Rearing experiments with five species of Australian freshwater fishes. I. Inducement to spawning

1967 ◽  
Vol 18 (2) ◽  
pp. 137 ◽  
Author(s):  
JS Lake
Keyword(s):  
Water Level ◽  
Perca Fluviatilis ◽  
Demersal Eggs ◽  
Run Off ◽  
Short Period ◽  
Pelagic Eggs ◽  
Additional Water ◽  
Triggering Mechanisms ◽  
Dry Soil ◽  
Australian Freshwater

Experimental work on the reproduction of five species of fish endemic to Australia indicates the importance of specific water temperatures and floods as triggering mechanisms for spawning and for subsequent survival of young. Evidence has been obtained which suggests that the factor which stimulates the fish to spawn is produced when water comes into contact with dry soil. The species studied were Tandanus tandanus, Plectroplites ambiguus, Maccullochella macquariensis, Bidyanus bidyanus, and Carassiops klunzingeri. The spawning of these species is compared with some observations made on the heterochthonous Perca fluviatilis. Plectroplites ambiguus and Bidyanus bidyanus spawn at water temperatures above 23°C provided there is an accompanying rise in water level; both species produce pelagic eggs. Tandanus tandanus spawns at a temperature of 24°C and demersal eggs are laid in a gravel nest; a rise in water level is not essential. Maccullochella macquariensis spawns at 20°C provided there is a slight "run off" of water into the pond; eggs are laid in hollow logs or in similar situations. Carassiops klunzingeri spawns at 22.5°C and the eggs adhere to grass and twigs at the water's edge. Perca fluviadilis spawns at 11.5°C and all fish spawn in ponds over a short period if additional water is added, this ensures a more uniform water temperature throughout the pond.

Rearing experiments with five species of Australian freshwater fishes. II. Morphogenesis and ontogeny

1967 ◽  
Vol 18 (2) ◽  
pp. 155 ◽  
Author(s):  
JS Lake
Keyword(s):  
Early Stage ◽  
Average Length ◽  
Perca Fluviatilis ◽  
Early Life History ◽  
Coarse Sand ◽  
Stage Of Development ◽  
History Of ◽  
Pelagic Eggs ◽  
Newly Hatched Larvae ◽  
Australian Freshwater

The eggs, embryonic development, and larvae of five species of fish, endemic to Australia, are described and compared. They are Tandanus tandanus, Plectroplites ambiguus, Maccullochella macquariensis, Bidyanus bidyanus, and Carassiops klunzingeri. Plectroplites ambiguus and B. bidyanus both have pelagic eggs with diameters of 3.9 and 2.8 mm, respectively. Hatching times for these two species are similar being about 30 hr at water temperatures of about 25°C. The newly hatched larvae are at an early stage of development and average 3.2 and 3.6 mm in length, respectively. The eggs of T. tandanus are demersal, non-adhesive, average 3.2 mm in diameter, and are laid in a nest usually made in gravel or coarse sand. Hatching takes 6-7 days at a temperature between 20 and 25°C and the newly hatched larvae emerge at an average length of 7.1 mm. Maccullochella macquariensis lays eggs which are demersal and adhesive and this species utilizes hard objects such as the inside of sunken hollow logs for attachment of the eggs. Eggs average 3.4 mm in diameter, hatching can take place in 6 days at temperatures approaching 25°C but the larvae are at an earlier stage of development than those which hatch later. Under river conditions hatching probably takes place at temperatures nearer 20°C when they may take 10-14 days to hatch. Early hatched larvae may be only 6 mm in length: those which take longer to hatch, even at the same temperature, are usually about 9 mm in length. The eggs of C. klunzingeri are very small, ovoid, and when water-hardened may vary in diameter from 0.4 to 0.5 mm. Hatching takes place in 47-53 hr at a temperature range of 18-23°C. The larvae average 1.9 mm when newly hatched and are undeveloped. Observations on the early life history of Perca fluviatilis, an introduced species, are also described. These observations indicate that high minimum water temperatures before spawning or during growth of the embryo may contribute to the control of the distribution of this species either by causing damage to the oocytes of the adult fish or by premature hatching of the eggs. High summer water temperatures alone, were previously accepted as the reason for the control of the distribution of this species.

