The natural life history of milkfish

Following brief descriptions of the various phases in the natural life history of the milkfish (Chanos chanos), namely adults, eggs and embryos, larvae, fry and metamorphosis, juveniles and sub-adults, a summary is provided of the life history, providing also a schematic diagram.

Biology, ecology and the fishery of Mukene, Rastrineobola argentea

Food and feeding, condition factor, breeding periods, growth and size at first maturity of a small pelagic cyprinid Rastrineobola argentea (P.) in Lake Victoria are determined. Fishing gears and methods that have been used in the exploitation of the species and could be harmful to the fishery are outlined. Management measures leading to possible sustainable exploitation of the fishery are suggested. Adult R. argentea feed on zooplankton during daytime. Juveniles feed on planktonic early instars of lakefly larvae. Although the species breeds throughout the year, two breeding peaks were observed during the drier months of August and December January. Least breeding was observed in the rainy months of April-May and October November. Fishes from the open water station at Bugaia showed higher numbers of breeding individuals than those from inshore areas. The mean monthly condition factor of fish from Napoleon Gulf confirmed breeding peaks as obtained from the number of fish with ripe gonads. The species showed a mean instantaneous growth rate (K) of 1.75 and attains length infinity (Lx) of 54mm. Females of the species in these waters show a reduced size at maturity as compared to ten years ago when exploitation of the species was at minimal levels. The males have however not changed much.

Techniques to improve the shear strength of impacted bone graft: the effect of particle size and washing of the graft.

BACKGROUND: When fresh morselized graft is compacted, as in impaction bone-grafting for revision hip surgery, fat and marrow fluid is either exuded or trapped in the voids between particles. We hypothesized that the presence of incompressible fluid damps and resists compressive forces during impaction and prevents the graft particles from moving into a closer formation, thus reducing the graft strength. In addition, viscous fluid such as fat may act as an interparticle lubricant, thus reducing the interlocking of the particles. METHODS: We performed mechanical shear testing in the laboratory with use of fresh-frozen human femoral-head allografts that had been passed through different orthopaedic bone mills to produce graft of differing particle-size distributions (grading). RESULTS: After compaction of fresh graft, fat and marrow fluid continued to escape on application of normal loads. Washed graft, however, had little lubricating fluid and better contact between the particles, increasing the shear resistance. On mechanical testing, washed graft was significantly (p < 0.001) more resistant to shearing forces than fresh graft was. This feature was consistent for different bone mills that produced graft of different particle-size distributions and shear strengths. CONCLUSIONS: Removal of fat and marrow fluid from milled human allograft by washing the graft allows the production of stronger compacted graft that is more resistant to shear, which is the usual mode of failure. Further research into the optimum grading of particle sizes from bone mills is required.

Techniques to improve the shear strength of impacted bone graft: The effect of particle size and washing of the graft

Background: When fresh morselized graft is compacted, as in impaction bone-grafting for revision hip surgery, fat and marrow fluid is either exuded or trapped in the voids between particles. We hypothesized that the presence of incompressible fluid damps and resists compressive forces during impaction and prevents the graft particles from moving into a closer formation, thus reducing the graft strength. In addition, viscous fluid such as fat may act as an interparticle lubricant, thus reducing the interlocking of the particles. Methods: We performed mechanical shear testing in the laboratory with use of fresh-frozen human femoral-head allografts that had been passed through different orthopaedic bone mills to produce graft of differing particle-size distributions (grading). Results: After compaction of fresh graft, fat and marrow fluid continued to escape on application of normal loads. Washed graft, however, had little lubricating fluid and better contact between the particles, increasing the shear resistance. On mechanical testing, washed graft was significantly (p < 0.001) more resistant to shearing forces than fresh graft was. This feature was consistent for different bone mills that produced graft of different particle-size distributions and shear strengths. Conclusions: Removal of fat and marrow fluid from milled human allograft by washing the graft allows the production of stronger compacted graft that is more resistant to shear, which is the usual mode of failure. Further research into the optimum grading of particle sizes from bone mills is required. Clinical Relevance: Understanding the mechanical properties of milled human allograft is important when impaction grafting is used for mechanical support. A simple means of improving the mechanical strength of graft produced by currently available bone mills, including an intraoperative washing technique, is described.

