Growth in captivity and aspects of reproductive biology of the Antarctic fish parasite Aega antarctica (Crustacea,Isopoda)

Summary Specimens of the fish parasite Aega antarctica caught in the Weddell Sea and off the South Shetlands and South Orkneys were kept in aquaria for more than 2 years. These isopods were fed with plaice (Pleuronectes platessa) from the North Sea. Growth in captivity was very slow. For the first growth phase before reaching sexual maturity of females the value K = 0.12 was calculated for the Bertalanffy growth constant. Mature males are markedly smaller than breeding females (average lengths: 16.0 and 22.5 mm). An age of more than 5 years was calculated for an average-sized male, females spawn at an age of more than 10 years. No evidence for protandric hermaphroditism could be found.     

Population age structure in males and juveniles of the Antarctic Krill,Euphausia superba Dana

Summary Further results are reported on the age structure of populations of the Antarctic krill, using the age pigment lipofuscin. Study of the males shows a five-year adult life span as in females in an earlier study. Only a single age group was found in the juvenile stage.     

The length weight relationship, age, growth and reproduction of the roach Rutilus rutilus (L.) in Lake Volvi

The length-weight relationship of a sample of 233 roach ( Rutilus rutilus ) can be described by the following equations: y =0·0356 x ^3·405 and y =0·0215 ×^3·606 for males and females respectively. In both equations y equals the body weight in grams and × is the standard length in centimetres. The average condition factor K was 2·01 with a range of 1·71 to 2·26. The roach's span of life was 13 years for both sexes. The growth increment is greater during the first year of life (about 56 mm), decreasing to approximately 17 mm at the end of the sixth year of life and then becoming constant at about 12 mm per year. Roach become sexually mature at age 1 + for males and one year later for females. The mean absolute fecundity was 9294 eggs; with a range from 920 to 32 810. The growth of the gonads is related to the age of the fish. Spawning occurs during the first half of April, at a mean water temperature of 10° C.     

A skeletochronological study of age, growth and longevity in a population of the frog Rana ridibunda from southern Europe

Age at sexual maturity and longevity in a population of Rana ridibunda from north-eastern Greece were studied by skeletochronology performed on the phalanges. Analysis of the age structure was based on counting the lines of arrested growth (LAGs). Sexual maturity for both sexes arises during the first year or after the first hibernation. Ages ranged from 1 to 5 years (mean=2.96) among 52 males and from 1 to 5 years (mean=3.73) among 56 females. The mean snout-vent length was 69.03+/-12.6mm in males and 82.38+/-13.27 mm in females. The difference between the sexes in age and size was significant. Growth of individuals was fitted on? The von Bertalanffy model. The growth coefficient (K) was 0.57 in males and 0.54 in females, mainly due to faster male growth between metamorphosis and maturation.     

Occurrence of the autofluorescent pigment, lipofuscin, in polar crustaceans and its potential as an age marker

In crustaceans, the lack of reliable methods often prevents the determination of individual age. The quantification of the autofluorescent age pigment, lipofuscin, has revealed promising results in boreal and tropical species. We studied the presence of morphological lipofuscin and its possible application as an age marker in five Arctic and five Antarctic species, comprising decapods, amphipods and a euphausiid. Lipofuscin granules were located in the brain, using confocal fluorescence microscopy, and quantified from digital images. The pigment was found in 94 of 100 individuals and in all 10 species, and granules occurred in easily detectable amounts in 5 species. Two scavenging amphipod species, the Antarctic Waldeckia obesa and the Arctic Eurythenes gryllus, revealed the most conspicuous and numerous granules. There was a broad, though weak, correlation of lipofuscin concentration with individual body size within a species, but not with absolute body size of one species compared to another. In larvae of the decapod Chorismus antarcticus, lipofuscin accumulation was quantified over the 1st 4 months after larval release. Morphological lipofuscin is a potential index of age in those investigated species with a sufficient accumulation rate of the pigment.     