scholarly journals Spatial distribution of water level impact to back-barrier bays

2018 ◽  
Author(s):  
Alfredo L. Aretxabaleta ◽  
Neil K. Ganju ◽  
Zafer Defne ◽  
Richard P. Signell
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Water Levels ◽  
Analytical Models ◽  
Barnegat Bay ◽  
Sea Level Fluctuations ◽  
Flooding Hazard ◽  
Short Period ◽  
Inlet Geometry ◽  
Spatial Estimates

Abstract. Water level in semi-enclosed bays, landward of barrier islands, is mainly driven by offshore sea level fluctuations that are modulated by bay geometry and bathymetry, causing spatial variability in the ensuing response (transfer). Local wind setup can have a secondary role that depends on wind speed, fetch, and relative orientation of the wind direction and the bay. Inlet geometry and bathymetry primarily regulate the magnitude of the transfer between open ocean and bay. Tides and short-period offshore oscillations are more damped in the bays than longer-lasting offshore fluctuations, such as storm surge and sea level rise. We compare observed and modeled water levels at stations in a mid-Atlantic bay (Barnegat Bay) with offshore water level proxies. Observed water levels in Barnegat Bay are compared and combined with model results from the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system to evaluate the spatial structure of the water level transfer. Analytical models based on the dimensional characteristics of the bay are used to combine the observed data and the numerical model results in a physically consistent approach. Model water level transfers match observed values at locations inside the Bay in the storm frequency band (transfers ranging from 70–100 %) and tidal frequencies (10–55 %). The contribution of frequency-dependent local setup caused by wind acting along the bay is also considered. The approach provides transfer estimates for locations inside the Bay where observations were not available resulting in a complete spatial characterization. The approach allows for the study of the Bay response to alternative forcing scenarios (landscape changes, future storms, and rising sea level). Detailed spatial estimates of water level transfer can inform decisions on inlet management and contribute to the assessment of current and future flooding hazard in back-barrier bays and along mainland shorelines.

scholarly journals The lunar and solar diurnal variations of water-level in a well at Kew observatory, Richmond

1918 ◽  
Vol 94 (663) ◽  
pp. 476-478
Keyword(s):  
Water Level ◽  
Royal Society ◽  
Correlation Coefficients ◽  
Barometric Pressure ◽  
Diurnal Variations ◽  
Range Of Movement ◽  
Nearest Point ◽  
Similar Relation ◽  
Short Period ◽  
The Mean

In a paper communicated to the Royal Meteorological Society, it was shown that the experimental well at Kew Observatory responded to the lunar fortnightly oscillation of mean level in the River Thames, which is 300 yards from the Observatory at its nearest point. The sensitiveness of the water-level to barometric pressure has also been investigated, and the results have been given in a paper recently read before the Royal Society. The present paper deals with the effects of the short-period tides in the solar and lunar series, S 1 , S 2 , S 3 , S 4 , and M 1 , M 2 , M 3 , M 4 . Two-hourly measurements, both in lunar and solar time, were made on the traces obtained during the first two years, August, 1914-August, 1916, omitting days of very irregular movement. Monthly mean inequalities were then computed. Well marked solar and lunar diurnal variations were found in each month, taking the form of double oscillations with two maxima and two minima during the 24 hours. The range of movement was in each case found to be highly associated with the mean height of the water in the well, the correlation coefficients being 0·89 (lunar) and 0·90 (solar). A similar relation had been previously found to exist in the case of barometric pressure.

