Life history and population dynamics of the exotic snail Potamopyrgus antipodarum (Prosobranchia : Hydrobiidae) in Lake Purrumbete, Victoria, Australia

1998 ◽  
Vol 49 (1) ◽  
pp. 73 ◽  
Author(s):  
E. S. G. Schreiber ◽  
A. Glaister ◽  
G. P. Quinn ◽  
P. S. Lake
Keyword(s):  
Population Dynamics ◽  
Reproductive Output ◽  
Size Structure ◽  
Seasonal Pattern ◽  
Potamopyrgus Antipodarum ◽  
Seasonal Patterns ◽  
High Fecundity ◽  
Successful Invader ◽  
Density Population ◽  
Different Levels

The density, population size-structure, and fecundity of the exotic snail Potamopyrgus antipodarum are described, for a period of two years, on two shores subject to different levels of disturbance in Lake Purrumbete. The population dynamics of Potamopyrgus antipodarum showed the same seasonal pattern in the numbers of embryos carried per individual female in both years, but seasonal patterns in density and potential reproductive output of the population differed between shores. Densities of Potamopyrgus antipodarum were high, with a trend for highest densities to occur in spring and summer. The population consisted almost entirely of females, which is indicative of a parthenogenic mode of reproduction. Fecundity was high, with the number of embryos carried per female peaking in spring. In summer, the population was dominated by small individuals, but some small snails were present at all times of the year. Potamopyrgus antipodarum was found to be a very successful invader of Lake Purrumbete, with high densities, high fecundity, parthenogenesis and the presence of embryos throughout the year contributing to this success.

Seasonal Reproduction in Musky Rat-kangaroos, Hypsiprymnodon moschatus: a Response to Changes in Resource Availability

1997 ◽  
Vol 24 (5) ◽  
pp. 561 ◽  
Author(s):  
Andrew J. Dennis ◽  
Helene Marsh
Keyword(s):  
Resource Availability ◽  
Seasonal Changes ◽  
Reproductive Output ◽  
Selective Pressure ◽  
Seasonal Pattern ◽  
Seasonal Reproduction ◽  
Reproductive Pattern ◽  
High Fecundity ◽  
Male And Female ◽  
Breeding Seasons

Musky rat-kangaroos had a seasonal reproductive pattern. Males underwent a dramatic testicular expansion in October and the testes remained enlarged until April, when they reduced in size again. Females carried 1–3 pouch young from around March until October; juveniles were suckled until late December. Two primary food resources, fruits and litter fauna, underwent regular seasonal changes in abundance. The availability of fruits fluctuated to a greater degree than did that of litter fauna, both within and between years, which probably constituted the main selective pressure for a seasonal pattern of reproduction and high fecundity relative to most other macropodoids. Variation in the availability of fruits between years correlated with changes in the reproductive output of both male and female musky rat-kangaroos during breeding seasons.

Seasonal Variation of Suicide in the City of São Paulo, Brazil, 1996–2010

Crisis ◽  
2014 ◽  
Vol 35 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Daniel Hideki Bando ◽  
Fernando Madalena Volpe
Keyword(s):  
Seasonal Pattern ◽  
Total Sample ◽  
Sao Paulo ◽  
Seasonal Patterns ◽  
São Paulo ◽  
Health Statistics ◽  
Males And Females ◽  
June July ◽  
The City ◽  
Over Time

Background: In light of the few reports from intertropical latitudes and their conflicting results, we aimed to replicate and update the investigation of seasonal patterns of suicide occurrences in the city of São Paulo, Brazil. Methods: Data relating to male and female suicides were extracted from the Mortality Information Enhancement Program (PRO-AIM), the official health statistics of the municipality of São Paulo. Seasonality was assessed by studying distribution of suicides over time using cosinor analyses. Results: There were 6,916 registered suicides (76.7% men), with an average of 39.0 ± 7.0 observed suicides per month. For the total sample and for both sexes, cosinor analysis estimated a significant seasonal pattern. For the total sample and for males suicide peaked in November (late spring) with a trough in May–June (late autumn). For females, the estimated peak occurred in January, and the trough in June–July. Conclusions: A seasonal pattern of suicides was found for both males and females, peaking in spring/summer and dipping in fall/winter. The scarcity of reports from intertropical latitudes warrants promoting more studies in this area.

Persistence of giants: population dynamics of the limpet Scutellastra laticostata on rocky shores in Western Australia

2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black
Keyword(s):  
Population Dynamics ◽  
Western Australia ◽  
Size Structure ◽  
Survival Rates ◽  
Maximum Size ◽  
High Rate ◽  
Adult Survival ◽  
Rocky Shores ◽  
Adult Size ◽  
Decadal Time Scale

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.

scholarly journals Seasonal pattern of hepatitis E virus prevalence in swine in two different geographical areas of China

2013 ◽  
Vol 141 (11) ◽  
pp. 2403-2409 ◽  
Author(s):  
Y. H. LU ◽  
H. Z. QIAN ◽  
A. Q. HU ◽  
X. QIN ◽  
Q. W. JIANG ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Seasonal Pattern ◽  
Eastern China ◽  
Geographical Area ◽  
Hepatitis E ◽  
Southwestern China ◽  
Seasonal Patterns ◽  
Virus Prevalence ◽  
Swine Hepatitis ◽  
A Minor

SUMMARYWe studied seasonal patterns of swine hepatitis E virus (HEV) infection in China. From 2008 to 2011, 4200 swine bile specimens were collected for the detection of HEV RNA. A total of 92/2400 (3·83%) specimens in eastern China and 47/1800 (2·61%) specimens in southwestern China were positive for HEV. Seasonal patterns differing by geographical area were suggested. In eastern China, the major peak of HEV RNA prevalence was during March–April, with a minor peak during September–October, and a dip during July–August. In southwestern China, the peak was during September–October and the dip during March–April. The majority of subtype 4a cases (63/82, 76·83%) were detected in the first half of the year, while the majority of subtype 4b cases (26/29, 89·66%) were concentrated in the second half of the year, suggesting that different subtypes contribute to different peaks. Our results indicate that the distribution of HEV subtypes is associated with seasonal patterns.

