ◽  
Laurent Bertino ◽  
Nuncio Murukesh
Keyword(s):  
Sea Ice ◽  
Deep Water ◽  
Atlantic Water ◽  
The Arctic ◽  
Deep Water Formation ◽  
Sea Ice Concentration ◽  
Nordic Seas ◽  
Ice Concentration ◽  
Water Formation

<p>Enhanced intrusion of warm and saline Atlantic Water (AW) to the Arctic Ocean (AO) in recent years has drawn wide interest of the scientific community owing to its potential role in ‘Arctic Amplification’. Not only the AW has warmed over the last few decades , but its transfer efficiency have also undergone significant modifications due to changes in atmosphere and ocean dynamics at regional to large scales. The Nordic Seas (NS), in this regard, play a vital role as the major exchange of polar and sub-polar waters takes place in this region. Further, the AW and its significant modification on its way to AO via the Nordic Seas has large scale implications on e.g., deep water formation, air-sea heat fluxes. Previous studies have suggested that a change in the sub-polar gyre dynamics in the North Atlantic controls the AW anomalies that enter the NS and eventually end up in the AO. However, the role of NS dynamics in resulting in the modifications of these AW anomalies are not well studied. Here in this study, we show that the Nordic Seas are not only a passive conduit of AW anomalies but the ocean circulations in the Nordic Seas, particularly the Greenland Sea Gyre (GSG) circulation can significantly change the AW characteristics between the entry and exit point of AW in the NS. Further, it is shown that the change in GSG circulation can modify the AW heat distribution in the Nordic Seas and can potentially influence the sea ice concentration therein. Projected enhanced atmospheric forcing in the NS in a warming Arctic scenario and the warming trend of the AW can amplify the role of NS circulation in AW propagation and its impact on sea ice, freshwater budget and deep water formation.</p>

Conventional and Deep-Water Shipping Passages Along the Northern Sea Route

2019 ◽  
pp. 314-337
Author(s):  
Andrey Afonin ◽  
Evgeniy Olkhovik ◽  
Alexander Tezikov
Keyword(s):  
Deep Water ◽  
The Arctic ◽  
Intensity Increase ◽  
State University ◽  
Factors Affecting ◽  
Northern Sea Route ◽  
Major Development ◽  
Previous Decade ◽  
Principal Factors ◽  
Research Findings

The chapter presents a description of conventional and deep-water shipping routes within the water areas of the Northern Sea Route (NSR). There are provided the evaluation of the hydrographical survey of the Arctic Ocean seabed with respect to navigational safety along with the summary of the principal factors affecting the efficiency and safety of shipping in the polar water. The chapter discusses the current situation and major development tendencies of the NSR, in particular the forecasted growth of navigation intensity, increase of the shares of high ice-strengthened heavy-tonnage vessels and hazardous cargoes in transportation, and spread of the year-round navigation zone to the East. Some of the research findings obtained during the previous decade at the Arctic Faculty of Admiral Makarov State University of Maritime and Inland Shipping are provided. The assessment of the effects of shallows and ice on the working capacity of the NSR for deep-draft vessels is provided.

scholarly journals Carbon isotope (δ<sup>13</sup>C) excursions suggest times of major methane release during the last 14 kyr in Fram Strait, the deep-water gateway to the Arctic

2015 ◽  
Vol 11 (4) ◽  
pp. 669-685 ◽  
Author(s):  
C. Consolaro ◽  
T. L. Rasmussen ◽  
G. Panieri ◽  
J. Mienert ◽  
S. Bünz ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Isotope ◽  
Deep Water ◽  
Planktonic Foraminifera ◽  
Sediment Supply ◽  
The Arctic ◽  
Fram Strait ◽  
The North ◽  
Carbon Isotope Excursion

Abstract. We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dates reveal a detailed chronology for the last 14 ka BP. The δ 13C record measured on the benthonic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope excursion (CIE I and CIE II, respectively). The values were as low as −4.37‰ in CIE I, correlating with the Bølling–Allerød interstadials, and as low as −3.41‰ in CIE II, correlating with the early Holocene. In the Bølling–Allerød interstadials, the planktonic foraminifera also show negative values, probably indicating secondary methane-derived authigenic precipitation affecting the foraminiferal shells. After a cleaning procedure designed to remove authigenic carbonate coatings on benthonic foraminiferal tests from this event, the 13C values are still negative (as low as −2.75‰). The CIE I and CIE II occurred during periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic, suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

Palaeo-oceanography, margin stratigraphy and palaeophysiography of the Tertiary North Atlantic and Norwegian-Greenland seas

1980 ◽  
Vol 294 (1409) ◽  
pp. 177-185 ◽  
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Global Climate ◽  
Circulation Pattern ◽  
The Arctic ◽  
Continental Margins ◽  
Long Distance ◽  
Sea Level Fluctuations ◽  
The North ◽  
Border Zones

The Tertiary was a period of dramatic changes of the palaeo-oceanography of the world’s oceans in general and of the North Atlantic in particular. These changes were caused by (1) the bathymetric evolution of ocean basins and intrabasin pathways (opening of the Norwegian-Greenland Seas and of the pathway to the Arctic Ocean, interruption of the circumglobal equatorial seaway); (2) the geographical development of the oceans and adjacent marginal basins in the context of rapid and intensive eustatic sea level fluctuations; and (3) the deterioration of the global climate throughout the Tertiary (change from a non-glacial to a glacial world, causing major changes in circulation of the surface and deep water). A biostratigraphy of Tertiary sediments deposited close to the continental margins has been developed by using remains of planktonic floras and faunas. Their presence in these sediments and their usefulness for long distance correlations of margin sediments, depend upon the circulation pattern and hydrographic gradients of the oceanic surface and deep water masses, the climatic regime over the continental border zones, and the probability of their post-depositional preservation.

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