Seasonal succession and long-term stability of pelagic community in a productive reservoir

2005 ◽  
Vol 56 (8) ◽  
pp. 1137 ◽  
Author(s):  
V. F. Matveev ◽  
L. K. Matveeva
Keyword(s):  
Time Series ◽  
Water Level ◽  
Seasonal Succession ◽  
Perca Fluviatilis ◽  
Taxonomic Composition ◽  
Stationary Time Series ◽  
Introduced Fish ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Murray River

In Lake Hume, a reservoir located in an active agricultural zone of the Murray River catchment, Australia, time series for the abundances of phytoplankton and zooplankton taxa, monitored from 1991 through to 1996, were stationary (without trends), and plankton taxonomic composition did not change. This indicated ecosystem resilience to strong fluctuations in reservoir water level, and to other potential agricultural impacts, for example eutrophication and pollution. Although biological stressors such as introduced fish and invertebrate predators are known to affect planktonic communities and reduce biodiversity in lakes, high densities of planktivorous stages of alien European perch (Perca fluviatilis) and the presence of carp (Cyprinus carpio) did not translate into non-stationary time series or declining trends for plankton in Lake Hume. However, the seasonal successions observed in the reservoir in different years did not conform well to the Plankton Ecology Group (PEG) model. Significant deviations of the Lake Hume successional pattern from the PEG model included maxima for phytoplankton abundance being in winter and the presence of a clear water phase without large zooplankton grazers. The instability of the water level in Lake Hume probably causes the dynamics of most planktonic populations to be less predictable, but did not initiate the declining trends that have been observed in some other Australian reservoirs. Both the PEG model and the present study suggest that hydrology is one of the major drivers of seasonal succession.

Factors affecting the phenology of the first brood of the sugar-cane froghopper Aeneolamia varia saccharina (Dist.) (Homoptera, Cercopidae) in Trinidad

1975 ◽  
Vol 65 (3) ◽  
pp. 359-372 ◽  
Author(s):  
A. B. S. King
Keyword(s):  
Adult Emergence ◽  
Dry Season ◽  
Soil Conditions ◽  
Factors Affecting ◽  
Expected Time ◽  
Short Period ◽  
Incubation Periods ◽  
Close Relationship ◽  
Dry Soil ◽  
Predictive Relationship

AbstractThe size and occurrence of the first brood of adults of Aeneolamia varia saccharina (Dist.) are examined in relation to the pattern of egg eclosion and rainfall. The proportion of eggs hatching within a month of oviposition in the laboratory (short-period eggs) decreased from over 90% in August to less than 20% in January, but the incubation periods of the remaining, long-period eggs were longest in those laid during October and November. The overall hatching distributions tended to be bimodal with most eggs hatching during the early months of the year under moist conditions at 26°C. Dry soil conditions delay eclosion, and eggs obtained from fields during the dry season and then incubated under moist conditions tended to hatch at the normally expected time of the first rains in May. The numbers of eggs expected to produce the first brood, computed from laboratory hatching data and estimates of the numbers and fecundities of froghoppers during the second, third and fourth broods, were less than the actual numbers sampled just before the first rains. There was a close relationship between the first rainfall of over one inch within 48 h and adult emergence 27 and 34 days later, and 85% of field egg populations in May had hatched and/or died by the week after the first rains. However some variation in the date of their occurrence accounted for non-synchrony of first broods over the region. The numbers of diapause eggs in fields sampled during the dry season failed to give a good predictive relationship with first brood adult populations, probably because of density dependent mortality of eggs or hatchling nymphs.

Model Test Study on Embankment Instability Induced by Rapid Drawdown of Water Level at Yellow River Downstream

2010 ◽  
Vol 160-162 ◽  
pp. 750-755
Author(s):  
Yu Kun Zhao ◽  
Ji Hong Yang ◽  
Qing An Li
Keyword(s):  
Water Level ◽  
Model Test ◽  
Yellow River ◽  
Digital Camera ◽  
Hydrodynamic Pressure ◽  
Test Methods ◽  
Test Study ◽  
Short Period ◽  
Water Lever ◽  
Water Level Decline

