Reproductive biology of the abyssal holothurian Amperima rosea: an opportunistic response to variable flux of surface derived organic matter?

2003 ◽  
Vol 83 (1) ◽  
pp. 175-188 ◽  
Author(s):  
B.D. Wigham ◽  
P.A. Tyler ◽  
D.S.M. Billett
Keyword(s):  
Organic Matter ◽  
Larval Development ◽  
Reproductive Biology ◽  
Radical Change ◽  
Sudden Increase ◽  
Environmental Forcing ◽  
High Fecundity ◽  
North East ◽  
Stage Of Development ◽  
Reproductive Events

A radical change in the abundance of invertebrate megafauna has occurred over a vast area of the Porcupine Abyssal Plain, north-east Atlantic, in recent years. In particular, the holothurian Amperima rosea has increased in abundance by three orders of magnitude. The sudden increase in abundance of A. rosea appears to be the result of environmental forcing rather than localized stochastic population variations. Amperima rosea produces small eggs ([les ]200 μm) indicating (1) planktotrophic larval development or (2) lecithotrophic larval development with an abbreviated larval stage. It also reaches maturity at a very small size. The reproductive biology of A. rosea indicates that it can increase rapidly in population size and can colonize large areas quickly. It has high fecundity, as predicted by gonad indices and observed in histological studies. Fecundity was greater in winter than in summer months, but there was no clear evidence of seasonal or episodic reproductive events. All males, irrespective of sample season or year, were mature with spermatozoa. Most oocytes were of an intermediate size (70 to 120 μm), either at the late previtellogenic (70–90 μm) or early vitellogenic (100–120 μm) stage of development. It is postulated that development of full vitellogenesis, leading to episodic spawning, might be dependent on certain environmental stimuli. The most likely stimulus is food supply. Amperima rosea has been shown to feed preferentially on phytodetritus and to have a requirement for certain sterols in its diet. Qualitative changes in the flux of organic matter to the sea-floor may control vitellogenesis and fecundity, and hence have an effect on the population dynamics of the species.

Sexual reproduction and larval development of Rhaphidrilus nemasoma Monticelli, 1910 (Polychaeta: Ctenodrilidae)

1989 ◽  
Vol 67 (10) ◽  
pp. 2345-2351 ◽  
Author(s):  
Pei-Yuan Qian ◽  
Fu-Shiang Chia
Keyword(s):  
British Columbia ◽  
Sexual Reproduction ◽  
Larval Development ◽  
Intertidal Zone ◽  
Vancouver Island ◽  
Benthic Diatoms ◽  
Egg Mass ◽  
High Fecundity ◽  
Egg Masses ◽  
Trochophore Stage

Adult specimens and egg masses of Rhaphidrilus nemasoma were collected in the low intertidal zone from Execution Rock, Bamfield, Vancouver Island, British Columbia, in June of 1986. Each egg mass contained about 1000 eggs. The eggs were green, spherical, and measured 125–145 μm in diameter. Larval development took place within the egg mass until the three-or four-setiger stage, at which time they emerged from the egg mass. Newly emerged larvae crawled on the bottom of the culture beakers and fed on benthic diatoms. Metamorphosis took place soon after emergence and was completed within 2 weeks. Paddle cilia were observed at the early trochophore stage, and their possible function, and the extremely high fecundity of this polychaete, are discussed.

scholarly journals A new Synbranchus (Teleostei: Synbranchiformes: Synbranchidae) from ilha de Marajó, Pará, Brazil, with notes on its reproductive biology and larval development

2005 ◽  
Vol 3 (3) ◽  
pp. 319-328 ◽  
Author(s):  
Sandra E. Favorito ◽  
Angela M. Zanata ◽  
Maria I. Assumpção
Keyword(s):  
New Species ◽  
Larval Development ◽  
Reproductive Biology ◽  
Color Pattern ◽  
The Other ◽  
Larval Stages ◽  
Marajó Island ◽  
Northern Brazil

Synbranchus lampreia, new species, is described from rio Goiapi, Marajó Island, Pará, northern Brazil. It differs from the other two described species of the genus by its color pattern, which consists of large roundish black blotches scattered over a light brown or yellowish ground pigmentation and presence of inconspicuous brown small spots distributed among the large dark spots. The species is further distinguished from S. marmoratus by a higher number of vertebrae and from S. madeira by a shorter postanal length. Information about reproductive aspects is provided and larval stages are described and illustrated.

scholarly journals Historical and legal discourse in the context of classical and postclassical legal understanding

2021 ◽  
pp. 106-111
Author(s):  
Tetiana Bondaruk
Keyword(s):  
Legal System ◽  
Legal Discourse ◽  
Radical Change ◽  
Legal Environment ◽  
Stage Of Development ◽  
Starting Point ◽  
Legal Space ◽  
New Research ◽  
Legal Understanding ◽  
Research Tools

