Colonization of wood substrates by the aquatic xylophage Xylotopus par (Diptera: Chironomidae) and a description of its life history

1987 ◽  
Vol 65 (9) ◽  
pp. 2280-2286 ◽  
Author(s):  
Michael G. Kaufman ◽  
Robert H. King
Keyword(s):  
Growth Period ◽  
Biomass Accumulation ◽  
Developmental Rate ◽  
Wood Block ◽  
Accelerated Growth ◽  
Density And Biomass ◽  
Relationship Of ◽  
Number Of Individuals ◽  
Summer Growth ◽  
Introduced Substrates

Xylotopus par populations were monitored in a central Michigan stream during the summer growth period by sampling two types of indigenous logs and four types of introduced wood block "baits." Populations of larvae in the two indigenous logs were very similar over the course of the study with regard to number of individuals, biomass accumulation, developmental rate, and spatial distribution within colonized areas. Populations of larvae in the wood baits followed trends in density and biomass accumulation that differed between wood types. A positive relationship of the parameters with substrate softness was observed. Populations of larvae in the introduced wood baits developed faster than those in indigenous logs, with portions of the bait-inhabiting populations apparently able to complete development during the summer. Populations in indigenous logs normally require a full year for development and the accelerated growth in the "fresh," introduced substrates indicates a plastic phenology that allows X. par to exploit wood of variable quality. A prerequisite for terrestrial decay in determining wood suitability for X. par is also discussed.

The Relationship of Learning Rate and Developmental Rate

1959 ◽  
Vol 26 (2) ◽  
pp. 68-69 ◽  
Keyword(s):  
Developmental Rate ◽  
Learning Rate ◽  
Relationship Of ◽  
The Relationship

Summer–winter transitions in Antarctic ponds I: The physical environment

2011 ◽  
Vol 23 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Ian Hawes ◽  
Karl Safi ◽  
Brian Sorrell ◽  
Jenny Webster-Brown ◽  
David Arscott
Keyword(s):  
Physical Environment ◽  
Average Rate ◽  
Growth Period ◽  
Ice Formation ◽  
Freezing Process ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Continental Antarctica ◽  
The Antarctic ◽  
Summer Growth

AbstractMeltwater ponds are one of the most widespread aquatic habitats in ice-free areas of continental Antarctica. While most studies of such systems occur during the Antarctic summer, here we report on ice formation and water column attributes in four meltwater ponds on the McMurdo Ice Shelf during autumn, when they went from ice-free to > 80 cm thickness of ice. Ice thickness grew at an average rate of 1.5 cm d-1 in all ponds and as ice formed, salts and gases were excluded. This resulted in conductivity rising from 3–5 to > 60 mS cm-1 and contributed to the ebullition of gases. Incorporation of gas bubbles in the ice resulted in a high albedo and under-ice irradiance declined faster than incident, the former falling below 1 W m-2 (daily average) by early April. After two months of ice formation, only 0–15% of the volume of each pond was still liquid, although this represented 5–35% of the pond sediment area, where much of the biological activity was concentrated. We suggest that the stresses that the freezing process imposes may be as important to structuring the biotic communities as those during the more benign summer growth period.

SWINE PERFORMANCE ENHANCEMENT WITH COOLING AS INFLUENCED BY SUMMER GROWTH PERIOD AND WEATHER

2013 ◽  
Author(s):  
T. C. Bridges ◽  
L. W. Turner ◽  
R. S. Gates and D. G. Overhults
Keyword(s):  
Performance Enhancement ◽  
Growth Period ◽  
Summer Growth

scholarly journals Zooplankton body-size structure and biomass in tropical floodplain lakes: relationship with planktivorous fishes

2012 ◽  
Vol 23 (3) ◽  
pp. 217-228 ◽  
Author(s):  
Claudia Costa Bonecker ◽  
Fábio de Azevedo ◽  
Nadson Ressyé Simões
Keyword(s):  
Chlorophyll A ◽  
Size Structure ◽  
Zooplankton Community ◽  
Dry Season ◽  
Size Class ◽  
Fish Density ◽  
Upper Paraná River Floodplain ◽  
Negative Effect ◽  
Density And Biomass ◽  
Number Of Individuals

