Cycle de développement, croissance et production de Pisidium amnicum (Mollusca: Bivalvia) dans le Saint-Laurent (Québec)

1981 ◽  
Vol 59 (12) ◽  
pp. 2350-2359 ◽  
Author(s):  
B. Vincent ◽  
G. Vaillancourt ◽  
N. Lafontaine
Keyword(s):  
Population Dynamics ◽  
Sexual Maturity ◽  
Dry Weight ◽  
Mortality Rates ◽  
The Other ◽  
Annual Production ◽  
Bithynia Tentaculata ◽  
The Mean ◽  
Total Dry Weight ◽  
St Lawrence River

The population dynamics of Pisidium amnicum have been studied in one population of the St. Lawrence River over a 2-year period during which 19 samples were taken. The species can live up to 3 years and it is iteroparous; individuals generally attain sexual maturity after 1 year and they reproduce twice, once at 2 and once at 3 years of age. In adults, mortality is lower in winter than during the rest of the year and mortality rates are twice as high during the 1st year than during the 2nd year. Total dry weight (PT, in milligrams) is related to maximum length (L, in millimetres) according to the equation PT = 0.0283∙L3,80 and flesh dry weight (PC, in milligrams) is related to length as follows: PC = 0.007∙L3,18. The annual production to mean biomass (P/B) ratio is 1.4, the mean annual production being 1.298 mg/m2 of total dry weight and 107 mg/m2 of flesh weight. Comparing these results with those obtained for the gastropod Bithynia tentaculata in the same environment and at the same period of the year has shown that the growth of Pisidium amnicum is far less influenced by the temperature regime than that of the other species and that its production is at least 10 times lower.

Cycle de developpement, croissance et production de Sphaerium striatinum (Bivalvia : Pisidiidae) dans le Saint-Laurent (Québec)

1984 ◽  
Vol 62 (12) ◽  
pp. 2418-2424 ◽  
Author(s):  
B. Vincent ◽  
N. Lafontaine
Keyword(s):  
Life Span ◽  
Dry Weight ◽  
Individual Growth ◽  
Total Production ◽  
Maximum Increase ◽  
Total Growth ◽  
The Mean ◽  
Total Dry Weight ◽  
Individual Size ◽  
St Lawrence River

The life cycle of a population of Sphaerium striatinum in the St. Lawrence River (Québec) was studied over a 13-month period. This species has a life-span of 2–3 years and is iteroparous; individuals start producing young at the age of 1 year. Growth in length reached a maximum of 0.010 mm/day between the ages of 0 and 8 months, while the maximum increase in weight occurred during the 2nd year, representing 46% of the total growth. The mean population density was 737 individuals/m2 for the months of May to November 1979; the mean biomass values were 20.6 and 2.1 g/m2, respectively, for total dry weight and dry weight minus shells. Young of the year and yearlings combined represent 96% of the total production, which was calculated to be 14.9 g (total dry weight)/m2. The production to biomass ratio (P/B) decreased with the age of a generation and was 0.72 for the entire population. A comparison of our results with those in the literature indicates that individual growth rates are slower in the St. Lawrence population and that larvae, adults, and reproductive individuals are smaller in size; however, the population's life expectancy is greater. This longer life-span and smaller individual size, along with a delayed sexual maturity, can be explained by the environmental temperature regime.[Journal translation]

The population dynamics of metacercariae of Apatemon gracilis (Trematoda: Digenea) in three species of lake-dwelling leeches

Parasitology ◽  
1986 ◽  
Vol 93 (3) ◽  
pp. 517-530 ◽  
Author(s):  
S. M. Spelling ◽  
J. O. Young
Keyword(s):  
Population Dynamics ◽  
Relative Density ◽  
Sexual Maturity ◽  
Egg Production ◽  
Seasonal Pattern ◽  
Distinct Pattern ◽  
The Other ◽  
Mean Intensity ◽  
Density Values ◽  
Host Mortality

