Seasonal changes in abundance of Gammarus oceanicus (Crustacea, Amphipoda) in Newfoundland

1976 ◽  
Vol 54 (11) ◽  
pp. 2019-2022 ◽  
Author(s):  
D. H. Steele
Keyword(s):  
Seasonal Changes ◽  
Environmental Temperature ◽  
Late Summer ◽  
Stone Size ◽  
Late Autumn ◽  
Early Autumn

Abundance of Gammarus oceanicus reaches a peak in late summer – early autumn and declines to a low in the spring just before the young are produced. G. oceanicus disappears from the upper beach in late autumn, but is found permanently at lower levels. At low tide the numbers found under stones vary directly with stone size and inversely with the level of the stone on the beach. This, in turn, is related to environmental temperature. In the microhabitat under the stones, temperature varies inversely with stone size and directly with the level on the beach.

Seasonal Changes in the Germination Responses of Buried Witchgrass (Panicum capillare) Seeds

Weed Science ◽  
1986 ◽  
Vol 34 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seasonal Changes ◽  
Late Summer ◽  
Late Spring ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Late Autumn ◽  
Buried Seeds ◽  
Autumn And Winter

Buried seeds of witchgrass (Panicum capillare L., # PANCA) exposed to natural seasonal temperature changes in Lexington, KY, for 0 to 35 months exhibited annual dormancy/nondormancy cycles. Seeds were dormant at maturity in early October. During burial in late autumn and winter, fresh seeds and those that had been buried for 1 and 2 years became nondormant. Nondormant seeds germinated from 76 to 100% in light at daily thermoperiods of 15/6, 20/10, 25/15, 30/15, and 35/20 C, while in darkness they germinated from 1 to 24%. In late spring, seeds lost the ability to germinate in darkness, and by late summer 63 to 100% of them had lost the ability to germinate in light. As seeds became nondormant, they germinated (in light) at high (35/20, 30/15 C) and then at lower (25/15, 20/10, and 15/6 C) temperatures. As seeds reentered dormancy, they lost the ability to germinate (in light) at 15/6 C and at higher thermoperiods 2 to 3 months later.

Seasonal changes in the germination responses of seeds of Veronica peregrina during burial, and ecological implications

1983 ◽  
Vol 61 (12) ◽  
pp. 3332-3336 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seasonal Changes ◽  
Natural Habitat ◽  
General Pattern ◽  
Late Summer ◽  
Early Spring ◽  
Late Winter ◽  
Seasonal Temperature ◽  
Light In August ◽  
Late Autumn ◽  
Response To Temperature

Seeds of Veronica peregrina collected from a field population in central Kentucky were buried in soil and exposed to seasonal temperature changes. Fresh seeds and those exhumed after 1–26 months were tested in light and darkness at five thermoperiods simulating those in the natural habitat from early spring through late autumn. Freshly matured seeds were dormant, but they came out of dormancy in June and July and germinated to 98–100% in light in August at thermoperiods of 20:10, 25:15, 30:15, and 35:20 °C. Seeds retained the ability to germinate to high percentages at these temperatures until late winter and spring, but they never germinated to high percentages in darkness. Thus, in the natural habitat in July and August germination is prevented only by darkness and (or) insufficient soil moisture. At simulated habitat temperatures, seeds germinated to 88–100% in March and April but to only 21–69% in May and June. Seeds incubated at 15:6 °C showed a decline in germination percentages in late summer and autumn and an increase during late autumn and winter. The same general pattern of seasonal changes in germination response to temperature occurred during the 2nd year of burial.

Seasonal distribution of loline alkaloid concentration in meadow fescue infected with Neotyphodium uncinatum

2011 ◽  
Vol 62 (7) ◽  
pp. 603 ◽  
Author(s):  
Brian Patchett ◽  
Ravi Gooneratne ◽  
Lester Fletcher ◽  
Bruce Chapman
Keyword(s):  
Late Summer ◽  
Seasonal Distribution ◽  
Late Spring ◽  
Selected Lines ◽  
Meadow Fescue ◽  
Late Autumn ◽  
Early Autumn ◽  
Harvest Dates ◽  
Loline Alkaloids ◽  
First Time

Loline alkaloids are present in meadow fescue containing the endophyte (Neotyphodium uncinatum Gams, Petrini and Schmidt) (Clavicipitacae). Root, crown and shoot loline alkaloid concentrations in 10 selected lines from meadow fescue ecotypes are reported for the first time, from a Canterbury farm during 2004–05. The concentrations of four loline alkaloid derivatives, N-formyl loline (NFL), N-acetyl loline (NAL), N-acetyl norloline (NANL) and N-methyl loline (NML), in these lines (each line represented by one genotype) were determined at four harvest dates during late spring, late summer, and early and late autumn. There were marked differences in loline alkaloid concentration between lines and seasons. Maximum shoot loline concentration was recorded in summer (up to 2860 µg/g in Fp408). Root loline alkaloid concentration was substantially higher in late autumn (up to 790 µg/g in Fp408) and the shoot concentration correspondingly lower than in spring, summer and early autumn suggesting loline alkaloid transportation from shoots to roots. In the lines tested at each of the four harvest dates in spring, summer, and autumn, the root, crown, and shoot alkaloid concentration with minor exceptions was NFL > NAL > NANL > NML.