AIM: This study evaluated whether the size structure of the zooplankton community, as analyzed from density and biomass, would be influenced by bottom-up and/or top-down mechanisms in isolated lakes from the Upper Paraná River floodplain during dry and rainy periods. METHODS: zooplankton individuals were classified as: smaller-sized (<300 µm), intermediate-sized (301 to 600 µm) and larger-sized (greater than 601 µm). Fish abundance was indexed by the capture per unit effort (CPUE; number of individuals.100 m-2). Productivity was measured as chlorophyll-a. RESULTS: The size structure of the community did not show significant relationship with chlorophyll-a concentration (p > 0.05), but it was associated to the increase in fish density during the dry season. The percentage of individuals with intermediate sizes (301 to 600 µm), in both biomass and density, was positively related to the fish density (R2 = 0.78 for biomass, p < 0.001; R2 = 0.58 for density, p = 0.02), indicating an increase numerical and mass of this size class with fish density. The percentage of larger-sized individuals (>600 µm), in both biomass (R2 = 0.86, p < 0.001) and density (R2 = 0.69, p = 0.02) was negatively associated to the fish density, reflecting a decrease of this size class with the increase of fish in the environment. CONCLUSIONS: This can implicate a direct and negative effect of the predation on larger-sized individuals, as well as indirect and positive effect on the intermediate-sized individuals, but it occurred only on dry season. Thus, different mechanisms act on the size structure of the zooplankton community between dry and rainy season.

The Study of the Different Seedling Organs Biomass Models on Introduction Fast-Growing Poplar

2014 ◽  
Vol 962-965 ◽  
pp. 695-698
Author(s):  
Pei Yong Lian ◽  
Zhi Gang Yan
Keyword(s):  
Change Process ◽  
Growth Period ◽  
Biomass Accumulation ◽  
Analysis Method ◽  
Seasonal Growth ◽  
Multivariate Statistical ◽  
Biomass Models ◽  
Nursery Stock ◽  
Statistical Analysis Method ◽  
Poplar Seedlings

With the introduction of four poplar varieties as the research object, in the growth period, the density of 30cm × 40cm biomass of seedlings were studied. The biomass of different organs of different varieties at seedling stage in different periods of change process, to explore the various organs of poplar seedlings seasonal growth model and biomass accumulation, using multivariate statistical analysis method, the various organs biomass model was established on various poplar species, it can play a guiding role on nursery stock production.

Unexploited Percid Populations of West Blue Lake, Manitoba, and their Interactions

1977 ◽  
Vol 34 (10) ◽  
pp. 1655-1669 ◽  
Author(s):  
J. R. M. Kelso ◽  
F. J. Ward
Keyword(s):  
Yellow Perch ◽  
Perca Flavescens ◽  
Growth Period ◽  
Older Individuals ◽  
Behavioral Differences ◽  
Food Items ◽  
Blue Lake ◽  
Early Fall ◽  
Summer Growth ◽  
Main Food Item

West Blue Lake, Manitoba, essentially unaffected by man, sustains populations of yellow perch, Perca flavescens, and walleye, Stizostedion vitreum vitreum, which interact in two fundamental ways: perch are a major source of energy for walleye and the two species share common food organisms.Perch adults, juveniles and fry generally contributed 80–90% of the energy required for the annual walleye production (340 kg) and, on the basis of conversion experiments, provided for at least 1.7 kg∙ha−1 of the observed production of 2.1 kg∙ha−1. The brief summer growth period, combined with moderate mortality, caused biomass to reach a maximum in early fall at which time production ceased.Although walleye utilized yellow perch as its basic energy supply, behavioral differences tended to offer protection to juvenile and adult perch. Walleye were active at night, whereas older perch w ere inactive. Age 0 perch, during their epilimnetic phase, on the other hand, were active at night and vulnerable to walleye predation providing at least 18% of the observed walleye production.Walleye and yellow perch shared the same food resources although at different times and to different degrees. This competition was most intense between walleye (> 25 cm) and adult perch (> 12 cm). A main food item shared was amphipods. Most other food items (sticklebacks, mayflies, crayfish) were also shared but none in equal proportions by the two percids.Neither of the percid species showed a preponderance of older individuals and both showed evidence of strong and weak year-classes — walleye to a greater degree. Also, for walleye at least, production was only 2.1 kg∙ha−1, and biomass appeared to be stable, approximately 900 kg. Growth for both species was less than most other percid communities and was restricted to a brief, ≈ 80 day, period. Key words: unexploited, yellow perch, walleye, feeding, behavior, production, population structure

