共查询到20条相似文献,搜索用时 15 毫秒
1.
Dynamics of Mya arenaria beds in two bights of the Chupa Inlet (Kandalaksha Bay, White Sea) were studied on a long-term basis. Observations were carried
out at 1– to 3-year intervals from 1979 up to 1999. The studied soft-shell clam beds were characterised by a substantial instability
of age structure. Since 1988, only one year-class has dominated in the beds while other generations have been scarce and recruitment
was not observed. This pattern of Mya bed dynamics was related neither to interannual environmental changes nor to differential reproduction success or predation
effects in the benthic assemblages. Favourable conditions for spat formation in 1988 (low abundance of other M. arenaria generations), as well as for juvenile survival during the following winter, resulted in high abundance of juveniles in both
investigated locations in 1989. The mortality rate (μ) in this 1988 generation varied throughout the period of investigation and was related to age. The mortality level decreased
for the first 2–4 years of the life cycle, then stabilised for the next 3–4 years, and eventually increased in subsequent
years. Overall μ values ranged from 0 to 1.68 year–1. The oldest specimens observed were 17 years old and had a maximum shell length of 79 mm. Significant differences in average
growth rates were observed between molluscs of different locations.
Communicated by H.-D. Franke 相似文献
2.
Sergey V. Naidenko 《Acta theriologica》2006,51(1):91-98
Body mass changes of Eurasian lynxLynx lynx Linnaeus, 1758 kittens during the first four months of their life were studied in 1989–1999 in captivity. Four hundred thirteen
records of body mass from 63 lynx kittens were analysed. The body mass of lynx kittens up to four months of age increased
as a linear function with age. Daily growth rate (in grams) was minimal when the kittens were switching from milk to solid
food at the age 41–60 days and was maximal at the age 61–80 days. Body mass dynamic and daily growth rates of kittens depended
on the husbandry conditions of adult animals (or probably on their subspecies) and litter size, but did not depend on the
sex of the kittens. Specific spontaneous fights during kittens’ ontogenesis showed the trend to affect kittens’ body mass
dynamic and daily growth rate on some stages of kittens’ development. 相似文献
3.
N. I. Selin 《Russian Journal of Marine Biology》2010,36(4):258-269
Numerous shells of bivalves, which study attributed to 37 species, were collected from samples of ground taken with a Van
Veen dredge sampler at the northeast coast of Sakhalin Island at depths of about 10–60 m in June–October 2003–2009. Tellina lutea, Mactromeris polynyma, Serripes groenlandicus, Macoma spp., Liocyma fluctuosum, and Siliqua alta occurred most often in the samples. The assessment of growth in 18 bivalve species revealed common patterns of age variations
that were irrespective of their way of life, maximum body size, and maximum age. The greatest annual increment in shell length
was observed in the first 4 years of life, and the asymptotic size of the mollusks was reached with a 10-fold decrease in
the annual growth rate. The life span of the mollusks varied from 2 up to 41 years and sometimes significantly differed from
that of the studied species in other areas of their range, clearly displaying the ecological conditionality of this parameter.
Species with maximum ages of less than 10 years were the most numerous in the bivalve community of the region. The results
of the research are discussed in relation to the nature of the environment at the northeast coast of Sakhalin Island. 相似文献
4.
Chronological ages of Alouattaon Barro Colorado Island (BCI) were estimated from longitudinal dental wear. Combining these data with visual censuses, we
approximated the study population’s age profile. A stable model was then constructed; from it we derived agespecific mortality
rates. Mortality of immature animals is high, with 88% of the males and 65% of the females dying before 5 years. Adult mortality
is low until 11 years, when it accelerates. The average adult life span is 16.6 years for males and 15.5 for females. The
maximum life span is over 20 years. A pubertal male growth spurt occurs from 3 to 5 years, at which time females are primiparous.
