scholarly journals Scavenging amphipods of the Tonga Trench: an analysis of community assemblage and population structure

2021 ◽  
Author(s):  
◽  
James Peter Ashley Wilson
Keyword(s):  
Population Structure ◽  
Hydrostatic Pressure ◽  
Current Knowledge ◽  
Food Sources ◽  
Depth Range ◽  
The South ◽  
Life Project ◽  
Total Length ◽  
Vertical Range ◽  
Hadal Zone

<p>The hadal zone is the common name for the deepest section of the ocean (6,000-11,000 m depth). It encompasses 45 % of the ocean’s depth range, and is mostly represented by oceanic trenches. Trench habitats lack sufficient sampling and the communities within are not well understood. Often, samples are derived from a single depth and thus the population dynamics of trench communities have not been analysed comprehensively.  Scavenging amphipods are abundant and diverse taxa in the trench environment, and have been found in every trench sampled to date. They rapidly intercept and consume carrion falls at the deepest trench depths, and act as key prey items to predators in the shallower depths of the hadal zone. There appears to be a relationship of increasing abundance and decreasing diversity of scavenging amphipods with depth. However in the Tonga Trench, sampling of hadal amphipods has been limited, and these patterns remain unclear.  The QUELLE (Quest for the Limit of Life) project in 2013 was led by The Japan Agency for Marine-Earth Science and Technology (JAMSTEC). As part of this project, the YOK 13-10 voyage examined scavenging amphipods in the Tonga Trench. The voyage used baited traps to sample depths of ˜6,250 m and ˜10,800 m from October 6 – October 21 in 2013. The main objectives of the present study were to: identify scavenging amphipod assemblages within the Tonga Trench and compare them to other trenches of the South Pacific; analyse the population structure of Hirondellea dubia between depths in the Tonga Trench; and identify a suitable total length proxy for H. dubia.  Six species of amphipods were identified from depths of ˜6,250 m and ˜10,800 m in the Tonga Trench. At ˜6,250 m Alicella gigantea, Eurythenes gryllus, H. dubia, Bathycallisoma schellenbergi, an alicellid species, and a gammarid species were recovered. In contrast, H. dubia was the only species recovered from ˜10,800 m. The abundance of amphipods was higher at the ˜10,800 m site while the diversity was much lower.  The assemblage of scavenging amphipods in the Tonga Trench was similar to those from past sampling efforts in the same trench. There were also similarities to the assemblages in the adjacent Kermadec Trench, and together these observations support the classification of these two trenches as a single biogeographic province. The assemblages in the Peru-Chile Trench in the South East Pacific were more dissimilar sharing only a few species. The present study provides new Tonga Trench records of the vertical ranges of A. gigantea, E. gryllus, and H. dubia. It also extends the maximum known depth of H. dubia to 10,807 m. This thesis expanded our current knowledge of A. gigantea, by reporting the first instance of this large amphipod in the Tonga Trench, and the second known instance of the species at hadal depths.  An analysis of Hirondellea dubia population structure revealed ontogenetic vertical structuring in the Tonga Trench. Juveniles dominated the composition in the shallow end of the H. dubia vertical range, while very few juveniles were found at the deepest site. Juveniles were substantially smaller at ˜6,250 m compared to ˜10,800 m, and this may suggest that juveniles migrate down the trench slope with increasing age. The most likely mechanism for distributing juveniles to the shallower depths is the ascending migration of brooding females. However, this is still not certain as no brooding females were captured. The shallower depth provides a higher quality of food source and the reduced hydrostatic pressure allows for a faster metabolic rate. Thus, this distribution is likely driven by the distribution of food sources throughout the trench in combination with hydrostatic pressure.  The dimensions of several established proxies for total length were evaluated for H. dubia. Pereonite 2-7 had the strongest correlation to total length, however it was highly distorted by dorsal curvature. Both the pereonite 2-7 and the pleosome were considered inaccurate due to sexual dimorphism making them inappropriate as proxies. Pereonite 1 was proportionately larger in juvenile lifestages. However, overall pereonite 1 was considered the strongest candidate for a proxy, this is because it was the least influenced by dorsal curvature and was a conspicuous segment that was easy to measure.</p>

scholarly journals Scavenging amphipods of the Tonga Trench: an analysis of community assemblage and population structure

