Sightings of Antarctic minke whales, Balaenoptera bonaerensis, near the Kiev Peninsula (West Antarctica) during the summer period of 2019

Antarctic Peninsula region is experiencing one of the fastest rates of climate change on Earth. Its waters are known as important feeding grounds for the Antarctic minke whales (Balaenoptera bonaerensis). The purpose of the present study was to reveal the summer and early autumn presence of the Antarctic minke whales in the area adjacent to the Kiev Peninsula of West Antarctica and to estimate the encounter rates of the species in the area. The boat-based photo-identification cetacean studies were initiated as part of the long-term monitoring program based at the Akademik Vernadsky station near the Kiev Peninsula of West Antarctica. From 22 January to 7 April 2019, 35 boat and yacht cruises of the 821 nautical miles of total length were conducted. There were encountered 13 Antarctic minke whales in 7 sightings. The encounter rate was 0.015 whales per nautical mile. Minke whales were encountered only in 5% of the total sightings. Three more whales were opportunistically seen from the top of Galindez Island. There were single whales sighted and small groups of up to 3 specimens (Med = 2). At least 2 individuals were identified as juveniles. Primary behavior for whales in 7 sightings was foraging, and 2 groups were observed while travelling. A total 9 individuals of the Antarctic minke whales were photo-identified during the survey, and no matches were found between the different encounters. Our pilot study indicates summer and early autumn presence of the Antarctic minke whales in the area adjacent to the Kiev Peninsula. But encounter rates seem to be low in comparison with results of some previous surveys. Our results show the possibility to monitor minke whales in the area, and further long-term complex monitoring is essential for understanding the ecology and population dynamics of the Antarctic minke whales in rapidly changing marine environment of the Antarctic Peninsula.

Mass balance of the Antarctic ice sheet 1992–2016: reconciling results from GRACE gravimetry with ICESat, ERS1/2 and Envisat altimetry

Journal of Glaciology ◽

10.1017/jog.2021.8 ◽

2021 ◽

pp. 1-27

Author(s):

H. Jay Zwally ◽

John W. Robbins ◽

Scott B. Luthcke ◽

Bryant D. Loomis ◽

Frédérique Rémy

Keyword(s):

Mass Balance ◽

Antarctic Peninsula ◽

East Antarctica ◽

Mantle Material ◽

West Antarctica ◽

Mantle Viscosity ◽

Grounding Line ◽

The Antarctic ◽

Total Gain

Abstract GRACE and ICESat Antarctic mass-balance differences are resolved utilizing their dependencies on corrections for changes in mass and volume of the same underlying mantle material forced by ice-loading changes. Modeled gravimetry corrections are 5.22 times altimetry corrections over East Antarctica (EA) and 4.51 times over West Antarctica (WA), with inferred mantle densities 4.75 and 4.11 g cm−3. Derived sensitivities (Sg, Sa) to bedrock motion enable calculation of motion (δB0) needed to equalize GRACE and ICESat mass changes during 2003–08. For EA, δB0 is −2.2 mm a−1 subsidence with mass matching at 150 Gt a−1, inland WA is −3.5 mm a−1 at 66 Gt a−1, and coastal WA is only −0.35 mm a−1 at −95 Gt a−1. WA subsidence is attributed to low mantle viscosity with faster responses to post-LGM deglaciation and to ice growth during Holocene grounding-line readvance. EA subsidence is attributed to Holocene dynamic thickening. With Antarctic Peninsula loss of −26 Gt a−1, the Antarctic total gain is 95 ± 25 Gt a−1 during 2003–08, compared to 144 ± 61 Gt a−1 from ERS1/2 during 1992–2001. Beginning in 2009, large increases in coastal WA dynamic losses overcame long-term EA and inland WA gains bringing Antarctica close to balance at −12 ± 64 Gt a−1 by 2012–16.

