scholarly journals Deep-sea starfish from the Arctic have well-developed eyes in the dark

2018 ◽  
Vol 285 (1872) ◽  
pp. 20172743 ◽  
Author(s):  
Marie Helene Birk ◽  
Martin E. Blicher ◽  
Anders Garm
Keyword(s):  
Spatial Resolution ◽  
Deep Sea ◽  
Optical Quality ◽  
The Arctic ◽  
Depth Range ◽  
Enhanced Sensitivity ◽  
Quality Of Vision ◽  
Almost All ◽  
Macro Benthos ◽  
Shallow Water Species

Asteroids, starfish, are important members of the macro-benthos in almost all marine environments including the deep sea. Starfish are in general assumed to be largely olfactory guided, but recent studies have shown that two tropical shallow water species rely on vision alone to find their habitat at short distances. Their compound eyes are found at the tip of each arm and they vary little between examined species. Still, nothing is known about vision in the species found in the aphotic zone of the deep sea or whether they even have eyes. Here, 13 species of starfish from Greenland waters, covering a depth range from shallow waters to the deep sea below 1000 m, were examined for the presence of eyes and optical and morphological examinations were used to estimate the quality of vision. Further, species found in the aphotic zone below 320 m were checked for bioluminescence. All species, except the infaunal Ctenodiscus crispatus , had eyes, and two were found to be bioluminescent. Interestingly, one of the species found in the aphotic zone, Novodinia americana , had close to the highest spatial resolution known for starfish eyes along with being bioluminescent. Accordingly, we hypothesize that this species communicates visually using bioluminescent flashes putatively for reproductive purposes. Other species have greatly enhanced sensitivity with few large ommatidia but at the sacrifice of spatial resolution. The discovery of eyes in deep-sea starfish with a huge variation in optical quality and sensitivity indicates that their visual ecology also differs greatly.

scholarly journals THE HALACARID GENUS LOHMANNELLA (HALACARIDAE, ACARI): LIST OF SPECIES, NOTES ON CHARACTERS, DISTRIBUTION, ECOLOGY AND A TABULAR KEY

Acarina ◽  
2021 ◽  
Vol 29 (2) ◽  
pp. 189-232
Author(s):  
Ilse Bartsch
Keyword(s):  
Shallow Water ◽  
Deep Sea ◽  
Marine Species ◽  
Morphological Characters ◽  
Published Data ◽  
Depth Range ◽  
Climatic Zones ◽  
Shallow Water Species ◽  
The Tropics ◽  
Water Species

Presently, 39 Lohmannella species are accepted as valid, but future examinations may prove some of them to be junior synonyms of others. This article lists the most important descriptive papers, as well as the former names for each of the 39 species. The characters of another five species, known by their adults, are outlined but not given a name. Based on the published data, short diagnoses as well as notes on the distribution and habitats are added. In addition, the poorly known female of Lohmannella bihamata is described and illustrated. This article provides a table of morphological characters that are meant to facilitate the identification of Lohmannella species. The genus Lohmannella is spread worldwide, inhabiting all water depths and all climatic zones; its representatives live in marine and fresh water. Although the majority of Lohmannella species have been found at sea, five species have been recovered from fresh or slightly brackish water. In the following sentences, the number of unnamed species is given in square brackets. Records of 33 [plus two] marine species are exclusively from the littoral and/or bathyal zone (0–1,000 m deep); records of three [plus three] species are from the deep sea (deeper than 1,000 m); and one record is from the littoral / deep sea depth range. Most species have been found in the temperate and polar areas: namely, 12 [plus two] have been recorded north of 23°N and 20 south of 23°S. The data from the tropics include a single shallow water (0–200 m deep) record, one unnamed species from the 400–520 m depth and one [plus two] species from the depth of more than 1,000 m. Most southern hemisphere shallow water species are morphologically distinct from the bathyal and abyssal species, as well as from the northern hemisphere species.

COMPROMISE AND ORIGINAL ACQUISITION: EXPLAINING RIGHTS TO THE ARCTIC

2015 ◽  
Vol 32 (1) ◽  
pp. 149-170 ◽  
Author(s):  
Cara Nine
Keyword(s):  
Political Philosophy ◽  
Natural Resources ◽  
Deep Sea ◽  
Large Degree ◽  
Geographic Area ◽  
Ocean Floor ◽  
The Arctic ◽  
Human Settlement ◽  
The Commons ◽  
Original Acquisition

Abstract:Up until now, political philosophy has explained the acquisition of natural resources, in one way or another, through the terms of human settlement. An agent acquires natural resources by moving into the geographic area that contains these resources. Even how we make claims to the ocean floor depends on settlement — claimants must be adjacent to settled land. This essay extends original acquisition theories so that they can respond to cases that do not presuppose any conditions of human settlement. I suggest that resource rights in the deep sea may be created, alternatively, through acts of compromise. Compromise can alleviate conflict, allowing for claimants to move beyond stalemate to acquire goods. It also allows for a large degree of flexibility in the specification of rights, and thereby can explain nontraditional rights over areas of migration. The tricky part of a theory that grants rights through agreement is explaining why external parties, those not part of the agreement, have a duty to respect those rights. A compromise under certain conditions, I argue, places all persons under a duty to respect the rights created by the compromise. Thus, when two parties compromise, they may acquire goods from the commons — creating a duty for all others to respect the parties’ rights over these goods. Importantly, rights created through compromise are constrained by a set of concerns for those excluded.

