scholarly journals Reproductive Biology and Embryonic Diapause as a Survival Strategy for the East Asian Endemic Eagle Ray Aetobatus narutobiei

2021 ◽  
Vol 8 ◽  
Author(s):  
Atsuko Yamaguchi ◽  
Keisuke Furumitsu ◽  
Jennifer Wyffels
Keyword(s):  
Life History ◽  
East Asian ◽  
Control Program ◽  
Survival Strategy ◽  
Embryonic Diapause ◽  
Predator Control ◽  
Disc Width ◽  
History Of ◽  
The Government ◽  
Reproductive Cycles

Batoids comprise five of the seven most threatened families of sharks and rays. The East Asian endemic Naru eagle ray Aetobatus narutobiei is a large bodied ray whose estuarine habitat overlaps with an economically valuable bivalve fishery. In response to decreased bivalve yields, the government initiated a predator control program and as a result, Naru eagle rays have faced intense and targeted fishing pressure during the last two decades. The long-term impacts of the predator control program on the population of rays and bivalves and their balance in the ecosystem are unknown because the life history of the Naru eagle ray has not been characterized. To begin to fill these critical knowledge gaps, the reproductive life history of the Naru eagle was described. Females mature at a larger size than males and require nearly twice as many years to reach maturity (DW50, 952.0 mm vs. 764.2 mm; Age50, 6.0 years vs. 3.5 years). Both males and females reproduce annually and their reproductive cycles are synchronized and seasonal. Females have a single ovary and paired uteri, are viviparous, and reproduce via matrotrophic histotrophy. Mating occurs in August and September and gestation lasts approximately 12 months including a 9.5-month diapause that begins soon after mating and ends in June of the following year, leaving 2.5 months for embryos to complete development. Fecundity ranged from 1 to 7 embryos per brood (n = 158, mean ± SD = 3.36 ± 1.26) and was positively correlated with female disc width (linear regression; F = 105.73, d.f. = 151, P < 0.05). Naru eagle rays are vulnerable to overfishing because of their low fecundity, long reproductive cycle and long time to reach sexual maturity. Obligate embryonic diapause during overwintering and seasonal migrations is a survival strategy that benefits the adults and neonates. This research is a valuable resource to help guide science-based management, conservation and protection of the endemic Asian A. narutobiei and its nursery areas.

Reproductive life history of snakes in temperate regions: what are the differences between oviparous and viviparous species?

2019 ◽  
Vol 40 (3) ◽  
pp. 291-303
Author(s):  
Gisela Paola Bellini ◽  
Vanesa Arzamendia ◽  
Alejandro Raúl Giraudo
Keyword(s):  
Life History ◽  
Hydrological Cycle ◽  
Reproductive Potential ◽  
Reproductive Traits ◽  
Reproductive Mode ◽  
Raw Material ◽  
Genetic Characteristics ◽  
Reproductive Life ◽  
History Of ◽  
Reproductive Cycles

Abstract Studying life history (LH) allows a broader understanding of organisms and populations’ responses to their environments. Snakes display an immense diversity in terms of reproductive traits, which is reflected in LH traits. The aim of this study is to compare reproductive biology and morphological variables in viviparous and oviparous snakes of a temperate South American community. We studied nearly 1000 specimens of eight oviparous and seven viviparous species pertaining to the four taxonomic families that inhabit the Paraná basin floodplain. Dimorphic variables did not show a different tendency between oviparous and viviparous species. Our results showed that the reproductive mode determined some reproductive traits of a snake’s LH, such as reproductive frequency and reproductive potential. Oviparous snakes reproduce annually, while viviparous snakes reproduce biannually or multi-annually. All species showed seasonal reproductive cycles and no correlation between clutch size (fecundity) and maternal body size. The reproductive strategy of both oviparous and viviparous species of the Paraná River floodplain was to adjust their reproductive cycles to both hydrological cycle of the river and temperature regime. The reproductive traits under study are suggested to have been influenced by environmental factors as well as by genetic characteristics. The studied assemblage is the result of an admixture of evolutionarily distinct clades, each contributing a set of species with different reproductive traits. Although we do not ignore this fact, we emphasize the importance of studying reproductive LH as raw material for an integrative analysis.

Reproductive Activity of the Interstitial Copepods of a Sandy Beach

1972 ◽  
Vol 52 (3) ◽  
pp. 507-524 ◽  
Author(s):  
Roger P. Harris
Keyword(s):  
Life History ◽  
Field Study ◽  
Sandy Beach ◽  
Reproductive Activity ◽  
Harpacticoid Copepods ◽  
History Of ◽  
Reproductive Cycles

Information on the reproduction of interstitial harpacticoid copepods is mainly restricted to occasional references in the taxonomic literature to the presence of ovigerous females in collections. C. G. Rao (1967) provides the only account of the life-history of an exclusively interstitial species. The only detailed field study of seasonal reproductive cycles of harpacticoid copepods are of two species of Platychelipus Brady on a mudflat (Barnett, 1970), and of a sand-dwelling benthic copepod, Asellopsis intermedia (T. Scott) (Lasker, Wells & Mclntyre, 1970).

scholarly journals On the Variation, Races and Migrations of the Mackerel (Scomber scomber)

1898 ◽  
Vol 5 (3) ◽  
pp. 235-295 ◽  
Author(s):  
Walter Garstang
Keyword(s):  
Life History ◽  
Scientific Investigation ◽  
Large Fish ◽  
The South ◽  
History Of ◽  
The Government

