Age and growth of lanternfishes, Symbolophorus californiensis and Ceratoscopelus warmingii (Myctophidae), in the Kuroshio–Oyashio Transition Zone

To estimate the age and growth of dominant lanternfishes in the Kuroshio–Oyashio Transition Zone, we examined the sagittal otolith microstructure of Symbolophorus californiensis (n = 30) and Ceratoscopelus warmingii (n = 93) collected from the western North Pacific during 1997–2003. Age of S. californiensis ranged from 81 to 541 days corresponding to postmetamorphosis stage (juveniles and adults), and the von Bertalanffy model was fitted: L _t  = 128[1 − exp{−0.003(t − 1.52)}], where L is the standard length (mm) and t is age in days. Age of C. warmingii ranged from 6 to 416 days, and growth before metamorphosis was linear (L _t  = 0.346t + 1.51), and the von Bertalanffy model was fitted to the postmetamorphosis stage: L _t  = 80.8 [1 − exp{−0.00769(t − 34.4)}]. Growth of these two lanternfishes was faster than that of other lanternfishes in previous studies but considerably slower than that of Japanese sardine (Sardinops melanostictus) and anchovy (Engraulis japonicus) distributed in the Kuroshio–Oyashio Transition Zone. Temperature and prey availability are discussed in relation to this difference in growth rate.     

Use of otoliths to determine age and growth of a tropical flatfish Cyclopsetta querna (Paralichthyidae) from the southeast coast of the Gulf of California, Mexico

Age and growth of the tropical flatfish Cyclopsetta querna were determined from the sagittal otoliths. From yearly marginal growth increment trends, it was concluded that the opaque and hyaline zones were formed annually. The oldest individual was a 43.2-cm (5-year-old) female. No significant differences in length-at-age were found between sexes. The von Bertalanffy growth equation for the entire population was L_t = 60.71 (1 − e ^{(−0.245(t−0.408))}). The life span of these species is short, about 5 years. The otoliths proved a reliable structure to determine age of this species.     

Allocation policy of female freshwater pearl mussels

Living exclusively in trout streams which are very poor in nutrients, freshwater pearl mussels are physiologically adapted to the low food supply by a reduced metabolism. Longevity of these mussels spans decades and life-time fecundity of females is very high (up to 2*10⁸ larvae). Their resource allocation policy favours survival over current reproduction. Reproductive effort (per reproductive period) falls within the lowest range of values reported for molluscs (0.8–5.3% of the total organic substance). The soft parts (without larvae) of reproducing females are heavier compared to pausing ones, indicating that only those females reproduce which exceed a threshold value of body weight. The more they exceed this value the more larvae they produce. Surplus energy (the amount above the threshold) is not completely devoted to reproduction but is in part invested in somatic functions. At the population level this allocation system results in largely size independent fecundity values, varying considerably between individuals and in a variable percentage (5–54%) of females taking part in reproduction every year. The evolution of this system must be attributed to the reduced metabolism and growth. This provides the basis for a very long life accompanied with many spawning periods. Accordingly fitness can be improved by extending longevity. Received: 27 April 1998 / Accepted: 13 July 1998     

Development of sexual dimorphism in two sympatric skinks with different growth rates

Sexual size dimorphism (SSD) is widespread in animals, especially in lizards (Reptilia: Squamata), and is driven by fecundity selection, male–male competition, or other adaptive hypotheses. However, these selective pressures may vary through different life history periods; thus, it is essential to assess the relationship between growth and SSD. In this study, we tracked SSD dynamics between a “fading‐tail color skink” (blue tail skink whose tail is only blue during its juvenile stage: Plestiodon elegans) and a “nonfade color” tail skink (retains a blue tail throughout life: Plestiodon quadrilineatus) under a controlled experimental environment. We fitted growth curves of morphological traits (body mass, SVL, and TL) using three growth models (Logistic, Gompertz, and von Bertalanffy). We found that both skinks have male‐biased SSD as adults. Body mass has a higher goodness of fit (as represented by very high R² values) using the von Bertalanffy model than the other two models. In contrast, SVL and TL for both skinks had higher goodness of fit when using the Gompertz model. Two lizards displayed divergent life history tactics: P. elegans grows faster, matures earlier (at 65 weeks), and presents an allometric growth rate, whereas P. quadrilineatus grows slower, matures later (at 106 weeks), and presents an isometric growth rate. Our findings imply that species‐ and sex‐specific trade‐offs in the allocation of energy to growth and reproduction may cause the growth patterns to diverge, ultimately resulting in the dissimilar patterns of SSD.     