Branching diffusion processes in population genetics

1976 ◽  
Vol 8 (04) ◽  
pp. 659-689 ◽  
Author(s):  
Stanley Sawyer
Keyword(s):  
Random Fields ◽  
Diffusion Processes ◽  
Migration Process ◽  
Expected Number ◽  
Explicit Formulas ◽  
Limit Laws ◽  
The Mean ◽  
Relationship Of ◽  
Number Of Individuals ◽  
Neutral Mutation Rate

A branching random field is considered as a model of either of two situations in genetics in which migration or dispersion plays a role. Specifically we consider the expected number of individualsNAin a (geographical) setAat timet, the covariance ofNAandNBfor two setsA, B, and the probabilityI(x, y, u) that two individuals found at locationsx, yat timetare of the same genetic type if the population is subject to a selectively neutral mutation rateu.The last also leads to limit laws for the average degree of relationship of individuals in various types of branching random fields. We also find the equations that the mean and bivariate densities satisfy, and explicit formulas when the underlying migration process is Brownian motion.

Study on the Interaction of Urban Planning Factors and Traffic Mobility in Gifu City by Using Historical Map, Statistics and Person Trip Survey Data

2012 ◽  
Vol 253-255 ◽  
pp. 1950-1955
Author(s):  
Min Guo ◽  
Fumitaka Kurauchi
Keyword(s):  
Urban Planning ◽  
Road Network ◽  
Growth Period ◽  
Developed Countries ◽  
Economic Prosperity ◽  
Rapid Urbanization ◽  
Late 20Th Century ◽  
Land Use Development ◽  
Relationship Of ◽  
The Relationship

Rapid urbanization and growing economic prosperity had brought a higher rate of motorization in developed countries and now in developing countries also. History can provide valuable information and lessons on the interplay of factors that shape urban growth and development. This study examines changes in urban planning factors especially in transportation system and traffic mobility of Gifu City during the late 20th century when Japan was in the high economic growth period. And by looking at the result, in Gifu, with development of motorization, as the same time as policy planning was made that attached importance to construct road network and the withdrawal of city tram, the land use development was also focused in surrounding area and suburban area. As the result, Motorization grew more and more in Gifu city and Gifu city is being plagued by the doughnut phenomenon. It is important to find the relationship of urban planning factors to give experience for future urban planning and transport planning.

scholarly journals Relationship of Epiphytic Growth of Mycosphaerella citri to Greasy Spot Development on Citrus and to Disease Control with Fenbuconazole

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 186-192 ◽  
Author(s):  
S. N. Mondal ◽  
L. W. Timmer
Keyword(s):  
Disease Control ◽  
Rainy Season ◽  
Exposure Period ◽  
Rough Lemon ◽  
Trap Plants ◽  
Relationship Of ◽  
Summer Growth ◽  
Ascospore Production ◽  
Citrus Trees

Greasy spot, caused by Mycosphaerella citri, produces foliar lesions and severe defoliation of citrus trees. Ascospore production and deposition by M. citri, development of epiphytic growth, and symptoms were monitored on grapefruit trees in the field and on rough lemon trap plants for 2 years. Ascospore production and deposition peaked in April to May both years. However, epiphytic mycelium did not develop extensively until the summer rainy season was well underway in July. Some epiphytic growth and symptoms formed on trap plants placed in the grove for 2-week periods throughout the year. In the summer, epiphytic growth was apparent 15 days after the exposure period, and symptoms appeared about 60 days after exposure, but development was much slower in cooler and drier months. One or two fenbuconazole applications before the development of epiphytic mycelium in July completely controlled greasy spot on spring growth leaves for 12 to 18 months. Applications in July or August were less effective. Epiphytic mycelium developed more rapidly on summer growth; therefore, fungicide applications need to be timed more precisely.

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