A New Monthly Pressure Dataset Poleward of 60°S since 1957

Journal of Climate ◽

10.1175/jcli-d-17-0879.1 ◽

2018 ◽

Vol 31 (10) ◽

pp. 3865-3874 ◽

Cited By ~ 6

Author(s):

Ryan L. Fogt ◽

Logan N. Clark ◽

Julien P. Nicolas

Keyword(s):

Antarctic Peninsula ◽

Marked Improvement ◽

First Generation ◽

Kriging Interpolation ◽

West Antarctica ◽

Antarctic Continent ◽

Key Drivers ◽

The Antarctic ◽

Circulation Changes

This study presents a new monthly pressure dataset poleward of 60°S, from 1957 to 2016, based on a kriging interpolation from observed pressure anomalies across the Antarctic continent. Overall, the reconstruction performs well when evaluated against ERA-Interim. In comparison to other reanalyses, the reconstruction has interannual variability after 1970 similar to products that span the entire twentieth century and is a marked improvement on the first-generation reanalysis products. The reconstruction also produces weaker pressure trends than the reanalysis products evaluated here, which are consistent with observations. However, the skill of the reconstruction is weaker in the South Pacific and therefore does not improve the understanding of long-term pressure variability and trends in this region, where circulation changes have been key drivers of climate variability in West Antarctica and the Antarctic Peninsula.

Mysterious bio-duck sound attributed to the Antarctic minke whale ( Balaenoptera bonaerensis )

Biology Letters ◽

10.1098/rsbl.2014.0175 ◽

2014 ◽

Vol 10 (4) ◽

pp. 20140175 ◽

Cited By ~ 23

Author(s):

Denise Risch ◽

Nicholas J. Gales ◽

Jason Gedamke ◽

Lars Kindermann ◽

Douglas P. Nowacek ◽

...

Keyword(s):

Southern Ocean ◽

Conclusive Evidence ◽

Antarctic Minke Whale ◽

Minke Whales ◽

Antarctic Waters ◽

The Subject ◽

Acoustic Recording ◽

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales ( Balaenoptera bonaerensis ). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.

An Assessment of ERA5 Reanalysis for Antarctic Near-Surface Air Temperature

Atmosphere ◽

10.3390/atmos12020217 ◽

2021 ◽

Vol 12 (2) ◽

pp. 217

Author(s):

Jiangping Zhu ◽

Aihong Xie ◽

Xiang Qin ◽

Yetang Wang ◽

Bing Xu ◽

...

Keyword(s):

Linear Relationship ◽

Antarctic Peninsula ◽

Austral Summer ◽

Correlation Coefficients ◽

East Antarctica ◽

West Antarctica ◽

Austral Spring ◽

Reanalysis Dataset ◽

Near Surface ◽

The European Center for Medium-Range Weather Forecasts (ECMWF) released its latest reanalysis dataset named ERA5 in 2017. To assess the performance of ERA5 in Antarctica, we compare the near-surface temperature data from ERA5 and ERA-Interim with the measured data from 41 weather stations. ERA5 has a strong linear relationship with monthly observations, and the statistical significant correlation coefficients (p < 0.05) are higher than 0.95 at all stations selected. The performance of ERA5 shows regional differences, and the correlations are high in West Antarctica and low in East Antarctica. Compared with ERA5, ERA-Interim has a slightly higher linear relationship with observations in the Antarctic Peninsula. ERA5 agrees well with the temperature observations in austral spring, with significant correlation coefficients higher than 0.90 and bias lower than 0.70 °C. The temperature trend from ERA5 is consistent with that from observations, in which a cooling trend dominates East Antarctica and West Antarctica, while a warming trend exists in the Antarctic Peninsula except during austral summer. Generally, ERA5 can effectively represent the temperature changes in Antarctica and its three subregions. Although ERA5 has bias, ERA5 can play an important role as a powerful tool to explore the climate change in Antarctica with sparse in situ observations.

