Larval and pupal microhabitat selection by Simulium truncatum Lundström, S. rostratum Lundström, and S. verecundum AA (Diptera: Simuliidae)

1993 ◽  
Vol 71 (2) ◽  
pp. 358-367 ◽  
Author(s):  
John W. McCreadie ◽  
Murray H. Colbo
Keyword(s):  
Water Depth ◽  
Stream Velocity ◽  
Microhabitat Selection ◽  
Larval Size ◽  
Maximum Abundance ◽  
Preference Curve ◽  
Peak Abundance

Larval and pupal microhabitat selection by the cytospecies Simulium truncatum Lundström, S. rostratum Lundström, and S. verecundum AA was investigated. Last-instar larvae of S. truncatum and S. rostratum selected different microhabitats as shown by their response to velocity, depth, and outlets. Optimal stream velocity for larval S. truncatum and S. rostratum was estimated as 0.36 and 0.69–0.73 m/s, respectively. The microdistribution of S. truncatum showed a parabolic response to outflows with peak abundance occurring between 10.5 and 16.0 m from outlets. The distance-preference curve for S. rostratum was the complete inverse of that for S. truncatum, with maximum abundance of S. rostratum occurring immediately below and 20 m removed from the outlet. Abundance of larval S. truncatum decreased exponentially with depth (0.03–0.34 m), whereas the microdistribution of S. rostratum and a mixed 5. rostratum/S. verecundum AA population was not influenced by water depth (0.03–0.19 m). The microdistribution of pupae was similar to that of last-instar larvae for both S. truncatum and S. rostratum. Although larval microdistribution was influenced by velocity (S. truncatum, S. rostratum) and depth (S. truncatum), it was not possible to explain these patterns in relation to larval size.

Factors determining the peak abundance of Metopolophium dirhodum (Homoptera: Aphididae) on cereals

1991 ◽  
Vol 81 (1) ◽  
pp. 57-64 ◽  
Author(s):  
A. Honěk
Keyword(s):  
Population Growth ◽  
Host Plant ◽  
Growth Rates ◽  
Plant Size ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Metopolophium Dirhodum ◽  
Population Growth Rates ◽  
Maximum Abundance ◽  
Peak Abundance

AbstractFrom 1986 to 1989, the factors that determined the abundance of Metopolophium dirhodum (Walker) on cereals were studied in western Czechoslovakia. Forty seven sites were selected within cereal fields, mainly of winter wheat. Host plant size and leaf area varied between sites. The maximum abundance of M. dirhodum per tiller varied annually and with host plant stature. The main factor determining maximum abundance was the length of time for which the aphid population grew. M. dirhodum populations differed both in the time of the onset and termination of their growth. On stunted plants population growth started, with little variation, 200 day degrees later than on well developed plants. Within years, nearly all populations ceased growing simultaneously. In years of low or medium aphid abundance it was 40 to 90 day degrees earlier than in aphid outbreak years, and this extension of the population growth was the principal cause of the outbreak. Population growth rates varied slightly with plant quality and differed little between years. They were not important factors determining maximum abundances. 55–75% of the aphids occupied the flag leaves. The lower leaves of well developed plants were more heavily populated than nutritionally and water stressed smaller plants. The population growth rates on particular leaves were related to leaf nitrogen content, but not water content. A relationship for calculating the maximum abundances from a census made during the middle phase of population growth was proposed.

Risk of parasitism and microhabitat selection in juvenile sticklebacks

1989 ◽  
Vol 67 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Robert Poulin ◽  
Gerard J. FitzGerald
Keyword(s):  
Spatial Distribution ◽  
Water Depth ◽  
Laboratory Experiments ◽  
Gasterosteus Aculeatus ◽  
Infected Fish ◽  
Microhabitat Selection ◽  
Intensity Of Infection ◽  
Microhabitat Distribution

In laboratory experiments, we tested the following hypotheses: (i) that juvenile threespine (Gasterosteus aculeatus) and blackspotted (Gasterosteus wheatlandi) sticklebacks face higher risks of parasitism by the ectoparasite Argulus canadensis in shallow, vegetated microhabitats and (ii) that they can alter their microhabitat distribution in response to parasites. Reducing water depth increased the number of parasites per infected fish in G. aculeatus and increased the percentage of G. wheatlandi infected. For both species, intensity of infection and percentage of fish infected were greater among fish inhabiting vegetated microhabitats than among fish living in open microhabitats. In the absence of fish, A. canadensis swam near the bottom and in the vegetation. Fish of both species swam near the bottom in the absence of the parasites, but swam near the surface in the presence of parasites. Without parasites, both species of fish preferred to swim in vegetation. With parasites present, the spatial distribution of G. aculeatus changed only slightly, whereas G. wheatlandi became evenly distributed between open and vegetated microhabitats. These results suggest that microhabitat selection by juvenile sticklebacks may serve to reduce the risk of parasitism.

