The life history of Branchinecta mackini Dexter (Crustacea: Anostraca) in an argillotrophic lake of Alberta

1977 ◽  
Vol 55 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Graham R. Daborn

The life history of B. mackini was studied in a large argillotrophic lake during 1970–1972. Hatching began immediately after spring thaw and was terminated by rising salinity 10 days to 2 weeks later. Growth rates reached maxima of 1 mm/day at 4 weeks of age and then declined as mean size approached 22–23 mm at 7–8 weeks. Clutch sizes varied as a function of female length. Maximum biomass of 580 mg dry weight/m2 (2700 cal/m2) was reached in late May, of which 3.9% per day was consumed by B. gigas. Source of the energy is presumed to be a bacteria – organic matter complex associated with suspended particles. Life cycle details are compared with other fairy shrimp species and the role of B. mackini in the community is discussed.

2008 ◽  
Vol 19 (4) ◽  
pp. 228-231 ◽  
Author(s):  
Stefano Fenoglio ◽  
Tiziano Bo ◽  
Jesus López-Rodríguez ◽  
José Tierno de Figueroa

Some aspects of the life history of a population of Brachyptera risi were investigated in a North Apennine stream and compared with previously studied European populations. In our study area, this species showed a univoltine fast seasonal life cycle. Nymphs were present from January to the beginning of May, probably spending the rest of the year mainly in egg diapause. Fine particulate organic matter was the principal component of the diet, while diatoms and other algae were also found in the guts. This finding suggests the existence of greater trophic plasticity of the species. Individuals of this population act as gatherer-collectors but not as scrapers as usually pointed out for other European populations. We also detected considerable amounts of animal matter in the gut contents. The density of B. risi nymphs in the study area was very variable during the study period, ranging from 0 to 2,348 ind/m2.


2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Esethu Monakali

This article offers an analysis of the identity work of a black transgender woman through life history research. Identity work pertains to the ongoing effort of authoring oneself and positions the individual as the agent; not a passive recipient of identity scripts. The findings draw from three life history interviews. Using thematic analysis, the following themes emerge: institutionalisation of gender norms; gender and sexuality unintelligibility; transitioning and passing; and lastly, gender expression and public spaces. The discussion follows from a poststructuralist conception of identity, which frames identity as fluid and as being continually established. The study contends that identity work is a complex and fragmented process, which is shaped by other social identities. To that end, the study also acknowledges the role of collective agency in shaping gender identity.


Author(s):  
J. B. Brown-Gilpin

The wide variety of reproductive patterns and behaviour in the many species of Nereidae already studied clearly justifies further research. But the life history of Nereis fucata (Savigny) is not only of interest from the comparative point of view. Its commensal habit (it occurs within shells occupied by hermit crabs) immediately gives it a special importance. This alone warrants a detailed study, particularly as no commensal polychaete has yet been reared through to metamorphosis and settlement on its host (Davenport, 1955; Davenport & Hickok, 1957). The numerous interesting problems which arise, and the experimental methods needed to study them, are, however, beyond the range of a paper on nereid development. It is therefore proposed to confine the present account to the reproduction and development up to the time when the larvae settle on the bottom. The complete life cycle, the mechanism of host-adoption, and related topics, will be reported in later papers.


Hydrobiologia ◽  
2006 ◽  
Vol 559 (1) ◽  
pp. 183-192 ◽  
Author(s):  
H. V. S. Azevedo-Pereira ◽  
M. A. S. Graça ◽  
J. M. González