Preliminary observations on the life history of the white-streaked grouper, <Emphasis Type="Italic">Epinephelus ongus</Emphasis>, from Okinawa,Japan

A preliminary analysis of 175 specimens of the white-streaked grouper, Epinephelus ongus (Serranidae), was undertaken to determine life history characteristics of the species. Sagittal otoliths, stomachs, and a subsample of gonads were removed to determine age at length, diet, and reproductive strategy. The von Bertalanffy growth equation was used to describe growth in this species and yielded the growth parameters L^∞ = 438.3, K = 0.04334, and t₀ = −8.752. Fish ranged in age from 1 to 20 years. Diet was consistent with other serranid species and included crabs, shrimps, octopi, and fishes. Based on a very limited number of specimens (n = 12), the larger size and older age of males compared to females suggests that E. ongus may be a protogynous hermaphrodite.     

Length-based growth,maturity and natural mortality of the cockfish <Emphasis Type="Italic">Callorhinchus callorhynchus</Emphasis> (Linnaeus, 1758) off Coquimbo,Chile

The growth rate, reproductive aspects, and natural mortality of chimaeras and ratfish are poorly known. In this study, life-history parameters for cockfish Callorhinchus callorhynchus (Holocephali—Callorhinchidae) are estimated, which is an important fish resource exploited in Chile. Specimens were sampled from the artisanal fishery captures, from November 2006 to November 2007. The standard length (SL) of males fluctuated between 20 and 62 cm, and between 21 and 70 cm for females. Von Bertalanffy growth parameters were estimated through length-frequency data analysis using MULTIFAN. The length-weight relationship and von Bertalanffy growth parameters were significantly different for males and females, as well as the length at 50% maturity. For males a model with 5 age-classes was the best, with asymptotic length L _∞ = 52 cm SL, growth coefficient K = 0.473 yr⁻¹, and age at length zero t ₀ = −0.690 yrs. For females the best model was represented by 10 age-classes (L _∞ = 70.3 cm SL, K = 0.193 yr⁻¹, t ₀ = −1.158 yrs) in the length-frequency data sets. Length at 50% maturity of males was estimated in 43.7 cm SL, and in 50.2 cm SL for females. The natural mortality rate fluctuated between 0.42 and 0.82 yr⁻¹ for males and between 0.12 and 0.37 yr⁻¹ for females, depending upon the method used. It is concluded that C. callorhynchus is a species with life-history parameters significantly different between males and females, and such differences should be taken into account in future population dynamics analysis.     

Why protogynous hermaphrodite males are relatively larger than females? Testing growth hypotheses in Mediterranean rainbow wrasse <Emphasis Type="Italic">Coris julis</Emphasis> (Linnaeus, 1758)

Several growth hypotheses have been tested to investigate why males of the sequential hermaphrodite, Mediterranean rainbow wrasse, Coris julis (Linnaeus, 1758), are relatively larger than females of the same age. Individual growth trajectories were estimated to test these hypotheses. A good linear relationship between otolith size and body size was observed (r ²  = 0.71, n = 609), thus, past somatic growth of any specific fish can be inferred from the longitudinal data described by the width of annual increments in the otolith. These data were successfully analyzed by a non-linear mixed-effect model (von Bertalanffy growth model) using a Bayesian approach. The results obtained suggest that Mediterranean rainbow wrasse secondary males are relatively larger than females because 1) fish that change sex are already the larger individuals in their age group (specifically those with higher growth rate, k _{secondary males}  = 0.199 and k _females  = 0.161) and 2) they experience a growth spurt after sex change. The differences in growth observed in this species and in other protogynous hermaphrodites could be related to differences in social organization, which, in turn, are related to differences in the sex change mechanisms.     

Fermented whey – an inexpensive feed source for a laboratory-scale selenium-bioremediation reactor system inoculated with Thauera selenatis

It is critical that an inexpensive electron- donor/carbon-source be found for selenium bioremedia-tion using the selenate-respiring bacterium, Thauera selenatis. Since acetate is a preferred substrate for growth of this organism, a method was developed for fermenting the lactose in whey to large amounts of acetate. Indigenous whey microorganisms fermented the whey lactose in this manner when grown in continuous culture at a very slow dilution rate (D = 0.05 h⁻¹). The successful use of the fermented whey lactose as the carbon-source/electron-donor feed for a laboratory-scale selenium-bioremediation reactor system, inoculated with T. selenatis, treating selenium-contaminated drainage water was also demonstrated. Selenium oxyanions and nitrate were reduced by 98%. Received: 30 October 1998 / Received revision: 26 January 1999 / Accepted: 5 February 1999     

Interspecific and intraspecific variation in tree seedling survival: effects of allocation to roots versus carbohydrate reserves

