Found 14046 items
1 January, 2004
The distribution and density of the Amazon's two contrasting endemic dolphins-boto, or Amazon river dolphin, Inia geoffrensis, and tucuxi, Sotalia fluviatilis-were examined on two adjoining large rivers in western Brazil.…1 January, 2004
The size and structure of a community of Amazon river dolphins or botos, Inia geoffrensis (de Blainville, 1817), was investigated using boat surveys and long-term observations of recognisable animals. Year-round,…1 January, 2004
Habitat use by the boto, or Amazon river dolphin Inia geoffrensis, was investigated in and around the Mamiraua Reserve, Brazil. Largely forested with numerous channels and lakes, Mamiraua comprises a…1 January, 2004 by John Turner, Thomas Lachlan-Cope
Intermittent atmospheric blocking-high activity in the South Tasman Sea is shown to play a key role in delivering substantial snowfall as far south as at least 75degreesS on the central…1 January, 2004 by Simeon Hill
In stock assessments of short-lived species, De Lury depletion models are commonly applied in which commercial catches and changing catch rates are used to estimate resource abundance. These methods are…1 January, 2004 by Mark Clilverd
This paper discusses the use of ground magnetometer data to derive plasma mass density profiles of the dayside plasmapause region with spatial and temporal resolution in the range 0.15-0.4 R-E…Read more on Monitoring the plasmapause using geomagnetic field line resonances
1 January, 2004 by Andrew Clarke, John King, Michael Meredith
[ 1] A year-round sequence of hydrographic casts is used to trace the evolution of the upper ocean waters in Marguerite Bay, western Antarctic Peninsula (wAP), between 1998 and 2002.…1 January, 2004 by Richard Horne
We analyze wave and particle data from the CRRES satellite to determine the variability of plasmaspheric hiss (0.1 < f < 2 kHz) with respect to substorm activity as measured…1 January, 2004
The Himalia Ridge Formation (Fossil Bluff Group), Alexander Island is a 2.2-km-thick sequence of Upper Jurassic-Lower Cretaceous conglomerates, sandstones and mudstones, derived from an andesitic volcanic arc and deposited in…1 January, 2004 by Roger Worland
Antarctica has long been recognised as a putative analogue for Mars' past (1) and any life there is surviving in extreme conditions. Raman spectroscopy has been proved as a suitable…Read more on Raman spectroscopic studies of Antarctic endoliths and epiliths
1 January, 2004
Macaroni Eudyptes chrysolophus and gentoo Pygoscelis papua penguins occur sympatrically at Bird Island (54degrees00'S, 38degrees02'W), South Georgia, and have a similar diet. Macaroni penguins forage at shallower depths and further…1 January, 2004
This study investigated the degree to which the behavior of a predator in the marine environment can be used to indicate the availability of prey. It examined this in Antarctic…1 January, 2004 by Mark Belchier, Simon Morley
The biology of the bigeye grenadier Macrourus holotrachys caught as by-catch in the Patagonian toothfish Dissostichus eleginoides longline fishery conducted around South Georgia was investigated to improve data available for…Read more on The biology of the bigeye grenadier at South Georgia
1 January, 2004 by Robert Mulvaney
Over the period 1972-98 the height of the snow surface at eight Antarctic sites in Palmer Land and on Alexander Island has been measured with respect to fixed points on…Read more on Recent variations in surface mass balance of the Antarctic Peninsula ice sheet
1 January, 2004 by Eugene Murphy, Jonathan Watkins, Sally Thorpe
A coupled physical-biological model analysis was undertaken to examine the seasonal development of the distribution of antarctic krill (Euphausia superba Dana) in the Scotia Sea. The origin and fate of…1 January, 2004 by Eugene Murphy, Michael Meredith, Philip Trathan, Peter Ward, Sally Thorpe
