scholarly journals Modelling the extinction of Steller's sea cow

2005 ◽  
Vol 2 (1) ◽  
pp. 94-97 ◽  
Author(s):  
S.T Turvey ◽  
C.L Risley
Keyword(s):  
Environmental Changes ◽  
Historical Period ◽  
Sea Otter ◽  
Commander Islands ◽  
Mammal Species ◽  
Life History Data ◽  
Extinction Event ◽  
Sea Cow ◽  
Bering Island ◽  
Catastrophic Impact

Steller's sea cow, a giant sirenian discovered in 1741 and extinct by 1768, is one of the few megafaunal mammal species to have died out during the historical period. The species is traditionally considered to have been exterminated by ‘blitzkrieg’-style direct overharvesting for food, but it has also been proposed that its extinction resulted from a sea urchin population explosion triggered by extirpation of local sea otter populations that eliminated the shallow-water kelps on which sea cows fed. Hunting records from eighteenth century Russian expeditions to the Commander Islands, in conjunction with life-history data extrapolated from dugongs, permit modelling of sea cow extinction dynamics. Sea cows were massively and wastefully overexploited, being hunted at over seven times the sustainable limit, and suggesting that the initial Bering Island sea cow population must have been higher than suggested by previous researchers to allow the species to survive even until 1768. Environmental changes caused by sea otter declines are unlikely to have contributed to this extinction event. This indicates that megafaunal extinctions can be effected by small bands of hunters using pre-industrial technologies, and highlights the catastrophic impact of wastefulness when overexploiting resources mistakenly perceived as ‘infinite’.

scholarly journals The Commander population of sea otter Enhydra lutris: history of exploitation and recovery, evaluation of modern state

2014 ◽  
Vol 179 (4) ◽  
pp. 91-102
Author(s):  
Sergej V. Zagrebelniy
Keyword(s):  
Coastal Waters ◽  
Modern State ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Commander Islands ◽  
Sex Structure ◽  
The Usa ◽  
Demographic Processes ◽  
History Of ◽  
Bering Island

Demographic processes within the groups of sea otter on Commander Islands (Bering and Medny Islands) are described for the period from the beginning of its recovery on Bering Island in the late 1970s. Mortality rate is proposed as an indicator of this population condition. Stable spatial and age-sex structure of sea otter on Bering Island is observed since 1999 that is accompanied by high mortality among mature animals (8 years old and elder). Density of the sea otter distribution in the coastal waters is estimated from the data on findings of dead animals. Age-sex structure of the population varies between the sites and has seasonal variation. Strained feeding conditions for the sea otter on Bering Island are defined on the materials of underwater survey conducted by the USA researchers in 2008-2009. Three ways of development are proposed for the Commander population of sea otter.

scholarly journals Steller’s sea cow genome suggests this species began going extinct before the arrival of Paleolithic humans

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fedor S. Sharko ◽  
Eugenia S. Boulygina ◽  
Svetlana V. Tsygankova ◽  
Natalia V. Slobodova ◽  
Dmitry A. Alekseev ◽  
...  
Keyword(s):  
Bering Sea ◽  
De Novo ◽  
Anthropogenic Activity ◽  
Commander Islands ◽  
The North ◽  
Extinction Process ◽  
Sea Cow ◽  
The North Pacific ◽  
The Bering Sea ◽  
Woolly Mammoth

AbstractAnthropogenic activity is the top factor directly related to the extinction of several animal species. The last Steller’s sea cow (Hydrodamalis gigas) population on the Commander Islands (Russia) was wiped out in the second half of the 18th century due to sailors and fur traders hunting it for the meat and fat. However, new data suggests that the extinction process of this species began much earlier. Here, we present a nuclear de novo assembled genome of H. gigas with a 25.4× depth coverage. Our results demonstrate that the heterozygosity of the last population of this animal is low and comparable to the last woolly mammoth population that inhabited Wrangel Island 4000 years ago. Besides, as a matter of consideration, our findings also demonstrate that the extinction of this marine mammal starts along the North Pacific coastal line much earlier than the first Paleolithic humans arrived in the Bering sea region.

Isolated Fluvial Population of Dolly Varden Salvelinus malma on Bering Island (Commander Islands)

2021 ◽  
Vol 61 (3) ◽  
pp. 418-432
Author(s):  
A. M. Malyutina ◽  
K. V. Kuzishchin ◽  
A. V. Semenova ◽  
M. A. Gruzdeva
Keyword(s):  
Dolly Varden ◽  
Salvelinus Malma ◽  
Commander Islands ◽  
Dolly Varden Salvelinus Malma ◽  
Bering Island

scholarly journals Contrasting changes in space use induced by climate change in two Arctic marine mammal species

2019 ◽  
Vol 15 (3) ◽  
pp. 20180834 ◽  
Author(s):  
Charmain D. Hamilton ◽  
Jade Vacquié-Garcia ◽  
Kit M. Kovacs ◽  
Rolf A. Ims ◽  
Jack Kohler ◽  
...  
Keyword(s):  
Climate Change ◽  
Marine Mammals ◽  
Environmental Changes ◽  
Life Cycles ◽  
The Arctic ◽  
Delphinapterus Leucas ◽  
Behavioural Plasticity ◽  
Mammal Species ◽  
Dietary Specialization ◽  
Environmental Pressures

