scholarly journals Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

2020 ◽  
Author(s):  
Junya Hirai ◽  
Aiko Tachibana ◽  
Atsushi Tsuda
Keyword(s):  
Community Structure ◽  
Environmental Conditions ◽  
Evolutionary History ◽  
Large Scale ◽  
The Arctic ◽  
Copepod Community ◽  
The Pacific ◽  
Low Latitudes ◽  
The Pacific Ocean ◽  
Epipelagic Layer

AbstractA clear insight into large-scale community structure of planktonic copepods is critical to understanding mechanisms controlling diversity and biogeography of marine taxa, owing to their high abundance, ubiquity, and sensitivity to environmental changes. Here, we applied a 28S metabarcoding approach to large-scale communities of epipelagic and mesopelagic copepods at 70 stations across the Pacific Ocean and three stations in the Arctic Ocean. Major patterns of community structure and diversity, influenced by water mass structures, agreed with results from previous morphology-based studies. However, large-scale metabarcoding approach could detected community changes even under stable environmental conditions, including changes in the north/south subtropical gyres and east/west areas within each subtropical gyre. There were strong effects of epipelagic environment on mesopelagic communities, and community subdivisions were observed in the environmentally-stable mesopelagic layer. In each sampling station, higher operational taxonomic unit (OTU) numbers and lower phylogenetic diversity were observed in the mesopelagic layer than in the epipelagic layer, indicating a recent rapid increase of species numbers in the mesopelagic layer. The phylogenetic analysis utilizing representative sequences of OTUs revealed trends of recent emergence of cold-water OTUs mainly distributed at high latitudes with low water temperatures. Conversely, high diversity of copepods at low latitudes was suggested to have been formed through long evolutionary history under high water temperature. The metabarcoding results suggest that evolutionary processes have strong impacts on current patterns of copepod diversity, and support the “out of the tropics” theory explaining latitudinal diversity gradients of copepods. Both diversity patterns in epipelagic and mesopelagic showed high correlations to sea surface temperature; thus, predicted global warming may have a significant impact on copepod diversity in both layers.Author SummaryMarine planktonic copepods are highly dominant and diverse, and revealing their community structure and diversity is important to understanding marine ecosystems. We used molecular-based metabarcoding to reveal a total of 205 copepod communities in the ‘sunlight’ or epipelagic layer (0– 200 m) and the ‘twilight’ or mesopelagic layer (200–500 m and 500–1,000 m), mainly in the Pacific Ocean (data for 70 stations), but also in the Arctic Ocean (data for three stations). Different copepod communities were found in each geographical region with different environmental conditions, including tropical, subtropical, transition, Kuroshio Current, California Current, subarctic and arctic areas. The metabarcoding method sensitively detected small changes of copepod community even in environmentally-stable subtropical ocean systems and the mesopelagic layer. A high diversity of copepods was detected at low latitudes, and copepod diversity was higher in the mesopelagic layer than in the epipelagic layer in each area. These diversity patterns were influenced by both evolutionary history and present environmental conditions. The copepod community in the mesopelagic layer was strongly influenced by environmental conditions in the epipelagic layer. Thus, predicted climate changes may affect marine ecosystems not only in the epipelagic layer but also in the mesopelagic layer.

scholarly journals A subduction influence on ocean ridge basalts outside the Pacific subduction shield

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
A. Y. Yang ◽  
C. H. Langmuir ◽  
Y. Cai ◽  
P. Michael ◽  
S. L. Goldstein ◽  
...  
Keyword(s):  
Upper Mantle ◽  
The Arctic ◽  
Mantle Flow ◽  
Mantle Heterogeneity ◽  
Gakkel Ridge ◽  
The Pacific ◽  
Mid Ocean Ridge ◽  
The Pacific Ocean ◽  
Back Arc ◽  
Ocean Ridge

