Winter distribution and overwintering strategies of the Antarctic copepod species Calanoides acutus, Rhincalanus gigas and Calanus propinquus (Crustacea,Calanoida) in the Weddell Sea

AbstractThis study presents culture experiments of the cold water species Neogloboquadrina pachyderma (sinistral) and provides new insights into the incorporation of elements in foraminiferal calcite of common and newly established proxies for paleoenvironmental applications (shell Mg/Ca, Sr/Ca and Na/Ca). Specimens were collected from sea ice during the austral winter in the Antarctic Weddell Sea and subsequently cultured at different salinities and a constant temperature. Incorporation of the fluorescent dye calcein showed new chamber formation in the culture at salinities of 30, 31, and 69. Cultured foraminifers at salinities of 46 to 83 only revealed chamber wall thickening, indicated by the fluorescence of the whole shell. Signs of reproduction and the associated gametogenic calcite were not observed in any of the culture experiments. Trace element analyses were performed using an electron microprobe, which revealed increased shell Mg/Ca, Sr/Ca, and Na/Ca values at higher salinities, with Mg/Ca showing the lowest sensitivity to salinity changes. This study enhances the knowledge about unusually high element concentrations in foraminifera shells from high latitudes. Neogloboquadrina pachyderma appears to be able to calcify in the Antarctic sea ice within brine channels, which have low temperatures and exceptionally high salinities due to ongoing sea ice formation.

Download Full-text

An Antarctic shelf population of the deep-sea, Pacific brachiopod Neorhynchia strebeli

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400071757 ◽

1997 ◽

Vol 77 (2) ◽

pp. 399-407 ◽

Cited By ~ 7

Author(s):

David K.A. Barnes ◽

Lloyd S. Peck

Keyword(s):

Deep Sea ◽

Growth Function ◽

Weddell Sea ◽

Von Bertalanffy ◽

Growth Rings ◽

Von Bertalanffy Growth Function ◽

Annual Periodicity ◽

A Site ◽

The Antarctic ◽

Order Rhynchonellida

Thirty-five specimens of the articulate brachiopod Neorhynchia strebeli were collected from a site at 814 m in the Weddell Sea. This was only the second species of the order Rhynchonellida to be found in Antarctica. Formerly N. strebeli was known solely from abyssal Pacific Ocean localities. A circumantarctic distribution is suggested in addition to the known deep-sea Pacific range. The specimens of this collection showed considerable commissure variation, suggesting that the previously proposed erection of two subspecies on the basis of this character is erroneous, and emphasises the phenotypic plasticity of some articulate brachiopods. The valve lengths and the number of alpha growth rings in the sample showed a normal distribution and a von Bertalanffy growth function was fitted to the data: Lt = 23 (1-exp[-0·228t]). If the alpha growth rings were of annual periodicity, the ages attained by the Antarctic N. strebeli of 11 y would be substantially lower than those reported for other Weddell Sea brachiopods. The epibiotic communities occurring on the valves of N. strebeli were impoverished, which is characteristic of deep water Antarctic brachiopods. The few specimens collected with their substratum were attached to small pebbles, but the typical attachment substrata may be different.

Download Full-text

Very low frequency electromagnetic phenomena: ‘whistlers’ and micropulsations

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1977.0085 ◽

1977 ◽

Vol 279 (963) ◽

pp. 225-238 ◽

Cited By ~ 6

Keyword(s):

