共查询到20条相似文献,搜索用时 15 毫秒
1.
During the summers of 2006–2008 extensive ship- and aircraft-based surveys were carried out in the Greenland Sea off Northeast
Greenland. This resulted in 13 observations in a total of 17 bowhead whales Balaena mysticetus of the very small and critically endangered Spitsbergen stock. Although the observed number of whales seems high compared
to previous surveys it is not possible to infer a population increase, due to the high observation effort in recent years.
However, the observation of a young individual is encouraging as it seems to be the first observed young whale in this stock
for decades. 相似文献
2.
The age of bowhead whales captured by Native Alaskan hunters in the Bering, Chukchi and Beaufort Seas has been estimated via
chemical analyses of the eye lenses, and other techniques. The racemization-age estimates indicate that bowhead whales (Balaena mysticetus) have a lifespan of more than a century. Stone and ivory weapon fragments recovered from bowhead whales hunted in Wainwright
and Barrow (Alaska) in 1981, 1992, 1993 and 1997, provided rough but independent assessments of the whales’ longevity; however,
their date of manufacture was unknown. Adding further confirmation of these age estimates, this note describes bomb lance
fragments recovered recently (2007) and about 30 years ago (1980) from bowhead whales harvested by Eskimo hunters that were
“dateable” and likely manufactured between 1879 and 1885. 相似文献
3.
N. R. Reinhart S. H. Ferguson W. R. Koski J. W. Higdon B. LeBlanc O. Tervo P. D. Jepson 《Polar Biology》2013,36(8):1133-1146
Killer whales (Orcinus orca) are increasing in occurrence and residence time in the eastern Canadian Arctic (ECA) in part due to a decrease in sea ice associated with global climate change. Killer whales prey on bowhead whales (Balaena mysticetus) of the Eastern Canada-West Greenland (EC-WG) population, but their patterns of predation pressure and effect on the EC-WG population’s ability to recover from historical whaling remain unknown. We analyzed photographs of individual bowhead whale flukes from five regions within the EC-WG population’s geographic range (Cumberland Sound, Foxe Basin, Isabella Bay, Repulse Bay and Disko Bay), taken during 1986 and from 2007 to 2012, to estimate the occurrence of rake marks (parallel scars caused by killer whale teeth). Of 598 identified whales, 10.2 % bore rake marks from killer whales. A higher occurrence of rake marks was found in Repulse and Disko Bays, where primarily adult bowhead whales occur seasonally, than in Foxe Basin, where juveniles and females with calves occur. Older bowheads, which have had greater exposure time to killer whales due to their age, had higher occurrences of rake marks than juveniles and calves, which may indicate that younger whales do not survive killer whale attacks. A high proportion of adult females also had rake marks, perhaps due to protecting their calves from killer whale predation. In order to quantify the effect of killer whales on EC-WG population recovery, further research is needed on the relationship between the occurrence of rake marks and bowhead adult, calf, and juvenile mortality in the ECA, as well as more information about Arctic killer whale ecology. 相似文献
4.
Saxifraga caespitose is a taxonomically difficult and poorly studied circumpolar arctic–alpine species. Two different phenotypes with distinct
growth habits were collected at two shared localities in Spitsbergen. The natural genetic variation of both phenotypes was
tested by AFLPs in order to investigate whether the differences at the phenothypical level are reflected at the genetic level.
Low level of molecular variability between “tall” and “short” plants may suggest that the morphological variation could be
due to phenotypic plasticity rather than genetic background. 相似文献
5.
