Life cycle of Diaptomus oregonensis Lilljeborg in Sunfish Lake, Ontario

1970 ◽  
Vol 48 (6) ◽  
pp. 1299-1302 ◽  
Author(s):  
H. C. Lai ◽  
J. C. H. Carter
Keyword(s):  
Life Cycle ◽  
Lake Ontario ◽  
Resting Eggs ◽  
Meromictic Lake ◽  
Third Generation ◽  
Food Scarcity ◽  
Diaptomus Oregonensis

The life cycle of Diaptomus oregonensis in a partially meromictic lake was investigated during 1966–68. Three annual generations were produced in each of 1967 and 1968 when conditions were optimal. In 1966 no third generation appeared and D. oregonensis vanished in September, presumably after depositing resting eggs. Food scarcity is suggested as the cause of both slow summer development and production of resting eggs.

Invasion of Lake Ontario by the Ponto–Caspian predatory cladoceran Cercopagis pengoi

1999 ◽  
Vol 56 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Hugh J MacIsaac ◽  
Igor A Grigorovich ◽  
James A Hoyle ◽  
Norman D Yan ◽  
Vadim E Panov
Keyword(s):  
Great Lakes ◽  
Ballast Water ◽  
Lake Ontario ◽  
Resting Eggs ◽  
The Body ◽  
Population Densities ◽  
Exchange Programs ◽  
Neva Estuary ◽  
Cercopagis Pengoi ◽  
Source Populations

Cercopagis pengoi, a waterflea native to the Ponto-Caspian region, was discovered during 1998 in Lake Ontario. Individuals were found throughout the lake during summer snagged on sportfishing lines. The population included parthenogenetic (92%) and sexual (2%) females and males (6%). Cercopagis has a very long caudal appendage that is more than five times the body length and terminates in a distinctive loop. Females and males from Lake Ontario were significantly smaller than individuals from the Neva Estuary, Baltic Sea. In Eurasia, C. pengoi occurs in relatively warm fresh and brackish waters (0-14‰) at population densities usually <3000 individuals·m-3; mean and maximum population densities in Lake Ontario were 170 and 322 individuals·m-3, respectively. The presence of females with resting eggs indicates that Cercopagis will likely establish in Lake Ontario. As with other recently introduced invertebrates, Cercopagis likely was transported to the Great Lakes in ballast water from eastern Europe. The rapid influx of Ponto-Caspian species into the Great Lakes warrants further study including identification of source populations, mechanisms of dispersal, impacts on recipient ecosystems, and efficacy of ballast water exchange programs.

Seasonal abundance and size variation in Antarctic populations of the Cladoceran Daphniopsis studeri

1995 ◽  
Vol 7 (4) ◽  
pp. 393-394 ◽  
Author(s):  
P.R. Bayliss ◽  
J. Laybourn-Parry
Keyword(s):  
Life Cycle ◽  
Size Variation ◽  
Personal Communication ◽  
Resting Eggs ◽  
Sexual Cycle ◽  
Seasonal Abundance ◽  
Preliminary Survey ◽  
Freshwater Lakes ◽  
Subantarctic Islands ◽  
Vestfold Hills

Continental freshwater lakes of Antarctica are characterized by species-poor biota (Heywood 1977). The plankton is dominated by algae, bacteria and protozoa (Koob & Leister 1972, Parker et al. 1982, Laybourn-Parry et al. 1991). Three species of micro-crustacea have been reported from Eastern Antarctica, the cladoceron Daphniopsis studeri, Ruhe and two copepods, Acanthocyclops mirnyi, Borutsky & Vinogradov, and Boeckella poppei, Mrazek (Borutsky & Vinogradov 1957, Akatova 1964, Bayley & Burton 1993). The origin of D. studeri in lakes of the Vestfold Hills has been documented (Laybourn-Parry & Marchant 1992) and it is generally thought that populations are derived from subantarctic islands and mainland South America. Populations of D. studeri from three freshwater lakes of the Vestfold Hills, have been studied in more detail in a preliminary survey of its occurrence and basic life cycle (Laybourn-Parry & Marchant 1992) during which it was observed that the population consisted entirely of parthenogenic females appearing to produce only subitaneous eggs. Herbert (1981) reported that some Arctic and Antarctic cladocerans were capable of producing ephippial (wintering) eggs asexually. D. studeri also occurs in some of the brackish lakes of the Vestfold Hills with salinities of <4 ppt. These populations were found to possess male individuals (J. Gibson, personal communication 1991) suggesting a sexual cycle and production of resting eggs. There is no evidence of this in the freshwater lakes of the region.