Low Frequency ◽

Dynamical Behaviour ◽

Weddell Sea ◽

Particle Interactions ◽

Terrestrial Environment ◽

Wave Amplification ◽

A Chain ◽

Magnetic Conjugacy ◽

Sea Area ◽

The Antarctic

Observations of natural electromagnetic phenomena, embracing frequencies ranging from millihertz to tens of kilohertz, have made a major contribution to our knowledge of the terrestrial environment extending out to many Earth’s radii. The Antarctic has offered exceptional opportunities in this field for a number of reasons, including: (i) the location of Antarctic bases (including Halley Bay) at key magnetic latitudes, (ii) magnetic conjugacy to Northern Hemisphere thunderstorm sources, (iii) low interference levels. Important aspects of this research are the investigation of the role of wave-particle interactions in the magnetosphere and that of the structure and dynamical behaviour of the plasmapause, using both passive and active techniques. Comparisons of observations made at antarctic stations and their northern geomagnetic conjugates show close similarities in dominant pulsation periods and demonstrate the uniqueness of the Weddell Sea area in relation to magnetospheric wave amplification at the higher frequencies. An extra dimension to this work is being added, during the International Magnetospheric Study (1976-8), through the development of a chain of stations employing the goniometer (direction-finding) technique pioneered at Halley Bay by Sheffield University.

Download Full-text

Remote sensing of multiyear ice in the Antarctic

10.5194/dach2022-284 ◽

2021 ◽

Author(s):

Christian Melsheimer ◽

Gunnar Spreen

Keyword(s):

Time Series ◽

Sea Ice ◽

Global Climate ◽

Ice Cover ◽

Cold Season ◽

Arctic Sea Ice ◽

Weddell Sea ◽

Detailed Knowledge ◽

The Antarctic ◽

Multiyear Ice

The changing sea ice cover of polar seas is of key importance for the exchange of heat and moisture between atmosphere and ocean and hence for weather and climate, and in addition, the sea ice and its long-term changes are &#160;an indicator for global change. &#160;In order to properly understand and model the evolution of the sea ice cover and its interaction with the global climate system, we need detailed knowledge about sea ice, i.e., not only its extent, but also, e.g., its thickness and its type. We can broadly distinguish a few different sea ice types that have different dynamic and thermodynamic properties, namely: young ice (YI, thin/smooth new ice), first-year ice (FYI, formed during one cold season), and multiyear ice (MYI, which has survived at least one melt season). The&#160; latter is of particular interest as it is usually thicker than other ice types (thus, takes more time to melt), much less saline, and may accommodate a unique ecosystem. Sea ice types in the Antarctic, until recently, have not been monitored much because of the lack of appropriate remote&#160; sensing methods. While the Antarctic sea ice is greatly dominated by FYI, there are, nevertheless, considerable amounts of MYI, in particular in the Weddell Sea. We have recently adapted an algorithm for the detection of Arctic sea ice types for application in the Antarctic. The algorithm uses data from space-borne microwave radiometers and scatterometers as input. So far we have compiled a time series of daily Antarctic MYI data (and also an estimate of YI and FYI) data at a spatial resolution of 12.5 km, starting in 2013, but excluding the melt seasons when the algorithm does not work. Here give an overview of the data, showing, e.g., the quite large interannual variability of MYI and its evolution in the Weddell Sea, and discuss shortcomings of the algorithm and possible ways forward. The time series of daily Antarctic MYI data can in principle be extended backwards to the year 2000, when the used satellite data first became available, and with planned future satellite missions, it can be continued for years to come.

Download Full-text

Molecular systematics of Thouarella (Octocorallia:Primnoidae) with the description of three new species from the Southern Ocean based on combined molecular and morphological evidence

Invertebrate Systematics ◽

10.1071/is20078 ◽

2021 ◽

Author(s):

Mónica Núñez-Flores ◽

Daniel Gomez-Uchida ◽

Pablo J. López-González

Keyword(s):