Lipid accumulation by migrating monarch butterflies (Danaus plexippus L.)

1993 ◽  
Vol 71 (1) ◽  
pp. 76-82 ◽  
Author(s):  
David L. Gibo ◽  
Jody A. McCurdy
Keyword(s):  
Lipid Accumulation ◽  
Seasonal Changes ◽  
Late Phase ◽  
Danaus Plexippus ◽  
Late Summer ◽  
Dry Mass ◽  
Middle Phase ◽  
Southern Ontario ◽  
Lipid Mass ◽  
Peak Abundance

The migration of Danaus plexippus during the late summer in southern Ontario in 1986 lasted for about 8 weeks and consisted of three phases, an early phase characterized by increasing abundance, a middle phase of peak abundance, and a late phase characterized by declining abundance. As the season progressed, systematic changes were observed in wet mass, dry mass, lean dry mass, lipid mass, and forewing length. Wet mass, lean dry mass, and forewing length were similar for early- and middle-phase individuals, but declined in late-phase migrants. Lipid mass peaked in the middle phase of the migration and then declined abruptly in the late phase. Dry mass also peaked in the middle phase, reflecting changes in lipid mass and lean dry mass. We hypothesize that the observed changes in lipid mass and lean dry mass over the 8 weeks resulted from changes in population structure as well as seasonal changes in the weather, and in availability of nectar. Opposing conclusions reached in previous studies of lipid accumulation in D. plexippus are probably the result of failure to control for phase of migration.

scholarly journals Tendencies and Seasonality in the Change of the Prices of Residential Real Estates by Neighborhoods in the Capital of Bulgaria, Sofia

2018 ◽  
Vol 6 (1) ◽  
pp. 152-164
Author(s):  
Nikolay Stoenchev ◽  
Yana Hrischeva
Keyword(s):  
Present Article ◽  
Late Autumn ◽  
Early Autumn ◽  
The Mean ◽  
Annual Period ◽  
Real Estates

Abstract The aim of the present article is to research the availability of rules in the change of the prices of the most spread flats in the neighbourhoods of Sofia. The results from a research in the change of the offered prices of the residential real estates by months for an annual period of time (from October 2016 to September 2017) have been presented. The presence of an uprising tendency for the bigger share of the neighbourhoods has been proven. For those of them where there is a tendency missing are calculated indices for seasonality by the method of the mean chronological value. Upcoming seasonal deviations of the mean monthly prices from the average annual by the separate types of flats (studios, one-bedroom and two-bedroom flats), whereas the highest values are registered in the summer and the early autumn - the months August and September, and the lowest in the late autumn - the months October and November. The most significant are the fluctuations in the variation of the prices in the studios, followed by the two-bedroom flats and one-bedroom flats. The results could be useful to some potential investors.

Colpoma crispum. [Descriptions of Fungi and Bacteria].

1997 ◽  
Author(s):  
D. W. Minter
Keyword(s):  
Picea Abies ◽  
Geographical Distribution ◽  
Northern Hemisphere ◽  
Pseudotsuga Menziesii ◽  
Late Summer ◽  
Juniperus Virginiana ◽  
North West ◽  
Early Autumn

Abstract A description is provided for Colpoma crispum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: On dead, rather brittle twigs of Picea abies, but usually attached but sometimes fallen by the time ascomata contain ascospores. Probably involved in self-pruning of the tree, but associated with lichen colonies unlike species of Therrya on Pinus (IMI Descriptions 1297 and 1298), and Colpoma on Quercus (IMI Description 942) which occur on twigs without lichen colonies. HOSTS: Juniperus virginiana (twig), Larix sp. (bark, twig), Picea abies (bark, twig), Picea sp. (bark), Pseudotsuga menziesii (twig). GEOGRAPHICAL DISTRIBUTION: Germany, Italy, Sweden, UK (England, Scotland, Wales), Ukraine, USA (Oregon). Unsuccessful searches in north-west Poland. Altitude records exist up to 950m (Ukraine). TRANSMISSION: By air-borne ascospores in humid conditions. In the temperate northern hemisphere, ascocarps probably mostly open in late summer and early autumn.