2021 ◽  
Author(s):  
◽  
James Peter Ashley Wilson
Keyword(s):  
Population Structure ◽  
Hydrostatic Pressure ◽  
Current Knowledge ◽  
Food Sources ◽  
Depth Range ◽  
The South ◽  
Life Project ◽  
Total Length ◽  
Vertical Range ◽  
Hadal Zone

<p>The hadal zone is the common name for the deepest section of the ocean (6,000-11,000 m depth). It encompasses 45 % of the ocean’s depth range, and is mostly represented by oceanic trenches. Trench habitats lack sufficient sampling and the communities within are not well understood. Often, samples are derived from a single depth and thus the population dynamics of trench communities have not been analysed comprehensively.  Scavenging amphipods are abundant and diverse taxa in the trench environment, and have been found in every trench sampled to date. They rapidly intercept and consume carrion falls at the deepest trench depths, and act as key prey items to predators in the shallower depths of the hadal zone. There appears to be a relationship of increasing abundance and decreasing diversity of scavenging amphipods with depth. However in the Tonga Trench, sampling of hadal amphipods has been limited, and these patterns remain unclear.  The QUELLE (Quest for the Limit of Life) project in 2013 was led by The Japan Agency for Marine-Earth Science and Technology (JAMSTEC). As part of this project, the YOK 13-10 voyage examined scavenging amphipods in the Tonga Trench. The voyage used baited traps to sample depths of ˜6,250 m and ˜10,800 m from October 6 – October 21 in 2013. The main objectives of the present study were to: identify scavenging amphipod assemblages within the Tonga Trench and compare them to other trenches of the South Pacific; analyse the population structure of Hirondellea dubia between depths in the Tonga Trench; and identify a suitable total length proxy for H. dubia.  Six species of amphipods were identified from depths of ˜6,250 m and ˜10,800 m in the Tonga Trench. At ˜6,250 m Alicella gigantea, Eurythenes gryllus, H. dubia, Bathycallisoma schellenbergi, an alicellid species, and a gammarid species were recovered. In contrast, H. dubia was the only species recovered from ˜10,800 m. The abundance of amphipods was higher at the ˜10,800 m site while the diversity was much lower.  The assemblage of scavenging amphipods in the Tonga Trench was similar to those from past sampling efforts in the same trench. There were also similarities to the assemblages in the adjacent Kermadec Trench, and together these observations support the classification of these two trenches as a single biogeographic province. The assemblages in the Peru-Chile Trench in the South East Pacific were more dissimilar sharing only a few species. The present study provides new Tonga Trench records of the vertical ranges of A. gigantea, E. gryllus, and H. dubia. It also extends the maximum known depth of H. dubia to 10,807 m. This thesis expanded our current knowledge of A. gigantea, by reporting the first instance of this large amphipod in the Tonga Trench, and the second known instance of the species at hadal depths.  An analysis of Hirondellea dubia population structure revealed ontogenetic vertical structuring in the Tonga Trench. Juveniles dominated the composition in the shallow end of the H. dubia vertical range, while very few juveniles were found at the deepest site. Juveniles were substantially smaller at ˜6,250 m compared to ˜10,800 m, and this may suggest that juveniles migrate down the trench slope with increasing age. The most likely mechanism for distributing juveniles to the shallower depths is the ascending migration of brooding females. However, this is still not certain as no brooding females were captured. The shallower depth provides a higher quality of food source and the reduced hydrostatic pressure allows for a faster metabolic rate. Thus, this distribution is likely driven by the distribution of food sources throughout the trench in combination with hydrostatic pressure.  The dimensions of several established proxies for total length were evaluated for H. dubia. Pereonite 2-7 had the strongest correlation to total length, however it was highly distorted by dorsal curvature. Both the pereonite 2-7 and the pleosome were considered inaccurate due to sexual dimorphism making them inappropriate as proxies. Pereonite 1 was proportionately larger in juvenile lifestages. However, overall pereonite 1 was considered the strongest candidate for a proxy, this is because it was the least influenced by dorsal curvature and was a conspicuous segment that was easy to measure.</p>

scholarly journals Meat and Human Health—Current Knowledge and Research Gaps

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1556
Author(s):  
Nina Rica Wium Geiker ◽  
Hanne Christine Bertram ◽  
Heddie Mejborn ◽  
Lars O. Dragsted ◽  
Lars Kristensen ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Biological Effects ◽  
Saturated Fatty Acids ◽  
Saturated Fat ◽  
Meat Consumption ◽  
Metabolic Effects ◽  
Food Sources ◽  
Current Evidence ◽  
Processed Meat ◽  
Total Energy Consumption

