Quaternary equatorial Atlantic deep-sea ostracodes: evidence for a distinct tropical fauna in the deep sea

2021 ◽  
pp. 1-41
Author(s):  
Moriaki Yasuhara ◽  
Hisayo Okahashi ◽  
Huai-Hsuan May Huang ◽  
Yuanyuan Hong ◽  
Hokuto Iwatani ◽  
...  
Keyword(s):  
Deep Sea ◽  
Wide Distribution ◽  
Equatorial Atlantic ◽  
Ocean Drilling Program ◽  
Low Latitude ◽  
Biogeographic Patterns ◽  
Deep Waters ◽  
Equatorial Atlantic Ocean ◽  
Faunal Element ◽  
Globally Distributed

Abstract Low-latitude, deep-sea faunas remain poorly understood and described. Here, we systematically describe Quaternary deep-sea ostracodes from the Ocean Drilling Program (ODP) Site 925 (Ceara Rise; 4°12.2'N, 43°29.3′W; 3040 m water depth) in the equatorial Atlantic Ocean. Twenty-six genera and 52 species were examined and illustrated with high-resolution scanning electron microscopy images. Six new species are described herein: Pseudocythere spinae, Hemiparacytheridea zarikiani, Pedicythere canis, Xylocythere denticulata, Paracytherois obtusa, and Poseidonamicus sculptus. The results show that deep-sea ostracodes have a tropical faunal element that is distinctive from higher latitude ostracodes, and that is globally distributed in low latitudes. This tropical faunal component is possibly a Tethyan legacy of a fauna that was widely distributed in tropical and extratropical latitudes in deep waters during greenhouse conditions in the Cretaceous and early Cenozoic. Global cooling thereafter shrank its distribution, limiting it to tropical latitudes, perhaps with the relatively warm uppermost bathyal area acting as the source or refuge of this faunal component. Because similar present-day biogeographic patterns (i.e., presence and wide distribution of tropical deep-sea fauna) are known in other deep-sea benthic groups, this scenario might be applicable to the deep-sea benthos more broadly. UUID: http://zoobank.org/552d4cb2-c0db-463a-ae3f-b2efcc0985df.

Bioluminescence

1962 ◽  
Vol 265 (1322) ◽  
pp. 355-359 ◽  
Keyword(s):  
Deep Sea ◽  
Marine Biology ◽  
Low Frequency ◽  
Wide Distribution ◽  
Deep Waters ◽  
Numerical Abundance ◽  
Light Organs ◽  
Sensory Modalities ◽  
Intensive Investigation ◽  
Sea Fish

In the early days of marine biology, a century ago, when many new species were being discovered, scientists were puzzled by strange organs that some of these animals possessed. Various functions were ascribed to them, such as pressurereceptors, infra-red detectors and accessory eyes. It is now known that many of these puzzling organs are photophores or light-organs. Deep-sea animals possess the same sensory modalities as surface and shallowwater species—smell, sight, hearing, vibrational sense, touch. Sensory organs may be accentuated or specialized in certain ways to make them more efficient in the peculiar conditions obtaining in deep waters. Signals which animals emit are sounds, low-frequency vibrations, odours and light. In an environment where perceptible daylight is wanting, light is produced by the animals themselves. Very many deep-sea animals have well-developed eyes: to function these eyes need light, and the light is provided by luminescence. It is now apparent that luminescence is a wide-spread and common phenomenon in the deep sea. The abundance, complexity and wide distribution of light-organs among bathypelagic animals attest to this. In an intensive investigation of a small area near Bermuda, Beebe (1937) found that two-thirds of the species of deep-sea fish captured below 700 m were luminous; reckoned as individuals, over ninetenths were luminous. This high proportion of luminous fish was due to the numerical abundance of cyclothonids and myctophids in the catches.

