scholarly journals First tracking of the oceanic spawning migrations of Australasian short-finned eels (Anguilla australis)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wayne M. Koster ◽  
Kim Aarestrup ◽  
Kim Birnie-Gauvin ◽  
Ben Church ◽  
David Dawson ◽  
...  
Keyword(s):  
Deep Water ◽  
Marine Mammals ◽  
Euphotic Zone ◽  
Life Time ◽  
Marine Predators ◽  
North East ◽  
The North ◽  
Anguilla Australis ◽  
Mesopelagic Zone ◽  
Diel Vertical Migrations

AbstractAnguillid eel populations have declined dramatically over the last 50 years in many regions of the world, and numerous species are now under threat. A critical life-history phase is migration from freshwater to distant oceans, culminating in a single life-time spawning event. For many anguillids, especially those in the southern hemisphere, mystery still shrouds their oceanic spawning migrations. We investigated the oceanic spawning migrations of the Australasian short-finned eel (Anguilla australis) using pop-up satellite archival tags. Eels were collected from river estuaries (38° S, 142° E) in south-eastern temperate Australia. In 2019, 16 eels were tracked for up to about 5 months, ~ 2620 km from release, and as far north as the tropical Coral Sea (22° S, 155° E) off the north-east coast of Australia. Eels from southern Australia appeared to access deep water off the Australian coast via two main routes: (i) directly east via Bass Strait, or (ii) south-east around Tasmania, which is the shortest route to deep water. Tagged eels exhibited strong diel vertical migrations, alternating between the warm euphotic zone (~ 100–300 m, 15–20 °C) at night and the mesopelagic zone (~ 700–900 m, 6–8 °C) during the day. Marine predators, probably lamnid sharks, tuna, or marine mammals, ended many eel migrations (at least ~ 30%), largely before the eels had left the Australian continental shelf. The long and risky marine migrations of Australasian eels highlight the need for better information on the processes contributing to eel mortality throughout the life cycle, including the impacts of future changes to oceanic currents, predator abundance and direct anthropogenic disturbances.

scholarly journals First Tracking of the Oceanic Spawning Migrations of Australasian Short- Finned Eels (Anguilla Australis)

2021 ◽  
Author(s):  
Wayne Koster ◽  
Kim Aarestrup ◽  
Kim Birnie-Gauvin ◽  
Ben Church ◽  
David Dawson ◽  
...  
Keyword(s):  
Deep Water ◽  
Marine Mammals ◽  
Euphotic Zone ◽  
Life Time ◽  
Marine Predators ◽  
North East ◽  
The North ◽  
Anguilla Australis ◽  
Mesopelagic Zone ◽  
Diel Vertical Migrations

Abstract Across their near-global range, anguillid eel populations have declined dramatically over the last fifty years and many species are now threatened. A critical life history phase is migration from freshwater to distant oceans, culminating in their single life-time spawning event. For many anguillids, especially those in the southern hemisphere, mystery still shrouds their oceanic spawning migrations. We investigated the oceanic spawning migrations of the Australasian short-finned eel (Anguilla australis) using pop-up satellite archival tags. Eels were collected from river estuaries (38°S, 142°E) in south-eastern temperate Australia. In 2019, sixteen eels were tracked for up to about 5 months, ~2620 km from release, and as far north as the tropical Coral Sea (22°S, 155°E) off the north-east coast of Australia. Eels from southern Australia appeared to access deep water off the Australian coast via two main routes: (i) directly east via Bass Strait, or (ii) south-east around Tasmania, which is the shortest route to deep water. Tagged eels exhibited strong diel vertical migrations, alternating between the warm euphotic zone (~100 to 300 m, 15 to 20°C) at night, and the mesopelagic zone (~700 m to 900 m, 6 to 8°C) during the day. Marine predators, probably lamnid sharks, tuna, or marine mammals, ended many eel migrations (at least ~30%), with many eels lost before leaving the Australian continental shelf. The long and risky marine migrations of Australasian eels highlight the need for better information on the processes contributing to eel mortality across the life cycle, including the impacts of future changes to oceanic currents, predator abundance and direct anthropogenic disturbances.