Meat is highly nutritious and contributes with several essential nutrients which are difficult to obtain in the right amounts from other food sources. Industrially processed meat contains preservatives including salts, possibly exerting negative effects on health. During maturation, some processed meat products develop a specific microbiota, forming probiotic metabolites with physiological and biological effects yet unidentified, while the concentration of nutrients also increases. Meat is a source of saturated fatty acids, and current WHO nutrition recommendations advise limiting saturated fat to less than ten percent of total energy consumption. Recent meta-analyses of both observational and randomized controlled trials do not support any effect of saturated fat on cardiovascular disease or diabetes. The current evidence regarding the effect of meat consumption on health is potentially confounded, and there is a need for sufficiently powered high-quality trials assessing the health effects of meat consumption. Future studies should include biomarkers of meat intake, identify metabolic pathways and include detailed study of fermented and other processed meats and their potential of increasing nutrient availability and metabolic effects of compounds.

scholarly journals Biodiversity of echinoids and their epibionts around the Scotia Arc, Antarctica

2008 ◽  
Vol 20 (3) ◽  
pp. 227-244 ◽  
Author(s):  
Katrin Linse ◽  
Lisa J. Walker ◽  
David K.A. Barnes
Keyword(s):  
Southern Ocean ◽  
Current Knowledge ◽  
Sea Urchins ◽  
Marine Biodiversity ◽  
Current View ◽  
Depth Range ◽  
Tissue Mass ◽  
Scotia Arc ◽  
Biodiversity Changes ◽  
Study Species

AbstractThe Scotia Arc, linking the Magellan region with the Antarctic Peninsula, comprises young and old islands both near continents and isolated, and is the only semi-continuous link between cool temperate and Antarctic environments. It is an ideal region for studies on how marine biodiversity changes across an extended transition zone. Echinoids (sea urchins) and their associated epibionts were found across depths from 91–1045 m, with 19 species from shelf and four from slope depths. The 23 species from 38 trawls represent 31% of all echinoid species known from the Southern Ocean and 38% of the shelf/upper slope echinoids. The specimens collected comprise representatives of the five families Cidaridae, Echinidae, Temnopleuridae, Schizasteridae and Pourtalesiidae. Echinoids are probably a good model for how well we know Antarctic shelf and slope megabenthos; none of the species we report are new to science but we found nine (39%) of our study species present at new localities, some thousands of kilometres from previous findings. New biogeographic ranges are illustrated forCtenocidaris gigantea,C. nutrix,C. spinosa,Abatus curvidens,A. ingens,A. shackletoni,Amphineustes rostratus,Tripylaster philippiandPourtalesia aurorae. Southern Ocean echinoids show eurybathy as the mean depth range of our study species was 1241 m and only one was at less than 500 m. The current view of echinoid dominance of super-abundance in the shallows seems to be not transferable to shelf and slope depths as only one of 38 trawls was dominated by echinoids. Current knowledge on maximum sizes in Antarctic echinoids seems to be good as our morphometric measurements were mainly within known size ranges. Regular echinoids increased predictably in mass with increasing test length, apart fromCtenocidaris spinosa. Tissue mass of cidaroid species was ~17%, but across irregular species varied from 17.7–8.9%. No epibionts were found on irregular echinoids or Echinidae but 70 cidaroids examined carried 51 species representing ten classes. Many of these species are reported as cidaroid epibionts for the first time. Cidaroids and their epibionts constituted > 38% of the total macrofaunal richness in the trawls they were present in. Echinoids and their epibionts clearly contribute significantly to Southern Ocean biodiversity but are minor components of biomass except in the shallows.