SUMMARYMonthly samples of the leeches Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis were taken over a two-year period from an eutrophic, English lake to detect metacercariae of the trematode, Apatemon gracilis. In each cohort of each of the three leeches, prevalence was low in young individuals, rose to a peak in autumn/winter, and then declined until the cohort had almost died out; in E. octoculata and H. stagnalis a final brief increase occurred. Mean intensity and relative density values followed a similar seasonal pattern of change to that of prevalence in these last two species, but in G. complanata values fluctuated irregularly with no distinct pattern. The frequency distribution of the parasite in G. complanata was highly over-dispersed, but less so in the other two species. Infected E. octoculata reached sexual maturity. The parasite reduced egg production in G. complanata and H. stagnalis, but only by maximum values of 2·5 and 9% respectively. This reduction in fecundity is low compared to the subsequent high mortality, at 95% or more, of newly recruited young from as yet unidentified causes. Parasite-related host mortality was difficult to assess in young leeches, but there was some evidence for its occurrence in older leeches of E. octoculata and H. stagnalis. However, this is unlikely to play a prominent role in the control and regulation of lacustrine leech populations.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

scholarly journals Valorization of Vineyard By-Products to Obtain Composted Digestate and Biochar Suitable for Nursery Grapevine (Vitis vinifera L.) Production

Agronomy ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 420 ◽  
Author(s):  
Domenico Ronga ◽  
Enrico Francia ◽  
Giulio Allesina ◽  
Simone Pedrazzi ◽  
Massimo Zaccardelli ◽  
...  
Keyword(s):  
Vitis Vinifera ◽  
Dry Weight ◽  
The Other ◽  
Vitis Vinifera L ◽  
Growing Media ◽  
Shoot Dry Weight ◽  
Planting Material ◽  
Dry Biomass ◽  
Total Dry Weight ◽  
By Products

Although compost and biochar received high attention as growing media, little information is available on the potential of vineyard by-products for the production and use of composted solid digestate (CSD) and biochar (BC). In the present study, two experiments are reported on CSD and BC mixed with commercial peat (CP) for grapevine planting material production. Four doses (0, 10%, 20%, 40% vol.) of CSD and BC were assessed in the first and second experiment, respectively. CSD mixed at a dose of 10% recorded the highest values of shoot dry weight (SDW) and a fraction of total dry biomass allocated to shoot (FTS), both cropping bench-graft and bare-rooted vine. On the other hand, CSD mixed at a dose of 40% displayed the highest values of SDW and FTS, cropping two-year-old vine. BC used at a dose of 10% improved SDW, root dry weight, total dry weight, FTS, shoot diameter, and height on bare-rooted vine. The present study shows that CSD and BC, coming from the valorization of vineyard by-products, can be used in the production of innovative growing media suitable for nursery grapevine production. Further studies are needed to assess the combined applications of CSD and BC in the same growing media.

Production and Population Dynamics of the Crayfish Orconectes virilis in Three Michigan Lakes

1977 ◽  
Vol 34 (11) ◽  
pp. 2030-2040 ◽  
Author(s):  
Walter T. Momot ◽  
Howard Gowing
Keyword(s):  
Population Dynamics ◽  
Growth Rates ◽  
Age Groups ◽  
Mortality Rates ◽  
Reproductive Age ◽  
Annual Production ◽  
Effective Density ◽  
Orconectes Virilis ◽  
Brood Stock ◽  
Density Dependent

Fluctuations in mortality rather than in growth rates produced most of the year-to-year differences in biomass accumulation of three different populations of the crayfish Orconectes virilis. Yearly biomass changes resulted from density-dependent control of mortality and fecundity during certain portions of the life cycle. Density-dependent changes in mortality rates controlled population size for adults in all lakes and for young-of-the-year in two of the three study lakes. Growth rates were much less responsive to fluctuating densities. Disparity between the number of ovarian and attached eggs increased as density of age I+ crayfish increased. This provided a strong density regulator on fecundity. Differences occurred in the number of recruits produced by a brood stock that survive to the end of the first growing season in the various lakes. Yet the number of females surviving to reproductive age 2 yr later was strongly regulated. Strong population regulation produced two female recruits of breeding age for every two–six parental breeding females. The high biomass and production levels of crayfish discovered in West Lost Lake in 1962–63 also occurred in the other area lakes. Higher but variable levels of recruitment resulted in larger standing crops and production in West Lost lake. This resulted from less effective density controls on the mortality rates of younger age-groups in that lake. Despite great variation in biomass of from 46 to 213 kg/ha and annual production from 60 to 142 kg/ha, the annual turnover ratio of the biomass was found to vary only between 0.94 and 1.53. Key words: crayfish, Orconectes virilis, population dynamics, annual production, Michigan lakes