Population dynamics and life history of a geographically restricted seahorse, Hippocampus whitei

The aim of this study was to collect data on population dynamics and life history for White's seahorse Hippocampus whitei, a geographically restricted species that is listed as data deficient under the IUCN Red List. Data from H. whitei populations were collected from two regions, Port Stephens (north) and Sydney Harbour (south) in New South Wales, Australia, covering most of the known range of H. whitei, from 2005 to 2010. Over 1000 individuals were tagged using fluorescent elastomer and on subsequent recaptures were re-measured for growth data that were used in a forced Gulland-Holt plot to develop growth parameters for use in a specialized von Bertalanffy growth-function model. Growth parameters for Port Stephens were: females L(∞) = 149·2 mm and K = 2·034 per year and males L(∞) = 147·9 mm and K = 2·520 per year compared with estimates from Sydney Harbour: females L(∞) = 139·8 mm and K = 1·285 per year and males L(∞) = 141·6 mm and K = 1·223 per year. Whilst there was no significant difference in growth between sexes for each region, H. whitei in Port Stephens grew significantly quicker and larger and matured and reproduced at a younger age than those from Sydney Harbour. The life span of H. whitei is at least 5 years in the wild with six individuals recorded reaching this age. Data collected on breeding pairs found that H. whitei displays life-long monogamy with three pairs observed remaining pair bonded over three consecutive breeding years. Baseline population densities were derived for two Port Stephens' sites (0·035 and 0·110 m(-2) ) and for Manly in Sydney Harbour (1·050 m(-2) ). Even though the life-history parameters of H. whitei suggest it may be reasonably resilient, precaution should be taken in its future management as a result of its limited geographical distribution and increasing pressures from anthropogenic sources on its habitats.     

Life history traits of the striped seabream Lithognathus mormyrus (Pisces,Sparidae) from two coastal fishing grounds in the Strait of Sicily

Striped seabream Lithognathus mormyrus [n = 1269; total lengths (TLs) = 112–350 mm] were investigated in two coastal Sicilian fishing grounds (central Mediterranean Sea). Samples were collected from the two landing harbours, Licata and Selinunte, between October 1999 and September 2000. Seasonal and spatial variations in population structure, age, growth, reproduction and mortality were studied. It was found that seasonal differences in the main modes of length–frequency distributions corresponded well with the seasonal growth. The recruits in Licata grew faster and attained a larger size (by 10–20 mm) at ages up to 2 years than in Selinunte. Growth thereafter was relatively slow, with Selinunte specimens growing at a slightly faster rate. Spawning occurred between June and August. Length at the first maturity was different between females and males in the Selinunte (190–181 mm) and Licata (183–171 mm) fishing grounds. The species displayed protandrous hermaphroditism, and somatic growth practically ceased during the period of sex inversion. Total fishing mortality was considerably higher in Licata (F between 0.53 and 0.63 per year) than in Selinunte (F between 0.22 and 0.29 per year). Therefore it is suggested that the striped seabream population in Licata is more vulnerable to overfishing than that in Selinunte.     

Changes in oxidative stress parameters in relation to age, growth and reproduction in the short-lived catarina scallop Argopecten ventricosus reared in its natural environment

Increase in oxidative damage and decrease in cellular maintenance is often associated with aging, but, in marine ectotherms, both processes are also strongly influenced by somatic growth, maturation and reproduction. In this study, we used a single cohort of the short-lived catarina scallop Argopecten ventricosus, to investigate the effects of somatic growth, reproduction and aging on oxidative damage parameters (protein carbonyls, TBARS and lipofuscin) and cellular maintenance mechanisms (antioxidant activity and apoptosis) in scallops, caged in their natural environment. The concentrations of protein carbonyls and TBARS increased steeply during the early period of fast growth and during reproduction in one-year-old scallops. However, oxidative damage was transient, and apoptotic cell death played a pivotal role in eliminating damage in gill, mantle and muscle tissues of young scallops. Animals were able to reproduce again in the second year, but the reduced intensity of apoptosis impaired subsequent removal of damaged cells. In late survivors low antioxidant capacity and apoptotic activity together with a fast accumulation of the age pigment lipofuscin was observed. Rates of oxygen consumption and oxidative stress markers were strongly dependent on somatic growth and reproductive state but not on temperature. Compared to longer-lived bivalves, A. ventricosus seems more susceptible to oxidative stress with higher tissue-specific protein carbonyl levels and fast accumulation of lipofuscin in animals surviving the second spawning. Superoxide dismutase activity and apoptotic cell death intensity were however higher in this short-lived scallop than in longer-lived bivalves. The life strategy of this short-lived and intensely predated scallop supports rapid somatic growth and fitness as well as early maturation at young age at the cost of fast cellular degradation in second year scallops.     