During December 2000 and January 2001 we conducted a high-resolution hydrographic and bioacoustic transect (RRS James Clark Ross cruise 57) that extended across the South Georgia shelf from close to…1 January, 2004
Within the past 7 years, the northern Larsen Ice Shelf has broken up so it is now possible to sample the sea floor that formerly lay beneath it. Box cores…1 January, 2004 by Philip Trathan
Procellariiform seabirds (petrels, albatrosses and shearwaters) forage over thousands of square kilometres for patchily distributed prey resources. While these birds are known for their large olfactory bulbs and excellent sense…Read more on Testing olfactory foraging strategies in an Antarctic seabird assemblage
1 January, 2004 by David Pearce, Kevin Newsham
We tested the preferences of three nematode taxa, Geomonhystera villosa, Plectus spp. and Teratocephalus spp., extracted from moss at Signy Island in the Maritime Antarctic, for two microalgae, three microfungi…Read more on Differing preferences of Antarctic soil nematodes for microbial prey
1 January, 2004 by Keith Nicholls
We report on oceanographic observations made at the northern end of Larsen C Ice Shelf in the western Weddell Sea. It appears that the Larsen C continental shelf is flushed…Read more on Summertime water masses off the northern Larsen C Ice Shelf, Antarctica
1 January, 2004 by Keith Nicholls
[1] Multiyear time series of ocean current and temperatures from beneath Filchner-Ronne Ice Shelf, Antarctica, demonstrate both seasonal and interannual variability. The seasonal signal is visible at all measurement sites,…1 January, 2004 by Keith Makinson, Keith Nicholls
We present oceanographic data from beneath the northern Ronne Ice Shelf. The data were collected during the austral summer of 2002–2003 from four sites located near the ice front in…Read more on Circulation and water masses beneath the northern Ronne Ice Shelf, Antarctica
1 January, 2004
During the late Neogene, the Lambert Glacier–Amery Ice Shelf drainage system flowed across Prydz Bay in an ice stream that reached the shelf edge and built a trough mouth fan…Read more on Prydz Bay fan and the history of extreme ice advances in Prydz Bay
1 January, 2004 by Andrew Orr, Gareth Marshall
[1] We demonstrate a mechanism whereby the impact of stronger circumpolar westerly winds on the mountains of the Antarctic Peninsula contributes significantly to the enhanced warming trend observed over its…1 January, 2004
As the German contribution to the Southern Ocean Global Ocean Ecosystems Dynamics Study (SO GLOBEC), RV Polarstern visited the Eastern Bellingshausen Sea between 18 April and 1 May 2001. This…1 January, 2004 by Gareth Chisham, Michael Pinnock
Super Dual Auroral Radar Network (DARN) radars often detect a distinct transition in line-of-sight Doppler velocity spread, or spectral width, from 200 m s(-1) at higher latitude. They also detect…1 January, 2004
December 25th 2003 will see the Beagle 2 lander arrive at the surface of Mars in the Isidis region, allowing for the first time in situ measurements of ultraviolet (UV)…1 January, 2004 by Lloyd Peck
1. The anostracan fairy shrimp Branchinecta gaini inhabits one of the most hostile environments on earth, living in pools and lakes in Antarctica. Between January 2002 and January 2003 temperatures…1 January, 2004 by Lloyd Peck
Burrowing was investigated in two Antarctic infaunal bivalve molluscs, Laternula elliptica and Yoldia eightsi, representing amongst the least and most active members of the class Bivalvia in the Southern Ocean.…1 January, 2004 by David Barnes, Lloyd Peck
Oxygen consumption (MO2) and activity were evaluated in Antarctic Bryozoa. Three species representing two different morphologies, flat sheet, laminar forms, Isoseculiflustra tenuis and Kymella polaris, and the bush form Camptoplites…Read more on Metabolic flexibility: the key to long-term evolutionary success in Bryozoa?