Estimation of the feeding record of pregnant Antarctic minke whales (Balaenoptera bonaerensis) using carbon and nitrogen stable isotope analysis of baleen plates

Polar Biology ◽

10.1007/s00300-021-02816-5 ◽

2021 ◽

Vol 44 (3) ◽

pp. 621-629

Author(s):

Mayuka Uchida ◽

Ippei Suzuki ◽

Keizo Ito ◽

Mayumi Ishizuka ◽

Yoshinori Ikenaka ◽

...

Keyword(s):

Growth Rate ◽

Stable Isotope ◽

Antarctic Krill ◽

Isotope Analysis ◽

Stomach Contents ◽

Annual Growth Rate ◽

Pleuragramma Antarcticum ◽

Minke Whales ◽

AbstractAntarctic minke whales (Balaenoptera bonaerensis) are migratory capital breeders that experience intensive summer feeding on Antarctic krill (Euphausia superba) in the Southern Ocean and winter breeding at lower latitudes, but their prey outside of the Antarctic is unknown. Stable isotope analyses were conducted on δ13C and δ15N from the baleen plates of ten pregnant Antarctic minke whales to understand the growth rate of the baleen plate and their diet in lower latitudes. Two to three oscillations along the length of the edge of the baleen plate were observed in δ15N, and the annual growth rate was estimated to be 75.2 ± 20.4 mm, with a small amplitude (0.97 ± 0.21 ‰). Bayesian stable isotope mixing models were used to understand the dominant prey that contributed to the isotopic component of the baleen plate using Antarctic krill from the stomach contents and reported values of Antarctic coastal krill (Euphausia crystallorophias), Antarctic silver fish (Pleuragramma antarcticum), Australian krill spp., and Australian pelagic fish spp.. The models showed that the diet composition of the most recent three records from the base of the baleen plates (model 1) and the highest δ15N values in each baleen plate (model 2) were predominantly Antarctic krill, with a contribution rate of approximately 80%. The rates were approximately 10% for Antarctic coastal krill and less than 2.0% for the two Australian prey groups in both models. These results suggest that pregnant Antarctic minke whales did not feed on enough prey outside of the Antarctic to change the stable isotope values in their baleen plates.

Decline in body condition in the Antarctic minke whale (Balaenoptera bonaerensis) in the Southern Ocean during the 1990s

Polar Biology ◽

10.1007/s00300-020-02783-3 ◽

2021 ◽

Vol 44 (2) ◽

pp. 259-273

Author(s):

Céline Cunen ◽

Lars Walløe ◽

Kenji Konishi ◽

Nils Lid Hjort

Keyword(s):

Model Selection ◽

Body Condition ◽

Model Building ◽

Research Question ◽

Information Criterion ◽

The Body ◽

Antarctic Minke Whale ◽

Minke Whales ◽

AbstractChanges in the body condition of Antarctic minke whales (Balaenoptera bonaerensis) have been investigated in a number of studies, but remain contested. Here we provide a new analysis of body condition measurements, with particularly careful attention to the statistical model building and to model selection issues. We analyse body condition data for a large number (4704) of minke whales caught between 1987 and 2005. The data consist of five different variables related to body condition (fat weight, blubber thickness and girth) and a number of temporal, spatial and biological covariates. The body condition variables are analysed using linear mixed-effects models, for which we provide sound biological motivation. Further, we conduct model selection with the focused information criterion (FIC), reflecting the fact that we have a clearly specified research question, which leads us to a clear focus parameter of particular interest. We find that there has been a substantial decline in body condition over the study period (the net declines are estimated to 10% for fat weight, 7% for blubber thickness and 3% for the girth). Interestingly, there seems to be some differences in body condition trends between males and females and in different regions of the Antarctic. The decline in body condition could indicate major changes in the Antarctic ecosystem, in particular, increased competition from some larger krill-eating whale species.