Production of Chironomus, Procladius, and Chaoborus at Different Levels of Phytoplankton Biomass in Lake Memphremagog, Quebec–Vermont

1977 ◽  
Vol 34 (11) ◽  
pp. 2001-2007 ◽  
Author(s):  
R. M. Dermott ◽  
J. Kalff ◽  
W. C. Leggett ◽  
J. Spence
Keyword(s):  
Phytoplankton Biomass ◽  
Standing Stock ◽  
Dry Weight ◽  
Annual Production ◽  
The South ◽  
Algal Production ◽  
The North ◽  
Chaoborus Punctipennis ◽  
The Mean ◽  
Different Levels

In Lake Memphremagog a north–south gradient in algal production and biomass exists during the ice-free period, with highest production in the southern areas. In response, the mean annual benthic standing stock (dry weight) in the south basin was 2.8 times greater than in the north basin at comparable depth. Mean annual standing stock of Procladius denticulatus and Chironomus anthracinus were significantly (5.8 and 3.1 times, respectively) higher in the south, while that of Chaoborus punctipennus did not differ significantly between areas. Annual production of P. denticulatus was greater in the south (0.861 g/m2) than in the north (0.143 g/m2). Similarly for Chironomus anthracinus annual production was greater in the south (3.393 g/m2) than in the north (1.264 g/m2). Production of Chaoborus punctipennis was greater in the north (0.066 g/m2) than in the south (0.348 g/m2). P:B ratios were less variable. Key words: Lake Memphremagog, benthos, production, nutrient gradient, mortality

Reproduction et dynamique de population de la barbotte brune Ictalurus nebulosus (Le Sueur) dans la frayère de la rivière aux Pins, fleuve Saint-Laurent, près de Montréal (Québec)

1982 ◽  
Vol 60 (1) ◽  
pp. 31-39
Author(s):  
Gilles Harvey ◽  
Rejean Fortin
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Sexual Maturity ◽  
Total Mortality ◽  
Northern Pike ◽  
Spawning Activity ◽  
Brown Bullhead ◽  
Ictalurus Nebulosus ◽  
Dynamique De Population ◽  
St Lawrence River

Two trap nets set in Rivière aux Pins, near its confluence with the St. Lawrence River, permitted the capture and subsequent marking or tagging of adult brown bullhead for the study of their reproductive biology and population dynamics. Spawning activity is examined in relation to water temperature and water level which, in 1976 and 1977, was controlled by means of a log weir, in order to enhance northern pike reproductive success. The study of sex ratio, sexual maturity, gonadosomatic ratio, and fecundity served to characterize the Rivière aux Pins bullhead spawning population. The results of the captures, markings, taggings, and recaptures led to the evaluation of total mortality, several aspects of exploitation by sport fishing, movements, population density, biomass, production, and yield.

The effect of autotetraploidy in five varieties of subterranean clover (Trifolium subterraneum L.).