In April 2006, a dedicated survey of bowhead whales (Balaena mysticetus) was conducted on the former whaling ground in West Greenland to determine the current wintering population abundance. This effort included a double platform aerial survey design, satellite tracking of the movements of nine whales, and estimation of high-resolution surface time from 14 whales instrumented with time-depth recorders. Bowhead whales were estimated to spend an average of 24% (cv=0.03) of the time at or above 2m depth, the maximum depth at which they can be seen on the trackline. This resulted in a fully corrected abundance estimate of 1229 (95% CI: 495-2939) bowhead whales when the availability factor was applied and sightings missed by observers were corrected. This surprisingly large population estimate is puzzling given that the change in abundance cannot be explained by a recent or rapid growth in population size. One possible explanation is that the population, which demonstrates high age and sex segregation, has recently attained a certain threshold size elsewhere, and a higher abundance of mature females appears on the winter and spring feeding ground in West Greenland. This in combination with the latest severe reduction in sea ice facilitating access to coastal areas might explain the surprising increase in bowhead whale abundance in West Greenland. 相似文献
6.
The trachymedusa Ptychogastria polaris Allman, 1878 has been identified in seabed photographs from high-Arctic shelves and upper continental slopes off Northeast
Greenland and in the northern Barents Sea. It was found to be a common epifaunal element, being present at 34 of 57 stations
in 40- to 495-m depth and at 7 of 11 stations in 70- to 330-m depth, respectively. All specimens recorded in the photographs
either sat directly at, or hovered very closely (≤ about 1 cm) over, the sea bed, indicating a primarily epibenthic life style
of this hydrozoan species. The small-scale (i.e. within-station) distribution of medusae was rather patchy, with frequencies
along photographic transects – consisting of 35–73 pictures distributed over seabed strips of 150- to 300-m length – varying
from 1 to 58% off Northeast Greenland and from 1 to 34% in the Barents Sea. Absolute maximum density was 6 ind m−2, and station mean abundances ranged from 0.01 to 0.91 ind m−2 and from 0.01 to 0.52 ind m−2, respectively. Values tended to decrease with water depth, albeit significantly only off Northeast Greenland. Otherwise,
no clear relationships to environmental conditions, such as geomorphology or near-bottom water hydrography, were detected.
Circumstantial evidence suggests that seabed granulometry and potential food supply are important distribution determinants.
However, further investigations are required to identify more stringently the key factors controlling the distribution of
P. polaris.
Received: 8 September 1997 / Accepted: 12 September 1997 相似文献
7.
Little is known about the biology and feeding ecology of Arctogadus glacialis (Peters, 1874), an endemic gadid fish species occurring circumpolarly in both ice-free and ice-covered Arctic seas. In this
study we analysed specimens sampled from bottom trawl and Agassiz trawl catches conducted at eight stations in water depths
from 115 to 490 m in the Northeast Water Polynya off Greenland in August 1990. Size composition and sex ratios were assessed
for 585 fish with standard lengths ranging from 7.8 to 34.5 cm. Median fish sizes at the stations ranged between 8.6 and 18.8 cm.
Quantitative stomach content analyses of a subsample of 175 specimens revealed that in the Northeast Water A. glacialis fed almost exclusively on pelagic prey. Truly benthic organisms were not found in the stomachs, and sympagic species were
rarely recorded. Overall, calanoid copepods were the major prey in terms of numbers. However, stomach contents varied considerably
between fish size groups. In terms of prey biomass, copepods dominated the diet of small fish (<12 cm), primarily occurring
at shallow stations (115–250 m), whereas amphipods and mysids were relatively more important for larger fish (>16 cm), which
dominated the catches at deep stations (360–480 m). The broad variety of diet composition indicated an opportunistic pelagic
feeding pattern.
Received: 6 November 1997 / Accepted: 11 May 1998 相似文献
8.
The stomach contents of four bowhead whales (Balaena mysticetus) harvested between 1994 and 2008 from the Canadian Arctic were examined to assess diet composition. Three samples were collected
from bowhead whales of the Eastern Canada–West Greenland (EC–WG) population and represent, according to our knowledge, the
first diet analysis from this bowhead whale stock. We also examined the stomach content of one bowhead whale from the Bering-Chukchi-Beaufort
(BCB) population hunted in 1996. All four whales had food in their stomachs and their diet varied from exclusively pelagic
(BCB whale), with Limnocalanus macrurus being the main prey, to epibenthic and benthic (EC–WG) with Mysis oculata playing an important role. These results indicate broad foraging spectrum of the bowhead whales and add to a basic knowledge
of their diet. 相似文献
9.