Observaciones sobre la reproducción, desarrollo embrionario y larval de la anchoíta argentina (Engraulis anchoita)

The first studies on the problems related to the reproduction of marine fish in Argentina (SW Atlantic ocean) have been carried out with a species of great economic importance, the anchovy (Engraulis anchoita Hubbs and Marini). The spawning period of this species during the period 1963-64 has been determined. By the application of the quantitative collection method, it has been established that spawning commenced in the areas close to the coast during the first few days of September and at a water temperature of 10,3° C and reached its greatest intensity in October (up 1569 eggs/1 square metre surface water) at a temperature varying between 11,5-13,8° C. From the middle of November the anchovy continues to reproduce in a less intensive form and further out to Sea, up to at least the month of May. The intensity of reproduction reaches a peek in February, and at a water temperature of 20° C. It is believed that two physiologically distinct populations of Engraulis anchoita may exist, the first reproducing in Spring and the second in Autumn. It has been established that a daily spawning rhythm occurs, between the hours of 8 and 12 p. m. During this period it was possible to obtain mature females with which artificial fertilization was performed. The rate of development was determined, which at a temperature of 14-15° C is from 69-72 hours, and at a temperature of 19-20° C from 50-53 hours. A temperature of 49° C was found be lethal. The different embryonic and larval stages of development are illustrated diagramatically and individually described. The preliminary studies on the larvae and juveniles caught in the Sea during the period of reproduction led to the formulation of certain conclusions whith reference that the juveniles, as yet larvae, begin to group together at an early age, and the younger individuals the more uniform are the schoals whith regards to the total size of the specimens. It has shown that the anchovy during its first year of life tends to display littoral behaviour. RESUMEN EN ESPAÑOL: Los primeros estudios de los problemas referentes a la reproducción de los peces marinos en la Argentina (océano Atlántico sudoccidental) se han efectuado sobre una especie de gran importancia económica, Engraulis anchoita Hubbs y Marini. Se ha determinado la época de desove de la anchoíta en un período anual 1963-64. Aplicando el método de recolección cuantitativo se ha establecido que el desove de esta especie ha empezado en las zonas muy cercanas a la costa, en los primeros días de setiembre a la temperatura 10,3° C y ha alcanzado mayor intensidad en octubre (hasta 1569 huevos en 1 m2 de la superficie del agua) a la temperatura 11,5°-13,8° C. Desde mediados de noviembre la anchoíta sigue reproduciéndose en forma poco intensiva y más mar afuera, hasta por lo menos el mes de mayo. La intensidad de reproducción para este segundo período alcanza un pico, aunque muy pequeño en febrero a la temperatura 20° C. Se hace la suposición de que pueden existir dos de distintas características fisiológicas poblaciones de Engraulis anchoita una de reproducción primaveral y otra de reproducción otoñal. Además se ha establecido que existe un ritmo diario de desove que comprende las horas 20-24. En las horas de postura se pudo conseguir hembras maduras y con sus productos sexuales se efectuó la fecundación artificial. Se determinó la velocidad de desarrollo que a la temperatura 14°-15° C es de 69-72 horas y en la temperatura 19°- 20° C es de 50-53 horas. La temperatura 4° resultó ser letal. Se realizaron dibujos y descripciones correspondientes a los distintos estadios embrionarios y larvales. Los estudios preliminares de las larvas y juveniles de la anchoíta, capturados en el mar en la época de reproducción, permitieron sacar ciertas conclusiones sobre el crecimiento en sus primeros meses de vida. Se observó que los juveniles, larvas todavía, empiezan a agruparse muy temprano y cuanto más jóvenes son los individuos, tanto más uniformes son los cardúmenes en las dimensiones de los ejemplares. Se demostró que la anchoíta en su primer año de vida tiene costumbres muy costeras.

Morphometrics, length-weight relationship and condition of Rastrineobola argentea (Pellegrin 1904) in the Winam Gulf of Lake Victoria (Kenya)

Correlation between total length (TL), fork length (FL) and standard length (SL) of Raslrineobola argentea (pellegrin 1904) in the Winam Gulf of Lake Victoria indicate that FL = 0.92 TL - 0.74 and SL = 0.90 TL - 1.74. Length-weight relationship of log-transformed data shows that the slopes of the regression lines were 3.06 to 3.22 for juveniles, 2.70 to 3.05 for males and 3.24 to 3.71 for females. The slopes were significantly different between groups at at a =0.05. The Fulton's condition factor (K) was highest in December (1.019-1.073) and March/April (1.015-1.030) but lowest in June (1:00-1.025) for all stations. Significant differences between groups demands for the use of different growth models for juveniles, males and females especially for the von Bertalanffy growth equation which uses length-weight relationship. Observed cyclic viations in condition factor suggests two peak breeding seasons for this species in the Winam Gulf. The practical lmplications of these results in stock assessment using length-based fish stock assessment methods is briefly discussed.