Seasonal variation in births in rural East Pakistan

1972 ◽  
Vol 4 (1) ◽  
pp. 107-116 ◽  
Author(s):  
John Stoeckel ◽  
A. K. M. Alauddin Choudhury
Keyword(s):  
Seasonal Variation ◽  
Social Factors ◽  
Seasonal Pattern ◽  
Seasonal Patterns ◽  
First Order ◽  
Monthly Temperature ◽  
Monthly Distribution ◽  
Number Of Births

SummaryAn analysis of the monthly distribution of births in two areas of Matlab Thana, East Pakistan, indicates that there is a seasonal variation in births different from what would be expected by chance. The highest proportion of births occur in the last three months of a year and the lowest proportion between May and July. Investigation into some of the environmental and social factors which might contribute to the seasonal pattern revealed the following: mean minimum monthly temperature 9 months before birth was inversely related to the number of births; all occupations had seasonal patterns different from what would be expected by chance and the business and mill-and-office occupations had distributions significantly different from each other; the distribution of births for all pregnancy orders was different from chance and the distribution for first order pregnancies was significantly different from those for third and fourth or higher orders.

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.

The population dynamics of aphids on fire weed: a comparison of local populations and metapopulations

1978 ◽  
Vol 56 (12) ◽  
pp. 2554-2564 ◽  
Author(s):  
John F. Addicott
Keyword(s):  
Population Dynamics ◽  
Spatial Heterogeneity ◽  
Rocky Mountains ◽  
Median Number ◽  
Marked Variation ◽  
High Frequencies ◽  
Local Populations ◽  
Epilobium Angustifolium ◽  
Population Processes ◽  
Different Levels

Local populations of four species of aphids (Macrosiphum Valerianae, Aphis varions, A. helianthi, and A. salicariae) occur on shoots of fireweed (Epilobium angustifolium) in the Rocky Mountains of Colorado, U.S.A. Through exhaustive and repeated nondestructive sampling of the local populations on over 3800 shoots of fireweed, information was obtained on the dynamics of both the local populations and the metapopulation of each species. The dynamics of the metapopulation were analyzed in terms of the frequency of shoots occupied by aphids and the median number of aphids per occupied shoot. There were significant differences between species in both parameters, but high densities were not necessarily accompanied by high frequencies. Local populations were initiated throughout the summer, and there was marked variation in the duration and size of these populations. Most populations lasted only a few weeks, but others lasted up to 14 weeks. This turnover of local populations within the metapopulation implies that local populations must be studied in order to understand the dynamics of the metapopulation. There is a discussion of the relationships between population processes occurring at different levels of spatial heterogeneity.

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.

scholarly journals Spatial and Seasonal Variations of Standardized Photosynthetic Parameters under Different Environmental Conditions for Young Planted Larix olgensis Henry Trees

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 522 ◽  
Author(s):  
Qiang Liu ◽  
Fengri Li
Keyword(s):  
Environmental Conditions ◽  
Seasonal Variations ◽  
Seasonal Pattern ◽  
Repeated Measurements ◽  
Seasonal Patterns ◽  
Photosynthetic Parameters ◽  
Relative Depth ◽  
Larix Olgensis ◽  
Vertical Variations ◽  
Larix Olgensis Henry

Understanding the spatial and seasonal variations in leaf physiology is critical for accurately modeling the carbon uptake, physiological processes and growth of entire canopies and stands. For a 17-year-old Larix olgensis Henry plantation, vertical whorl-by-whorl sampling and analyses of seasonally repeated measurements of major photosynthetic parameters were conducted, and the correlations between photosynthetic parameters and environmental conditions, leaf morphological traits and spatial position within the crown were analyzed. According to the correlations, the photosynthetic parameters were standardized based on the environmental conditions to avoid the influence of the changing environment on the patterns of spatial and seasonal variations of photosynthetic parameters. The results showed that the standardized light-saturated net photosynthetic rate (SPmax), standardized dark respiration (SRd) and standardized stomatal conductance under saturated light (Sgs-sat) were all negatively related to the relative depth into the crown (RDINC) throughout the growing season. However, their vertical patterns were different during the development of the phenological phase. In addition, different gradients of environmental conditions also influenced the values and the range of the vertical variation in photosynthesis. High temperature and low humidity usually resulted in smaller values and weaker vertical variations of SPmax and Sgs-sat, but larger values and more obvious vertical variations in SRd. SPmax and Sgs-sat usually exhibited a parabolic seasonal pattern in different vertical positions within the crown; however, SRd generally followed a concave pattern. These seasonal patterns were all weaker with increasing RDINC. Different environments also exhibited a significant influence on the seasonal patterns of photosynthesis. We suggested that standardization is necessary before analyzing spatial and seasonal variations. A single environmental condition could not represent the spatial and seasonal patterns under all gradients of the environment. Spatial and seasonal variations should be simultaneously analyzed because they are related to each other.

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