scholarly journals Marine late Saalian to Eemian environments and climatic variability in the Danish shelf area

2000 ◽  
Vol 79 (2-3) ◽  
pp. 335-343 ◽  
Author(s):  
Marit-Solveig Seidenkrantz ◽  
Karen Luise Knudsen ◽  
Peter Kristensen
Keyword(s):  
Climate Variability ◽  
Shallow Water ◽  
Oxygen Isotope ◽  
Deep Water ◽  
Climatic Variability ◽  
Shelf Area ◽  
North East ◽  
The North ◽  
Mis 5E

AbstractThe marine Eemian (marine oxygen-isotope substage 5e: MIS 5e) is represented by shallow-water deposits in southern and western Denmark, while relatively deep-water environments occurred to the north and north-east, where complete interglacial successions seem to be present. We present an overview of the marine Eemian deposits in Denmark, and discuss in more detail indications of climate variability, both for the late Saalian and within the Eemian.

Reproductive patterns in two deep-water solitary corals from the north-east Atlantic—Flabellum alabastrumandF. angulare(Cnidaria: Anthozoa: Scleractinia)

2010 ◽  
Vol 91 (3) ◽  
pp. 669-675 ◽  
Author(s):  
Rhian G. Waller ◽  
Paul A. Tyler
Keyword(s):  
Sex Ratio ◽  
Deep Water ◽  
Oocyte Size ◽  
East Atlantic ◽  
Broadcast Spawning ◽  
Reproductive Patterns ◽  
Size Dependent ◽  
North East ◽  
The North ◽  
Rockall Trough

Gametogenesis and reproductive periodicity of the solitary scleractiniansFlabellum alabastrum(from the Rockall Trough) andF. angulare(from the Porcupine Seabight) were investigated. Samples were collected between depths from 1370 to 2190 m forF. alabastrumand 2412 to 2467 m forF. angulare. Both species showed gonochorism with a 1:1 sex-ratio and broadcast spawning of gametes is inferred from the lack of brooded planulae. Oocyte sizes were large in both species (925 μm inF. alabastrumand 1015 μm inF. angulare), suggesting lecithotrophic larval development. Fecundity and periodicity of oocyte development differed between the two species.Flabellum alabastrumproduced a maximum of 2800 oocytes per polyp quasi-continuously, whereas the deeper speciesF. angulareproduced a maximum of 550 oocytes per polyp either seasonally or periodically. Both species showed size-dependent fecundity. The data show a decrease in oocyte size and fecundity with depth, in concordance with other deep-water scleractinian species.

Ophlitaspongia and Ophlitaspongia papilla reinstated, and a new species of Ophlitaspongia described (Porifera: Demospongiae: Microcionidae)

1999 ◽  
Vol 79 (4) ◽  
pp. 609-620 ◽  
Author(s):  
C.M. Howson ◽  
S.J. Chambers
Keyword(s):  
New Species ◽  
North Atlantic ◽  
Deep Water ◽  
The Other ◽  
East Atlantic ◽  
Halichondria Panicea ◽  
North East ◽  
The North ◽  
The North Atlantic ◽  
A New Species

A new species of Ophlitaspongia (Porifera: Microcionidae) from wave-exposed sublittoral rock in the north-east Atlantic is described and compared to the two other species recorded from the genus in the north-east Atlantic. The species known as Ophlitaspongia seriata is considered to be a junior synonym of Halichondria panicea. Consequently, the name O. papilla has been reinstated. The other recorded species O. basifixa, is from deep water. Ophlitaspongia basifixa has characters which differentiate it from Ophlitaspongia sp. nov. The genus Ophlitaspongia has been separated from related genera and reinstated for species in the North Atlantic.