Aspects of the biology of the Lake Tanganyika sardine, Limnothrissa miodon (Boulenger), in Lake Kariba

Juveniles of limnothrissa miodon (Boulenger) were introduced into the man-made Lake Kariba in 1967-1968. Thirty months of night-fishing for this species from Sinazongwe, near the centre of the Kariba North bank, from 1971 to 1974 are described. Biological studies were carried out on samples of the catch during most of these months. Limnological studies were carried out over a period of four months in 1973. Limnothrissa is breeding successfully and its number have greatly increased. It has reached an equilibrium level of population size at a lower density than that of Lake Tanganyika sardines, but nevertheless is an important factor in the ecology of Lake Kariba. The growth rate, size at maturity and maximum size are all less than those of Lake Tanganyika Limnothrissa. A marked disruption in the orderly progression of length frequency modes occurs in September, for which the present body of evidence cannot supply an explanation.

PATTERNS OF SPATIAL-DISPERSION, LOCOMOTION AND FORAGING BEHAVIOR IN 3 GROUPS OF THE YUNNAN SNUB-NOSED LANGUR (RHINOPITHECUS-BIETI)

Aspects of the behaviour of three groups of Yunnan snub-nosed langurs, Rhinopithecus bieti, were observed over the course of three field seasons from 1986 to 1988. The major findings of the study were: (1) The habitats of R. bieti were mainly at heights of 3,600-4,150 m above sea level. (2) Groups were very large, with group sizes ranging from more than 100 to 269 individuals. (3) Spatial dispersion densities ranged from about 27 to 106 m2/individual during sleeping and resting, to feeding dispersions as large as 5,000-15,000 m2. (4) The locomotor repertoire of R. bieti consisted largely of walking, jumping and climbing. On very rare occasions, semibrachiation was observed, but true brachiation was never observed. The locomotor repertoires of juveniles were more diverse than those of subadults or adults. (5) Communication consisted mainly of eye-to-eye contact accompanied by murmurs; while loud calls were heard only rarely. (6) Groups moved between sleeping and feeding sites in single file. It is concluded that R. bieti is a mainly terrestrial species.

FEEDING AND VOCAL BEHAVIORS OF BLACK GIBBONS (HYLOBATES-CONCOLOR) IN YUNNAN - A PRELIMINARY-STUDY

Feeding and vocal behaviours of wild black gibbons (Hylobates concolor) were observed from 1987 to 1989 in south-western Yunnan, notably H. concolor jingdongensis at Mt. Wuliang (24-degrees 18-42'N, 100-degrees 30-50'E) in the early spring of 1989. 12 plant species were observed to have been eaten by the gibbons; these included tree species, lianas and epiphytes. Approximately 21 % of feeding time was devoted to eating fruits, 61 % to leaf buds and shoots, 7 % to flowers and 11 % to leaves. The gibbons preferred fruits to leaves even though they commonly ate leaves. In this study, the morning songs (duet and solo), reponsive (territorial) songs, alarm calls and communication calls were recorded. The gibbons sang their morning songs mainly in the early morning, with a single bout lasting more than 10 min on average. The singing of a group would trigger other groups, and all groups in an area tended to sing sequentially. The morning duet song bout was dominated by an adult male. The male emitted booms, aa notes, early multimodulated figures, intermediate multimodulated figures and codas, the latter occurring only in duets following the female's great call. The female uttered great calls and abortive great calls. The subadults or juveniles also took part in the morning songs. Lone males were heard to utter solos which lasted longer than the duets of the pairs.

A simple prediction model for asphalt surface texture incorporating mix gradation and air voids

This paper presents the results of a preliminary study that seeks to show how asphalt grading and air voids are related to the texture depth of asphalt. The fiftieth percentile particle size (D50) is shown to be a good predictor of texture depth measurements from a collected database of field and laboratory studies. The D50 is used to normalise collected texture data and this 'relative texture' is shown to correlate with air voids. Regression analyses confirm that air voids should be included along with a measure of gradation in the interpretation of asphalt surface texture.The derived formulae are used to develop correlation charts.

Analysis of asphalt concrete permeability data using representative pore size

The permeability of asphalt concrete has been the subject of much study by pavement engineers over the last decade. The work undertaken has tended to focus on high air voids as the primary indicator of permeable asphalt concrete. This paper presents a simple approach for understanding the parameters that affect permeability. Principles explained by Taylor in 1956 in channel theory work for soils are used to derive a new parameter-representative pore size. Representative pore size is related to the air voids in the compacted mix and the D75 of the asphalt mix grading curve. Collected Superpave permeability data from published literature and data collected by the writers at the Queensland Department of Transport and Main Roads is shown to be better correlated with representative pore size than air voids, reducing the scatter considerably. Using the database of collected field and laboratory permeability values an equation is proposed that pavement engineers can use to estimate the permeability of in-place pavements. © 2011 ASCE.