New Species ◽

Southern Ocean ◽

Species Delimitation ◽

Nuclear Dna ◽

Phylogenetic Analyses ◽

Weddell Sea ◽

Morphological Evidence ◽

Three New Species ◽

Taxonomic Framework ◽

The Antarctic

Thouarella Gray, 1870, is one of the most speciose genera among gorgonians of the family Primnoidae (Cnidaria:Octocorallia:Anthozoa), being remarkably diverse in the Antarctic and sub-Antarctic seafloor. However, their diversity in the Southern Ocean is likely underestimated. Phylogenetic analyses of mitochondrial and nuclear DNA markers were integrated with species delimitation approaches as well as morphological colonial and polyps features and skeletal SEM examinations to describe and illustrate three new species within Thouarella, from the Weddell Sea, Southern Ocean: T. amundseni sp. nov., T. dolichoespinosa sp. nov. and T. pseudoislai sp. nov. Our species delimitation results suggest, for the first time, the potential presence of Antarctic and sub-Antarctic cryptic species of primnoids, based on the likely presence of sibling species within T. undulata and T. crenelata. With the three new species here described, the global diversity of Thouarella has increased to 41 species, 15 of which are endemic to the Antarctic and sub-Antarctic waters. Consequently, our results provide new steps for uncovering the shelf benthonic macrofauna’s hidden diversity in the Southern Ocean. Finally, we recommend using an integrative taxonomic framework in this group of organisms and species delimitation approaches because the distinctions between some Thouarella species based only on a superficial examination of their macro- and micromorphological features is, in many cases, limited.

Download Full-text

An amended description of two Gyrodactylus species (Platyhelminthes: Monogenea) parasitizing Antarctic Notothenioid fish

Journal of Helminthology ◽

10.1017/s0022149x18001098 ◽

2018 ◽

Vol 94 ◽

Cited By ~ 1

Author(s):

I. Heglasová ◽

V. Nezhybová ◽

I. Přikrylová

Keyword(s):

Internal Transcribed Spacer ◽

Host Record ◽

Sister Group ◽

Weddell Sea ◽

Locality Record ◽

New Host ◽

New Host Record ◽

Notothenia Coriiceps ◽

Species Groups ◽

The Antarctic

Abstract Species identification based on the morphometry of opisthaptoral hard parts, in combination with internal transcribed spacer ribosomal DNA (ITS rDNA) region sequences, confirmed the presence of four viviparous Gyrodactylus von Nordman, 1832 (Plathyhelminthes, Monogenea) species on Nototheniid fish from the Prince Gustav Channel (Weddell Sea, Antarctica). Gyrodactylus antarcticus Gusev, 1967 was found mostly on Trematomus newnesi Boulenger (93 specimens) but also on T. bernacchii Boulenger (one specimen), the latter representing a new host record for this species. Gyrodactylus byrdi Hargis & Dillon, 1968 and G. coriicepsi Rokicka, Lumme & Ziętara, 2009 were recorded on their type hosts, T. newnesi and Notothenia coriiceps Richardson, respectively. Gyrodactylus wilkesi Hargis & Dillon, 1968 was found mostly on the fins of T. bernacchii (29 specimens), but also on T. hansoni Boulenger (one specimen) and T. newnesi (three specimens). The finding of G. wilkesi on T. newnesi represents a new host record. The low number of Gyrodactylus specimens may indicate an accidental infection. The occurence of all four Gyrodactylus species in the Prince Gustav Channel represents a new locality record. According to phylogentic methods, the newly redescribed monogeneans belong to the Antarctic lineage, forming a sister group to North American and European marine Gyrodactylus species, and consist of two species groups, one comprising G. coriicepsi and G. nudifronsi Rokicka, Lumme & Ziętara, 2009, and the other G. anarcticus and G. wilkesi.

Download Full-text

Albedo of the ice covered Weddell and Bellingshausen Seas

The Cryosphere ◽

10.5194/tc-6-479-2012 ◽

2012 ◽

Vol 6 (2) ◽

pp. 479-491 ◽

Cited By ~ 9

Author(s):

A. I. Weiss ◽

J. C. King ◽

T. A. Lachlan-Cope ◽

R. S. Ladkin

Keyword(s):

Sea Ice ◽

Surface Albedo ◽

Austral Summer ◽

Open Water ◽

Weddell Sea ◽

First Year ◽

Pack Ice ◽

Bellingshausen Sea ◽

The Mean ◽

The Antarctic

Abstract. This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of αi = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the western Weddell Sea was αi = 0.75 ± 0.05. In the southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of αi = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow covered pack ice had the highest albedo values. All sea ice areas consisted of a mixture of a large range of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations do not work well for areas with new, young ice.

Download Full-text