1 January, 2004 by Lloyd Peck
1. Biological capacities to respond to changing environments dictate success or failure of populations and species over time. The major environmental feature in this context is often temperature, and organisms…Read more on Extreme sensitivity of biological function to temperature in Antarctic marine species
1 January, 2004 by Richard Phillips
Although albatrosses typically show strong natal philopatry, a small proportion of birds emigrate to distant colonies, occasionally establishing new breeding sites and potentially initiating speciation events. Patterns of albatross distribution…1 January, 2004 by Richard Phillips
Breeding ecology of brown skuas (Catharacta antarctica lonnbergi) was studied at Bird Island, South Georgia in the austral summers of 2000/2001-2003/2004. A complete census recorded 467 breeding pairs in 3.55…1 January, 2004 by Janet Silk, Richard Phillips, Vsevolod Afanasyev
Geolocation (Global Location Sensing or GLS logging) using archival light-recording tags offers considerable potential for tracking animal movements, yet few studies of flying seabirds have exploited this technology. Our study…Read more on Accuracy of geolocation estimates for flying seabirds
1 January, 2004 by Janet Silk, Richard Phillips
Sexual segregation by micro- or macrohabitat is common in birds, and usually attributed to size-mediated dominance and exclusion of females by larger males, trophic niche divergence or reproductive role specialization.…1 January, 2004 by Eric Wolff
An analytical method for the direct determination of mercury (Hg) in polar snow and ice cores and surface snow based on inductively coupled plasma sector field mass spectrometry (ICP-SFMS) has…1 January, 2004 by Robert Larter
1 January, 2004 by Andrew Clarke
The mega-epibenthos of two different geographic areas, the Antarctic Peninsula and the high Antarctic (eastern Weddell Sea), were investigated using underwater video. The distribution of the marine fauna at shallow…1 January, 2004
The Ellsworth-Whitmore Mountains (EWM) are one of five terranes that form West Antarctica. Constraining the positions of these terranes in pre-break up Gondwana is crucial to understanding the history of…1 January, 2004 by Eric Wolff, Robert Mulvaney
It has recently been shown that much sea-salt aerosol around the coast of Antarctica is generated not from open water, but from the surface of newly formed sea ice. Previous…Read more on A reinterpretation of sea-salt records in Greenland and Antarctic ice cores?
1 January, 2004 by David Barnes
Patterns of zooplankton vertical movement are often difficult to interpret because of multiple, complex and confounding environmental factors. Behavioural adaptations to these environmental variables are compared within and between the…1 January, 2004
Hope Bay and Botany Bay, Graham Land, Antarctica have yielded two of the most diverse floras known from the Jurassic. Because of its high diversity, as well as its early…Read more on Lower Jurassic floras from Hope Bay and Botany Bay, Antarctica
1 January, 2004
Resolving the spatial variability in the population structure of Antarctic krill (Euphausia superba) requires a synoptic sample, as in the design of the CCAMLR 2000 Survey. However, this approach is…1 January, 2004
The measurement of spatial overlap between predators and fisheries exploiting a common prey source is dependent upon the measurement scale used; inappropriate scales may produce misleading results. Previous assessments of…1 January, 2004 by Jonathan Watkins
Baleen whales are an important group of predators on Antarctic krill in the Southern Ocean. During the CCAMLR 2000 Survey to estimate the biomass and distribution of Antarctic krill, International…1 January, 2004
A non-hydrostatic numerical weather prediction model has been employed to Simulate idealized katabatic flows over a moderate slope and adjoining ice shelf. The topography of Coats Land and the adjoining…Read more on The dynamics of idealized katabatic flow over a moderate slope and ice shelf
1 January, 2004 by Philip Leat, Teal Riley
U-Pb SHRIMP ages are reported for three rhyolite flows from the Lebombo rift region of the Karoo volcanic province. Two flows are interbedded with the Sabie River Basalt Formation and…1 January, 2004 by Mark Clilverd