Sexual size differences develop primarily during this time. The 1976 age profile had anomalously few animals aged 7 years
and males aged 8–9 and 15–16 years. With corroborating evidence, we hypothesize that these deficits resulted from excessive
rainfall in 1963 and 1971, which reduced the fall fruit crop and led to a high juvenile mortality. Within half of our study
troops, some adult males have nearly identical ages, suggesting an active process of agemate coalition. We hypothesize a form
of kin selection, wherein peripheral male cohorts from the same natal troop have greater survival and social success than
solitary animals. The stable model suggests an annual growth rate of 1.5% during the 1970s. Estimates of 16.7 and 4% for the
previous two decades, following a yellow-fever epidemic, imply that the BCI population is becoming stationary. A very different
age structure existed on neighboring Orchid Island in 1976, suggesting general food limitation. By contrast, the lowered,
but continuing growth on BCI suggests a less drastic limiting mechanism. We hypothesize that intratroop social competition
limits population growth by regulating subadult survival rates during food scarcity cycles. 相似文献
5.
Annual monitoring of the benthic fauna living at the Frisian Front (southern North Sea) has shown a tenfold decrease in the
dominant brittlestar Amphiura filiformis in 1993–1995. In search of evidence that this decline was caused by a change in benthic food supply, we analysed variations
in the shell growth of the bivalve Mya truncata from the Frisian Front during the period of interest. For this purpose, the widths of the internal growth bands in the chondrophore
of M. truncata were standardised and assigned to calendar years. Averaging the yearly band width in the period 1985–2000 among 25 individuals
revealed low growth rates in 1986 and 1992. Growth of M. truncata quickly recovered after 1992, while A. filiformis densities remained at low levels. Moreover, the 1986 dip in M. truncata growth had no equivalent in A. filiformis density. We conclude that there is no direct coupling between fluctuations in density of A. filiformis and variations in growth of M. truncata. The data we collected during this study on the size and spatial distribution of M. truncata are discussed in the light of plans for the protection and conservation of long-lived benthic organisms in the North Sea.
Communicated by E. Rachor 相似文献
6.
Akifumi Makita Yasuo Konno Noboru Fujita Ken′ichi Takada Etsuji Hamabata 《Ecological Research》1993,8(2):215-224
The recovery process of aSasa tsuboiana population after a mass flowering and death in 1977 was investigated by 15 years of observation in the Hira Mountains, Kinki
district, western Japan. Seed production was high (6600–13 800 seeds m−2 inSasa plots and 3900 seeds m−2 in a forest plot) but emergent seedling density was low (14–21 seedlings m−2), probably because of seed predation byMicrotus montebelli occurring between seed shedding and the next spring. The seedling density had decreased further by the next year and theS. tsuboiana population recovered from only a limited number of seedlings. In spite of such a low initial density, theS. tsuboiana population was able to regenerate successfully and attained the previous full stand height in 7–16 years.Miscantbus sinensis invaded and delayed the recovery ofS. tsuboiana in one plot, butS. tsuboiana became dominant as it caught up with the height ofM. sinensis. Seedling growth patterns, such as frequent tillering, the onset of rhizome extension in the early stage of seedling growth
and frequent culm production from rhizomes, played important roles in the successful regeneration ofS. tsuboiana. 相似文献
7.
Changes in ovarian follicular kinetics were studied in relation to aging in the Indian skipper frog
Rana cyanophlyctis.Age was determined by skeletochronology, by counting the number of growth rings and lines of arrest of growth from the cross
sections of 4th phalange of 4th toe. For follicular kinetics study oocytes were counted under binocular using 10% of Bouin’s
fixed ovary and they were classified into first growth phase, medium-sized second growth phase, large-sized second growth
phase and atretic follicles.
Analysis of phalangeal cross sections indicated that frogs ranging 14–54 g in body weight and 4.9–8.9 cm in body size showed
1–7 year rings. Frogs that weighed 14–16 g showed 1 year ring, and contained immature ovaries; those with 18 g body weight
had one to two year rings, in which second growth phase oocytes appeared for the first time in the primiparous ovary. Frogs
with 20–54 g body weight showed 2–5 year rings in which ovary contained 5–24% of second growth phase oocytes. Further, body
weight, body size, ovarian weight, number and size of second growth phase oocytes and total number of oocytes showed a significant
(P < 0.05) positive correlation, while, the number of first growth phase and atretic follicles showed a poor correlation with
age.