AbstractThe plate tectonic cycle produces chemically distinct mid-ocean ridge basalts and arc volcanics, with the latter enriched in elements such as Ba, Rb, Th, Sr and Pb and depleted in Nb owing to the water-rich flux from the subducted slab. Basalts from back-arc basins, with intermediate compositions, show that such a slab flux can be transported behind the volcanic front of the arc and incorporated into mantle flow. Hence it is puzzling why melts of subduction-modified mantle have rarely been recognized in mid-ocean ridge basalts. Here we report the first mid-ocean ridge basalt samples with distinct arc signatures, akin to back-arc basin basalts, from the Arctic Gakkel Ridge. A new high precision dataset for 576 Gakkel samples suggests a pervasive subduction influence in this region. This influence can also be identified in Atlantic and Indian mid-ocean ridge basalts but is nearly absent in Pacific mid-ocean ridge basalts. Such a hemispheric-scale upper mantle heterogeneity reflects subduction modification of the asthenospheric mantle which is incorporated into mantle flow, and whose geographical distribution is controlled dominantly by a “subduction shield” that has surrounded the Pacific Ocean for 180 Myr. Simple modeling suggests that a slab flux equivalent to ~13% of the output at arcs is incorporated into the convecting upper mantle.

Little-known arctic species Montacuta spitzbergensis (Bivalvia: Montacutidae) from the north-western Pacific with notes on Montacuta substriata and Tellimya ferruginosa

2008 ◽  
Vol 88 (2) ◽  
pp. 347-356 ◽  
Author(s):  
Gennady M. Kamenev
Keyword(s):  
Sea Of Okhotsk ◽  
First Record ◽  
Western Pacific ◽  
The Arctic ◽  
Arctic Species ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
North Western ◽  
North Western Pacific

An expanded description of a little-known arctic species Montacuta spitzbergensis from the Sea of Okhotsk with new data on its morphology, ecology and geographical distribution is given. This is the first record of M. spitzbergensis from the north-western Pacific. It differs from other species of Montacuta in its large (to 8.4 mm), elongate–ovate, thick shell with wide, slightly curved hinge plate, wide, short, and shallow resilifer, and weakly developed external ligament. This species occurs in the Arctic Ocean (Spitsbergen, Barents, Kara, Laptev and Chukchi Seas) and the Pacific Ocean (Sea of Okhotsk) at depths from 9 to 232 m at a bottom temperature from −1.62°C to +2.50°C. The hinge structure of the type species of the genera Montacuta and Tellimya is also discussed.

scholarly journals Causes of the Record-Breaking Pacific Northwest Heatwave, Late June 2021

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1434
Author(s):  
James E. Overland
Keyword(s):  
Pacific Northwest ◽  
Large Scale ◽  
Polar Vortex ◽  
The Arctic ◽  
Large Temperature ◽  
Extreme Heat Event ◽  
The Pacific ◽  
Heat Event ◽  
Large Scale Atmospheric Circulation ◽  
The Bering Sea

The extreme heat event that hit the Pacific Northwest (Oregon, Washington, southern British Columbia) at the end of June 2021 was 3 °C greater than the previous Seattle record of 39 °C; larger extremes of 49 °C were observed further inland that were 6 °C above previous record. There were hundreds of deaths over the region and loss of marine life and forests. At the large scale prior to the event, the polar vortex was split over the Arctic. A polar vortex instability center formed over the Bering Sea and then extended southward along the west coast of North America. The associated tropospheric trough (low geopotential heights) established a multi-day synoptic scale Omega Block (west-east oriented low/high/low geopotential heights) centered over the Pacific Northwest. Warming was sustained in the region due to subsidence/adiabatic heating and solar radiation, which were the main reasons for such large temperature extremes. The seasonal transition at the end of spring suggests the possibility of a southern excursion of a polar vortex/jet stream pair. Both the Pacific Northwest event in 2021 and the Siberian heatwave climax in June 2020 may be examples of crossing a critical state in large-scale atmospheric circulation variability.