Global warming is inducing major environmental changes in the Arctic. These changes will differentially affect species owing to differences in climate sensitivity and behavioural plasticity. Arctic endemic marine mammals are expected to be impacted significantly by ongoing changes in their key habitats owing to their long life cycles and dependence on ice. Herein, unique biotelemetry datasets for ringed seals (RS; Pusa hispida ) and white whales (WW; Delphinapterus leucas ) from Svalbard, Norway, spanning two decades (1995–2016) are used to investigate how these species have responded to reduced sea-ice cover and increased Atlantic water influxes. Tidal glacier fronts were traditionally important foraging areas for both species. Following a period with dramatic environmental change, RS now spend significantly more time near tidal glaciers, where Arctic prey presumably still concentrate. Conversely, WW spend significantly less time near tidal glacier fronts and display spatial patterns that suggest that they are foraging on Atlantic fishes that are new to the region. Differences in levels of dietary specialization and overall behavioural plasticity are likely reasons for similar environmental pressures affecting these species differently. Climate change adjustments through behavioural plasticity will be vital for species survival in the Arctic, given the rapidity of change and limited dispersal options.

Reconciling global land model estimates and country reporting of anthropogenic land CO2 sources and sinks with the CMIP6 LUMIP NOAA/GFDL LM4.1 simulations

2020 ◽  
Author(s):  
Elena Shevliakova ◽  
Sergey Malyshev ◽  
Richard Houghton ◽  
Louis Verchot
Keyword(s):  
Land Use ◽  
Environmental Changes ◽  
Historical Period ◽  
Land Cover Changes ◽  
Land Use Land Cover ◽  
Earth System ◽  
Sources And Sinks ◽  
Global Land ◽  
Natural Response ◽  
Earth System Models

<p>Global land models, which often served as components Earth system models, and national GHG inventories rely on different methods and produce different estimates of anthropogenic CO<sub>2</sub> emissions and uptakes from land use land cover changes throughout historical period. For example, for 2005 -2014, the sum of the national GHG inventories net emission estimates is 0.1 ± 1.0 GtCO2 yr<sup>–1</sup> while the bookkeeping models is 5.2 ± 2.6 GtCO2 yr<sup>–1</sup> (IPCC SPM 2019).  Previous estimates with the 16 global stand-alone land models produced an estimate of the net land sink of 11.2 ± 2.6 GtCO2 yr<sup>–1</sup> during 2007– 2016 for the natural response of land to human-induced environmental changes such as increasing atmospheric CO<sub>2</sub> concentration, nitrogen deposition, and climate change (IPCC SPM 2019).  However, these 16 models do not provide separate estimates for the managed and unmanaged lands. </p><p> </p><p>Here we use results from simulations with the NOAA/GFDL new land model LM4.1 from the CMIP6 Land Use Model Inercomparison Project (LUMIP) to demonstrate how to reconcile the discrepancy between the inventories and land models estimates of the anthropogenic CO<sub>2 </sub>land emissions by using bookkeeping accounting approach applied to the model results.  In addition, we separate estimates of land fluxes on managed and unmanaged lands. Key features of this model include advanced, second generation dynamic vegetation representation and canopy competition, fire, and land use representation driven by full set of gross transitions from the CMIP6 land use scenarios.  We demonstrate how bookkeeping accounting combined with the LUMIP experiments can enhance understanding of land sector net emission estimates and their applications.</p>

scholarly journals Spatial and temporal effects of grazing management and rainfall on the vertebrate fauna of a tropical savanna

2012 ◽  
Vol 34 (2) ◽  
pp. 173 ◽  
Author(s):  
A. S. Kutt ◽  
E. P. Vanderduys ◽  
P. O'Reagain
Keyword(s):  
Environmental Changes ◽  
Vegetation Type ◽  
Annual Rainfall ◽  
Stocking Rate ◽  
Limited Information ◽  
Mammal Species ◽  
Vertebrate Fauna ◽  
Domestic Livestock ◽  
Generalised Linear Modelling ◽  
Stocking Rates