The results suggest that in nature, the age of
Rana cyanophlyctis
ranges between 1–7 years. Phalangeal growth rings are formed annually. Females attain sexual maturity in 2nd year. Frogs with
2–5 years of age may constitute breeding females. Body weight, body size, ovarian mass, number of second growth phase and
total oocytes, and egg size increase with age up to 5 years. 相似文献
8.
Spatial and age-dependent tree-ring growth responses of Larix gmelinii to climate in northeastern China 总被引:2,自引:0,他引:2
Tree-ring width chronologies from 276 Larix gmelinii cores taken in northeastern China were used to analyze spatial and age-dependent growth–climate response relationships. Tree
radial growth from five localities showed similar patterns, while exhibiting different tree-ring growth responses to local
climate. The rotated principal component analysis (RPCA) indicated that tree age, growing season moisture conditions, and
ambient air temperature variations resulted from location differences (e.g., longitude, latitude, and altitude), which could
explain the non-stationary spatial climate–growth relations observed. The study tested the fundamental assumption that the
climate–growth of L. gmelinii was age independent after the removal of size trends and disturbance signals. The age-related climate–growth relationship
might potentially improve the veracity of past climate reconstructions. Bootstrapped correlation function analyses suggested
that the response of L. gmelinii radial growth to climate differed between trees ≥150 years old and <150 years old. Mean sensitivity and standard deviation
for trees increased with age in the <150 years old tree class; whereas trees ≥150 years old had no significant relationship
with age. These results showed that the assumption of age-independent climate–growth relationship is invalid at these sites.
Physiological processes and/or hydraulic constraints dependent on tree age, together with detrending techniques could be the
possible causal factors of clear age-dependent responses. These results suggested the importance of incorporating trees of
all ages into the chronology to recover a detailed climatic signal in a reconstruction of L. gmelinii for this region. 相似文献
9.
Aspects of the biology of Abra segmentum were investigated at low salinities in a Mediterranean coastal lagoon (Monolimni Lagoon, Northern Aegean Sea). Monthly samples
were collected during the period from February 1998 to January 1999. Recruitment occurred from mid-spring to early autumn
(0.3–5.7 psu) and recruits grew during summer and autumn (1.2–5.7 psu), while a major part vanished during next autumn, displaying
a maximum life span of about 20 months. A positive correlation was found between the percentage of individuals having a shell
length of ≤3.5 mm and temperature; age group 0 showed a growth rate of 0.97 mm per month, and the largest individual collected
had a 19.76 mm shell length. The population density sharply increased during late spring (0.3–1.2 psu); this increase was
followed by a decline during summer and, afterwards, a gradual increase up to late autumn. Secondary production calculated
by the size–frequency method gave a mean annual density (n) of 3,357 individuals m−2, a mean annual biomass (B) of 21.98 g DW m−2, an annual production (P) of 73.72 g DW m−2 and a P:B ratio of 3.35. A comparison of the present data with available data of A. segmentum populations from higher salinity habitats revealed that this bivalve in the study area showed a life history pattern similar
to that of other populations of the species and a comparatively high growth rate, maximum body size, n, B, P and P:B ratio. Our findings suggest that the studied aspects of A. segmentum biology could not be markedly affected by low salinities. 相似文献
10.
The embryonic, larval and juvenile development of blue whiting,Sillago parvisquamis Gill, are described from a series of laboratory-reared specimens. Mean egg diameter and mean total length (TL) of newly-hatched
larvae were 0.71 mm and 1.58 mm, respectively. The eggs were non-adhesive, buoyant and spherical with an oil globule (mean
diameter 0.18 mm). Hatching occurred about 20 hours after fertilization at a temperature of 24.0–25.0°C, newly-hatched larvae
having 38–40 myomeres. The yolk and oil globule were completely absorbed 3 days after hatching at 2.8–3.2 (mean 3.0) mm TL.