Іntroduction. Historical and legal science, as well as the science of law in general, is acutely faced with challenges related to the new stage of development of humanities knowledge and the corresponding change of research paradigm that occurs during the struggle between classical and nonclassical (postclassical) types of legal understanding Тhe aim of the article. Тhese processes need to be understood and "adapted" in particular in the historical and legal discourse. In particular, it is proposed to analyze the phenomenon of deformation of the phenomenon of law, and the resulting differentiation of the subject, in particular in historical and legal research, and the coherence of research tools offered within the classical and nonclassical types of legal understanding Results. Modern methodological research is a natural reaction of the domestic legal process to the dominance of the monistic materialist approach to the study of legal phenomena, which actualizes anthropological and axiological approaches. Both anthropologization and axiologization of law cause the deformalization of the phenomenon of law, creating a conceptual In the light of the above, it seems important to consider in relation to the relationship such concepts as legal reality (historical and legal reality), legal life, legal system as central, and legal space, legal field, legal environment as peripheral. At the same time, attention is drawn to the normative nature of the legal system, the ontological nature of legal reality, the inconsistency of legal life as a starting point in the choice of methodological tools. Introduction to the historical and legal discourse of «ontological metaphors»: legal communication, legal event, legal life, legal space, legal field, legal environment, etc., will activate the intersubjective model of knowledge of law as a sociocultural phenomenon, draw attention to the dynamics of law, using an arsenal of non-classical methodology. Conclusions. An overview of some trends that lead to a change in the object and subject of jurisprudence shows a radical change in its methodology, which should form research tools to answer new research questions. This process is part of the process of modern «cultivation» of integrated thinking as opposed to or in addition to analytical and systemic, which is characterized by consideration of reality in mechanistic categories, and, being irreversible, requires appropriate historical and legal reflections

Design Model As a Means of Thinking in Architectural Practice and Theory of Renaissance

2021 ◽  
pp. 146-158
Author(s):  
П. В. Капустин
Keyword(s):  
Radical Change ◽  
Traditional Model ◽  
Historical Evolution ◽  
Critical Aspect ◽  
Considerable Part ◽  
Architectural Practice ◽  
Model Method ◽  
Stage Of Development ◽  
Architectural Models ◽  
Basic Ideas

Состояние проблемы. Реконструкция исторической эволюции архитектурного проектирования сегодня становится актуальной необходимостью. Причины, условия, процессы формирования базовых представлений и методов, легших в основу проектного типа мышления и действия, до сих пор довольно мало изучены, особенно в критическом аспекте. Между тем немалая часть сегодняшних проблем и затруднений, как становится понятно, берет начало в эпохе зарождения профессионального проектного метода, в событиях Нового времени. Центром этого метода стало моделирование, вопросы эволюции которого рассмотрены в настоящей работе. Результаты. Рассмотрен этап становления проектирования в архитектурной деятельности в Ренессансе, прежде всего методологический вклад Л. Б. Альберти. Показана трансформация традиционного модельного способа зодческой работы в Раннем Возрождении, связанная с обособлением креативных действий, персонализацией замысла, изменениями в цеховых коммуникациях. Ремесленный способ работы зодчего вступает в профессиональную эру, что ведет к кардинальному изменению характера и места архитектурных моделей. Выводы. Требуется переосмысление, даже переоценка значения моделирования в эволюции проектирования: на место привычной картины безоблачного прогресса должна прийти критическая и проблематизирующая теория, дающая основания для инструментального отношения к моделированию как одному из методов, не лишенному недостатков. Statement of the problem. Reconstruction of the historical evolution of architectural designing is becoming an urgent need today. The reasons, conditions, processes for the formation of basic ideas and methods that formed the basis of the designing type of thinking and action are still quite poorly understood, especially in a critical aspect. Meanwhile, a considerable part of today's problems and difficulties, as it becomes clear, originates in the era of the emergence of the professional method of designing, in the events of the Modernity. The center of this method is modeling, the evolution of which is considered in this work. Result. The stage of development of design in architectural activity in the Renaissance is considered, most importantly, the methodological contribution of L. B. Alberti. The transformation of the traditional model method of architectural work in the Early Renaissance is shown associated with the isolation of creative actions, personalization of the concept, changes in craft's communications. The craftsman's way of working enters the professional era, which results in a radical change in the nature and place of architectural models. Conclusions. Rethinking, even a reassessment of the importance of modeling in the evolution of designing is required instead of the usual picture of cloudless progress, a critical and problematizing theory should come providing foundations for an instrumental attitude to modeling as one of the methods that is not devoid of shortcomings.