scholarly journals The effect of γ-radiation on resting eggs and life cycle of cladoceran Moina macrocopa

2016 ◽  
Vol 466 (1) ◽  
pp. 61-65 ◽  
Author(s):  
E. S. Zadereev ◽  
T. S. Lopatina ◽  
T. A. Zotina ◽  
N. A. Oskina ◽  
D. V. Dementyev ◽  
...  
Keyword(s):  
Life Cycle ◽  
Resting Eggs ◽  
Γ Radiation ◽  
Moina Macrocopa

scholarly journals Revisión de las consideraciones metodológicas utilizadas en estudios ambientales con enfoque de ciclo de vida sobre la producción de microalgas con fines energéticos

2018 ◽  
Vol 2 (1) ◽  
pp. 35-59
Author(s):  
Paula Daniela Rodriguez ◽  
Alejandro Pablo Arena ◽  
Bárbara María Civit ◽  
Roxana Piastrellini
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Flat Plate ◽  
Production Systems ◽  
Life Cycle Approach ◽  
Third Generation ◽  
Iso 14040 ◽  
Methodological Choices ◽  
The Impact ◽  
Air Lift

A Avaliação do Ciclo de Vida (ACV) tem sido utilizada por diversos autores para avaliar a produção de microalgas com fins energéticos. No entanto, desde a perspectiva energética e ambiental, não existem conclusões gerais sobre ela, não só pelas diferenças tecnológicas entre os sistemas estudados, mas também pelas distintas escolhas metodológicas adotadas pelos autores. Este trabalho tem como objetivo encontrar os principais aspectos que dificultam a comparação dos resultados de diversos estudos com abordagem de ciclo de vida de sistemas de produção de microalgas com fins energéticos, e propor recomendações que permitam harmonizar as escolhas metodológicas de futuros estudos. Para isso, foi realizada uma ampla revisão bibliográfica e foram selecionadas aquelas publicações que consideram o cultivo de microalgas em sistemas fechados, ou seja, fotobiorreatores de qualquer configuração (tubulares, flat-plate, air-lift, etc.). As treze publicações escolhidas foram avaliadas conforme as diretrizes presentes nas normas ISO 14040 e 14044. Os resultados indicam que fatores como o produto estudado, a unidade funcional selecionada, os limites do sistema, os procedimentos da atribuição de cargas ambientais utilizados, as fontes de dados, os métodos de avaliação de impactos e as categorias de impactos escolhidas diferem amplamente entre os estudos, impossibilitando a comparação dos mesmos para chegar a resultados confiáveis. Portanto considera-se necessário harmonizar as escolhas metodológicas dos futuros estudos de ACV de biocombustíveis de terceira geração. Para isso, propõe-se uma série de recomendações que visam a colaboração na avaliação dos impactos ambientais desses sistemas.  Palavras-chave: Avaliação do ciclo de vida. Bioenergia. Biocombustível de terceira geração.ResumenEl Análisis del Ciclo de Vida (ACV) ha sido utilizado por distintos autores para evaluar la producción de microalgas con fines energéticos. Sin embargo, desde la perspectiva energética y ambiental, no existen conclusiones generales acerca de ella, no sólo por las diferencias tecnológicas entre los sistemas estudiados, sino también por las distintas elecciones metodológicas adoptadas por los autores. Este trabajo tiene como objetivos hallar los principales aspectos que dificultan la comparación de los resultados de diversos estudios con enfoque de ciclo de vida de sistemas de producción de microalgas con fines energéticos, y proponer recomendaciones que permitan armonizar las elecciones metodológicas de futuros estudios. Para ello, se llevó a cabo una amplia revisión de la literatura y se seleccionaron aquellas publicaciones que consideran el cultivo de microalgas en sistemas cerrados, esto es fotobiorreactores de cualquier configuración (tubulares, flat-plate, air-lift, etc.). Las 13 publicaciones elegidas se evaluaron según los lineamientos ofrecidos por las normas ISO 14040 y 14044. Los resultados indican que factores como el producto estudiado, la unidad funcional seleccionada, los límites del sistema, los procedimientos de asignación de cargas ambientales utilizados, las fuentes de datos, los métodos de evaluación de impactos y las categorías de impacto escogidas difieren ampliamente entre estudios, imposibilitando la comparación