Use of axially graded burnable boron for hot-spot temperature reduction in a pressurized water reactor core

Shortly after the loading of a pressurized water reactor (PWR) core, the axial power distribution in fresh fuel has already attained the characteristic, almost flat shape, typical of burned fuel. At beginning of cycle (BOC), however, the axial distribution is centrally peaked. In assemblies hosting uniform burnable boron rods, this BOC peaking is even more pronounced. A reduction in the axial peaking is today often achieved by shortening the burnable boron rods by some 30 cm at each edge. It is shown that a two-zone grading of the boron rod leads, in a representative PWR cycle, to a reduction of the hot-spot temperature of approximately 70 °C, compared with the nongraded case. However, with a proper three-zone grading of the boron rod, an additional 20 °C may be cut off the hot-spot temperature. Further, with a slightly skewed application of this three-zone grading, an additional 50 °C may be cut off. The representative PWR cycle studied was cycle 11 of the Indian Point 2 station, with a simplification in the number of fuel types and in the burnup distribution. The analysis was based on a complete three-dimensional burnup calculation. The code system was ELCOS, with BOXER as an assembly code for the generation of burnup-dependent cross sections and SILWER as a three-dimensional core code with thermal-hydraulic feedback.

Population dynamics and maturation cycle of Camallanus cotti (Nematoda : Camallanidae) in the Chinese hooksnout carp Opsariichthys bidens (Osteichthyes : Cyprinidae) from a reservoir in China

The seasonal population dynamics and maturation cycle of the nematode Camallanus cotti in the posterior intestine of Chinese hooksnout carp Opsariichthys bidens have been studied in the Danjiangkou Reservoir of the Hubei Province in central China from September 2004 to November, 2005. The overall prevalence, mean abundance and intensity of C cotti among fish sampled (n = 700 fish) were 47%, 2.29 +/- 12.38 ( +/- S.D.) and 1-307 (average 4.89 +/- 17.74), respectively. The overall sexual ratio of female to male nematodes (excluding L3 and L4 juveniles) was 1.17:1. Statistical results showed weakly positive correlations betweerl fish length and the number of nematodes per host. The dynamics of infection of the nematode exhibited significant seasonal pattern in changes in mean abundance. A similar pattern was found for changes in nematode prevalence, although this was not statistically significant. Higher levels of infection were observed among fish sampled in summer months and the lower in the winter. Neither the prevalence nor the abundance of the parasite was significantly different between male and female hosts. The pattern of frequency distribution of the parasite in the host was found to be over-dispersed throughout the sampling period. In addition, studies on the development and maturation of the parasite in O. bidens revealed that development (maturation), recruitment of the next generation, and reproduction may be continuous year-round, although reproduction may peak during the winter. (c) 2007 Elsevier B.V. All rights reserved.

Effects of solar UV radiation on germination of conchospores and morphogenesis of sporelings in Porphyra haitanensis (Rhodophyta)

The effects of ultraviolet radiation (UVR 280-400 nm) on the germination of Porphyra haitanensis conchospores and on the growth and morphogenesis of the subsequent sporelings were investigated by culturing the released conchospores under natural sunlight from 29 September to 6 October 2005. Germination increased with time and was faster when UV-B was excluded using cut-off filters. There were significant negative effects of UV-B radiation on growth and cell division of sporelings, with decreases up to 18% for thallus length, between 6 and 18% for thallus width, up to 29% for thallus area, and between 6 and 14% for cell size as compared to PAR-controls. UV-A had a significant positive effect on morphogenesis, enhancing the formation of sporelings with cells dividing transversely; on the other hand, UV-B delayed the formation of such sporelings. We also tested the effects of solar UVR on the growth of P. haitanensis juveniles and found no significant effects. Our results indicate that UV-A has an important role in the germination and morphogenesis of the species, but on the other hand, sporelings of P. haitanensis are more sensitive to UV-B radiation than juveniles.

Nutritional homeostasis in carnivorous southern catfish (Silurus meridionalis): is there a mechanism for increased energy expenditure during carbohydrate overfeeding?

In previous growth experiments with carnivorous southern catfish (Silurus meridionalis), the non-fecal energy lose was positively related to dietary. carbohydrate level. To test whether metabolic energy expenditure accounts for such energy loss, an experiment was performed with southern catfish juveniles (33.2-71.9 g) to study the effect of dietary carbohydrate level on fasting metabolic rate and specific dynamic action (SDA) at 27.5 degreesC. The fasting metabolic rate in this catfish was increased with dietary carbohydrate level, and the specific dynamic action (SDA) coefficient (energy expended on SDA as percent of assimilated energy) was not affected by dietary carbohydrate level. The results suggest that in southern catfish, carbohydrate overfeeding increases metabolic rate to oxidize unwanted assimilated carbohydrate. A discussion on the poor capacity of intermediate metabolism for adapting dietary carbohydrate in carnivorous fish and its possible relationship with facultative component of SDA was also documented in this paper. (C) 2004 Elsevier Inc. All rights reserved.