Clivia mirabilis (Amaryllidaceae: Haemantheae) a new species from Northern Cape, South Africa

Bothalia ◽  
2002 ◽  
Vol 32 (1) ◽  
pp. 1-7 ◽  
Author(s):  
J. P. Rourke
Keyword(s):  
South Africa ◽  
New Species ◽  
Vegetative Growth ◽  
Mediterranean Climate ◽  
Nature Reserve ◽  
Late Summer ◽  
Distribution Area ◽  
Early Autumn ◽  
Northern Cape ◽  
A New Species

Clivia mirabilis Rourke is a new pendulous tubular-flowered species from Oorlogskloof Nature Reserve in Northern Cape. Its distribution area is some 800 km outside the previously accepted range of the genus Clivia. This sun-tolerant species is adapted to an arid Mediterranean climate, producing vegetative growth in winter and maturing its seeds rapidly in late summer/early autumn to synchronize with the arrival of winter rains.

Temperature modulation of photoperiodism and the timing of late-season changes in life history for an aphid, Acyrthosiphon pisum

2011 ◽  
Vol 143 (1) ◽  
pp. 56-71 ◽  
Author(s):  
M.A.H. Smith ◽  
P.A. MacKay ◽  
R.J. Lamb
Keyword(s):  
Sexual Reproduction ◽  
Seasonal Changes ◽  
Acyrthosiphon Pisum ◽  
Late Summer ◽  
Day Length ◽  
Temperature Modulation ◽  
Four Seasons ◽  
Aphid Clone ◽  
Photoperiodic Responses

AbstractWhere winters are severe, aphids reproduce parthenogenetically and viviparously in summer, switch to sexual reproduction in late summer, and produce winter-hardy eggs by the end of the season. The role of day length and temperature in initiating seasonal changes from parthenogenetic to sexual reproduction by pea aphids, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), are described and the selection pressures that affect the timing of this transition are investigated. Over four seasons, a pea aphid clone was sampled from field cages through late summer in southern Manitoba, Canada, and reared in the laboratory to determine the phenotypes of progeny produced as the season progressed. The timing of transitions from one phenotype to another under natural day length and temperature, and the critical day lengths that caused the transitions, coincided with expectations from laboratory studies of photoperiodic responses. Males and mating females appeared later when the weather in August was warm than when it was cool. The timing of seasonal changes was adapted to minimize the physiological time to the end of the season, which maximized the number of asexual summer generations. Ambient temperature modulated the response to day length and fine-tuned the timing of sexual reproduction to adapt for annual variation in autumn weather.

The biology of Gammarus (Crustacea, Amphipoda) in the northwestern Atlantic. X. Gammarus finmarchicus Dahl

1975 ◽  
Vol 53 (8) ◽  
pp. 1110-1115 ◽  
Author(s):  
D. H. Steele ◽  
V. J. Steele
Keyword(s):  
Life Cycle ◽  
New Brunswick ◽  
Long Island ◽  
Long Island Sound ◽  
Western Atlantic ◽  
Late Autumn ◽  
Early Autumn ◽  
Autumn And Winter ◽  
Island Sound

Gammarus finmarchicus is an amphi-Atlantic species. In the western Atlantic it is found from the island of St. Pierre south to Long Island Sound. At St. Andrews, New Brunswick, 50% maturity occurs at 10.5 mm in the females. Reproduction is in progress throughout the year, but small females evidently are in a resting condition during September–October before breeding. The release of young by the population is greater in the spring, summer, and early autumn than it is in late autumn and winter. The young released in the spring and summer do not reproduce until the next year so that the life cycle is annual.

The reproductive cycle of the viviparous seaperch, Cymatogaster aggregata Gibbons

1968 ◽  
Vol 46 (6) ◽  
pp. 1221-1234 ◽  
Author(s):  
John P. Wiebe
Keyword(s):  
Oocyte Maturation ◽  
Reproductive Cycle ◽  
Sertoli Cells ◽  
Reproductive Behavior ◽  
Seasonal Changes ◽  
Environmental Temperature ◽  
Interstitial Cells ◽  
Early Spring ◽  
Seminiferous Tubules ◽  
Male And Female

The natural reproductive cycle of male and female Cymatogaster aggregata is described with reference to gametogenesis, development of secondary sex structures, reproductive behavior, and gestation. Spermatocytogenesis starts in early spring and by June or July clusters of spermatozoa fill the seminiferous tubules. Concurrently the Sertoli cells and interstitial cells of Leydig increase in size and secondary sex structures develop on the male anal fin. When the sexes mingle in summer, the males perform very elaborate reproductive behavior. Fertilization occurs about mid-December—5 months after mating—and the ovary is then modified to maintain the young embryos until parturition in mid-summer. Oocyte formation is highest in July and August, just after parturition, while vitellogenesis and oocyte maturation occur mainiy from October to December. These seasonal changes are discussed in relation to changes in environmental temperature and photoperiod.

Sign in / Sign up

Export Citation Format

Share Document