Manmade control of the radiation belts for the protection of space-based infrastructure has been suggested on the basis of theoretical calculations. In this paper we put forward an experimental test…Read more on Testing the importance of precipitation loss mechanisms in the inner radiation belt
1 January, 2004 by Paul Rodhouse
All fish, and other motile fishery resources, make migrations. These range from tens or hundreds of metres to large-scale oceanic migrations over thousands of kilometres. Migrations are usually cyclical over…Read more on Migration of fishery resources in the World’s oceans
1 January, 2004
Deep-sea coral reefs live in the cold, dark waters of the oceans but like shallow water tropical coral reefs they have a distinct, diverse and sometimes highly endemic associated animal…Read more on The biology, ecology and vulnerability of deep-water coral reefs
1 January, 2004
While much remains unknown about seamount communities, scientific evidence suggests that high seas bottom trawling may have significant and irreversible impacts on the diversity and ecology of seamounts and other…Read more on The biology, ecology and vulnerability of seamount communities
1 January, 2004 by Howard Roscoe
Descent of air from stratosphere to troposphere in Antarctic winter is proposed to be feasible, because of forcing from above by subsidence plus wave-breaking, together with suction from below to…Read more on Possible descent across the ‘Tropopause’ in Antarctic winter
1 January, 2004 by Howard Roscoe
Jodie Dunn is to be commended for her entertaining and well-researched article in Weather (Dunn 2004). However, some of the arguments deserve to be amplified, and they demonstrate interesting and…1 January, 2004 by Howard Roscoe
Twenty years ago there were large disagreements between instruments measuring stratospheric H2O and NO2, and there were no reliable long-term records. Now, there is greatly improved agreement between techniques, there…1 January, 2004 by Howard Roscoe, Jonathan Shanklin
Measurements of total ozone in Antarctica during early winter show an increase, consistent with the observed descent of stratospheric air and the convergence that accompanies descent. Measurements in the vortex…1 January, 2004 by Gareth Marshall
The variability of size and source of significant precipitation events were studied at an Antarctic ice core drilling site: Dolleman Island (DI). located on the eastern coast of the Antarctic…1 January, 2004 by Robert Mulvaney
A 181 m deep ice core drilled in 1994/95 on the south dome of Berkner Island, Antarctica, was analyzed for stable isotopes, major ions and microparticle concentrations. Samples for ion…1 January, 2004 by Eric Wolff
An extended high-resolution ice core record of dust deposition over the past 60 ka from Dome C, Antarctica, is presented. The data are in conflict with the idea that changes…1 January, 2004 by Dominic Hodgson
1. Lakes and ponds in the Larsemann Hills and Bolingen Islands (East-Antarctica) were characterised by cyanobacteria-dominated, benthic microbial mats. A 56-lake dataset representing the limnological diversity among the more than…1 January, 2004
Mapping the geometry of the ice sheet is fundamental to many advanced investigations, e.g., on ice dynamics, mass balance, ice – ocean interaction, ice – atmosphere interaction, and ice body…Read more on Meteoric marine and total ice thickness maps of Filchner-Ronne-Schelfeis, Antarctica
1 January, 2004
Stable nitrogen isotope ratios are routinely used to disentangle trophic relationships. Several authors have discussed factors in addition to diet that might contribute to variability in delta(15)N of consumers, but…1 January, 2004 by Geraint Tarling
Knowledge of crustacean moulting is derived mainly from benthic decapods, which often show profound changes in physiology and behaviour through the moult cycle. In contrast, euphausiids are suggested to be…1 January, 2004 by Hilmar Gudmundsson
The morphology of the drainage system of Unteraargletscher, Switzerland, and the diurnal variability of drainage conditions were investigated by conducting a series of tracer tests over a number of discharge…Read more on Diurnal variability of subglacial drainage conditions as revealed by tracer experiments