Genetic variation in Holocene bowhead whales from Svalbard 总被引:2,自引:1,他引:1
Bowhead whales (Balaena mysticetus) are distributed in the Arctic in five putative stocks. All stocks have been heavily depleted due to centuries of exploitation. In the present study, nucleotide sequence variation of the mitochondrial control region was determined from bone remains of 99 bowhead whales. The bones, 14C dated from recent to more than 50,000 bp, were collected on Svalbard (Spitsbergen) and are expected to relate to ancestors of the today nearly extinct Spitsbergen stock. Fifty-eight haplotypes were found, a few being frequent but many only found in one individual. The most abundant haplotypes of the Spitsbergen stock are the same as those most abundant in the extant Bering-Chukchi-Beaufort (BCB) Seas stock of bowhead whales. Although F(ST) indicates a slight but statistically significant genetic differentiation between the Spitsbergen and the BCB stocks this was not considered informative due to the very high levels of genetic diversity of mitochondrial DNA haplotypes in both bowhead whale stocks. Other measures such as K(ST) also indicated very low genetic differentiation between the two populations. Nucleotide diversity and haplotype diversity showed only minor differences between the Spitsbergen and BCB stocks. The data suggest that the historic Spitsbergen stock--before the severe bottleneck caused by whaling--did not have substantially more genetic variation than the extant BCB stock. The similar haplotypes of the Holocene Svalbard samples and the current BCB stock indicate significant migration between these two stocks and question the current designation of five distinct stocks of bowhead whales in the Arctic. 相似文献
10.
We demonstrated the new target for lodging resistance in rice (Oryza sativa L.) by the analysis of physiological function of a locus for lodging resistance in a typhoon (lrt5) with the near isogenic line under rice “Koshihikari” genetic background (tentatively named S1). The higher lodging resistance
of S1 was observed during a typhoon in September 2004 (28 days after heading), when most other plants in “Koshihikari” became
lodged. Visual observations showed that bending of the upper stems triggered lodging during the typhoon; the upper stem of
“Koshihikari” buckled completely, whereas that of S1 remained straight. In addition to the strong rain and winds during the
typhoon, the weight of the buckled upper plant parts increased the pressure on adjacent plants and caused a domino effect
in “Koshihikari”. Young’s modulus, an indicator of the rigidity of the culm, was significantly higher in S1 than in “Koshihikari”.
In the upper culm, the starch content in S1 was 4.8 times the value in “Koshihikari”, and senescence was delayed in the upper
leaves of S1. These results suggest that the rigidity of the upper culm by the higher starch content (as a result of delayed
senescence in the upper leaves) may be responsible for the higher lodging resistance during a typhoon in rice.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
Hurtado P 《Bulletin of mathematical biology》2008,70(8):2264-2282
Since its introduction into eastern North America in the 1940s, the eastern population of house finches (Carpodacus mexicanus) has become partially migratory, unlike its nonmigratory source population in southern California (Able and Belthoff in Proc.
R. Soc. Lond. 265 (1410), 2063–2071, 1998; Belthoff and Gauthreaux in Condor 93, 374–382, 1991). The infectious disease mycoplasmal conjunctivitis (pathogen Mycoplasma gallisepticum or “MG”), which has been monitored in the house finch population since its appearance around 1993 (Dhondt et al. in J. Wild.
Dis. 34 (2), 265–280, 1998), may induce higher mortality rates among populations in more northerly latitudes relative to more southerly populations.