1954 ◽  
Vol 5 (3) ◽  
pp. 356 ◽  
Author(s):  
WM Hutton ◽  
JW Peak
Keyword(s):  
Moisture Content ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
The Other ◽  
Seed Setting ◽  
Plant Parts ◽  
Green Matter ◽  
Total Dry Weight

Induced autotetraploidy in the Dwalganup variety of subterranean clover (Trifolium subterraneum L.) resulted in total dry weight increases of 60 and 65.5 per cent. at flowering and maturity respectively. In the other four varieties the tetraploids had decreased yields of dry matter compared with the diploids, although the decreases for leaf weights at flowering were nonsignificant in Mount Barker and Tallarook, as was the total dry weight reduction in Tallarook at maturity. There were no significant differences between the diploids and tetraploids in percentage moisture content. When early development was stimulated by growth in a glass-house, the tetraploids of all varieties showed a significant increase in yield of green matter. The level of increased growth was maintained only in Dwalganup, and decreased in other varieties during flowering. An analysis was made of the way in which the different plant parts mere changed by tetraploidy. Where decreased growth occurred, the leaves and stems were coarser. In all varieties a reduced seed-setting followed autotetraploidy, although in Dwalganup the yield of seed per plant was not affected.

Production of Bareroot Roses Using Underground Drip Irrigation

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 474a-474
Author(s):  
U.K. Schuch ◽  
J. Karlik ◽  
J.O. Becker
Keyword(s):  
United States ◽  
Drip Irrigation ◽  
Dry Weight ◽  
Growing Season ◽  
The United States ◽  
Rosa Hybrida ◽  
The Other ◽  
Kern County ◽  
Total Dry Weight ◽  
The Rose

The majority of rose producers in Kern County, Calif., use furrow irrigation to produce ≈50% of the rose plants in the United States. Two experiments were conducted to test the feasibility of producing bareroot roses using underground drip irrigation. Three rose (Rosa hybrida) cultivars, `Dr. Huey', `Manetti', and `Pink Simplicity', were used in both experiments. In the first experiment, drip tape was placed at a depth of 10, 20, 30, or 40 cm. After one growing season, plants irrigated with drip tape at 10-cm depth produced less shoot and total dry weight than plants irrigated with tape placed between 20 and 40 cm. `Manetti' was the most vigorous cultivar and produced ≈70% more shoot and total dry weight than the other two cultivars. In the second experiment, the plants of the three cultivars were spaced 15, 20, or 25 cm apart within the row and irrigated with drip tape placed at 20-cm depth. Total dry weight increased linearly with increased spacing of plants within the row. `Manetti' and `Pink Simplicity' produced higher shoot and total dry weight than `Dr. Huey' plants.

SIMULATION MODEL FOR THE POPULATION DYNAMICS OF THE CARROT WEEVIL, LISTRONOTUS OREGONENSIS (LECONTE) (COLEOPTERA: CURCULIONIDAE)

1991 ◽  
Vol 123 (1) ◽  
pp. 63-76 ◽  
Author(s):  
D.X. Zhao ◽  
G. Boivin ◽  
R.K. Stewart
Keyword(s):  
Population Dynamics ◽  
Simulation Model ◽  
Mortality Rates ◽  
Egg Parasitoid ◽  
Adult Density ◽  
Larval Population ◽  
Listronotus Oregonensis ◽  
The Mean ◽  
Carrot Weevil ◽  
The Impact

AbstractA simulation model was developed for the population dynamics of a carrot weevil, Listronotus oregonensis (LeConte), population on muck-grown carrots. The model includes mortality rates of eggs, larvae, and pupae for different sowing dates of carrots. It also incorporates the overwintered adult density, the temperature-dependent growth rates of the above-mentioned life stages, the age-, temperature-, and phenology-dependent oviposition rates, and the impact of an egg parasitoid, Anaphes sordidatus (Girault), on egg mortality rates. Model output was evaluated by comparing simulated results with observed results on the seasonal totals and time of population peaks of the egg and larval populations. The mean percentage differences between the simulated and observed seasonal egg totals were 3.1 ± 0.66 (SE) in 1987 and 1988, and 4.2 ± 0.05 in 1989. They were not statistically different. The mean percentage differences between the simulated and observed seasonal larval totals were 10 ± 3.33 in 1987 and 1988 and 29.8 ± 0.66 in 1989. Independent data sets (i.e. field data in 1989) showed a significant increase in the simulation error of the larval population. Sensitivity analysis indicated that A. sordidatus had a large influence on the population dynamics of L. oregonensis.

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