Rapid drawdown of water level is one of the most important factors that influencing the embankment stability. Based on the principle of geomechanical model test and hydroaulic model test methods, the model test was performed to study Yellow River downstream embankment instability induced by rapid drawdown of water level. The slope models with geometric scale of 1:25, 1:45, 1:62.5 were constructed in the transparent plexiglass model box with 1.6m long, 0.8m wide and 0.6m high. Changes on the slope were recorded during water level decline at different velocity by digital camera and slope tracer etc. The model test results showed that during the rapid drawdown process, there was only small cracks and not slippage in advance; when the water level dropped to a certain height, the sliding distance increased suddenly, which showed that the rate of water level decline was behind the river water, and the slope weight and downslope hydrodynamic pressure by the saturation line in slope body were higher than water lever exceeds the sliding force in a very short period of time, which caused landslide; after the sliding body appearing, slide was continuous and not mutation.

scholarly journals The Analysis of the Concrete Gravity Dam’s Foundation Uplift Pressure under the Function of Typhoon

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Kai Zhu ◽  
Chongshi Gu ◽  
Jianchun Qiu ◽  
Hao Li
Keyword(s):  
Statistical Model ◽  
Water Level ◽  
Multiple Correlation Coefficient ◽  
Concrete Gravity Dam ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Quantum Genetic Algorithm ◽  
Uplift Pressure ◽  
Short Period ◽  
Dam Safety Monitoring

How to evaluate the seepage safety status of the concrete gravity dam under the function of short-period heavy rainfall and the possible historical extreme reservoir water level during typhoon is an important issue considering the dam safety-monitoring. Based on analysis of the monitoring series of the foundation uplift pressure, this paper assumed the influential process of antecedent reservoir water level and rainfall as a process of normal distribution and introduced the mutation factor to reflect the uprush feature of uplift pressure under the function of high-influential typhoon. Moreover, the corresponding hysteresis days and influential days of the model are optimized with quantum genetic algorithm (QGA) to raise the fitting and prediction accuracy. It is verified that the new statistical model for fitting can obtain higher multiple correlation coefficient (0.972) compared with the traditional statistical model (0.925) and could also perfectly predict the uprush feature of the pressure during the typhoon, which is of certain theoretical and practical application value in the future.

Selecting velocity fields in urban pluvial floods from pre-calculated data

2020 ◽  
Author(s):  
Robert Sämann ◽  
Thomas Graf ◽  
Insa Neuweiler
Keyword(s):  
High Resolution ◽  
Water Level ◽  
Mean Square Error ◽  
Nearest Neighbor ◽  
Calculated Data ◽  
Velocity Fields ◽  
Water Levels ◽  
Mean Square ◽  
Run Off

<p><span>Early warning systems for floods in urban areas should forecast water levels and damage estimation to protect vulnerable regions. To estimate the danger of a flood for buildings and people, the energy of the flood has to be taken into account additionally to the water level. The energy is related to the flow velocity. For directing rescue workers or trace spreading of contaminants through flooded streets, a high resolution of the water’s energy in space and time is required. Direct numerical run-off calculation is too slow for a flood forecast in time. Therefore a database with pre-calculated events is needed and a method to select the water levels and velocity fields that are similar to a forecasted rain event. </span></p><p><span>We present a method, how to create a real-time forecast based on pre-calculated data. The selection and weighting of the pre-calculated data is based on the precipitation pattern in the flood region. A nearest neighbor approach is applied to find water levels and velocity fields from a database that are similar to the forecasting event. For the ranking of similarity, different new metrics are compared against each other. The quality of the metrics is tested with a new approach of comparing velocity fields on the surface and in the pipe system. Considering both domains is crucial for understanding the complex dynamic flow paths on the surface. An urban catchment of 5 km² with high resolution (~3 m³) triangular surface mesh and connected drainage system is used for a hydrodynamic run-off simulation. The 1D-2D coupled software HYSTEM EXTRAN is used to generate the water levels and velocity fields for strong rainfall events of the past 20 years. More than 900 events with a duration between 15 minutes and 24 hours and return periods between 10 and 100 years were calculated and stored as the “pre-calculated” dataset.</span></p><p><span>For comparing two events, the mean square error is calculated between the precipitation patterns with different approaches to select the start index and number of intervals. This number depends on the hydraulic response time, the temporal resolution and the length of the reference pattern. The quality of the nearest neighbor selection is quantified using the Nash–Sutcliffe model efficiency coefficient of pipe flow and the root mean square error of water level and velocity in significant surface cells. Additionally, the transport paths of artificial contamination spills are compared between the events to show the reproducibility of velocity fields for each metric. </span></p><p><span>Results show that the reaction time and the wetting state of the surface is very important. Single cell values correspond well between a forecasted and a dataset event. However, complex transport paths have a very high variability that is not reproducible with similar events. Further research is required to clarify if this is a result of the random walk approach or of the injection time of the particles. </span></p>

