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Approximating home ranges of humpback and fin whales in Drake Passage and Antarctica

Advances in Polar Science 2020年第4期31卷 248-257页

作者： joséluis orgeira Facundo ALVAREZ Departamento Biología de los Predadores Tope Instituto Antártico Argentino.Buenos AiresArgentina Programa de pós-graduação em Ecologia e Conservação.Campus de Nova Xavantina.Universidade do Estado de Mato Grosso Brasil

Identifying home ranges—those areas traversed by individuals in their normal foraging,mating,and parenting activities—is an important aspect of cetacean study.Understanding these ranges facilitates identification of resource use and conservation.Fin and humpback whales occur in Antarctica during the austral summer,but information regarding their home ranges is limited.Using opportunistically collected whale sighting data from eight consecutive summer seasons spanning 2010–2017,we approximate the home ranges of humpback and fin whales around Drake Passage(DRA),West of Antarctic Peninsula(WAP),South Shetland Islands(SSI),an area northwest of the Weddell Sea(WED),and around the South Orkney Islands(SOI).Approximate home ranges are identified using Kernel Density Estimation(KDE).Most fin whales occurred north and northwest of the SOI,which suggests that waters near these islands support concentrations of this species.Most humpback whales were observed around the SSI,but unlike fin whales,their distributions were highly variable in other areas.KDE suggests spatial segregation in areas where both species exist such as SOI,SSI,and WPA.Partial redundancy analysis(pRDA)suggests that the distributions of these species are more affected by spatial variables(latitude,longitude)than by local scale variables such as sea surface temperature and depth.This study presents a visual approximation of the home ranges of fin and humpback whales,and identifies variation in the effects of space and environmental variables on the distributions of these whales at different spatial scales.

关键词： humpback whale fin whale home range Antarctica Drake Passasge

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Occurrence of seabirds and marine mammals in the pelagic zone of the Patagonian Sea and north of the South Orkney Islands

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Advances in Polar Science 2018年第1期29卷 25-33页

作者： josé luis orgeira Departamento Biología de los Predadores Tope Instituto Antártico Argentino

The Patagonian Sea is one of the most productive ecosystems in the Southern Hemisphere. Unlike other coastal regions, however, few studies exist on the top predators in its pelagic zone. In March 2017, a survey of seabirds and marine mammals was carried out on board the R/V Puerto Deseado in the Patagonian Sea, which extends from the South Atlantic Ocean to the north of the South Orkney Islands, Antarctica. Four of the five oceanographic regimes described in this region were studied, and 23 seabird species and five marine mammal species were recorded. Great shearwater Puffinus gravis, Antarctic prion Pachyptila desolata, and fin whale Balaenoptera physalus were the most abundant species. In the 2615 km traveled, two hotspots for top predators were found, coinciding with frontal zones: one in the shelf-break front and the other in the Southern Front of the Antarctic Circumpolar Current. The highest bird diversity and the greatest cetacean concentrations were recorded in the polar regime in the presence of low ice-field debris(5%). The results suggest that at the end of the austral summer, the distribution of top predators in this section of the South Atlantic Ocean is highly unequal. Some oceanic areas have a few species aggregations which contrast with the vast pelagic areas that have scarce species presence and activity. The hotspots were associated with high-productivity areas, but it is likely that they were also facilitated by the time of year(post-reproductive season), as most of the species were concentrated and had fed prior to their migrations.

关键词： Antarctica top predators marine megafauna

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Long-term study of at-sea distribution of seabirds and marine mammals in the Scotia Sea, Antarctica

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Advances in Polar Science 2015年第2期26卷 158-167页

作者： josé luis orgeira Mariela del Carmen Alderete Yohana Gisell Jiménez Juan Cruz González Departamento Biología de Predadores Tope Instituto Antártico ArgentinoC1064AAF Buenos AiresArgentina Facultad de Ciencias Naturales e Instituto Miguel Lillo Universidad Nacional de TucumánCP 4000 TucumánArgentina

The Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on the Antarctic marine ecosystem and relationships among top predators. This paper presents the results of at-sea monitoring of seabirds and cetaceans over five consecutive summer seasons （2010--2014） in the Scotia Sea, Antarctica. A total of 11 656 flying birds belonging to 24 species were recorded in 884 ten-minute counts. Six Procellariiformes species were abundant： Black-browed Albatross, Cape Petrel, Southern Fulmar, Antarctic Prion, Wilson＇s Storm-petrel, and Black-bellied Storm-petrel. Only three of these species accounted for 82% of the total abundance： Antarctic Prion （40%）, Southern Fulmar （22%）, and Cape Petrel （20%）. A total of 678 baleen whales belonging to five species were recorded along a sampling effort of 2 351 nautical miles： Humpback, Sei, Southern Right, Fin, and Minke whales, which had different abundances during the study. The Fin Whale had the highest mean encounter rate for the 5 years （0.29 whales per nautical mile）, followed by the Humpback Whale （0.09 whales per nautical mile）. Annual dissimilarity in abundance of both seabirds and cetaceans occurred in conjunction with changes in the sea surface temperature and ice cover, showing the dependence of top predators on environmental changes. The largest aggregations of all top predators （seabirds and cetaceans） were recorded in two regions, west and south of the South Orkney Islands, suggesting important prey availability （especially krill） in those areas.

关键词： seabirds cetaceans Scotia Sea Antarctica

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Extraterrestrial microspherules from Bajada del Diablo,Chubut,Argentina

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Geoscience Frontiers 2017年第1期8卷 137-149页

作者： M.J.orgeira L.N.Castro G.A.Goldmann C.B.Prezzi E.Sileo D.R.Vega C.Franzosi R.D.Acevedo O.Martinez J.Rabassa J.F.Ponce O.R.Tofalo Departamento de Ciencias Geologicas-lGEBA Facultaci de Ciencias Exactas y NaturalesOniversidad de Buenos AiresCiudad UniversitariaPabelldn 11C1428EHABuenos AiresArgentina Consejo Nacional de lnvestigaciones Cientificas y Tecnicas de Argentina CONICEE Argentina Departamento de lngenierfa Agrfcola y Uso de la Tierra Facultad de AgronomiaUniversidad de Buenos AiresAv.San Martin 4453CI417DSEBuenos AiresArgentina INQUIMAE Departamento de Qufmica Inorganica.Analitica y Quimica Fisica.Facultad de Ciencias Exactas y Naturales.Universidad de Buenos AiresPabellon IICiudad Universitaria.C1428EHABuenos Aires.Argentina Gerencia de lnvestigacion y Aplicaciones Comision Nacional de Energfa AtomicaUniversidad Nacional General San MartinBuenos AiresArgentina Centro Austral de lnvestigaciones Cientificas CADIC-ConicetUshuaiaArgentina Universidad Nacional de la Patagonia"San Juan Bosco"Sede Esquel ChubutArgentina Universidad Nacional de la Patagonia"San Juan Bosco"Sede Ushuaia UshuaiaArgentina

The Quaternary infilling of a circular structure located in Bajada del Diablo,Chubut Province,Argentina has been proposed as a crater strewn field in previous studies.Here we report the finding of about 65 microspherules collected in a trench excavated in the center of the structure.The majority of handpicked specimens are single,but some of them exhibit compound forms.The single specimens are spherical with a mean size of 137 nm,whereas the more complex samples show peduncles and drop shapes.Dendritic crystal growth is recognized in the internal structure of some broken microspherules.Preliminary chemical composition from the surface and center of microspherules was determined by energy dispersive spectrometry employing EDS.Quantitative EMPA and XRD analysis indicate that the microspherules are mainly composed of Fe and O with magnetite,Fe0with subordinate wiistite.Following consideration of possible anthropogenic and volcanic origins,these spherulites are ascribed to an extraterrestrial input.An accumulation rate of 47 microspherules per m2/yr is estimated for the studied sediments.This value is two orders of magnitude higher than the reference flux for cosmic dust estimated for the last 1 Ma in the Transantarctic Mountains.The microspherules might have been generated as a byproduct of asteroid entry in the atmosphere.

关键词： Extraterrestrial microspherules Chemistry Bajada del Diablo Chubut Patagonia-Argentina

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