Further studies of plankton ecosystems in the eastern Indian Ocean. VIII. Seasonal, diurnal, and latitudinal variations in abundance of Euthecosomata along the 110°E. meridian

1977 ◽  
Vol 28 (5) ◽  
pp. 663 ◽  
Author(s):  
M Sakthivel
Keyword(s):  
Indian Ocean ◽  
Water Mass ◽  
Eastern Indian Ocean ◽  
The South ◽  
Subtropical Water ◽  
Maximum Abundance ◽  
Tropical Water ◽  
Nocturnal Increase ◽  
Latitudinal Variations ◽  
Peak Abundance

A number of tropical euthecosomes reached peak abundance in the northern tropical water mass between 9 and 20� s. during the south-east monsoon (May-September), with the maximum abundance north of 14� N. Creseis virgula, Hyalocylis striata, Diacria quadridentata and Cavolinia longirostris were typical of this water mass. A few species such as Limacina lesueuri, Styliola subula, Cuvierina columnella and Cavolinia inflexa reached their maximum abundance at other times of the year in the subtropical water mass (south of 20�S.). Limacina bulimoides was at a maximum around 14�S. during September-November and there was a second maximum around 23�S. (in different months). Nocturnal increase in occurrence and abundance was observed in Limacina leseuri, L. helicina rangii, Clio pyramidata, C.p. lanceolata, Styliola subula, Cuvierina columnella, Diacria quadridentata and Cavolinia inflexa.

Comparison of the performance of oscillating water column devices based on arrangements of water columns

2020 ◽  
Vol 14 (3) ◽  
pp. 7082-7093
Author(s):  
Jahirwan Ut Jasron ◽  
Sudjito Soeparmani ◽  
Lilis Yuliati ◽  
Djarot B. Darmadi
Keyword(s):  
Wave Propagation ◽  
Water Column ◽  
Water Depth ◽  
Graphical Form ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Water Columns ◽  
Single Column ◽  
Parallel Arrangement

The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.

A Study of the Average Flow in Open Channel with Baffle Blocks Distributed Uniformly

10.29007/zx1w ◽  
2018 ◽  
Author(s):  
Dung Tien Tran ◽  
Anh Tuan Le ◽  
Hong Nhung Le ◽  
Viet Hung Ho
Keyword(s):  
Water Level ◽  
Water Depth ◽  
Open Channel ◽  
Block Size ◽  
Average Flow ◽  
Modelling Studies ◽  
Baffle Block

A study of average flow in open channel with baffle blocks distributed uniformly has been considered by using channel with varied slopes. In this article, experimental and modelling studies were introduced when the correlation between the water depth and baffle block size is significant. The objective of the work is to give the rudimentary relations between discharge and water level in the channels. When the water depth is large, the effect of bottom channel friction on the flow is relatively small. This paper also gives applications of the software ‘Telemac-2D’ to simulate the flow under different conditions.

PENDUGAAN EROSI DAN NERACA AIR EMBUNG DI WILAYAH PERBATASAN KABUPATEN BELU NUSA TENGGARA TIMUR

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Wahyu Widiyono
Keyword(s):  
Water Balance ◽  
Water Resource ◽  
Water Depth ◽  
Rainy Season ◽  
Water Reservoir ◽  
Water Shortage ◽  
Regional Government ◽  
Environment Management ◽  
Individual Number ◽  
Rainfall Volume

Embung as a man made water reservoir is one of methods to overcome the water shortage in the border area, Belu District, East Nusa Tenggara Province. A number of 27 embungs were built by Regional Government in this area. Embung water and environment management is the main problem to sustain water resource. The research to inventory and identify of vegetation, to predict erosion, to monitor water balance, and to optimize water utilization were conducted, in 2005-2008. The research was undertaken in Embung Leosama. Methods were survey, observation, monitoring and analysis. Results were: (1). There were 7 species and 90 individual number of tree; (2). Prediction of erosion was 97.383 ton/ha/year; (3). Water depth as indicator of embung water balance was decrease due to a little rainfall volume in rainy season 2006/2007; but it was increase in 2007/2008; (4). Embung water can be optimized for drinking cattle, horticulture, nursery and regreening irrigation.Key Words: embung, erosion, water balance.

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