The determination and significance of past temperature changes in the upper layer of the equatorial Atlantic Ocean

1954 ◽  
Vol 222 (1150) ◽  
pp. 296-323 ◽  
Keyword(s):  
Atlantic Ocean ◽  
Deep Sea ◽  
Planktonic Foraminifera ◽  
Climatic Changes ◽  
Equatorial Atlantic ◽  
Temperature Changes ◽  
Sea Floor ◽  
The Core ◽  
Equatorial Atlantic Ocean ◽  
Rate Of Sedimentation

As sea water apart from liquid ammonia has the highest heat capacity of any solid or liquid the deposits collecting on the deep-sea floor, in favourable localities, give a far better record than the land of past temperature changes, provided the dominant component is planktonic Foraminifera, and that the rate of sedimentation of at least one of the other components has remained constant with time. There are three possible methods whereby past temperature changes in the upper layer of the Equatorial Atlantic Ocean can be revealed. The first is the productivity method. As the minimal factor which influences the productivity of planktonic Foraminifera is apparently temperature, it is possible in the ideal case where the rate of sedimentation of the non-calcareous components has remained constant with time; and where there has been no contribution to the carbonate content other than by the shells of planktonic Foraminifera, and provided there has been no appreciable solution of carbonate, to follow the changing temperature in the upper layer of the sea by determining the CO 2 content in a series of samples throughout the length of the core. This method is clearly applicable to the more general case where the rate of sedimentation of only one of the non-calcareous components has remained constant with time. A new technique has been developed for determining accurately the CO 2 content in globigerina ooze cores. The second method, due to Mr Ovey, depends on the species distribution of planktonic Foraminifera in 1000 specimens > 127 μ . The third method has been developed by Professor Urey and depends on the 18 O content of individual planktonic species. Consideration is given to the possibility of the CO 2 changes being spurious and unrelated to temperature changes. Perhaps the most convincing argument against this hypothesis is the similarity between the carbonate curve in the Atlantic core and the carbonate accumulation curves for the Pacific cores, as well as in the number of maxima and minima and in their respective ages. In the top portion of an undisturbed pilot core, there are apparently CO 2 oscillations of a shorter period. A continuous series of sections, approximately ½ cm thick, were taken down this core. It has been possible to determine the total weight of non-calcareous components, dried at 105° C, in a column of unit area down to any depth in the core, and by correlating two distinct CO 2 oscillations with two climatic changes of known ages, the mass contribution per year can be computed. The inverse relation between TiO 2 , Fe 2 O 3 and CaCO 3 suggests that there has been no marked deviations in the rate of sedimentation of the non-calcareous components with time. On this assumption, it is possible to compute the age at any depth. There is an apparent agreement between the ages of these oscillations and the ages of known second-order climatic changes. The fact that the age according to these computations of the top of the core is A. D. 1838 gives support to these correlations. There are two effects to be clearly distinguished: first, a long period change and secondly, minor oscillations superimposed on these major changes. The necessity for the development of a simple coring device to take short but wide undisturbed cores, which are truely representative of the natural sedimentary column of the deep-sea-floor, is pointed out.

Assessing the Global Meltwater Spike

1982 ◽  
Vol 17 (2) ◽  
pp. 148-172 ◽  
Author(s):  
Glenn A. Jones ◽  
William F. Ruddiman
Keyword(s):  
Deep Sea ◽  
Planktonic Foraminifera ◽  
World Ocean ◽  
Equatorial Atlantic ◽  
Low Salinity ◽  
Ice Volume ◽  
Middle Latitudes ◽  
Mixing Intensity ◽  
Entire World ◽  
Isotopic Signal

AbstractL. V. Worthington (1968, Meteorological Monographs 8, 63–67) hypothesized that a low-salinity lid covered the entire world ocean. By deconvolving isotopic curves from the western equatorial Pacific and equatorial Atlantic, W. H. Berger, R. F. Johnson, and J. S. Killingley (1977), Nature (London) 269, 661–663) and W. H. Berger (1978, Deep-Sea Research 25, 473–480) reconstructed “meltwater spikes” similar to those actually observed in the Gulf of Mexico and thus apparently confirmed the Worthington hypothesis. It is shown that this conclusion is unwarranted. The primary flaw in the reconstructed meltwater spikes is that the mixing intensity used in the deconvolution operation is overestimated. As a result, structure recorded in the mixed isotopic record becomes exaggerated in the attempt to restore the original unmixed record. This structure can be attributed to variable ice-volume decay during deglaciation, effects of differential solution on planktonic foraminifera, temporal changes in abundance of the foraminifera carrying the isotopic signal, and analytical error. An alternative geographic view to the global low-salinity lid is offered: a map showing portions of the ocean potentially affected by increased deglacial meltwater at middle and high latitudes and by increased precipitation-induced runoff at low and middle latitudes.

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