de los mismos para llegar a conclusiones confiables. Por lo tanto, se considera necesario armonizar las elecciones metodológicas de los futuros estudios de ACV de biocombustibles de tercera generación. Para ello, se propone una serie de recomendaciones dirigidas a colaborar en la evaluación de los impactos ambientales de estos sistemas. Palabras clave: Análisis del Ciclo de Vida. Bioenergía. Biocombustibles de terceira generación.AbstractThe Life Cycle Assessment (LCA) has been used by different authors to measure the production of microalgae for energy purposes. However, from the energy and environmental perspective, there are no general conclusions about this, not only because of the technological differences between the systems studied, but also because of the different methodological options adopted by the authors. The objective of this work is to find the main aspects that make it difficult to compare the results of several studies with a life cycle approach of microalgae production systems for energy purposes, and propose recommendations that allow harmonizing the methodological choices of future studies. For this, a wide review of the literature was carried out and those publications that consider the cultivation of microalgae in closed systems, that is, photobioreactors of any configuration (tubular, flat plate, air lift, etc.), were selected. The 13 selected publications were evaluated in accordance with the guidelines offered by the ISO 14040 and 14044 standards. The results indicate that factors such as the product studied, the selected functional unit, the limits of the system, the environmental allocation procedures used, the data resources, the impact evaluation methods and the impact categories chosen differ widely among the studies, making it impossible to compare them to arrive at reliable conclusions. Therefore, it is considered necessary to harmonize the methodological choices of future LCA studies of third generation biofuels. For this, a series of recommendations are proposed to collaborate in the evaluation of the environmental impacts of these systems.Keywords: Life Cycle Assessment. Bioenergy. Third generation biofuel.

scholarly journals The life-cycle of cladocera, with remarks on the physiology of growth and reproduction in crustacea

1915 ◽  
Vol 88 (605) ◽  
pp. 418-435 ◽  
Keyword(s):  
Life Cycle ◽  
High Temperature ◽  
Daphnia Pulex ◽  
Resting Eggs ◽  
The Common ◽  
Growth And Reproduction

In a paper on the life-cycle of Moina rectirosiris , published in 1913 (5), it was shown by the late Mr. G. H. Grosvenor and myself that it was possible to inhibit entirely the production of the sexual forms by isolating the parthenogenetic parents soon after birth, and keeping them at a constant high temperature of 25-30° C. It was proved that for a succession of eight generations the isolated parents at this temperature gave no males or ephippial females, while parents of the same generations kept crowded at a temperature of about 14° C. or 5° C. gave about 50 per cent, males. We were unable to determine how the effect of isolation and crowding of the parthenogenetic parents influenced the production of the sexual forms, but two alternative suggestions were made, either that in the crowded glasses the animals were unable to obtain sufficient nutriment and were partially starved, or else that some excretory matter accumulated in the crowded glasses which influenced the production of males and sexual females. In order to confirm the above results and to throw some light on the processes involved, breeding experiments have been carried on for some time with another species of Claclocera, the common Daphnia pulex. Mr. Robert Gurney very kindly gave me some dried mud from a pond winch was known to contain the resting eggs of these animals, and, on placing the mud in a bowl of water, after some weeks some young Daphnia hatched out. One of these was kept until it had produced young, and the offspring of these young ones were used to start the first experimental generation.

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