The present investigation was undertaken at the invitation of H.M. Treasury, in consequence of an application to the government from H.M. Inspectors of Irish Fisheries for a scientific investigation into the life-history of the mackerel. The problem to the solution of which the inspectors attached particular importance was the relation to one another of the spring and autumn schools of mackerel which regularly visit the Irish coasts. In the spring a multitude of large fish approach the south and west coasts of Ireland to breed. In the autumn schools of immature, but usually well-grown, mackerel come around the island. According to one of the inspectors, the Rev. W. S. Green, there is a sharply defined interval between the two visitations of fish.

scholarly journals Emergence of cutaneous leishmaniasis in Nepal

2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Kishor Pandey ◽  
Anup Bastola ◽  
Gong Haiyan ◽  
Uttam Raj Pyakurel ◽  
Basu Dev Pandey ◽  
...  
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Health Information System ◽  
Control Program ◽  
The Body ◽  
District Health ◽  
Laboratory Findings ◽  
Facial Region ◽  
History Of ◽  
System 2 ◽  
The Government

Abstract Background Cutaneous leishmaniasis (CL) is endemic in 70 countries worldwide. Nepal is considered non-endemic for CL and hence the control program is targeted to visceral leishmaniasis (VL) only. Here, we report the emergence of CL cases in different parts of Nepal. Methods We analyzed the CL and VL cases reported to Epidemiology and Diseases Control Division (EDCD), Ministry of Health and Population, Nepal through District Health Information System 2 (DHIS-2) and Early Warning and Reporting System (EWRS) during the past 4 years (2016–2019). Any laboratory-confirmed case was included in the study. Demographic and clinical details of each patient were transcribed into Excel sheets, verified with the case report forms and analyzed. Results VL has been reported in Nepal since 1980, but CL was reported very recently. From 2016 to 2019, 42 CL cases were reported from 26 different hospitals to EDCD which had been diagnosed on the basis of clinical presentation, and laboratory findings (demonstration of amastigotes in Giemsa-stained smears and rK39 test results). Majority of the patients (31.0%, 13/42) visited to the hospital within 1–6 months of onset of lesions. Facial region (38.1%, 16/42) was the common place where lesions were found ompared to other exposed parts of the body. CL was successfully treated with miltefosine for 28 days. The majority of CL patients did not have history of travel outside the endemic areas and there was no report of sandfly from these areas. Conclusion These evidences highlight that the Government of Nepal need to pay more efforts on CL and include it in differential diagnosis by clinicians, and plan for an active surveillance when the country is targeting leishmaniasis elimination by the year 2025 with the decreasing number of VL cases.

Monetary authority independence and stability in medieval Korea: the Koryŏ monetary system through four centuries of East Asian transformations, 918-1392

2014 ◽  
Vol 21 (3) ◽  
pp. 259-280 ◽  
Author(s):  
Jun Seong Ho
Keyword(s):  
Rural Economy ◽  
Intrinsic Value ◽  
East Asian ◽  
Second Phase ◽  
Paper Money ◽  
Monetary System ◽  
Regional Dynamics ◽  
History Of ◽  
The Government ◽  
Medieval Korea

This article surveys the monetary history of Koryŏ from the eleventh to the thirteenth century. During the first century of the dynasty, Koryŏ was at war with the Liao, prohibited trade with the enemy and pursued a policy of protecting its metal reserves. During the ban on metallic coins, rice and cloth served as commodity monies, ensuring price stability in a phase of sustained growth of the rural economy. A second phase began after the victory over the Liao in 1018. Backed by military strength, the government issued iron, bronze and silver currencies to facilitate international trade. The Koryŏ ‘silver vase’ currency, which circulated for three centuries, partly bridges the ‘black hole’ in East Asian monetary history from the Late Tang to the Ming period. The intrinsic value of the metallic currencies in conjunction with state issuance provided monetary stability. In turn monetary instability characterised the late Koryŏ, when the country came under the influence of the Mongol Yuan. The destabilising effect brought about by the introduction of Yuan paper money demonetarised the economy. By framing monetary history within a wider perspective of struggles for sovereignty and political hegemony, the article allows a better understanding of domestic and regional dynamics in East Asia.

Experimental life history of Echinostoma cinetorchis

1990 ◽  
Vol 28 (1) ◽  
pp. 39 ◽  
Author(s):  
S H Lee ◽  
J Y Chai ◽  
S T Hong ◽  
W M Sohn
Keyword(s):  
Life History ◽  
History Of

Making It Count

2020 ◽  
Author(s):  
Arunabh Ghosh
Keyword(s):  
Cold War ◽  
Statistical Data ◽  
New Technology ◽  
Political Leaders ◽  
Republic Of China ◽  
Great Leap Forward ◽  
History Of ◽  
History Of Statistics ◽  
The Government ◽  
The Great Leap Forward

In 1949, at the end of a long period of wars, one of the biggest challenges facing leaders of the new People's Republic of China was how much they did not know. The government of one of the world's largest nations was committed to fundamentally reengineering its society and economy via socialist planning while having almost no reliable statistical data about their own country. This book is the history of efforts to resolve this “crisis in counting.” The book explores the choices made by political leaders, statisticians, academics, statistical workers, and even literary figures in attempts to know the nation through numbers. It shows that early reliance on Soviet-inspired methods of exhaustive enumeration became increasingly untenable in China by the mid-1950s. Unprecedented and unexpected exchanges with Indian statisticians followed, as the Chinese sought to learn about the then-exciting new technology of random sampling. These developments were overtaken by the tumult of the Great Leap Forward (1958–1961), when probabilistic and exhaustive methods were rejected and statistics was refashioned into an ethnographic enterprise. By acknowledging Soviet and Indian influences, the book not only revises existing models of Cold War science but also globalizes wider developments in the history of statistics and data. Anchored in debates about statistics and its relationship to state building, the book offers fresh perspectives on China's transition to socialism.

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