Molecular barcoding of north-east Atlantic deep-water sharks: species identification and application to fisheries management and conservation

2008 ◽  
Vol 59 (3) ◽  
pp. 214 ◽  
Author(s):  
Teresa Moura ◽  
Mónica C. Silva ◽  
Ivone Figueiredo ◽  
Ana Neves ◽  
Pablo Durán Muñoz ◽  
...  
Keyword(s):  
Deep Water ◽  
Objective Assessment ◽  
Dna Barcode ◽  
Coi Gene ◽  
Shark Species ◽  
Identification Problems ◽  
East Atlantic ◽  
Molecular Barcoding ◽  
North East ◽  
The North

Two genera of elasmobranchii, Centrophorus and Centroscymnus, include species that represent the highest landings of deep-water sharks caught by fishing fleets operating in the north-east Atlantic. There are morphology-based identification problems among and within genera, and landings of processed shark products further prevent an objective assessment of these species. The present study is the first attempt to test the suitability of using a DNA barcode approach to discriminate accurately among the four most important commercial deep-water shark species: Centrophorus squamosus, Centrophorus granulosus, Centroscymnus coelolepis and, recently discovered in Portuguese ports, Centroscymnus owstoni. Sequence analyses of the mitochondrial DNA cytochrome c oxidase subunit I (COI) gene revealed low levels of haplotypic and genetic diversities. Higher levels of inter-specific relative to intra-specific divergences allowed discrimination among species, which form reciprocally monophyletic clades. Inclusion of published COI sequences from other species within the same genera revealed haplotype sharing among species, which calls into question the current taxonomy and accuracy of fisheries data available. Amplification of the COI gene coupled with MboI restriction digests was found to be a fast and inexpensive strategy to resolve within genera identification problems. Molecular barcoding constitutes a critical tool for the assessment and implementation of urgent management policies for this group of species.

scholarly journals Evaluation of indigenous land races of deep-water paddy of North East India for nutraceutical value

2021 ◽  
pp. 125-127
Author(s):  
KANDARPA KALITA
Keyword(s):  
Deep Water ◽  
Weather Condition ◽  
Red Rice ◽  
Ethnic Communities ◽  
African Countries ◽  
Land Races ◽  
North East India ◽  
North East ◽  
The North

Deep water paddy is a nature’s marvel for many ethnic communities living in flood prone river basins of some Asian and African countries. In recent times there is resurgence in interest on local land races in view of alarming depletion of agro-biodiversity and the urgency to preserve them. In Assam, the north eastern state of India, deep water paddy is being cultivated since time immemorial by several ethnic communities living in the Brahmaputra river basin. Although not properly enumerated, it is known that more than 70 land races of Bao Dhanexists. Moreover, recent works have revealed that contrary to general perception deep water paddy are rich in nutritional and nutraceutical values with 9% to 13% protein. Further interest on deep water paddy got a boost with the report that land races with red kernel (red rice) are rich in dietary antioxidant anthocyanin and study showed that they have impressive anti-oxidative activity in vitro. Deep water paddy or floating paddy popularly referred to as Bao dhan in Assam, represent a unique crop capable of withstanding diverse stress and man’s ingenuity to co-exist with hostile nature and weather condition. Owing to their antioxidant capacity and the associated health benefits, anthocyanins have gained increased attention in recent years, hence the study was initiated.

Records of deep water chondrichthyan fish caught on long-line in the Rockall Trough

2000 ◽  
Vol 80 (2) ◽  
pp. 377-378 ◽  
Author(s):  
M.W. Clarke
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Zoological Museum ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Long Line ◽  
Rockall Trough ◽  
Line Survey ◽  
Depth Ranges

A number of chondrichthyan fish species were caught on long-line in the Rockall Trough (north-east Atlantic) in 1997, which are first records for this area; Raja hyperborea, Raja kukujevi and Raja fullonica. The occurrence of R. hyperborea, usually found in colder boreal waters appears to be temperature related. The presence of the deep water squaliform shark Centrophorus uyato in the area was also confirmed and several species were caught at previously undocumented depths.The Rockall Trough is an extension of the North Atlantic deep environment (Mauchline, 1990). A long-line survey was undertaken in August 1997 on the eastern and southern slopes of the Rockall Trough (Figure 1), fishing gear and procedures are described by Connolly (1997). Identifications were undertaken by means of several texts (Compagno, 1984; Whitehead, et al., 1984; Stehmann, 1997). The specimens described below were lodged in the National Museum of Ireland (NMI) and the Hamburg University Zoological Museum, Germany (ZMH). Depth ranges, positions and catalogue numbers of the specimens described are given in Table 1.

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