1 January, 2004
Airglow emission and temperature observations by the wind imaging interferometer (WINDII) on the upper atmosphere research satellite (UARS) and ground-based stations revealed a rapid 2-day rise in the nighttime emission…1 January, 2004 by Jonathan Watkins, Peter Ward
This paper summarizes the results of krill demographic studies from the Commission for the Conservation of Antarctic Marine Living Resources 2000 Survey-a large-scale krill survey across the Scotia Sea conducted…1 January, 2004 by Andy Smith, Ed King, Hugh Corr, Richard Hindmarsh, Richard Hindmarsh
Radio-echo sounding reveals a 10 km-long lake beneath similar to3.4 km of ice near the Ellsworth Mountains in West Antarctica, 20 km from the ice divide. Subglacial Lake Ellsworth is…Read more on Subglacial Lake Ellsworth: a candidate for in situ exploration in West Antarctica
1 January, 2004 by Ed King
Upstream of Byrd Station (West Antarctica), ice-penetrating radar data reveal a distinctive fold structure within the ice, in which isochronous layers are unusually deep. The fold has an axis more…Read more on Ice flow direction change in interior West Antarctica
1 January, 2004 by John King
The hemispheric and regional atmospheric circulation influences the Southern Ocean in many and profound ways, including intense air-sea fluxes of momentum, energy, fresh water and dissolved gases. The Southern Ocean…Read more on Global and hemispheric climate variations affecting the Southern Ocean
1 January, 2004
Observations with a Meteor radar operating at 32.55 MHz have been used to derive daily atmospheric temperature data for an altitude of 90 km at mid-latitudes during November 1999 until…Read more on Meteor radar observations at middle and Arctic latitudes. Part 1: Mean temperatures
1 January, 2004 by Adrian Jenkins
[1] We present a model for the growth of frazil ice crystals and their accumulation as marine ice at the base of Antarctic ice shelves. The model describes the flow…Read more on Frazil ice formation in an ice shelf water plume
1 January, 2004 by Nigel Meredith, Richard Horne
[1] It has been suggested that whistler mode chorus waves play a role in acceleration and loss of radiation belt electrons during geomagnetic storms. In this paper we present data…Read more on Ground observations of chorus following geomagnetic storms
1 January, 2004 by Nigel Meredith
[ 1] It has been suggested that whistler mode chorus waves play a role in the acceleration and loss of radiation belt electrons during geomagnetic storms. In a previous statistical…1 January, 2004
A new species of the synallactid sea cucumber genus Pseudostichopus is described, P. aemaulatus sp. nov., based on genetic (DNA sequences of the mitochondrial gene Cytochrome Oxidase I [COI] gene)…1 January, 2004
The results of a combined geophysical and geochemical research programme on Deception Island, an active volcano at 62degrees43'S, 60degrees57'W in Bransfield Strait (Antarctica), are presented. Ultrahigh-resolution acoustic data obtained with…1 January, 2004 by Dominic Hodgson
Atmospheric pressure chemical ionisation reversed-phase high-performance liquid chromatography/multistage mass spectrometry has been used to study the mass spectral fragmentation of the cyanobacterial sheath pigment scytonemin and its reduced counterpart. The…1 January, 2004 by Dominic Hodgson
Bacteriophaeophytin a with geranylgeraniol as the C-17(3) esterifying alcohol has been identified in a sediment from Progress Lake, east Antarctica by using atmospheric pressure chemical ionisation liquid chromatography-mass spectrometry. This…1 January, 2004 by Dominic Hodgson
High performance liquid chromatography-mass spectrometry has permitted the identification of a homologous series of novel alkylsulfide derivatives of chlorophyll a containing between one and five carbon atoms, in sediment from…1 January, 2004 by Dominic Hodgson
High performance liquid chromatography-mass spectrometry has been used to identify the cyanophyta-derived ultraviolet screening pigment scytonemin and its reduced counterpart in an Antarctic lake sediment. The formation of an artefact…1 January, 2004 by Roger Worland