Here, we investigate the potential impact of this differential disease mortality on the migratory structure of the eastern
house finch population using an epidemic modeling approach. Analytical and computational results suggest the ongoing MG epidemic
in the eastern house finch could lead to increases in the percentage of and the total number of migrating individuals in a
population despite overall population declines, assuming relatively high winter mortality rates in the north eastern part
of their range. These results also suggest that empirical evidence of such a change in migratory structure would be most noticeable
in northerly inland populations that showed significant declines following the initial outbreak of MG in the east. 相似文献
12.
Zooplankton were quantitatively investigated in sediment trap samples deployed in the Greenland Sea at three locations (72°00.7'N,
7°02.5'W, 72°23.0'N, 7°42.7'W and 72°22.9'N, 7°42.7'W). Overall samples covered a period of three annual cycles (July 1989
to July 1992). The investigation of zooplankton, consisting almost exclusively of Crustacea (> 99%), shows that the majority
of the species must be regarded as “swimmers”, which actively invaded the traps. Crustacea were composed of 45 species, mainly
Copepoda, Amphipoda and Ostracoda. Each depth level showed a characteristic species composition. Diversity decreased with
depth. The samples were dominted by Copepoda in terms of abundance and by Amphipoda with respect to biomass. The seasonal
occurrence of Crustacea showed a maximum during winter and a minimum during summer. Carnivores were regularly found in the
collected material, indicating that they had been actively attracted by the organic matter emanating from the traps. Omnivores
showed a distinct seasonal occurrence. During winter, when primary production is low, omnivores change to a predatory way
of life and they were consequently also found in increasing numbers. Herbivores were always rare. Due to the high number of
“swimmers” found in winter, when particle flux is at its minimum, particle flux measurements may be severly biased at this
time of the year.
Received: 24 January 1996/Accepted: 28 June 1996 相似文献
13.
R. Weigmann-Haass 《Helgoland Marine Research》1997,51(1):69-82
The horizontal and vertical distribution and the abundance of ostracods, hyperiids (amphipods) and euphausiids in the Greenland
Sea along a transect parallel 74°45′N (from 15°45′E to 08°30′W) are described. The samples were taken by RV “Meteor” in late
autumn of 1988. 8 species of the above named groups have been recorded in two different water masses which were touched by
the transect. 5 stations were situated in the realm of the Atlantic waters of the Spitsbergen Current. HereDiscoconchoecia elegans, Meganyctiphanes norvegica, andThemisto compressa are indicators for the southern Atlantic water. 6 stations belong to the Arctic area dominated by Arctic Surface Water, whereBoroecia borealis, Themisto abyssorum, Thysanoessa longicaudata, andThysanoessa inermis are quite abundant as borealsubarctic species, whereasThemisto libellula is a true species of pure Arctic water.
Mitarbeiterin der Taxonomischen Arbeitsgruppe an der Biologischen Anstalt Helgoland 相似文献
Mitarbeiterin der Taxonomischen Arbeitsgruppe an der Biologischen Anstalt Helgoland 相似文献
14.
Yukio Takahata 《Primates; journal of primatology》1982,23(1):1-23
Some dyads of Japanese monkey adult males and females show remarkable spatial proximity and frequent exchanges of social behaviors.
It is suggested that some kind of “affinity” exists between them. Females obtain much unilateral benefit from “proximity effects”;
even lowranking females can dominate high-ranking females as long as they stay nearby their “affinitive” males. Males acquire
female followers in return. Mating relations and female mother-daughter relations play important roles in forming new “affinitive
relations.” Once monkeys have formed “affinitive relations,” however, they seldom mate with each other, as if they were kin-related.
Therefore, the acquisition of female followers appears inconsistent with a male's strategy for reproducing many genes in the
next generation.
This study was financed partly by the Cooperative Research Fund of the Primate Research Institute, Kyoto University. The outline
of this paper has already been published inTakahata (1980b). 相似文献
15.