Variability of Arctic Sea Ice Based on Quantile Regression and the Teleconnection with Large-Scale Climate Patterns

2020 ◽  
Vol 33 (10) ◽  
pp. 4009-4025
Author(s):  
Shuyu Zhang ◽  
Thian Yew Gan ◽  
Andrew B. G. Bush
Keyword(s):  
Sea Ice ◽  
Quantile Regression ◽  
Large Scale ◽  
Southern Oscillation ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Climate Indices ◽  
The Pacific ◽  
Arctic Sea ◽  
Climate Patterns

AbstractUnder global warming, Arctic sea ice has declined significantly in recent decades, with years of extremely low sea ice occurring more frequently. Recent studies suggest that teleconnections with large-scale climate patterns could induce the observed extreme sea ice loss. In this study, a probabilistic analysis of Arctic sea ice was conducted using quantile regression analysis with covariates, including time and climate indices. From temporal trends at quantile levels from 0.01 to 0.99, Arctic sea ice shows statistically significant decreases over all quantile levels, although of different magnitudes at different quantiles. At the representative extreme quantile levels of the 5th and 95th percentiles, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), and the Pacific–North American pattern (PNA) have more significant influence on Arctic sea ice than El Niño–Southern Oscillation (ENSO), the Pacific decadal oscillation (PDO), and the Atlantic multidecadal oscillation (AMO). Positive AO as well as positive NAO contribute to low winter sea ice, and a positive PNA contributes to low summer Arctic sea ice. If, in addition to these conditions, there is concurrently positive AMO and PDO, the sea ice decrease is amplified. Teleconnections between Arctic sea ice and the climate patterns were demonstrated through a composite analysis of the climate variables. The anomalously strong anticyclonic circulation during the years of positive AO, NAO, and PNA promotes more sea ice export through Fram Strait, resulting in excessive sea ice loss. The probabilistic analyses of the teleconnections between the Arctic sea ice and climate patterns confirm the crucial role that the climate patterns and their combinations play in overall sea ice reduction, but particularly for the low and high quantiles of sea ice concentration.

CALCULATION OF THE MAGNETIZATION OF UPLIFTS FROM COMBINING TOPOGRAPHIC AND MAGNETIC SURVEYS

Geophysics ◽  
1967 ◽  
Vol 32 (4) ◽  
pp. 678-707 ◽  
Author(s):  
M. L. Richards ◽  
V. Vacquier ◽  
G. D. Van Voorhis
Keyword(s):  
Pacific Ocean ◽  
Horizontal Plane ◽  
Large Scale ◽  
Geomagnetic Latitude ◽  
Pole Position ◽  
Present Position ◽  
Paleomagnetic Pole ◽  
The Pacific ◽  
Geomagnetic Pole ◽  
The Pacific Ocean

The direction and magnitude of the magnetization of a uniformly magnetized structure can be computed by combining topographic and magnetic surveys. The previously reported method has been extended to include more than one structure, each possessing its particular magnetization. Also, the bottom of the structure need not be a horizontal plane but can be an arbitrary surface. The method was applied to 21 seamounts, one laccolith and two Aleutian volcanoes. Four of the seamounts were found to be reversely magnetized. The virtual paleomagnetic pole positions for 16 Pacific Ocean seamounts, representing three widely separated locations, are significantly different from the present geomagnetic pole position but near Mesozoic virtual pole positions from Australia. For two locations, radiometric age determinations give an average date for their formation in the Cretaceous. The apparent 30 degree shift in geomagnetic latitude of the seamounts is interpreted as the result of large scale movements of the Pacific Ocean floor or, alternatively, as the result of the paleomagnetic equator being north of its present position in the Pacific during the growth of the seamounts.

scholarly journals Inter-Relations between the Arctic Sea Ice and the General Circulation of the Atmosphere (Abstract)

1987 ◽  
Vol 9 ◽  
pp. 252-252
Author(s):  
G. Wendler ◽  
M. Jeffries ◽  
Y. Nagashima
Keyword(s):  
Sea Ice ◽  
General Circulation ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Zonal Circulation ◽  
The Pacific ◽  
Arctic Sea ◽  
Ice Conditions ◽  
The Pacific Ocean ◽  
Opposing Effects