Notochord flexion was completed by 7.2–8.2 (7.7) mm TL, and pectoral and caudal fin rays fully developed by approximately
10 mm and 8.5 mm TL, respectively. Completion of fin development occurred in the following sequence: caudal, pectoral, anal
and second dorsal, first dorsal and pelvic, the last-mentioned by approximately 11 mm TL. The larvae ofS. parvisquamis andS. japonica, which closely resemble each other in general morphology and pigmentation, could be distinguished as follows. Newly-hatchedS. parvisquamis larvae had more myomeres thanS. japonica (38–40 vs. 32–34) and more melanophores on the dorsal surface of the body (19–28 vs. about 40).Sillago japonica had a vertical band of melanophores on the caudal peduncle, which was lacking in postflexionS. parvisquamis larvae. In addition, juveniles ofS. parvisquamis (larger than 23 mm TL) had melanophores on the body extending anteriorly to below the lateral line to form a midlateral band,
whereas no obvious band occurred on similarly-sizedS. japonica juveniles. 相似文献
11.
Environmental catastrophes, such as severe drought, can reduce host-plant quality and/or abundance, which in turn decrease
levels of herbivore populations. Such changes in herbivore populations affect populations of their natural enemies. As part
of a long-term field experiment (1983–1991), galls of Eurosta solidaginis from 16 fields in central Pennsylvania were systematically collected from goldenrod ramets. Galls were dissected to compare
the occurrence of E. solidaginis mortality caused by its natural enemies in 2 drought years (1988, 1991) with 5 pre-drought years (1983–1987) and 2 post-drought
years (1989–1990). Gall diameters were significantly smaller in both drought years and early larval death significantly decreased E. solidaginis survivorship in the first drought year. Of the natural enemies, the parasitoid wasp Eurytoma gigantea caused significant selection for larger gall size in all pre-drought years, the 1991 drought, and both post-drought years,
due to its differential attack of smaller galls. In spite of drought-induced small gall size in 1988, there was negligible
selection on gall size by natural enemies. However, populations of E. solidaginis did suffer local extirpations at nine of the 16 fields during the first drought year and population recoveries of the gall
inducer and natural enemies varied among fields in the post-drought years. As a consequence of reduced herbivore abundance
in drought and post-drought years, some natural-enemy populations were absent. Drought therefore drastically reduced the abundance
of E. solidaginis and natural enemies resulting in slow recoveries to pre-drought numbers.
Received: 16 April 1998 / Accepted: 4 August 1998 相似文献
12.
Mackerel from the northern indian ocean and the red sea arescomber australasicus, notscomber japonicus 总被引:1,自引:0,他引:1
The population ofScomber from the Red Sea and northern Indian Ocean (gulfs of Aden and Oman) is identified asS. australasicus rather thanS. japonicus based on having 30–33 vs. 26–29 interneural bones under the first and second dorsal fins and the combination of interneural
bone counts of 16–20 under the first dorsal fin (vs. 13–16) and first dorsal fin spine counts of 10–13 (vs. 9–10). These are
the best morphological characters to distinguish these two species. This change in identification constitutes a major range
extension forS. australasicus which was thought to be restricted to the Pacific Ocean and the southeastern Indian Ocean around Western Australia. 相似文献
13.
Climate change models predict that the range of the world’s smallest tortoise, Homopus signatus signatus, will aridify and contract in the next decades. To evaluate the effects of annual variation in rainfall on the growth of
H. s. signatus, we recorded annual growth rates of wild individuals from spring 2000 to spring 2004. Juveniles grew faster than did adults,
and females grew faster than did males. Growth correlated strongly with the amount of rain that fell during the time just
before and within the growth periods. Growth rates were lowest in 2002–2003, when almost no rain fell between September 2002
and August 2003. In this period, more than 54% of the tortoises had negative growth rates for their straight carapace length
(SCL), shell height (SH), and shell volume (SV); maximum shrinking for SCL, SH, and SV was 4, 11, and 12%, respectively. The
shell of H. s. signatus has some flexibility dorso-ventrally, so a reduction in internal matter due to starvation or dehydration may have caused
SH to shrink. Because the length and width of the shell seem more rigid, reversible bone resorption may have contributed to
shrinkage, particularly of the shell width and plastron length. Based on growth rates for all years, female H. s. signatus need 11–12 years to mature, approximately twice as long as would be expected allometrically for such a small species. However,
if aridification lowers average growth rates to the level of 2002–2003, females would require 30 years to mature. Additionally,
aridification would lower average and maximum female size, resulting in smaller eggs and hatchlings. These projected life
history responses to aridification heighten the threat posed by the predicted range contraction of this red-listed species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Hiroshi Kinoshita Peter R. Francis 《European journal of applied physiology and occupational physiology》1996,74(5):450-460
Age-related changes were investigated in the control of precision grip force during the lifting and holding of objects with
slippery (silk) and nonslippery (sandpaper) surface textures. Two groups of active elderly adults comprising individuals aged
69–79 years (n = 10), and 80–93 years (n = 10) together with a group of young adults aged 18–32 years (n = 10) participated in the study. Each subject lifted a free weight (3N) during which time gripping and lifting forces were
monitored. The elderly subjects, especially the individuals in the 81–93 year group, had a larger number of fluctuations in
the grip force rate curve and longer force application time than the younger subjects during lifting. The effect of prior
experience with one surface on the following different surface was more pronounced in the younger subjects than the elderly
subjects. These results suggest a decline in programmed force production capacity with increased age. The fingers of the elderly
subjects were more slippery and they exhibited a greater safety margin of the grip force while holding the object than the
younger adults. The overall results demonstrated that precision grip force control capacity declines with advancing age. It
is suggested that this decline is due mainly to age-related changes in skin properties, and cutaneous sensibility functions,
and in part to central nervous system function. 相似文献
15.