The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

1982 ◽  
Vol 62 (1) ◽  
pp. 45-55 ◽  
Author(s):  
P. A. Tyler ◽  
J. D. Gage
Keyword(s):  
Reproductive Biology ◽  
Deep Water ◽  
Larval Stage ◽  
North Pacific ◽  
Deep Sea ◽  
Direct Development ◽  
The Arctic ◽  
Shallow Waters ◽  
Arctic Seas ◽  
Rockall Trough

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

Bathymetric patterns of megafaunal assemblages from the arctic deep-sea observatory HAUSGARTEN

2009 ◽  
Vol 56 (10) ◽  
pp. 1856-1872 ◽  
Author(s):  
Thomas Soltwedel ◽  
Nina Jaeckisch ◽  
Nikolaus Ritter ◽  
Christiane Hasemann ◽  
Melanie Bergmann ◽  
...  
Keyword(s):  
Deep Sea ◽  
The Arctic

scholarly journals Ice Concentration Retrieval from the Analysis of Microwaves: A New Methodology Designed for the Copernicus Imaging Microwave Radiometer

2020 ◽  
Vol 12 (7) ◽  
pp. 1060 ◽  
Author(s):  
Lise Kilic ◽  
Catherine Prigent ◽  
Filipe Aires ◽  
Georg Heygster ◽  
Victor Pellet ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spatial Resolution ◽  
Microwave Radiometer ◽  
Optimal Estimation ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Special Focus ◽  
Polar Regions ◽  
Sea Ice Concentration ◽  
Ice Concentration

Over the last 25 years, the Arctic sea ice has seen its extent decline dramatically. Passive microwave observations, with their ability to penetrate clouds and their independency to sunlight, have been used to provide sea ice concentration (SIC) measurements since the 1970s. The Copernicus Imaging Microwave Radiometer (CIMR) is a high priority candidate mission within the European Copernicus Expansion program, with a special focus on the observation of the polar regions. It will observe at 6.9 and 10.65 GHz with 15 km spatial resolution, and at 18.7 and 36.5 GHz with 5 km spatial resolution. SIC algorithms are based on empirical methods, using the difference in radiometric signatures between the ocean and sea ice. Up to now, the existing algorithms have been limited in the number of channels they use. In this study, we proposed a new SIC algorithm called Ice Concentration REtrieval from the Analysis of Microwaves (IceCREAM). It can accommodate a large range of channels, and it is based on the optimal estimation. Linear relationships between the satellite measurements and the SIC are derived from the Round Robin Data Package of the sea ice Climate Change Initiative. The 6 and 10 GHz channels are very sensitive to the sea ice presence, whereas the 18 and 36 GHz channels have a better spatial resolution. A data fusion method is proposed to combine these two estimations. Therefore, IceCREAM will provide SIC estimates with the good accuracy of the 6+10GHz combination, and the high spatial resolution of the 18+36GHz combination.

scholarly journals Universal thermal climate index in Russia

2019 ◽  
pp. 3-19 ◽  
Author(s):  
V. V. Vinogradova
Keyword(s):  
Cold Stress ◽  
Thermal Conditions ◽  
The Arctic ◽  
Climate Index ◽  
Universal Thermal Climate Index ◽  
Environment Temperature ◽  
European Part Of Russia ◽  
Thermal Climate ◽  
Actual Environment ◽  
Almost All

The paper uses the universal thermal climate index (UTCI) to estimate the bioclimate in Russia, initiated by the Commission of the International society of Biometeorology. The UTCI index can be described as equivalent environment temperature (°C), which provides the same physiological impact on humans as the actual environment. Assessment of bioclimatic conditions is shown for the territory of Russia in the period of modern climate change (2001–2015). Cold stress conditions (from low to extreme) were observed in the almost all territory of Russia for about 8–11 months a year. During the rest of the year, the conditions are neutral or comfortable. The period of extreme and very high cold stress is reduced during the modern climate warming (compared to the period 1961–1990), especially in the Arctic, in the European part of Russia, in Western and Eastern Siberia. At the same time, the period with neutral and comfortable thermal conditions increases.

