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.

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.

Seasonal population dynamics and maturation of Neoechinorhynchus pungitius (Acanthocephala: Neoechinorhynchidae) infecting brook stickleback, Culaea inconstans, from Sioux Creek, Wisconsin, U.S.A.

1989 ◽  
Vol 67 (3) ◽  
pp. 590-595 ◽  
Author(s):  
Becky A. Lasee
Keyword(s):  
Population Dynamics ◽  
Egg Production ◽  
Seasonal Periodicity ◽  
Culaea Inconstans ◽  
Mean Intensity ◽  
Host Sex ◽  
Significant Difference ◽  
Brook Stickleback ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

Seasonal population dynamics and maturation of the acanthocephalan Neoechinorhynchus pungitius from brook stickleback (Culaea inconstans) were investigated. Stickleback were collected monthly at Sioux Creek, Wisconsin from April 1981 to May 1982 (excluding December, January, and February). Forty-seven percent (292/620) were infected with N. pungitius, which exhibited seasonal periodicity in prevalence, mean intensity, and maturation. Prevalence and mean intensities were lowest in summer and increased through autumn owing to recruitment of juvenile and immature worms. Prevalence and mean intensity reached their peaks by April and May, and N. pungitius infrapopulations were composed primarily of mature worms. Egg production began in May and continued throughout early summer. Neoechinorhynchus pungitius males appeared shorter lived than females, as the June and July infrapopulations were comprised mostly of females. Prevalence and mean intensity of N. pungitius increased as brook stickleback length increased. There was no significant difference between numbers of male and female fish infected or between mean intensity and host sex.

Abundance and stability of populations of chewing lice (Phthiraptera: Amblycera and Ischnocera) infesting two species of woodpeckers (Aves: Piciformes: Picidae)

2018 ◽  
Vol 150 (2) ◽  
pp. 180-189 ◽  
Author(s):  
Robert J. Lamb ◽  
Terry D. Galloway
Keyword(s):  
Population Dynamics ◽  
Sex Ratio ◽  
Population Variability ◽  
The Other ◽  
Population Stability ◽  
Mean Intensity ◽  
Chewing Lice ◽  
The Mean ◽  
Louse Species ◽  
Colaptes Auratus

AbstractThe annual abundance of chewing lice (Phthiraptera) was recorded from 1996 to 2015 in Manitoba, Canada, on two species of woodpeckers (Piciformes: Picidae). Yellow-bellied sapsuckers (Sphyrapicus varius (Linnaeus)) were infested with Menacanthus pici (Denny) (Amblycera: Menoponidae) and Penenirmus auritus (Scopoli) (Ischnocera: Philopteridae); northern flickers (Colaptes auratus (Linnaeus)) were also infested with M. pici, as well as two other Ischnocera, Penenirmus jungens (Kellogg) and Picicola porisma Dalgleish. The mean annual abundance varied from nine to 51 lice per bird for the four species, with prevalence, mean intensity, sex ratio, and nymphs per female also varying among louse species. Menacanthus pici populations on both hosts were unstable: abundance rose over two decades because of increasing prevalence, whereas the abundance of the other three louse species fluctuated around a mean. Population variability was similar for the lice on both hosts, with the metric, PV, ranging from 0.41 to 0.51 on a 0–1 scale, once the effect of the trend in abundance for M. pici had been removed. Although the population dynamics for species of lice on these two woodpeckers were distinct, inter-specific differences in population stability were less pronounced than observed in the few other species of bird lice studied in this way.

scholarly journals Kelkit Çayı (Tokat) Epilitik Diyatomeleri

2021 ◽  
Vol 9 (3) ◽  
pp. 470-475
Author(s):  
Metin Çağlar
Keyword(s):  
Relative Density ◽  
Water Samples ◽  
Similarity Index ◽  
The Other ◽  
Positive Effects ◽  
Epilithic Diatoms ◽  
Density Values ◽  
Agricultural Areas ◽  
Oxygen Measurements ◽  
Monthly Variations

In this study, monthly variations of epilithic diatoms in Kelkit Creek (Tokat) were studied from stone samples taken from two stations between March - December 2018: one station below the settlement area and the other one below agricultural areas. During this study, 18 taxa which belong to epilithic diatoms were recorded. Cymbella (3 taxa) and Nitzschia (3 taxa) were the diatoms mostly represented by the taxa, and Ulnaria ulna had the highest relative density recorded in both stations throughout the months. Sorensen Similarity Index was calculated as %56.41 between the two station diatoms. Also, temperature and dissolved oxygen measurements were done on the water samples taken from the stations. The measured variables were confirmed to make positive effects on the growth of diatoms in epiliton. Relative densities of the types of diatoms that were found in the epilithic flora were determined. In hand according to the results, the lowest relative density was recorded as 4.76 in march (Cymbella affinis) at Station 1 and 2.83 in march (Lindavia glomerata) at Station 2. Considering the highest relative density values, Navicula radiosa and Ulnaria ulna species were determined in december (13.56) at Station 1 and in march (9.43) for Ulnaria ulna at Station 2.