The Middle Classes in Non-Western Societies: Inner Dynamics and Self-Assertion Perspective

2015 ◽  
pp. 95-105
Author(s):  
A. Volodin
Keyword(s):  
Middle Class ◽  
Political Development ◽  
Building Blocks ◽  
The State ◽  
Western World ◽  
Middle Classes ◽  
North East ◽  
The North ◽  
Stage Of Development ◽  
The Social

The present article focuses on the entity of middle classes in non-Western societies. The social formation of this kind is a relatively new phenomenon. As far as the modern Western societies are concerned, the social and political “materialization” of the above-mentioned entity has covered the period of no less than five centuries. The middle class in modern transitional societies began to emerge quite recently, with a few notable exceptions, after gaining sovereignty. That is one of the reasons why political systems in the non-Western world are mostly fragile and susceptible to instability of different kinds and origins. The so called “Arab awakening” gives a vivid example for the “underdevelopment” of indigenous middle classes. Whilst in the advanced industrial societies middle classes were (and are) the building blocks of social structure, economic and political development, elite recruitment, etc., among the non-Western societies (with the salient exception of the North-East Asia) the process of the middle class institutionalization as well as its economic and political self-assertion is still under way, somewhere at the initial stage of development. Comparing various non-Western societies from the middle class inner dynamics as well as self-assertion perspective, the author concludes that in the ultimate analysis, the maturity of this process is dependent on the pro-active and creative role of the State. The latter serves as the main driving force of the middle class consolidation and the instrument of political and economic systems for increasing and advancing development. The cases of India, on one hand, and Indonesia, on the other, demonstrate convincingly that the State remains the leading institution of the society able to accelerate economic growth and development, but also to stimulate the emergence and socio-political assertion of the middle class in contemporary non-Western world.

Reproductive biology of two deep-water sharks from the British Isles, Centroscymnus coelolepis and Centrophorus squamosus (Chondrichthyes: Squalidae)

1999 ◽  
Vol 79 (5) ◽  
pp. 923-931 ◽  
Author(s):  
Marine Girard ◽  
Marie-Henriette Du Buit
Keyword(s):  
Reproductive Biology ◽  
Deep Sea ◽  
Average Length ◽  
Sexual Stage ◽  
British Isles ◽  
The West ◽  
Pregnant Females ◽  
Stage Of Development ◽  
First Maturity ◽  
Size At First Maturity

The reproductive biology of two aplacental viviparous deep sea sharks, Centroscymnus coelolepis and Centrophorus squamosus has been studied from 1735 and 675 specimens respectively, collected with bottom trawls between 600 and 1400 m depth off the west coast of the British Isles. A macroscopic maturity scale indicates that for both species, size at first maturity is greater in females than in males. In Centroscymnus coelolepis, genital maturity occurs at an average length of ∼86 cm for males and ∼102 cm for females. In Centrophorus squamosus, males are mature near 98 cm and females near 124 cm total length (TL). Smallest juveniles of both species are absent from catches: no specimens of Centroscymnus coelolepis shorter than 58 cm, nor specimens of Centrophorus squamosus shorter than 84 cm have been recorded. Ovarian fecundity is higher in Centroscymnus coelolepis than in Centrophorus squamosus. A maternal supply has been demonstrated for Centroscymnus coelolepis. Litter size has been estimated only in C. coelolepis because no pregnant females of Centrophorus squamosus were recovered. A dwarf embryo and a pair of twins have been observed. Segregation by sexual stage of development shows that immatures are generally found at greater depths than adults.

Aspects of the reproductive biology of some cattle-visiting Muscidae (Diptera) in north-east England

1985 ◽  
Vol 18 (3) ◽  
pp. 183-196 ◽  
Author(s):  
Stuart G. Ball ◽  
Gordon R. Port ◽  
Martin L. Luff
Keyword(s):  
Reproductive Biology ◽  
North East

Some aspects of reproductive biology of Gobius paganellus (Gobiidae) on the north-eastern coasts of Tunisia (Bizerta lagoon)

2013 ◽  
Vol 93 (8) ◽  
pp. 2235-2246 ◽  
Author(s):  
Ibtissem Louiz ◽  
Mossadok Ben Attia ◽  
Oum Kalthoum Ben Hassine
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Gonadosomatic Index ◽  
Length Distribution ◽  
Sexual Cycle ◽  
Hepatosomatic Index ◽  
Gobiid Fish ◽  
Spawning Period ◽  
North East ◽  
Bizerta Lagoon

The rock goby, Gobius paganellus one of the most common gobiid fish in Bizerta lagoon (north-east of Tunisia), is a gonochoric species that belongs to the Gobiidae family. This study provides the first detailed information of its reproductive biology in lagoon environments. Gobius paganellus was sampled monthly from January 2005 to December 2006 involving 1486 specimens. Total length distribution ranged between 38 and 125 mm. The maximum recorded total lengths were, respectively, 122 mm and 125 mm for female and male. Over the entire population, the sex-ratio was unbalanced in favour of females. According to months, a predominance of females sex-ratio was recorded during the spawning period while according to body size, males were dominating among larger size-classes. In both sexes, the variation of the gonadosomatic index (GSI) was independent of size. Macroscopic and microscopic examination of the gonads added to the monthly monitoring of gonadosomatic index and hepatosomatic index showed that gonads development begins in October and spawning period extends from December to March. The cyclic pattern of gonads development was determined by histology. Results indicated that G. paganellus exhibits a group-synchronous oocyte development. The sizes of first sexual maturity related to 50% of mature individuals were 78.3 mm (CI95: 77–84 mm) for males and 79 mm (CI95: 75–85 mms) for females. The discussion part underlined the impacts of some environmental factors and antropization of this lagoon on sexual cycle of G. paganellus.

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