Archaeological Discoveries in Sicily and Magna Graecia

1939 ◽  
Vol 59 (2) ◽  
pp. 213-228
Author(s):  
Umberto Zanotti-Bianco
Keyword(s):  
Eighteenth Century ◽  
Ground Level ◽  
The South ◽  
Total Length ◽  
Magna Graecia ◽  
South West ◽  
Southern Side ◽  
The Temple ◽  
Southern Flank

In my previous report (JHS, 1938, p. 247) I spoke of the work being carried on at Syracuse to bring to light the remains of the temple of Apollo. The east, north, and west sides had been freed by then, whilst the southern side was still hidden under seventeenth- and eighteenth-century houses, so that it had never been possible to dig trial trenches through their foundations to ascertain if any part of the temple was preserved there. The demolition of the houses and the excavation under the modern ground level beginning from the south-west angle have fully satisfied our hopes. Five columns of the southern flank of the peristasis have appeared, preserved to a height of over 2 metres, with the stylobate beneath them (Fig. 1): only the angle column had been destroyed during the building of the walls of the Spanish barracks. The cella is equally well preserved, and a third of its total length has already been liberated, although the work is in temporary suspense owing to unsettled disputes with the owners of the houses. The southern flank of the archaic Syracusan temple appears to be in much better condition than the others.

scholarly journals POPULATION STRUCTURE AND PRODUCTION OF COPAIBA OLEORESIN BETWEEN VALLEYS AND HILLSIDES OF THE MINING AREA OFTROMBETAS RIVER - PARÁ1

2016 ◽  
Vol 40 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Jonas Gebara ◽  
Antenor Pereira Barbosa ◽  
Isabel Maria Gonçalves Azevedo ◽  
Bruno Oliva Gimenez
Keyword(s):  
Population Structure ◽  
Forest Inventory ◽  
Sustainable Management ◽  
Natural Populations ◽  
Mining Area ◽  
National Forest ◽  
The South ◽  
Potential Production ◽  
Average Value ◽  
Bauxite Ore

ABSTRACT We aimed in this work to study natural populations of copaiba (Copaifera multijuga Hayne) on the Monte Branco mountain at Porto Trombetas-PA, in order to support sustainable management and the exploitation of oleoresin from copaiba. We studied the population structure of copaiba on hillsides and valleys of the south face of Monte Branco, within Saracá Taquera National Forest, where bauxite ore was extracted in the biennium 2013-2014 by Mineração Rio do Norte (MRN). We produced a 100% forest inventory of the specie and of oleoresin extraction in order to quantify the potential production of the remaining area. The density of copaiba individuals with DBH > 30 cm was 0.33 individuals per hectare in the hillside and 0.25 individuals per hectare in the valley. Both environments presented a density of 0.28 individuals per hectare. The average copaiba oleoresin yield was 0.661±0.334 liters in the hillside and 0.765±0.280 liters in the valley. The average value of both environments together (hillside and valley) was 0.714±0.218 liters. From all individuals with DBH over 30 cm, 38 (58%) produced some amount of oleoresin, averaging 1.113±0.562 liters in the hillside, 1.329±0.448 liters in the valley and 1.190±0.355 liters in both environments together. The results show the need for planning the use of the surroundings of the study area in order to reach the required volume of copaiba to make feasible the sustainable management of oleoresin extraction in the region.

scholarly journals Dietary Choline Intake: Current State of Knowledge Across the Life Cycle

Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1513 ◽  
Author(s):  
Alejandra Wiedeman ◽  
Susan Barr ◽  
Timothy Green ◽  
Zhaoming Xu ◽  
Sheila Innis ◽  
...  
Keyword(s):  
Life Cycle ◽  
Current Knowledge ◽  
Water Soluble ◽  
Food Sources ◽  
Soluble Form ◽  
Dietary Recommendations ◽  
Current State ◽  
Dietary Nutrient ◽  
Choline Intake ◽  
Dietary Choline