Satellite imagery has substantially improved the quality of sea-Ice observation over the last decades. Therefore, for a 25-year period, a statistical study based on the monthly Arctic sea-ice data and the monthly mean 700 mbar maps of the Northern Hemisphere was carried out to establish the relationships between sea-ice conditions and the general circulation of the atmosphere. It was found that sea-ice conditions have two opposing effects on the zonal circulation intensity, depending on the season. Heavier than normal ice in winter causes stronger than normal zonal circulation in the subsequent months, whereas heavier than normal ice in the summer–fall causes weaker zonal circulation in the subsequent months. Analyzing the two sectors, the Atlantic and Pacific ones separately, a negative correlation was found, which means a heavy ice year in the Atlantic Ocean is normally associated with a light one in the Pacific Ocean and vice versa.

Diversity of Small Mammals in the Pacific Coastal Desert of Peru and Chile and in the Adjacent Andean Area - Biogeography and Community Structure

1994 ◽  
Vol 42 (4) ◽  
pp. 527 ◽  
Author(s):  
PA Marquet
Keyword(s):  
Community Structure ◽  
Species Diversity ◽  
Small Mammals ◽  
Large Scale ◽  
Regional Scale ◽  
Desert Area ◽  
Evolutionary Processes ◽  
Coastal Desert ◽  
The Pacific ◽  
Similarities And Differences

Species diversity patterns of small mammals (sigmodontine rodents) in the Chilean-Peruvian Pacific coastal desert and adjacent Andean area (Puna) were analysed by means of latitudinal and altitudinal transects. The statistical analyses of the patterns show: (1) a wide variation in latitudinal species diversity, with a peak in the region where the Puna reaches its greatest areal extent; (2) the differentiation of at least four groups of distinct faunal elements resulting from the interaction of large-scale biogeographic, geological and evolutionary processes; (3) a positive correlation between species richness and altitude for the altitudinal transects located within the Pacific coastal desert area and Puna; and (4) a highly individualistic pattern of community structure at a regional scale. These results are discussed considering biogeographic, palaeoclimatic and evolutionary processes, such as the establishment of the Pacific coastal desert, and the existence of a major centre of species diversification in the Puna area. Similarities and differences between these community-level patterns and those in North American deserts are discussed.

An introductory overview to the concept of displaced terranes

1983 ◽  
Vol 20 (6) ◽  
pp. 994-999 ◽  
Author(s):  
Zvi Ben-Avraham ◽  
Amos Nur
Keyword(s):  
Large Scale ◽  
Continental Margins ◽  
Oceanic Plateaus ◽  
Introductory Overview ◽  
The Pacific ◽  
History Of ◽  
Accreted Terranes ◽  
Pacific Margin ◽  
The Pacific Ocean ◽  
Oceanic Plates

On land much of the Pacific margin is composed of allochthonous terranes, which are of continental and noncontinental origins. In the oceans numerous oceanic rises, some of which are submerged continental fragments, are presently embedded in the oceanic plates. These oceanic rises are probably future accreted terranes. They thus represent one stage in the development of allochthonous terranes found in orogenic zones. Minerals found in these terranes were formed at locations that in the past could have been thousands of kilometres away. This is because some oceanic terranes were split into several parts that moved with their respective plates in different directions. Also, faulting at the continental margins caused large-scale concurrent and post-accretionary horizontal translations of hundreds of kilometres of the allochthonous terranes.Studying the allochthonous terranes may provide important information about the Paleozoic and early Mesozoic history of the Pacific Ocean, because most of the oceanic crust of this age has disappeared leaving only those allochthonous terranes that were once oceanic plateaus within this crust. Understanding the history of the Pacific basin plates and of the allochthonous terranes may lead to the discovery of minerals within the submerged oceanic plateaus.

25.—Challenger's Voyage and the Black Sea Investigations at the close of the Nineteenth Century.