Large-scale Arctic sea ice motion from Sentinel-1 and the RADARSAT Constellation Mission

2021 ◽  
Author(s):  
Stephen Howell ◽  
Mike Brady ◽  
Alexander Komarov
Keyword(s):  
Sea Ice ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Large Scale ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
High Temporal Resolution ◽  
Sar Images ◽  
Sea Ice Extent ◽  
Arctic Sea

<p>As the Arctic’s sea ice extent continues to decline, remote sensing observations are becoming even more vital for the monitoring and understanding of this process.  Recently, the sea ice community has entered a new era of synthetic aperture radar (SAR) satellites operating at C-band with the launch of Sentinel-1A in 2014, Sentinel-1B in 2016 and the RADARSAT Constellation Mission (RCM) in 2019. These missions represent a collection of 5 spaceborne SAR sensors that together can routinely cover Arctic sea ice with a high spatial resolution (20-90 m) but also with a high temporal resolution (1-7 days) typically associated with passive microwave sensors. Here, we used ~28,000 SAR image pairs from Sentinel-1AB together with ~15,000 SAR images pairs from RCM to generate high spatiotemporal large-scale sea ice motion products across the pan-Arctic domain for 2020. The combined Sentinel-1AB and RCM sea ice motion product provides almost complete 7-day coverage over the entire pan-Arctic domain that also includes the pole-hole. Compared to the National Snow and Ice Data Center (NSIDC) Polar Pathfinder and Ocean and Sea Ice-Satellite Application Facility (OSI-SAF) sea ice motion products, ice speed was found to be faster with the Senintel-1AB and RCM product which is attributed to the higher spatial resolution of SAR imagery. More sea ice motion vectors were detected from the Sentinel-1AB and RCM product in during the summer months and within the narrow channels and inlets compared to the NSIDC Polar Pathfinder and OSI-SAF sea ice motion products. Overall, our results demonstrate that sea ice geophysical variables across the pan-Arctic domain can now be retrieved from multi-sensor SAR images at both high spatial and temporal resolution.</p>

Sea–ice concentration at 1 km resolution in summer from merged visible and microwave radiometer observations

2021 ◽  
Author(s):  
Valentin Ludwig ◽  
Gunnar Spreen
Keyword(s):  
Spatial Resolution ◽  
Microwave Radiometer ◽  
Thermal Infrared ◽  
Passive Microwave ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
Statistical Consistency ◽  
Microwave Data ◽  
Infrared Data

<p>Sea–ice concentration, the surface fraction of ice in a given area, is a key component of the Arctic climate system, governing for example the ocean–atmosphere heat exchange. Satellite–based remote sensing offers the possibility for large–scale monitoring of the sea–ice concentration. Using passive microwave measurements, it is possible to observe the sea–ice concentration all year long, almost independently of cloud coverage. The spatial resolution of these measurements is limited to 5 km and coarser. Data from the visible and thermal infrared spectrum offer finer resolutions of 250 m–1 km, but need clear–sky scenes and, in case of visible data, sunlight. In previous work, we developed and analysed a merged dataset of passive microwave and thermal infrared data, combining AMSR2 and MODIS satellite data at 1 km spatial resolution. It has benefits over passive microwave data in terms of the finer spatial resolution and an enhanced potential for lead detection. At the same time, it outperforms thermal infrared data due to its spatially continuous coverage and the statistical consistency with the extensively evaluated passive microwave data. Due to higher surface temperatures in summer, the thermal–infrared based retrieval is limited to winter and spring months. In this contribution, we present first results of extending the existing dataset to summer by using visible data instead of thermal infrared data. The reflectance contrast between ice and water is used for the sea–ice concentration retrieval and results of merging visible and microwave data at 1 km spatial resolution are presented. Difficulties for both, the microwave and visual, data are surface melt processes during summer, which make sea–ice concentration retrieval more challenging. The merged microwave, infrared and visual dataset opens the possibility for a year–long, spatially continuous sea ice concentration dataset at a spatial resolution of 1 km.</p>

The role and status of Nautilus in its natural habitat: evidence from deep-water remote camera photosequences

Paleobiology ◽  
1984 ◽  
Vol 10 (4) ◽  
pp. 469-486 ◽  
Author(s):  
W. Bruce Saunders
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Deep Water ◽  
Deep Sea ◽  
Natural Habitat ◽  
Normal Component ◽  
Depth Range ◽  
Reproductive Tactics ◽  
Opportunistic Predator ◽  
Remote Camera

Bottom site remote camera photosequences at depths of 73–538 m on forereef slopes in Palau show that Nautilus belauensis is a highly mobile, chemosensitive, epibenthic scavenger and opportunistic predator. The overall depth range of this species is ca. 70–500 m, but photosequences indicate a preferred range of 150–300 m. Nautilus is active both nocturnally and diurnally, locating bait sites within 1–2 h. Associated macrofauna includes caridean shrimps, crabs, and eels; teleosts are rare below 100 m, but sharks are recorded in most photosequences below 250 m. Summarily, Nautilus exhibits a combination of characters that typify deep-sea strategy, including reproductive tactics, growth rate, and population dynamics. This and other evidence suggest that fossil Nautilidae may have been deep-water forms, in contrast to the typically shallower water ammonoids, and that Nautilus is a normal component of the deep forereef rather than a late Cretaceous refugee from shallow water.

scholarly journals A New Species of Osedax (Siboglinidae: Annelida) From Colonization Experiments in the Arctic Deep Sea

2020 ◽  
Vol 7 ◽  
Author(s):  
Mari Heggernes Eilertsen ◽  
Thomas G. Dahlgren ◽  
Hans Tore Rapp
Keyword(s):  
New Species ◽  
Deep Sea ◽  
The Arctic ◽  
A New Species
Sign in / Sign up

Export Citation Format

Share Document