Choline, an essential dietary nutrient for humans, is required for the synthesis of the neurotransmitter, acetylcholine, the methyl group donor, betaine, and phospholipids; and therefore, choline is involved in a broad range of critical physiological functions across all stages of the life cycle. The current dietary recommendations for choline have been established as Adequate Intakes (AIs) for total choline; however, dietary choline is present in multiple different forms that are both water-soluble (e.g., free choline, phosphocholine, and glycerophosphocholine) and lipid-soluble (e.g., phosphatidylcholine and sphingomyelin). Interestingly, the different dietary choline forms consumed during infancy differ from those in adulthood. This can be explained by the primary food source, where the majority of choline present in human milk is in the water-soluble form, versus lipid-soluble forms for foods consumed later on. This review summarizes the current knowledge on dietary recommendations and assessment methods, and dietary choline intake from food sources across the life cycle.

scholarly journals Teacher as an Amateur Speech Therapist – Current Knowledge in the Field of Speech Therapy Prevention in Kindergartens

2017 ◽  
Vol 7 (3) ◽  
pp. 122-128
Author(s):  
Jana Vašíková
Keyword(s):  
Speech Therapy ◽  
Current Knowledge ◽  
Pedagogical Practice ◽  
The South ◽  
Education Legislation ◽  
Nursery Schools ◽  
Written Form ◽  
Speech Therapist ◽  
Depth Interviews ◽  
Insufficient Knowledge

Abstract Introduction: In our paper, we focus mainly on defining the term of speech therapy prevention, on the anchoring of speech therapy prevention in the legislation and education, the teacher as an actor and direct mediator of the primary speech therapy prevention, and his competence. The research part describes the data obtained by in-depth interviews with teachers in nursery schools in the Zlín region. Methods: The empirical part of the study was conducted through a qualitative research. We have obtained research data via interviews with teachers from nursery schools in the Zlín Region. The data, after transcribing them into written form, were subsequently analysed and interpreted. Results: Based on the results of the research, we can identify one of the most significant categories in the survey of the method of implementation of speech therapy prevention in selected nursery schools in the South Moravian Region. It’s called “Teacher as an amateur speech therapist”. Within this category, we can also distinguish between three types of teachers: teacher - speech therapist, speech therapy assistant as a substitute of speech therapist, teacher - preventionist, and speech therapist. Discussion: What is the cause of this situation? Poor education? Legislation? Pedagogical practice? Limitations: The research was realized only in the South Moravian Region (CZ) and cannot be applied to the entire population. Conclusions: It is evident from the results of the research that some respondents have insufficient knowledge about the competences of individual actors in the speech therapy prevention process as well as about the realization of speech therapy prevention in kindergartens.

scholarly journals Distribution and population structure of the rockfish Helicolenus dactylopterus (Pisces: Scorpaenidae) in the western Mediterranean

2001 ◽  
Vol 81 (1) ◽  
pp. 129-141 ◽  
Author(s):  
Enric Massutí ◽  
Joan Moranta ◽  
L. Gil de Sola ◽  
B. Morales-Nin ◽  
Llucia Prats
Keyword(s):  
Population Structure ◽  
Juvenile Fish ◽  
Western Mediterranean ◽  
Small Fish ◽  
Depth Range ◽  
Southern Area ◽  
Northern Areas ◽  
Helicolenus Dactylopterus ◽  
Spatio Temporal ◽  
And Cluster Analysis

The distribution and spatio–temporal variation of Helicolenus dactylopterus (Pisces: Scorpaenidae) population was studied from 816 bottom trawls developed along the Iberian coast. Multifactor analysis of variance was used to test the differences in abundance and biomass and cluster analysis was applied to detect differences in population structure. The results showed a bathymetric and latitudinal gradient in abundance and population structure along three geographic sectors in the surveyed area. In the southern area, the species was more frequent and showed a wider bathymetric distribution range than northwards. The depth range with the maximum frequency of occurrence was also wider in the southern area than northwards. Similar trends were observed in terms of abundance and biomass, with the highest and lowest indices in the southern and northern areas, respectively. The age composition of the catches showed that the population consisted mainly of young-of-the-year and juvenile fish. This fraction of the population is well represented, at a mesoscale, along the whole surveyed area, but adults are well represented only at a local scale, at the deepest strata surveyed in the southern area. In this case, recruits of age 0 and juveniles up to 4-y old were restricted to depths shallower than 500 m, while adult fish older than 6 y of age appeared below this depth. In the southern area, seasonal changes in the population structure were also observed, with modes of small fish (3–6 cm) from March to June, as a consequence of the species recruitment to the bottom. Some direct and indirect factors of biogeographic, environmental and anthropogenic origin affecting the observed gradient are discussed.