F. W. Tesch 《Helgoland Marine Research》1998,52(1):75-83
The age of glass eels arriving at the European coasts is estimated by different authors to range from 3/4 to 3+years; some
of these estimates are based on counts of “daily rings”. The present study reviews published data on North Atlantic length
frequency distributions. The only years for which larvae samples are available from the spawning area to the European continental
slope are 1979 and, to a certain extent, also 1922. In the spring of both years, length frequency distributions exhibited
two distinct maxima which are considered to belong to the AG 0 (mean lengths 12 and 18 mm for 1979 and 1922, respectively)
and the AG I (47 and 44 mm). In addition, a third, less distinct maximum is visible and the existence of an AG II must be
considered. Growth during the first year of life is calculated using the means of total lengths of sufficiently large samples,
collected with progressing season, of the years 1920, 21, 22, 79, 81. From the resulting linear regressions forAnguilla anguilla until the beginning of winter, a daily length increase of 0.15 mm was estimated. Growth ofA. rostrata was faster (0.22 mm·day−1) Daily length increase ofA. anguilla in winter was only 0.03 mm; during a possible second summer 0.06–0.09 mm·day−1 and during a possible third summer considerably less. There is a length increase of the European eel larvae from south to
north, known also from glass eels, which makes evaluation of length increase from west to east even more difficult. A higher
age of glass eels in the north than in the south is therefore likely. 相似文献
16.
Statolith shape and microstructure were studied in 151 specimens of the common arctic squid Gonatus fabricii (7.3–322 mm pen length) collected in the southern Norwegian Sea. Statolith development and growth both comprised two main
periods, which corresponded with the epipelagic and meso-bathypelagic ontogenetic periods of G. fabricii. During the epipelagic period (pen length range from 3 to 50–60 mm), statoliths quickly developed from the droplet-like form
in early paralarvae to the pre-definite stage in juveniles (30–50 mm pen length). Paralarval and juvenile statoliths grew
with high growth rates, and their microstructure contained narrow first-order growth increments. Three main growth zones (Z1,
Z2, Z3) developed during this period, being well distinguished from each other by specific patterns of microstructure and
separated from each other by distinct checks. During the meso-bathypelagic period (from 50–60 to 322 mm pen length), statoliths
hardly changed their shape and grew very slowly. Only one growth zone (Z4) was formed within the statolith microstructure,
characterized by disappearance of the first growth increments and formation of specific second-order bands. Each second-order
band consisted of approximately seven first-order increments. If the assumption “one increment-one day” is true for G. fabricii, the squid would then be a slow-growing animal with a life span for both sexes not exceeding 2 years.
Accepted: 25 May 1999 相似文献
17.
Population responses of Japanese serow (Capricornis crispus) to clear-cut logging and planted tree growth were studied by a direct count of the number observed in three areas, Takiyama
(305 ha), Gentouziro (270 ha), and Tanokashira (324 ha), near Wakinosawa Village, Aomori Prefecture, Japan, during 1976–89.