Grazing by domestic livestock is one of the most widespread uses of the rangelands of Australia. There is limited information on the effects of grazing by domestic livestock on the vertebrate fauna of Australia and the establishment of a long-term grazing experiment in north-eastern Queensland at Wambiana provided an opportunity to attempt an examination of the changes in vertebrate fauna as a consequence of the manipulation of stocking rates. The aim was to identify what the relative effects of vegetation type, stocking rate and other landscape-scale environmental factors were on the patterns recorded. Sixteen 1-ha sites were established within three replicated treatments (moderate, heavy and variable stocking rates). The sites were sampled in the wet and dry seasons in 1999–2000 (T0) and again in 2003–04 (T1). All paddocks of the treatments were burnt in 1999. Average annual rainfall declined markedly between the two sampling periods, which made interpretation of the data difficult. A total of 127 species of vertebrate fauna comprising five amphibian, 83 bird, 27 reptile and 12 mammal species were recorded. There was strong separation in faunal composition from T0 to T1 although changes in mean compositional dissimilarity between the grazing stocking rate treatments were less well defined. There was a relative change in abundance of 24 bird, four mammal and five reptile species from T0 to T1. The generalised linear modelling identified that, in the T1 data, there was significant variation in the abundance of 16 species explained by the grazing and vegetation factors. This study demonstrated that vertebrate fauna assemblage did change and that these changes were attributable to the interplay between the stocking rates, the vegetation types on the sites surveyed, the burning of the experimental paddocks and the decrease in rainfall over the course of the two surveys. It is recommended that the experiment is sampled again but that the focus should be on a rapid survey of abundant taxa (i.e. birds and reptiles) to allow an increase in the frequency of sampling and replication of the data. This would help to articulate more clearly the trajectory of vertebrate change due to the relative effects of stocking rates compared with wider landscape environmental changes. Given the increasing focus on pastoral development in northern Australia, any opportunity to incorporate the collection of data on biodiversity into grazing manipulation experiments should be taken for the assessment of the effects of land management on faunal species.

scholarly journals The moss flora of Bering Island (Commander Islands, North Pacific)

Arctoa ◽  
2012 ◽  
Vol 21 (1) ◽  
pp. 133-164 ◽  
Author(s):  
Vladimir E. Fedosov ◽  
Elena A. Ignatova ◽  
Michael S. Ignatov ◽  
Anatoly I. Maksimov ◽  
Valerij I. Zolotov
Keyword(s):  
North Pacific ◽  
Commander Islands ◽  
Bering Island

Regional to global correlation of Eocene–Oligocene boundary transition successions using biostratigraphic, geophysical and geochemical methods

2019 ◽  
Vol 157 (1) ◽  
pp. 80-100
Author(s):  
Brooks B. Ellwood ◽  
Lawrence Febo ◽  
Laurie Anderson ◽  
Rebecca T. Hackworth ◽  
Guy H. Means ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Central Italy ◽  
Geophysical Methods ◽  
Global Scale ◽  
Multiple Correlation ◽  
Southeastern Usa ◽  
Global Correlation ◽  
Extinction Event ◽  
Oxygen Stable Isotope ◽  
Stratotype Section

AbstractRegional to global high-resolution correlation and timing is critical when attempting to answer important geological questions, such as the greenhouse to icehouse transition that occurred during the Eocene–Oligocene boundary transition. Timing of these events on a global scale can only be answered using correlation among many sections, and multiple correlation proxies, including biostratigraphy, lithostratigraphy, geochemistry and geophysical methods. Here we present litho- and biostratigraphy for five successions located in the southeastern USA. To broaden the scope of correlation, we also employ carbon and oxygen stable isotope and magnetic susceptibility (χ) data to interpret these sections regionally, and correlate to the Global Boundary Stratotype Section and Point (GSSP) near Massignano in central Italy. Our results indicate that approaching the Eocene–Oligocene boundary, climate warmed slightly, but then δ18O data exhibit an abrupt c. +5 ‰ positive shift towards cooling that reached a maximum c. 1 m below the boundary at St Stephens Quarry, Alabama. This shift was accompanied by a c. −3 ‰ negative shift in δ13C interpreted to indicate environmental changes associated with the onset of the Eocene–Oligocene boundary planktonic foraminiferal extinction event. The observed cold pulse may be responsible for the final extinction of Hantkeninidae, used to define the beginning of the Rupelian Stage. Immediately preceding the boundary, Hantkeninidae species dropped significantly in abundance and size (pre-extinction dwarfing occurring before the final Eocene–Oligocene extinctions), and these changes may be the reason for inconsistencies in past Eocene–Oligocene boundary placement in the southeastern USA.

New taxa in Agrostis, Deschampsia, Hyalopoa and Poa (Poaceae) from the Russian Far East and East Siberia

2019 ◽  
pp. 14-24
Author(s):  
N. S. Probatova
Keyword(s):  
New Taxa ◽  
Russian Far East ◽  
Far East ◽  
East Siberia ◽  
Commander Islands ◽  
North West ◽  
Magadan Region ◽  
The Family ◽  
Bering Island ◽  
The Russian Far East

Six new taxa in the family Poaceae are described from the Russian Far East and from East Siberia: Deschampsia komandorensis Prob. (sect. Deschampsia) from Commander Islands (Bering Island, North-West Cape), Agrostis × avatschensis Prob. (A. kudoi Honda × A. mertensii Trin.) from Avachinskii Volcano in Kamchatka, Poa archarensis Prob. (sect. Stenopoa) (revealed chromosome number 2n = 28) from Amur Region and Yakutia, Poa × alexandrae Prob. (sect. Stenopoa) from Magadan Region, Hyalopoa amgunensis Prob. (H. aggr. lanatiflora) from Khabarovsk Territory (Amgun River basin), Poa turgensis Prob. (sect. Stenopoa) from Transbaikalia.

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