A continuum model of ice mélange and its role during retreat of the Antarctic Ice Sheet

10.5194/gmd-2018-28 ◽

2018 ◽

Author(s):

David Pollard ◽

Robert M. DeConto ◽

Richard B. Alley

Keyword(s):

Negative Feedback ◽

Continuum Model ◽

Rectangular Channel ◽

Back Pressure ◽

West Antarctica ◽

Mechanical Formulation ◽

Antarctic Marine ◽

Parameter Values ◽

Abstract. Rapidly retreating thick ice fronts can generate large amounts of mélange (floating ice debris), which may affect episodes of rapid retreat of Antarctic marine ice. In modern Greenland fjords, mélange provides substantial back pressure on calving ice faces, which slows ice-front velocities and calving rates. On the much larger scales of West Antarctica, it is unknown if mélange could clog seaways and provide enough back pressure to act as a negative feedback slowing retreat. Here we describe a new mélange model, using a continuum mechanical formulation that is computationally feasible for long-term continental Antarctic applications. It is tested in an idealized rectangular channel, and calibrated very basically using observed modern conditions in Jakobshavn fjord, West Greenland. The model is then applied to drastic retreat of Antarctic ice in response to warm mid-Pliocene climate. With mélange parameter values that yield reasonable modern Jakobshavn results, Antarctic marine ice still retreats drastically in the Pliocene simulations, with little slowdown despite the huge amounts of mélange generated. This holds both for the rapid early collapse of West Antarctica, and later retreat into major East Antarctic basins. If parameter values are changed to make the mélange much more resistive to flow, far outside the range for reasonable Jakobshavn results, West Antarctica still collapses and retreat is slowed or prevented only in a few East Antarctic basins.

Sub-decadal variations in outlet glacier terminus positions in Victoria Land, Oates Land and George V Land, East Antarctica (1972–2013)

Antarctic Science ◽

10.1017/s0954102017000074 ◽

2017 ◽

Vol 29 (5) ◽

pp. 468-483 ◽

Cited By ~ 8

Author(s):

A.M. Lovell ◽

C.R. Stokes ◽

S.S.R. Jamieson

Keyword(s):

Antarctic Peninsula ◽

East Antarctica ◽

West Antarctica ◽

Position Change ◽

Outlet Glacier ◽

Glacier Terminus ◽

Victoria Land ◽

Decadal Scale ◽

Decadal Variations ◽

AbstractRecent work has highlighted the sensitivity of marine-terminating glaciers to decadal-scale changes in the ocean–climate system in parts of East Antarctica. However, compared to Greenland, West Antarctica and the Antarctic Peninsula, little is known about recent glacier change and potential cause(s), with several regions yet to be studied in detail. In this paper, we map the terminus positions of 135 glaciers along the coastline of Victoria Land, Oates Land and George V Land from 1972–2013 at a higher temporal resolution (sub-decadal intervals) than in previous research. These three regions span a range of climatic and oceanic conditions and contain a variety of glacier types. Overall, from 1972–2013, 36% of glaciers advanced, 25% retreated and the remainder showed no discernible change. On sub-decadal timescales, there were no clear trends in glacier terminus position change. However, marine-terminating glaciers experienced larger terminus position changes compared with terrestrial glaciers, and those with an unconstrained floating tongue exhibited the largest variations. We conclude that, unlike in Greenland, West Antarctica and the Antarctic Peninsula, there is no clear glacier retreat in the study area and that most of the variations are more closely linked to glacier size and terminus type.

The scale of the whale: using video-tag data to evaluate sea-surface ice concentration from the perspective of individual Antarctic minke whales

Animal Biotelemetry ◽

10.1186/s40317-020-00218-8 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Jacob M. J. Linsky ◽

Nicole Wilson ◽

David E. Cade ◽

Jeremy A. Goldbogen ◽

David W. Johnston ◽

...