Biology of the silky shark Carcharhinus falciformis (Carcharhinidae) in the eastern Indian Ocean, including an approach to estimating age when timing of parturition is not well defined

Biological data were recorded for 1265 silky sharks Carcharhinus falciformis collected from fish landing sites in eastern Indonesia. These represented catches taken in most calendar months by gillnetting and longlining in the eastern Indian Ocean and contained individuals ranging from embryos to fully mature adults. The growth zones in centra, which were shown to form annually, were counted in the vertebrae in a sub-sample of 200 fish for ageing purposes. The embryo lengths in the 5 months for which there were such data, and the presence of neonates in virtually all months, however, indicated that birth occurs throughout the year and thus there was no well-defined birth date for ageing individual fish. The approximate birth date of each individual was thus estimated from a combination of the total length (L(T) ) at capture and backcalculated L(T) at the formation of the birth zone and at the first and last growth zones in the vertebral centra, together with the period that had elapsed between the formation of those last two growth zones. The number of eggs or embryos in uteri ranged from two to 14, with a mean of 7·2. The estimated mean L(T) at birth of females (811 mm, range: 799-823 mm) and males (812 mm, range: 794-830 mm), derived from the backcalculations corresponding to the birth zones in the centra, were not significantly different (P > 0·05). The L(T) ranges in the catches of post-natal females (570-2592 mm) and males (553-2289 mm) taken by gillnetting were wider than those of the females (1177-2623 mm) and males (1184-2409 mm) taken by longlining. The oldest female and male were 19 and 20 years-old, respectively. The von Bertalanffy growth curves for the two sexes did not differ significantly. The growth coefficient, k, and the asymptotic length, L(T∞). were 0·066 year?1 and 2994 mm for the curve fitted to the combined data for females and males. The lengths L(T50) and ages A(50) at which C. falciformis attained maturity were 2156 mm and 15 years for females and 2076 mm and 13 years for males. The very high proportion of C. falciformis with lengths 相似文献   

The age, growth and reproduction of Chondrostoma polylepis willkommi in a seasonal stream in the Guadalquivir River basin (southern Spain)

The age, growth and reproduction of Chondrostoma polylepis willkommi , an endemic cyprinid from the Iberian Peninsula, was studied for 2 years in a seasonal stream in the Guadalquivir River basin. Annual growth was low. Maximum ages observed were 5+ in males and 7+ in females. There was no significant difference in growth between sexes. Seasonal growth period started in May and continued for 2 to 6 months depending on age. The mean lengths of 1 + and 2+ age-groups decreased once the growth period had finished, probably related to reproductive stress and adverse ecological conditions, and this could explain the occurrence of Rosa Lee's phenomenon. Both sexes matured at the end of their second year of life (1+). There was a significant difference from 1: 1 in the overall sex ratio of 334 males to 464 females. Reproductive period started in March and lasted until May. Ch. p. willkommi was a multiple spawner that released two batches of eggs per female each year. The regression between fecundity ( F ) and fork length (l., mm) was: F =6.20 10³ L.^2.78. In females from age 2 + onwards, relative annual investment in somatic growth and reproduction was equivalent, implying that the same energy was allocated to reproduction as to maintenance/growth. Compared with other Ch. polylepis populations, the life-history patterns of this population, located in a small and seasonal stream in a southern latitude, were characterized by a low annual growth, a trade-off between reproduction and growth/maintenance, early maturity, low number of age-groups and high fecundity from multiple spawnings.     

Age structure, growth and reproduction of Leuciscus pyrenaicus in an intermittent stream in the Guadalquivir river basin, southern Spain

The age, growth and reproduction of Leuciscus pyrenaicus (Günther, 1868), an endemic cyprinid from the Iberian Peninsula, was studied from November 1987 to September 1989 in a small seasonal tributary of the Guadalquivir river basin. Maximum fork lengths observed were a 160 mm male with six scale annuli and a 171 mm female aged 7 +. Maximum ages observed were 7 + in males and 8 + in females. There were no significant differences in the annual growth increments between sexes. Seasonal growth period started in March and continued for 5 to 6 months. Mean lengths of 1 + specimens onwards diminished during summer and/or autumn. Males and females matured in their third and fourth year of life respectively. The overall sex ratio (272 males: 310 females) differed significantly from equality. Spawning began in May and ended in July. L. pyrenaicus is a multiple spawner that releases a minimum of two batches of eggs per female each year. Eggs in each batch were similar in both size (egg diameter) and number released. The relationship between fecundity (Fee) and fork length (mm) was represented by the formula: Fec=1.96 10⁻³ L^2.50.     