At Takiyama, a mature mixed forest ofThujopsis dolabrata var.hondai andFagus crenata decreased from 73 to 39% coverage of the area due to clear-cutting during 1978–83. The serow population maintained a relatively
low stable density (3–6 individuals per km2) until 1985–87, and increased 5–10 years after the clear-cutting, reaching 9–10 km−2 in 1988. At Gentouziro and Tanokashira, young plantations of Japanese cedar (Cryptomeria japonica) covered about half of each area. The population densities between 1980 and 1983 were relatively high (14–19 km−2), but declined thereafter, reaching 10–14 km−2 in 1988–89. These results indicated that the density increase resulted from an improvement of food supply due to growth of
scrub following the clear-cutting, and that the density decline resulted from a habitat change due to growth of planted Japanese
cedar and a decrease in the food supply. In Wakinosawa Village, serow density began to increase 5–10 years after forest cutting,
and the high population density, about three- or six-fold larger than that in mature forest, is expected to be maintained
for about 20 years after logging. 相似文献
18.
Tomoaki Iseki Kouki Mizuno Taro Ohta Kouji Nakayama Masaru Tanaka 《Ichthyological Research》2010,57(3):245-253
A total of 263 adult and preadult Chinese temperate bass Lateolabrax sp. caught at 20 locations in the coastal waters of western Japan from October 1999 to September 2008 were used for age,
growth and maturity examinations. Examination of marginal increments of transverse sections of otoliths showed that rings
(opaque zones) were formed once a year from spring to summer. According to the number of rings and the sampling month, ages
were assigned to individuals. For males, we obtained the following von Bertalanffy growth equation: L(t) = 618{1 − e−0.420 (t + 0.273)}. Females attain sizes over 600 mm SL mainly after 5 years of age and attain sizes of 850–1,000 mm SL at 8–10 years and over
1,100 mm SL about 15 years. Based on histological examinations of gonads and seasonal changes in gonadosomatic indices, potential
spawning period was confirmed during mid-October to late January. In males, the minimum size and age at first maturity were
estimated as 380 mm SL and 2 years old, respectively, though most males reach sexual maturity at 3–4 years old. Furthermore,
female specimens at the mature or developing stages were over 470 mm SL and 4 years old. 相似文献
19.
Age, growth, and reproductive biology of the Waigieu seaperch Psammoperca waigiensis were studied using 291 specimens obtained around Okinawa Island, Japan. Otolith opaque zones that formed every year correlated
with spawning activity and were thought to be annual rings. Growth of this species was rapid during the first 2 years, reaching
186.2–270.3 mm in standard length (SL). Females (196.6–334.0 mm SL) were larger than males (186.2–288.6 mm SL), caused by
differential growth between sexes, which started before 2 years of age. Most of the specimens were 1–11 years old and accounted
for 96% in total. Spawning season was estimated to be from April to October by gonadosomatic index (GSI) and histological
observation. The smallest mature female and male were 217.0 mm SL (2 years) and 206.0 mm SL (2 years), respectively. After
recruitment in rocky areas up to about 200.0 mm SL and 2 years of age, Psammoperca waigiensis were then found to soon mature. 相似文献
20.
Symphurus hondoensis Hubbs, 1915, originally described only from the holotype taken in 390–542 m in Suruga Bay Japan, has long been considered
a junior synonym ofS. strictus Gilbert, 1905, known from waters off Hawaii, Japan, the Philippine Islands, and South Africa. Based on new information from
the holotype and a specimen recently captured from deep waters (789–815 m) off Amami-Oshima Island, southern Japan,S. hondoensis is now established as a valid species.Symphurus hondoensis is unique among congeners in having the combination of a 1–2–3 pattern of interdigitation of proximal dorsal pterygiophores
and neural spines, 10 abdominal vertebrae, 14 caudalfin rays, 111–113 dorsal-fin rays, 95 anal-fin rays, 59 total vertebrae,
105–106 scales in longitudinal series, blind side nearly as darkly pigmented as the ocular surface, and a black peritoneum.
Recognition ofS. hondoensis increases the number of described species ofSymphurus in waters off Japan to three (S. orientalis Bleeker,S. strictus, andS. hondoensis), with at least one more underscribed species occurring in deepwater hydrothermal vent areas off southern Japan. 相似文献