1953 ◽  
Vol 31 (4) ◽  
pp. 351-373 ◽  
Author(s):  
Liang-Yu Wu

A cause of swimmer's itch in the lower Ottawa River is Trichobilharzia cameroni sp. nov. Its life cycle has been completed experimentally in laboratory-bred snails and in canaries and ducks, and the various stages are described. The eggs are spindle-shaped. The sporocysts are colorless and tubular. Mother sporocysts become mature in about a week. The younger daughter sporocyst is provided with spines on the anterior end and becomes mature in about three weeks. The development in the snail requires from 28 to 35 days. A few cercariae were found to live for up to 14 days at 50 °C., although their life at 16° to 18 °C. was about four days. Cercariae kept at room temperature for 60 to 72 hr. were found infective. The adults become mature in canaries and pass eggs in about 12 to 14 days. Physa gyrina is the species of snail naturally infected. It was found in one case giving off cercariae for five months after being kept in the laboratory. Domestic ducks were found to become infected until they were at least four months old, with the parasites developing to maturity in due course; no experiments were made with older ducks. Furthermore, miracidia were still recovered from the faeces four months after the duck had been experimentally infected, and it is suggested that migratory birds are the source of the local infection.


Africa ◽  
1996 ◽  
Vol 66 (3) ◽  
pp. 386-410 ◽  
Author(s):  
Chapurukha M. Kusimba

Ironsmiths occupy an important yet ambiguous position in many African societies. They are both revered and feared, because they wield social power which arises from their access to occult knowledge, not only of metallurgy but of healing, divination, circumcision and peacemaking. In some societies smiths enjoy high status and are the wealthiest people. In others they are feared, covertly maligned, and blamed for societal misfortunes. In still others the smiths' position is often marginal except when they are needed to intercede on their society's behalf to solve natural or cultural predicaments. The forge or smithy plays a central role in the community as tool-making centre, a place of refuge from violence, of purification, and for healing. This article examines the social context of iron forging among the ironsmiths of the Kenya coast, focusing on the role of iron forging in the coastal economy, the forge, the smiths' life cycle, the institution of apprenticeship, the ritual and technical power of smiths, the role of women in the smiths' community, and the future of iron forging on the coast. It is argued that, while coastal smiths are marginal and despised, they hold important ritual and spiritual powers in coastal society. The article concludes that a detailed understanding of the traditional crafts historically practised on the coast can do much to illuminate the complex history of coastal society.


Author(s):  
Andrea Carrasco ◽  
María E Díaz

Recent academic research highlights the role of leadership identity when thinking about the improvement of the educational field. Based on this research, this article aims to identify and analyze the elements that affect the development of leadership identity in female school principals within the Chilean context. This is achieved by working from a biographical-narrative approach, specifically from the life history technique. This analysis emerges from a considerate reflection on the teachings, and personal and professional milestones highlighted in the biogram. Both personally and professionally, a multiplicity of elements is observed in the life history of María Eliana, influencing the development of her leadership identity, particularly highlighting her self-recognition as a woman. This identity is oriented towards social justice, based on socio-emotional tools such as care, empathy, and participation; and understands and values the role these elements must take in Chilean education. The case study presents tensions for the Chilean educational system, which must be able to address the complexities that women experience while holding leadership positions, especially when challenged with the perspective that school is an inclusive space of social justice.


2013 ◽  
Vol 88 (2) ◽  
pp. 230-236 ◽  
Author(s):  
R. Brinesh ◽  
K.P. Janardanan

AbstractThe life-cycle stages of Pleurogenoides malampuzhensis sp. nov. infecting the Indian bullfrog Hoplobatrachus tigerinus (Daudin) and the skipper frog Euphlyctiscyanophlyctis (Schneider) occurring in irrigation canals and paddy fields in Malampuzha, which forms part of the district of Palakkad, Kerala, are described. The species is described, its systematic position discussed and compared with the related species, P. gastroporus (Luhe, 1901) and P. orientalis (Srivastava, 1934). The life-cycle stages, from cercaria to egg-producing adult, were successfully established in the laboratory. Virgulate xiphidiocercariae emerged from the snail Digoniostoma pulchella (Benson). Metacercariae are found in muscle tissues of dragonfly nymphs and become infective to the frogs within 22 days. The pre-patent period is 20 days. Growth and development of both metacercariae and adults are described.


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