Keyword(s):

Satellite Imagery ◽

Antarctic Peninsula ◽

Environmental Variables ◽

Cloud Cover ◽

Video Data ◽

Environmental Data ◽

Minke Whales ◽

Ice Concentration ◽

Surface Ice ◽

Abstract Background Advances in biologging technology allow researchers access to previously unobservable behavioral states and movement patterns of marine animals. To relate behaviors with environmental variables, features must be evaluated at scales relevant to the animal or behavior. Remotely sensed environmental data, collected via satellites, often suffers from the effects of cloud cover and lacks the spatial or temporal resolution to adequately link with individual animal behaviors or behavioral bouts. This study establishes a new method for remotely and continuously quantifying surface ice concentration (SIC) at a scale relevant to individual whales using on-animal tag video data. Results Motion-sensing and video-recording suction cup tags were deployed on 7 Antarctic minke whales (Balaenoptera bonaerensis) around the Antarctic Peninsula in February and March of 2018. To compare the scale of camera-tag observations with satellite imagery, the area of view was simulated using camera-tag parameters. For expected conditions, we found the visible area maximum to be ~ 100m2 which indicates that observations occur at an equivalent or finer scale than a single pixel of high-resolution visible spectrum satellite imagery. SIC was classified into one of six bins (0%, 1–20%, 21–40%, 41–60%, 61–80%, 81–100%) by two independent observers for the initial and final surfacing between dives. In the event of a disagreement, a third independent observer was introduced, and the median of the three observer’s values was used. Initial results (n = 6) show that Antarctic minke whales in the coastal bays of the Antarctic Peninsula spend 52% of their time in open water, and only 15% of their time in water with SIC greater than 20%. Over time, we find significant variation in observed SIC, indicating that Antarctic minke occupy an extremely dynamic environment. Sentinel-2 satellite-based approaches of sea ice assessment were not possible because of persistent cloud cover during the study period. Conclusion Tag-video offers a means to evaluate ice concentration at spatial and temporal scales relevant to the individual. Combined with information on underwater behavior, our ability to quantify SIC continuously at the scale of the animal will improve upon current remote sensing methods to understand the link between animal behavior and these dynamic environmental variables.

A revised geochronology of Thurston Island, West Antarctica, and correlations along the proto-Pacific margin of Gondwana

Antarctic Science ◽

10.1017/s0954102016000341 ◽

2016 ◽

Vol 29 (1) ◽

pp. 47-60 ◽

Cited By ~ 18

Author(s):

T.R. Riley ◽

M.J. Flowerdew ◽

R.J. Pankhurst ◽

P.T. Leat ◽

I.L. Millar ◽

...

Keyword(s):

Antarctic Peninsula ◽

West Antarctica ◽

Granitoid Magmatism ◽

Andean Cordillera ◽

Crustal Block ◽

Form Part ◽

Gondwana Margin ◽

Pacific Margin ◽

Mesozoic Magmatism ◽

AbstractThe continental margin of Gondwana preserves a record of long-lived magmatism from the Andean Cordillera to Australia. The crustal blocks of West Antarctica form part of this margin, with Palaeozoic–Mesozoic magmatism particularly well preserved in the Antarctic Peninsula and Marie Byrd Land. Magmatic events on the intervening Thurston Island crustal block are poorly defined, which has hindered accurate correlations along the margin. Six samples are dated here using U-Pb geochronology and cover the geological history on Thurston Island. The basement gneisses from Morgan Inlet have a protolith age of 349±2 Ma and correlate closely with the Devonian–Carboniferous magmatism of Marie Byrd Land and New Zealand. Triassic (240–220 Ma) magmatism is identified at two sites on Thurston Island, with Hf isotopes indicating magma extraction from Mesoproterozoic-age lower crust. Several sites on Thurston Island preserve rhyolitic tuffs that have been dated at 182 Ma and are likely to correlate with the successions in the Antarctic Peninsula, particularly given the pre-break-up position of the Thurston Island crustal block. Silicic volcanism was widespread in Patagonia and the Antarctic Peninsula at ~ 183 Ma forming the extensive Chon Aike Province. The most extensive episode of magmatism along the active margin took place during the mid-Cretaceous. This Cordillera ‘flare-up’ event of the Gondwana margin is also developed on Thurston Island with granitoid magmatism dated in the interval 110–100 Ma.