1972 ◽  
Vol 72 (1) ◽  
pp. 273-275
Author(s):  
I. A. Fedosseyev ◽  
A. F. Plakhotnick
Keyword(s):  
Nineteenth Century ◽  
World Ocean ◽  
The Arctic ◽  
The Black Sea ◽  
Important Work ◽  
The Pacific ◽  
The World ◽  
Antarctic Continent ◽  
The Pacific Ocean ◽  
The Antarctic

Though Russia, in contrast with England, had no broad access to the oceans, Russian oceanographers always took a great interest in the world ocean investigations. To confirm this we would first of all like to mention the Russian cruises around the world, made by I. F. Krusenstern and Ju. F. Lisjansky in 1803–06, V. M. Golovnin in 1806–13 and 1817–19, M. P. Lazarev in 1819–21 and 1822–25 (the second voyage, the main result of which was the discovery of the Antarctic Continent, was made together with F. F. Bellingshauzen), O. E. Kotsebu in 1815–18 and 1823–26, and F. O. Litke in 1826–29. The names of several Russian explorers who carried on important work in various parts of the Arctic and the Pacific Oceans in different periods of the nineteenth century are well known. At one time valuable results of the oceanological investigations, carried out by Admiral S. O. Makarov on the ship Vitjaz in the Pacific Ocean in 1886–89, attracted much attention. The fact that Vitjaz is lettered on the pediment of the Oceanographical Museum of Monaco among the ten ships most distinguished in oceanographical explorations from the whole world testifies to the scientific importance of Makarov's investigations.

scholarly journals Emergent Rarity Properties in Carabid Communities From Chinese Steppes With Different Climatic Conditions

2021 ◽  
Vol 9 ◽  
Author(s):  
Noelline Tsafack ◽  
Paulo A. V. Borges ◽  
Yingzhong Xie ◽  
Xinpu Wang ◽  
Simone Fattorini
Keyword(s):  
Community Structure ◽  
Environmental Conditions ◽  
Large Scale ◽  
Species Abundance ◽  
Climatic Conditions ◽  
Carabid Beetles ◽  
Model Parameters ◽  
Desert Steppe ◽  
Best Fit ◽  
Scale Of Analysis

Species abundance distributions (SADs) are increasingly used to investigate how species community structure changes in response to environmental variations. SAD models depict the relative abundance of species recorded in a community and express fundamental aspects of the community structure, namely patterns of commonness and rarity. However, the influence of differences in environmental conditions on SAD characteristics is still poorly understood. In this study we used SAD models of carabid beetles (Coleoptera: Carabidae) in three grassland ecosystems (desert, typical, and meadow steppes) in China. These ecosystems are characterized by different aridity conditions, thus offering an opportunity to investigate how SADs are influenced by differences in environmental conditions (mainly aridity and vegetation cover, and hence productivity). We used various SAD models, including the meta-community zero sum multinomial (mZSM), the lognormal (PLN) and Fisher’s logseries (LS), and uni- and multimodal gambin models. Analyses were done at the level of steppe type (coarse scale) and for different sectors within the same steppe (fine scale). We found that the mZSM model provided, in general, the best fit at both analysis scales. Model parameters were influenced by the scale of analysis. Moreover, the LS was the best fit in desert steppe SAD. If abundances are rarefied to the smallest sample, results are similar to those without rarefaction, but differences in models estimates become more evident. Gambin unimodal provided the best fit with the lowest α-value observed in desert steppe and higher values in typical and meadow steppes, with results which were strongly affected by the scale of analysis and the use of rarefaction. Our results indicate that all investigated communities are adequately modeled by two similar distributions, the mZSM and the LS, at both scales of analyses. This indicates (1) that all communities are characterized by a relatively small number of species, most of which are rare, and (2) that the meta-communities at the large scale maintain the basic SAD shape of the local communities. The gambin multimodal models produced exaggerated α-values, which indicates that they overfit simple communities. Overall, Fisher’s α, mZSM θ, and gambin α-values were substantially lower in the desert steppe and higher in the typical and meadow steppes, which implies a decreasing influence of environmental harshness (aridity) from the desert steppe to the typical and meadow steppes.

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