scholarly journals Population dynamics and performance of exotic versus indigenous chicken population in the selected districts of North Western Amhara, Ethiopia

2017 ◽  
Vol 1 (2) ◽  
pp. 90-99
Author(s):  
TILAHUN SISAY ◽  
KEFEYALEW ALEMAYEHU ◽  
ZEWDU WULETAW
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Production System ◽  
Egg Production ◽  
The Other ◽  
Indigenous Chicken ◽  
Other Hand ◽  
Chicken Population ◽  
And Performance ◽  
North Western

Sisay T, Alemayehu K, Wuletaw Z. 2017. Population dynamics and performance of exotic versus indigenous chicken population in the selected districts of North Western Amhara, Ethiopia. Trop Drylands 1: 90-99. Chicken in Ethiopia contributes, respectively, 98.5% and 99.2% of the national egg and chicken meat production. The total chicken population is estimated to be 56.87 million of which 95.86, 2.79 and 1.35% are indigenous, crossbred and exotic breeds, respectively. The objective of this paper was to quantify the population dynamics and performance of exotic versus indigenous chicken population in the selected districts of northwestern Amhara, Ethiopia. Banja and Burie districts and six Kebeles (three/district) were purposively selected. A total 180 respondents were selected by systematic and simple random sampling techniques for the survey. On the other hand, a total of 90 exotic chicken owners were purposively selected for monitoring and evaluation. GLM procedure of SAS (2002) was used to quantify the fixed effects of agroecology and breeds on the egg production performance. The results revealed that the majorities (91.12%) of distributed exotic chickens were kept in traditional/backyard production system. The overall mean egg production for exotic chickens (141.58±11.5) was too low. Significantly, the mean number of clutch per year per hen of Bovans Brown chicken was higher (4.51±0.11 days) than Bovans white breeds (3.5±0.10 days). Shortage at first egg was attained from midland of Koekoek chicken breed (5.38±0.24 months) than from highland (6.54±0.10 months) in Bovans Brown chicken. A highly significant difference in mortality was observed between Bovans Brown (89%) and Koekoek breed (32.4%), respectively due to traditional farmers' management practice. Distribution of different exotic chicken genotypes in the region is increasing from time to time for the upgrading of local chicken ecotypes but, the survival, productivity and population size of exotic and their crosses were too low. On the other hand, the population size of the indigenous chicken and its productivity remains almost constant. Causes of chick mortality in the study area were disease and predator which need to be considered in the development plan of the districts. This is due to the inappropriate production system, genotype, and management. Therefore, production and productivity will be increased through the selection of indigenous chicken ecotypes and crossbreed or upgrading by introduction exotic cocks, pullets and or fertile eggs of high egg producing strains with an appropriate production system and management in respective production system.

scholarly journals The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland

2021 ◽  
Vol 14 (1) ◽  
pp. 3-8
Author(s):  
Philip W. Tipping ◽  
Melissa R. Martin ◽  
Jeremiah R. Foley ◽  
Ryan M. Pierce ◽  
Lyn A. Gettys
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
Seedling Recruitment ◽  
Additional Treatment ◽  
Seed Rain ◽  
The Other ◽  
Melaleuca Quinquenervia ◽  
Biological Control Agents ◽  
Seedling Mortality ◽  
Sapling Growth

AbstractThe potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m−2. Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m−2, 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.

Population dynamics of Stenothoe valida Dana, 1852 (Amphipoda, Stenothoidae) at Cheongsapo beach of Busan, Republic of Korea

Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 413-429
Author(s):  
Ye Ji Lee ◽  
Won Gyu Park
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Sex Ratio ◽  
Brood Size ◽  
Ovigerous Female ◽  
Seasonal Pattern ◽  
Recruitment Rate ◽  
Republic Of Korea ◽  
Female Size ◽  
History Of

Abstract The population dynamics of Stenothoe valida Dana, 1852 were studied at Cheongsapo beach of Busan, Republic of Korea, from March 2019 to March 2020. Sampling was conducted once a month at low tide during spring tides. Specimens were grouped by the cephalic length at 0.025 mm intervals, and classified into four categories: females, ovigerous females, males and juveniles. The sex ratio, defined as females : total males + females, exceeded 0.5 during most of the study period. Brood size was significantly coupled with ovigerous female size. Two to four cohorts appeared at each study period. New cohorts occurred at almost every sampling except in the samples Jun-2, and Nov-2. Life span was estimated at 1-2 months. The juvenile ratio, the ratio of ovigerous females, and the recruitment rate estimated by FiSAT were commonly high in summer and winter. The life history of S. valida was not coupled with water temperature, but had a strong seasonal pattern.

