Chronobiology of Deep-Water Decapod Crustaceans on Continental Margins

2010 ◽  
pp. 155-225 ◽  
Author(s):  
Jacopo Aguzzi ◽  
Joan B. Company
Nature ◽  
2003 ◽  
Vol 426 (6964) ◽  
pp. 334-343 ◽  
Author(s):  
Nicky White ◽  
Mark Thompson ◽  
Tony Barwise

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.


2020 ◽  
Vol 90 (10) ◽  
pp. 1305-1321
Author(s):  
Alexandre Normandeau ◽  
D. Calvin Campbell

ABSTRACT Turbidity currents in submarine canyons transport large volumes of sediment and carbon to the deep sea and are known to present a major risk to submarine infrastructure. Understanding the origin, the triggers, the recurrence, and the timing of these events is important for predicting future events and mitigating their impact. Depending on the morphological and latitudinal setting of submarine canyons, different external controls will govern the recurrence of turbidity currents. Here, we assess the recurrence of turbidity currents in shelf-incising submarine canyons off eastern Canada in order to examine the effects of external forcings such as glacier retreat and sea level on the deep-water sedimentary record. We used multibeam bathymetry, sub-bottom profiles, and the analysis of turbidites in sediment cores to infer the triggers of turbidity currents over time and propose a conceptual model for the activity of turbidity currents during glacial retreat. The chronostratigraphy of turbidites shows that turbidity current activity in the glaciated The Gully submarine canyon (eastern Canada) was highest between 24 ka cal BP (LGM) and 17 ka cal BP, with > 100 turbidites per 1,000 yr, when the ice sheet was directly delivering sediment to submarine canyons. As the ice margin retreated, the dominant sediment supply switched to glaciofluvial and then to longshore drift, while RSL remained low. The recurrence of turbidity currents nonetheless decreased drastically to < 10 per 1000 yr during that time, pre-dating the rise in RSL. This timing suggests that the reduction of turbidity-current activity is closely linked to retreating glaciers rather than to sea-level rise, which occurred later. Following the retreat of the ice sheet, sea level rose progressively to drown the shallow banks on the continental shelf, and turbidity currents ceased being active after 13 ka cal BP. In the late Holocene, landslide and concomitant turbidity-current recurrence increased to 1 per 1,000 yrs, with at least four new events recorded in deep water. This study shows that glacial sediment supply and sea level controlled the type of sediment supply to the continental slope, which in turn controlled the triggers of turbidity currents over time and the flushing of sediment to the deep water. By comparing with other glaciated margins, we propose a conceptual model explaining the recurrence of turbidity currents, taking into account RSL change and the position of the ice margin relative to the shelf edge. This conceptual model can help predict turbidity-current activity and offshore geohazards on other ancient and modern glaciated continental margins.


1990 ◽  
Vol 148 (1) ◽  
pp. 221-233 ◽  
Author(s):  
M. F. LAND ◽  
D.-E. NILSSON

Macrocypridina lives at depths of 800 m, where residual daylight is very weak. It has a pair of mobile apposition compound eyes with large lenses, wide rhabdoms and high acceptance angles, all of which contribute to a calculated sensitivity comparable with the superposition eyes of deep-water decapod crustaceans. The axes of the 27 ommatidia in each eye are not uniformly distributed in space, with a modest acute zone in the anteroventral region. Here the interommatidial angles are about 6°, compared with 20° at the rear of the eye. The eyes make two kinds of spontaneous movements: large slow rotations of up to 50° around a transverse axis, anda superimposed 2 Hz tremor with an amplitude of 5°.


Author(s):  
Magnus L. Johnson ◽  
Edward Gaten ◽  
Peter M.J. Shelton

The spectral sensitivities of five species of decapod crustaceans have been determined by electroretinogram measurements. Their spectral sensitivities conform to the general picture for marine crustacea with high sensitivity to blue-green wavelengths and some showing sensitivity to violet/near ultraviolet. Two deep-water species (Paromola cuvieri and Chaceon (Geryon) affinis) have spectral sensitivity maxima below 500 nm, whereas the three coastal species examined (Crangonallmani, Pandalus montagui and Nephrops norvegicus) are maximally sensitive to light of longer wavelengths (510 to 525 nm).


2015 ◽  
Vol 66 (3) ◽  
pp. 217-233 ◽  
Author(s):  
Matúš Hyžný ◽  
Mathias Harzhauser ◽  
Wolfgang Danninger

AbstractDecapod crustaceans from the Ottnangian (middle Burdigalian, Lower Miocene) of the Western and Central Paratethys remain poorly known. In this study, we review and re-describe mud shrimps (Jaxea kuemeli), ghost shrimps (Gourretiasp.,Calliax michelottii) and brachyuran crabs of the families Leucosiidae, Polybiidae and Portunidae. A dorsal carapace of the genusCalliaxis reported for the first time in the fossil record. Re-examination of the type material ofRandallia strouhali(Leucosiidae) andGeryon ottnangensis(Geryonidae) resulted in a transfer of these species intoPalaeomyra(Leucosiidae) andLiocarcinus(Polybiidae), respectively.Achelous vindobonensis, originally described as a chela of a portunid crab, probably belongs to a member of Polybiidae and is provisionally treated asLiocarcinussp. Only two species,J. kuemeliandC. michelottii, are also known from the Karpatian, the succeeding Paratethyan stage. In most cases, the decapod assemblages of the Ottnangian consist of rather shallow-water taxa whereas the assemblages of the Karpatian consist of deep-water taxa from the middle and outer shelf. The Central Paratethyan assemblages show similarities in genus composition to the Proto-Mediterranean and recent Indo-Pacific regions.Gourretiasp. represents the earliest occurrence of the respective genus in the fossil record. The Oligocene–Early Miocene appearance ofPalaeomyraandLiocarcinusin the circum-Mediterranean implies that sources of present-day diversity hotspots in the Indo-Pacific trace to the Western Tethys (as for other decapod genera), although coeval decapod assemblages in the Indo-Pacific remain poorly known.


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