Sex‐related differences in the postmolt distribution of Weddell seals (Leptonychotes weddellii) in the southern Weddell Sea

The population of Weddell seals (Leptonychotes weddellii) in the southern Weddell Sea is in a unique position on the continental shelf edge, with vast shelf waters to the south, and deep Southern Ocean to the north. We describe sex‐related differences in the winter distribution of this population, from data collected by 20 conductivity‐temperature‐depth satellite relay data loggers deployed in February 2011 at the end of the annual molt. The regional daily speed was calculated, and a state‐space model was used to estimate behavioral states to positions along individuals’ tracks. GLMMs estimated that males and smaller individuals, diving in shallower water, traveled less far per day of deployment (males 14.6 ± 2.26 km/d, females 18.9 ± 2.42 km/d), and males were estimated to dive in shallower water (males 604 ± 382 m, females 1,875 ± 1,458 m). Males and smaller individuals were also estimated to be more resident; males spent an average 83.4% ± 7.7% of their time in a resident behavioral state, compared to females at 74.1% ± 7.1%. This evidence that male and female Weddell seals in the southern Weddell Sea are adopting different strategies has not been shown elsewhere along their circumpolar distribution.     

Postmetamorphic growth,survival, and age at first reproduction of the salamander,hynobius nebulosus tokyoensis Tago in relation to a consideration on the optimal timing of first reproduction

The postmetamorphic growth and survival of the salamander Hynobius nebulosus tokyoentisTago were surveyed in the study site located in Habu village of Hinodemachi, a suburb of Tokyo City, during 1975–1981. A laboratory experiment on the growth rate of juveniles was conducted in parallel with the field survey. The result indicated that this salamander grew at the rate of 8,mm in s.v.l. per year during the juvenile stage, but its growth rate decreased markedly as low as 1.8 mm for males and 1.1 mm for females, once it had attained sexual maturity. According to the “capture-recapture” procedure the annual survival rate after metamorphosis was found to be quite high; that is, approximately 0.7. By using the growth rate of juveniles and the difference between the sizes at metamorphosis and sexual maturity, the age at first reproduction was estimated to be 4 year for males and 5 year for females. From the data obtained in this study, the intrinsic rates of increase (r) were calculated for various values of age at first reproduction under different survival schedules, and the relationship between the age at first reproduction and fitness as measured by r was examined. The result indicated that an optimal age maximizing fitness always existed under respective survival schedules, and the observed age at first reproduction of this salamandei was found to coincide well with the predicted optimal age.     

The life history of rock gurnard (Trigloporus lastoviza, Brünn. 1768) in the Saronikos Gulf

Age, growth and reproduction of rock gurnard in the Saronikos Gulf (Greece) were studied. Otoliths from 638 specimens (sex combined) were read for age determination. The body length-otolith radius relationship was found linear (L = -18.0 + 4.99 _xR; where L = fish length in mm, R = otolith radius 20 X). The life span of females seemed to be longer than that of males, indicating a differential mortality with sex. The growth was lower than that in the Catalane Sea. The maximum age of fish collected was VIII and the maximum fork length estimated by von Bertalanffy equation was 356 mm. Weight increased as the 3.054252 power or the length. Reproduction was observed to take place between winter and early spring and occasionally in early winter. Males began to mature after completion of the second year and the females after the third. The exploitation rate was rather high, which suggests that the rock gurnard stock was overfished in Saronikos Gulf. The male to female ratio was usually 1:1.     

Age structure,growth and reproduction ofRutilus lemmingii in an intermittent stream of the Guadalquivir river basin,southern Spain

The age, growth and reproduction ofRutilus lemmingii (Steindachner, 1866), an endemic cyprinid from the Iberian Peninsula, was studied for over a period of two years in a small seasonal tributary of the Guadalquivir river basin. Approximately 65 % of the total growth in length occured in the first year of life. Males reached a maximum age of 3+ yr (Fork Length, F.L. = 114 mm) and females 4+ yr (F.L. = 144 mm). Both sexes matured during their second year of life (1 +). The overall sex ratio (334 males to 389 females) differed significantly from unity. Somatic condition decreased markedly during the reproductive period of March to May.R. lemmingii is a multiple spawner and releases two batches of eggs per female each year. Mean egg diameter of the first batch was larger than the second one. The regression between fecundity and Fork Length (mm) was: Fec = 0.014 F.L.Z.^2.858 Compared with available information, thisR. lemmingii population, located at a lower latitude, is characterized by fast growth, early maturity, high level of reproductive effort, and a short life-span. These life-history characteristices are typical of species in unstable environments, where adult mortality is high, variable or unpredictable.     

Effect of age on lipid peroxides, lipofuscin and ascorbic acid contents of the lungs of male garden lizard

Oxidative damage was assessed through the estimation of lipid peroxides (LP) in the lungs of an ageing short-lived species of reptile, Calotes versicolor, commonly known as the garden lizard. Attempts were also made to trace its relationship with the age pigment, lipofuscin and the antioxidant ascorbic acid. While LP increased with advancing age the contents of both lipofuscin and ascorbic acid did not show appreciable change during maturation ( < 1-1 year old) but declined during senescence phase (1 to 2-4 year old). While the pattern of age associated changes in LP and ascorbic acid indicate similarity with the pattern observed in most of the mammals, the reduction of lipofuscin in older lizards is a significant departure from the common trend.     