Seasonal growth and duration of the parasitic life stage of the landlocked sea lamprey (Petromyzon marinus)

1995 ◽  
Vol 52 (6) ◽  
pp. 1257-1264 ◽  
Author(s):  
Roger A. Bergstedt ◽  
William D. Swink
Keyword(s):  
Seasonal Pattern ◽  
Life Stage ◽  
Petromyzon Marinus ◽  
Biomass Accumulation ◽  
Sea Lamprey ◽  
Gonadal Development ◽  
Adult Size ◽  
Sea Lampreys ◽  
Mean Size ◽  
Host Mortality

We used lengths and weights of 2367 live parasitic-phase sea lampreys (Petromyzon marinus) collected from Lake Huron, 1984–1990, to calculate their mean size at half-month intervals. Growth in weight was linear during June through September; increments averaged 11.1 g per half month. Growth increased sharply in October to several times the summer rate. We speculate that the increase in growth in October is explained partly by water temperature and partly by an increase in appetite related to the onset of gonadal development. The greater compression of biomass accumulation in autumn than has been previously demonstrated better explains the autumn pulse of sea lamprey induced host mortality. Based on the seasonal pattern of growth and on recaptures of marked sea lampreys, we conclude that landlocked individuals grow to adult size and mature in one parasitic growth year. Regressions of weight (grams) on total length (millimetres) differed significantly among months, and the season of collection must be considered in predicting weight from length.

scholarly journals Population dynamics of the pea crab Austinixa aidae (Brachyura, Pinnotheridae): a symbiotic of the ghost shrimp Callichirus major (Thalassinidea, Callianassidae) from the southwestern Atlantic

2011 ◽  
Vol 101 (1-2) ◽  
pp. 5-14 ◽  
Author(s):  
Douglas F Peiró ◽  
Fernando L Mantelatto
Keyword(s):  
Population Dynamics ◽  
Sandy Beach ◽  
Southwestern Atlantic ◽  
Recruitment Pattern ◽  
Size Frequency Distribution ◽  
Ghost Shrimp ◽  
Density Values ◽  
Pea Crab ◽  
Biological Aspects ◽  
The Mean

The Pinnotheridae family is one of the most diverse and complex groups of brachyuran crabs, many of them symbionts of a wide variety of invertebrates. The present study describes the population dynamics of the pea crab Austinixa aidae (Righi, 1967), a symbiont associated with the burrows of the ghost shrimp Callichirus major (Say, 1818). Individuals (n = 588) were collected bimonthly from May, 2005 to September, 2006 along a sandy beach in the southwestern Atlantic, state of São Paulo, Brazil. Our data indicated that the population demography of A. aidae was characterized by a bimodal size-frequency distribution (between 2.0 and 4.0 mm and between 8.0 and 9.0 mm CW) that remained similar throughout the study period. Sex ratio does not differ significantly from 1:1 (p > 0.05), which confirms the pattern observed in other symbiontic pinnotherids. Density values (1.72 ± 1.34 ind. • ap.-1) are in agreement with those found for other species of the genus. The mean symbiosis incidence (75.6%) was one of the highest among species of the Pinnotheridae family, but it was the lowest among the three studied species of the genus. Recruitment pattern was annual, beginning in May and peaking in July, in both years, after the peak of ovigerous females in the population (from March to May). Our findings describe ecological and biological aspects of A. aidae similar to those of other species of this genus, even from different geographic localities.

scholarly journals DOMINANCE AND EPISTASIS IN HETEROSIS OF WHITE LEGHORN STRAIN CROSSES

1987 ◽  
Vol 67 (3) ◽  
pp. 663-680 ◽  
Author(s):  
R. W. FAIRFULL ◽  
R. S. GOWE ◽  
J. NAGAI
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Significant Contribution ◽  
Production Traits ◽  
White Leghorn ◽  
Cross Combination ◽  
Commercial Strain ◽  
Better Than

Four unrelated pure strains of White Leghorns including a grandparent strain from industry and 12 two-strain, 24 three-strain, 24 four-strain and 12 F2 strain crosses produced contemporaneously were used to examine the role of dominance and epistasis in heterosis. A control strain and a commercial strain were also included. For egg weight, the heterosis observed closely approximated that expected due to dominance alone. For sexual maturity and body weight, dominance was the major component of heterosis, but epistasis made a significant contribution — additive by additive (A × A) genetic effects for sexual maturity and 140-d body weight, and parental epistasis for mature body weight. Both dominance and epistasis played a significant role in heterosis for egg production traits. A × A, dominance by dominance (D × D) and additive by dominance (A × D) epistasis were all important for hen-housed egg production and hen-housed egg yield. For hen-day rate of egg production, A × A epistasis was significant only early in the laying year (to 273 d), A × D and D × D were significant to 385 d and in the full year (to 497 d); however, none (A × A, A × D and D × D) was significant near the end of lay (386–497 d). Overall heterosis estimates for full year egg production measured as hen-housed egg production to 497 d or hen-day rate from housing to 497 d clearly showed that on average two-strain crosses were superior to three-strain crosses which were superior to four-strain crosses which in turn exceeded the F2 crosses. Nevertheless, several three-strain crosses had performance for egg production that was equal to or better than the two-strain cross with the highest egg production. Thus, in commerce, where the level of egg production is of great economic importance, the testing and use of a specific three-way cross combination will usually result in a better commercial product. Key words: Heterosis, egg production genetics, epistasis, stocking rate, strain cross, White Leghorn

Sign in / Sign up

Export Citation Format

Share Document