?ystein Wiig Mads Peter Heide-J?rgensen Kristin L. Laidre Eva Garde Randall R. Reeves 《Polar Biology》2012,35(1):63-71
We analyzed variation in nine non-metric and eight metric variables in the skulls of 132 narwhals (Monodon monoceros) from five localities in Greenland (Inglefield Bredning, Melville Bay, Uummannaq, Disko Bay, and Scoresby Sound) and one
in the eastern Canadian Arctic (Eclipse Sound). Metric variables were used to compare the combined Disko Bay and Uummannaq
samples with the samples from Inglefield Bredning and Scoresby Sound using three different multivariate techniques for each
sex. None of the results were significant. Seven of the non-metric variables were independent of age and sex and were used
in comparing samples from the six localities. No differences were found among the four localities in West Greenland, but differences
were found in two of the non-metric variables between the combined West Greenland sample and the one from Scoresby Sound.
A major shortcoming of the analysis based on metric data was the small sample size from several of the areas, which resulted
in low statistical power. Genetic as well as environmental factors could explain the differences detected here between narwhals
living along the west and the east coasts of Greenland. 相似文献
16.
The origin of Arctic terrestrial and freshwater tardigrades 总被引:2,自引:0,他引:2
The tardigrade faunas of six Arctic sites (Canadian Axel Heiberg I., east and west coasts of Greenland, Iceland, Svalbard,
Novaya Zemlya and the Russian Taimyr Peninsula) form, with those of northern North America, a coherent “Nearctic-Arctic” biogeographic
cluster. This cluster is distinct from that of “Northern and Alpine Europe”. Few, if any, Arctic tardigrades survived Pleistocene
glaciation in situ amongst ice-free refugia. Similarly, few/none moved south ahead of the advancing ice-cap into the deglaciated
Palaearctic and Nearctic and subsequently returned north during the Holocene deglaciation. It is more probable that most Arctic
tardigrades are derived from wind-blown Nearctic propagules that colonized the region during the Holocene.
Received: 2 July 1997 / Accepted: 3 October 1997 相似文献
17.
Barbara Forrest 《Evolution》2010,3(2):170-182
The intelligent design (ID) creationist movement is now a quarter of a century old. ID proponents at the Discovery Institute,
headquartered in Seattle, WA, USA, insist that ID is not creationism. However, it is the direct descendant of the creation
science movement that began in the 1960s and continued until the definitive ruling against creationism by the US Supreme Court
in Edwards v. Aguillard
1987, which struck down laws that required balancing the teaching of evolution with creationism in public schools. Already anticipating
in the early 1980s that Arkansas and Louisiana “balanced treatment” laws would be declared unconstitutional, a group of creationists
led by Charles Thaxton began laying the groundwork for what is now the ID movement. After Edwards, Thaxton and his associates promoted ID aggressively until it, too, was declared unconstitutional by a federal judge in Kitzmiller et al. v. Dover Area School District 2005. Subsequently, in 2008, the Discovery Institute began its multistate promotion of model “academic freedom” legislation
that bears striking parallels to the 1980s balanced treatment laws. Because of Kitzmiller, ID proponents have written their model legislation in code language in an effort to avoid another court challenge. Yet despite
attempting to evade the legal constraints imposed by Edwards, they are merely recycling earlier creationist tactics that date back to the late 1970s and early 1980s. The tactics that
ID creationists now use—promoting legislation, publishing “educational” materials, establishing a “research” institute, and
sanitizing their terminology—are the recycled tactics of their creation science predecessors. 相似文献
18.
Shigeru M. Shirai Ryoji Kuranaga Hideki Sugiyama Masahito Higuchi 《Ichthyological Research》2006,53(4):357-368
We analyzed patterns of genetic diversity in the sailfin sandfish (Arctoscopus japonicus), focusing on population subdivisions within the Sea of Japan. We observed 270 specimens from nine sampling sites in 1999–2000,
i.e., seven sites in the Sea of Japan and two sites from the Pacific coast of Hokkaido. An additional site (30 specimens)
was sampled from eastern Korea in the spawning season of 2004 for comparison. Forty haplotypes, compiled into three haplogroups
(A–C), were detected based on the comparison of a 400-bp sequence of the anterior part of the mitochondrial control region.