The response of the carrot to water supply and fertilizer on a gravel soil

1944 ◽  
Vol 34 (2) ◽  
pp. 82-87 ◽  
Author(s):  
Rowland Marcus Woodman ◽  
Delphine Ainslie Johnson
Keyword(s):  
Water Supply ◽  
Water Level ◽  
Gravel Soil ◽  
Additional Water ◽  
Total Crop ◽  
The Mean ◽  
Complete Fertilizer

An experiment designed to show the effects of a complete fertilizer and of water applied extra to the rainfall on the yield of carrots grown on a gravel soil in good heart, has demonstrated that the fertilizer mixture was entirely without effect. The interaction water level × fertilizer was not significant, so that the increases in yield of carrot roots (increases which were 61·46 and 127·5 ― above the mean of the plots for rainfall only in the case of the total crop, and 61·73 and 111·5 ― for ware carrots, for 3 and 6 in. of water extra to the rainfall, respectively) were due entirely to the additional water. The response in yield of the roots of the total crop and of ware to the second application of extra water showed no falling off compared with the response to the first extra application. There was evidence to prove that additional water caused heavier infestation of the roots by aphis.

The causes of buoyancy in eggs of marine teleosts

1987 ◽  
Vol 67 (1) ◽  
pp. 169-182 ◽  
Author(s):  
J. C. A. Craik ◽  
S. M. Harvey
Keyword(s):  
Amino Acids ◽  
Water Content ◽  
Free Amino Acids ◽  
Free Amino ◽  
Sea Water ◽  
Inorganic Ions ◽  
Dry Weight ◽  
High Water Content ◽  
Demersal Eggs ◽  
Pelagic Eggs

Pelagic eggs and demersal eggs of teleosts both have osmotic concentrations similar to that of the maternal body fluids, less than half that of sea water. Pelagic eggs are buoyant because they contain such large quantities of this dilute aqueous fluid. While the demersal eggs of teleosts usually have a water content of 60–70%, the buoyant pelagic eggs of marine teleosts such as whiting, Norway pout, saithe, cod, haddock, turbot, dab, plaice, witch, long rough dab, halibut and sole typically have a very high water content (ca. 92 %) and a lipid content of 10–17% of egg dry weight. About 90% of the buoyancy of such eggs in sea water is caused by their high aqueous content, only about 10% being caused by lipid. The buoyant eggs of grenadier and ling have large oil globules and higher lipid contents, 27 and 35 % of dry weight respectively. Nevertheless, most of their buoyancy is provided by their high aqueous contents (89 and 81 % water). The high water content of pelagic eggs is brought about by a massive influx of water into the oocytes during meiotic maturation (ripening) after vitellogenesis but before ovulation. In cod and plaice, ripening is accompanied by a four- to five-fold increase in both water content and free amino-acids, and by a large influx of both potassium and sodium. In cod, free amino-acids contribute much more than these inorganic ions to the water influx and to the total osmotic concentration of the mature egg, but in plaice the relative contribution of inorganic ions approaches that of the free amino-acids.

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