Influence of age and individual identity in the use of breeding colony habitat by male Weddell seals in Erebus Bay,Antarctica

Male–male contest behavior can contribute to spatial distributions of male pinnipeds during breeding seasons. To maximize breeding opportunities, the most competitive males would be expected to be surrounded by the highest numbers of reproductive-age females. As information regarding fine-scale spatial ecology of Weddell seals is lacking, we performed an exploratory study using kernel density analyses to evaluate age-specific habitat use of male Weddell seals in Erebus Bay, Antarctica. Additionally, we investigated the relationship between age and number of surrounding reproductive-age females using a competing set of regression models in a Bayesian framework that considered different functional forms of age while incorporating individual heterogeneity. As male adult Weddell seals aged, to at least 20 years, they were more likely to be found in areas associated with the greatest densities of reproductive-age females, but individual heterogeneity also influenced the number of reproductive-age female neighbors. The youngest males tended to haul out in offshore areas associated with better hunting, and older males tended to settle in more nearshore areas associated with more pup production. Our findings from this preliminary investigation indicate that male Weddell seal spatial behavior during the breeding season varies with age and individual and might be related to reproductive activity.     

Quantification of the age-pigment lipofuscin in brains of known-age, pond-reared prawns Penaeus japonicus (Crustacea, decapoda)

A quantitative study of the lipofuscin content was carried out by image analysis in brains of known-age, pond-reared Penaeus japonicus (Crustacea, Decapoda) with the aim of assessing the applicability of the lipofuscin technique as an estimator of the physiological age in penaeids. With this purpose, three distinct measurements of lipofuscin levels (% area fraction, granule density and mean granule size) were recorded in ten sections of the olfactory lobe cell mass (OLCM) per animal. The image analysis was based on the autofluorescence emitted by the pigment, which accentuates the contrast between the lipofuscin granules and the background tissue. The concentration of lipofuscin increased significantly with age and was independent of sex. The relationship between age and lipofuscin concentration (area fraction and granule density) was best described by a seasonalized von Bertalanffy function, since the accumulation rate of the pigment dramatically slowed down in fall-winter, probably as a result of reduced seasonal metabolism. The present results confirm the potential of the lipofuscin method in the estimation of physiological age in penaeids and suggest that the application of this methodology can be useful in studies of age structure in wild populations and in the assessment of natural resources. J. Exp. Zool. 286:120-130, 2000.     

Seasonal changes in the number of neurocytes containing lipofuscin pigment in selected areas of the brain of Rana temporaria L

The number of neurocytes containing lipofuscin pigment (LEP) was determined in the nucleus infundibularis dorsalis (NID), the subfornical organ (SFO) and the medulla oblongata (MO) of the brain of sexually mature females and males of Rana temporaria L. approximately identical in length and age. The frogs were captured in their natural habitat in seven periods of the annual cycle. The number of LFP-positive neurocytes shows distinct seasonal variations in the analyzed areas. In general, neurocytes containing LFP were found in higher numbers during the winter months, and their significant drop was observed in summer. The results seem to suggest that cells containing LFP represent a certain kind of dynamic cellular system responding to various internal and/or external factors changing within a year.     

Age and growth of the round stingray Urobatis halleri at Seal Beach, California

The age and growth of the round stingray Urobatis halleri was determined using vertebral sections from animals collected at Seal Beach, California from 2002 to 2005. Annual periodicity was validated from U. halleri injected with oxytetracycline and maintained in captivity over a 2 year period ( n = 7). The coefficients estimated by the von Bertalanffy growth model were the disc width asymptote ( W _D∞) (286 mm for males and 224 mm for females) and K (0·09 year⁻¹ for males and 0·15 year⁻¹ for females). The age structure of the population consisted of mostly older, mature males and females. Age at maturity was estimated at 3·80 years for females and 3·75 years for males, and the maximum assessed age was 14 years old. Males were more numerous than females throughout the year; however, from May to September, females outnumbered males. The U. halleri age and growth coefficients were comparable to other species in the family Urolophidae. Based on the seasonality and age structure of this population, Seal Beach offers warm-water refuge for U. halleri of reproductive maturity, and the U. halleri at Seal Beach may garner some behavioural thermoregulation benefit.