In accordance with previous hypotheses from morphological and molecular analyses, genetic discontinuity between the Sea of
Japan and the Pacific coast of Hokkaido was conspicuous. Within the Sea of Japan, eight sampling sites were not genetically
uniform, and most of the variations among sites were detected between eastern Korea [the “eastern Korea” (EK) population:
distributed from the Korean Peninsula to Mishima, Yamaguchi Prefecture] and the other sites along the coast of Japan [the
“western Japan” (WJ) population: from Oki Islands to western Hokkaido] (Φ
CT
= 0.096, P = 0.0183). The WJ population, having lower genetic variability, showed significant departure from neutrality, indicating
influences through a recent population expansion. The period of the expansion can be estimated to have begun on the order
of 104 years ago. We consider that the present Japan Sea populations have been formed through the invasion of a small ancestral
stock to the Sea of Japan and its population expansion during the last glacial period or later. On the other hand, we failed
to detect distinct evidence of a population expansion in the EK population. Haplogroup C, detected in a high frequency in
this population, was estimated to have mixed with haplogroup A after rapid differentiations of the latter. Therefore, the
EK population, strongly influenced by such a mixture, might possess haplogroup C in a higher frequency and a different haplotype
composition from the WJ population. 相似文献
19.
E. V. Balushkina 《Inland Water Biology》2009,2(4):355-363
In the years 1994–2005, the values of the integrated index IP’ at some stations of the Neva Bay changed from 38.1 to 81.9%, water quality changed from class 3 to class 5, and the states
of some areas of the ecosystem that were evaluated as “tense” went to “catastrophic.” The integrated mean assessment of water
quality according to the IP’ index over the entire Neva Bay throughout 12 years (1994–2005) remained relatively stable, waters were assessed as “polluted”
(fourth class), and the state of the ecosystem was considered “critical.” The state of the eastern part of the Gulf of Finland
in 1994–2005 was less favorable. The species diversity of zoobenthos in the resort zone of the eastern part of the Gulf of
Finland is considerably lower than in the Neva Bay. Waters of the resort zone of the eastern part of the Gulf of Finland in
1994–2005 were assessed as one class lower than in the Neva Bay, i.e., as “polluted-dirty” (fourth-fifth class), and the state
of the ecosystem was assessed as being in a “crisis.” In the resort zone, there was a decline in species diversity and abundance
and biomass of benthic animals; i.e., all characteristics of the degradation of benthic animal communities were observed. 相似文献
20.
We studied the medicinal plants used by the Popoluca of the Sierra de Santa Marta (eastern Mexico). Using Moerman’s method of regression analysis we determined which ethnomedically used taxa are over-represented in the Popolucan pharmacopoeia (e.g., Asteraceae) and which are underrepresented (e.g., Orchidaceae). Moerman et al. (1999) found high correlation between the holarctic pharmacopoeias and assumed that apart from the relatedness of the northern floras a “global pattern of human knowledge“ may account for this finding. Although the Popoluca dwell in a habitat dominated by a neotropical flora but intermixed with important holarctic elements, they include considerably fewer neotropical taxa in their pharmacopoeia as one would expect if the historical transmitted knowledge were influencing their selection. This finding confirms the theory stated by Moerman et al. However, the Popoluca include some neotropical taxa in their pharmacopoeia and thus a moderate correlation exists between the Popolucan pharmacopoeia and the neotropical pharmacopoeia analysed by Moerman et al. We therefore conclude that apart from historically transmitted knowledge about specific taxa the “global pattern of human knowledge” addressed by Moerman et al. is largely based on “common selection criteria.” 相似文献