Many insects in temperate regions overwinter in diapause, during which they are cold hardy. In these insects, one of the metabolic adaptations to the unfavorable environmental conditions is the synthesis…1 January, 2004 by Iain Staniland
Using Antarctic fur seals (Arctocephalus gazella (Peters, 1875)) in a feeding trial, we investigated the use of milk fatty acids to determine diet. In a regime designed to replicate an…1 January, 2004 by Iain Staniland
We investigated intra-specific and geographic variation in the behaviour of female Antarctic fur seals Arctocephalus gazella by serially sampling 11 individuals throughout their breeding season using satellite tracking, time-depth recorders…1 January, 2004
Seven previously undescribed palynomorphs, Brazilea sp. B, ?Carbaneuletes sp. A, ?Reduviasporonites sp. and Algal palynomorph spp. 1 to 4, some of which are closely similar to the spores and filaments…1 January, 2004 by Hilmar Gudmundsson
Short-term variations in horizontal and vertical surface motion were studied with high temporal resolution during the ablation season in Lauteraargletscher, Bernese Alps, Switzerland. Horizontal surface flow speed oscillated diurnally, showing…1 January, 2004 by Richard Horne
Understanding the behavior of relativistic electrons in the Earth's outer radiation belt during substorms and storms is a current challenge in magnetospheric physics. In this paper, we model energetic electron…1 January, 2004 by Kevin Hughes
Biofilms present complex assemblies of micro-organisms attached to surfaces. They are dynamic structures in which various metabolic activities and interactions between the component cells occur. When phage come in contact…1 January, 2004 by Philip Trathan
Inferring feeding activities from undulations in diving depth profiles is widespread in studies of foraging marine predators. This idea, however, has rarely been tested because of practical difficulties in obtaining…1 January, 2004 by Michael Dunn, Philip Trathan
Marine birds and mammals spend most of their lives in the open ocean far from human observation, which makes obtaining information about their foraging behaviour difficult. Here, we show, by…Read more on Penguin-mounted cameras glimpse underwater group behaviour
1 January, 2004 by Philip Trathan
Knowledge of the spatial and temporal dynamics of foraging penguins is important to our understanding of the Southern Ocean marine ecosystem. We use satellite tracking to provide the first data…Read more on Winter distribution and behaviour of gentoo penguins Pygoscelis papua at South Georgia
1 January, 2004 by Geraint Tarling, Peter Ward
A modelling approach was developed to identify the most likely composition of life-cycle phenotypes and mortality rates for Calanoides acutus found within the Scotia Sea. A stage- and age-structured model…1 January, 2004
Global estimates of sea-surface temperature (SST) distributions represent an important prescribed boundary condition for atmosphere-only general circulation models (AGCMs) which aim to Simulate the behaviour of the past climate system.…1 January, 2004 by Sally Thorpe
A particle tracking scheme that uses velocity output from an interannually varying forced run of a global ocean circulation model (Parallel Ocean Climate Model; POCM_4C) allows variability in the transport…1 January, 2004 by Jaume Forcada
Exposure to organochlorines induces retinoid deficiency in mammals; hence, retinoids are potential biomarkers of the impact of these pollutants. Appropriate target tissues to monitor retinoids in cetaceans have not been…Read more on Tissue distribution of retinoids in common dolphins Delphinus delphis
1 January, 2004 by Jaume Forcada
We determined retinoid concentrations in various body positions of the blubber of 25 common dolphins (Delphinus delphis) to study topographical variation in concentrations. Specimens were obtained from incidental catches and…1 January, 2004 by Philip Trathan
Penguin populations are potentially sensitive indicators of ecological change in Antarctic and sub-Antarctic marine ecosystems. Aerial photographic surveys provide the most robust method for estimating breeding population size, particularly for…Read more on Image analysis of color aerial photography to estimate penguin population size