Discordance Mapping of Argyre Basin: An Insight into the Fluvial and Subglacial Origin of Valley Networks in the Argyre Basin Region

2021 ◽  
Author(s):  
Rickbir Bahia ◽  
Anna Galofre ◽  
Stephen Covey-Crump ◽  
Merren Jones ◽  
Neil Mitchell
Keyword(s):  
Ice Sheet ◽  
Morphological Characteristics ◽  
Drainage Density ◽  
Recent Analysis ◽  
Surface Slope ◽  
The South ◽  
Total Length ◽  
Topographic Slope ◽  
Valley Networks ◽  
Slope Direction

&lt;p&gt;&lt;strong&gt;Introduction:&lt;/strong&gt;&amp;#160; Martian valley networks are evidence for surface run-off and past water cycles on ancient Mars. Many of the networks resemble terrestrial precipitation-fed systems; however, recent analysis has found that the geometries and morphological characteristics of some valley networks are more comparable to subglacial valley formation. Subglacial valleys have morphological characteristics that make them distinct from fluvial valley systems (i.e., those formed via precipitation or sapping erosion). Unlike fluvial valley networks, which follow the surface slope of the underlying topography, sub-glacial networks are orientated in the direction of the surface slope of the overlying ice-sheet. Therefore, subglacial valleys may have orientations that are discordant with the underlying topography. Discordance analysis, a technique that compares the valley paleoslope direction and topographic slope direction, has been applied to Mars to determine areas that have undergone topographic modification since valley formation. This technique could also be a tool for identify valleys with potential sub-glacial origins.&lt;/p&gt;&lt;p&gt;In this study, we mapped and applied discordance analysis to valley networks in and around Argyre basin. Detailed analysis was performed on four valley networks on eastern Argyre, to determine whether their characteristics are indicative of a fluvial or sub-glacial origin.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; 2669 V-Shaped valleys (total length = 36155.5 km) and 45 U-Shaped valleys (total length = 2683.5 km) were identified. Most V-Shaped valleys dissect the eastern and northern rim of Argyre Basin, with fewer in the south and west. The densest northern valley networks have values up to 0.098 km&lt;sup&gt;-1&lt;/sup&gt;, compared to the densest in the south with values of only 0.040 km&lt;sup&gt;-1&lt;/sup&gt;. U-Shaped valleys are prominent along the south/south-west rim, but are lacking along the northern rim of Argyre.&lt;/p&gt;&lt;p&gt;Most valleys (47.8 %) are concordant (&lt; 45&amp;#176; discordance) with present slope direction. Two dense groups of discordant valleys are present adjacent to Hale Crater and Nia Vallis. These areas display features associated with the presence of an ice-sheet/glacier &amp;#8211; e.g., glacial moraines and eskers. Additionally, the morphology of these valley systems are consistent with a subglacial origin.&lt;/p&gt;&lt;p&gt;Fento Vallis and the Darwin Crater valley system are concordant with present topographic slope, and are in close proximity to one another; however, their morphologies differ greatly. Fento Vallis consists of 25 valleys (total valley length of ~ 690 km) and drainage density of 0.019 km&lt;sup&gt;-1&lt;/sup&gt;. The Darwin Crater valley network consists of 49 valleys (total valley length of ~ 1351 km) and drainage density of 0.048 km&lt;sup&gt;-1&lt;/sup&gt;. Fento Vallis displays features (e.g., inner channel eskers) indicative of a subglacial origin. Alternatively, the Darwin Crater System has a planform associated with fluvial activity and originates from cirque like depressions. Although the Darwin Crater system appears to have a fluvial origin, less than 100 km to the east is Pallacopas Vallis, which displays inner eskers indicating that it has a subglacial origin.&lt;/p&gt;&lt;p&gt;Three of the networks analysed, which are &gt; 1000 km apart from one another, are likely subglacial in origin. Their occurrence indicates that an ice-sheet or multiple ice-sheets were present along the eastern region of Argyre throughout its history.&lt;/p&gt;

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