We examined interspecific and intraspecific variation in tree seedling survival as a function of allocation to carbohydrate reserves and structural root biomass. We predicted that allocation to carbohydrate reserves would vary as a function of the phenology of shoot growth, because of a hypothesized tradeoff between aboveground growth and carbohydrate storage. Intraspecific variation in levels of carbohydrate reserves was induced through experimental defoliation of naturally occurring, 2-year-old seedlings of four northeastern tree species –Acer rubrum, A. saccharum, Quercus rubra, and Prunus serotina– with shoot growth strategies that ranged from highly determinate to indeterminate. Allocation to root structural biomass varied among species and as a function of light, but did not respond to the defoliation treatments. Allocation to carbohydrate reserves varied among species, and the two species with the most determinate shoot growth patterns had the highest total mass of carbohydrate reserves, but not the highest concentrations. Both the total mass and concentrations of carbohydrate reserves were significantly reduced by defoliation. Seedling survival during the year following the defoliation treatments did not vary among species, but did vary dramatically in response to defoliation. In general, there was an approximately linear relationship between carbohydrate reserves and subsequent survival, but no clear relationship between allocation to root structural biomass and subsequent survival. Because of the disproportionate amounts of reserves stored in roots, we would have erroneously concluded that allocation to roots was significantly and positively related to seedling survival if we had failed to distinguish between reserves and structural biomass in roots. Received: 14 December 1999 / Accepted: 2 June 1999     

Effect of feeding strategy on Zymomonas mobilis CP4 fed-batch fermentations and mathematical modeling of the system

In this work, the effect of the feeding strategy in Zymomonas mobilis CP4 fed-batch fermentations on the final biomass and ethanol concentrations was studied. Highest glucose yields to biomass (0.018 g/g) and to ethanol (0.188 g/g) were obtained in fed-batch fermentations carried out using different feeding rates with a glucose concentration in the feed equal to 100 g/l. Lower values (0.0102 g biomass/g glucose and 0.085 g ethanol/g glucose) were obtained when glucose accumulated to levels higher than 60 g/l. On the other hand, the highest biomass (5 g/l) and ethanol (39 g/l) concentrations were obtained using a glucose concentration in the feed equal to 220 g/l and exponentially varied feeding rates. Experimental data were used to validate the mathematical model of the system. The prediction errors of the model are 0.39, 14.36 and 3.24 g/l for the biomass, glucose and ethanol concentrations, respectively. Due to the complex relationship for describing the specific growth rate, a fed-batch culture in which glucose concentration is constant would not optimize the process. Received: 30 November 1999 / Received revision: 24 March 2000 / Accepted: 7 April 2000     

Resource allocation,hyperphagia and compensatory growth

Organisms often shown enhanced growth during recovery from starvation, and can even overtake continuously fed conspecifics (overcompensation). In an earlier paper (Ecology 84, 2777–2787), we studied the relative role played by hyperphagia and resource allocation in producing overcompensation in juvenile (non-reproductive) animals. We found that, although hyperphagia always produces growth compensation, overcompensation additionally requires protein allocation control which routes assimilate preferentially to structure during recovery. In this paper we extend our model to cover reproductively active individuals and demonstrate that growth rate overcompensation requires a similar combination of hyperphagia and allocation control which routes the part of enhanced assimilation not used for reproduction preferentially towards structural growth. We compare the properties of our dynamic energy budget model with an earlier proposal, due to Kooijman, which we extend to include hyperphagia. This formulation assumes that the rate of allocation to reserves is controlled by instantaneous feeding rate, and one would thus expect that an extension to include hyperphagia would not predict growth overcompensation. However, we show that a self-consistent representation of the hyperphagic response in Kooijman’s model overrides its fundamental dynamics, leading to preferential allocation to structural growth during recovery and hence to growth overcompensation.     

Growth, age at sexual maturity and condition in bearded seals (Erignathus barbatus) from Svalbard, Norway

The aim of this study was to describe growth, determine age at sexual maturity and investigate the condition of bearded seals (Erignathus barbatus) collected in the fjords of Spitsbergen, Svalbard, Norway. Morphometric data, teeth and sex organs were collected from 110 animals. Age was determined by reading the cementum layers in hard longitudinal sections of canine teeth. Sexual maturity in males was determined according to the size of the testes and bacula. Females were defined as being sexually mature according to findings of mature follicles or corpora lutea/albicantia. Von Bertalanffy growth curves were applied to both standard length and body mass, and asymptotic values for males and females were 231.1 ± 11.4 cm and 269.9 ± 26.2 kg, and 233.1 ± 7.5 cm and 275.3 ± 47.8 kg, respectively. Maximum recorded lengths and masses were 254 cm and 313 kg in males and 242 cm and 358 kg in females. All males older than 6 years were found to have been sexually mature. Females were found to attain sexual maturity at about 90% of the asymptotic length, corresponding to an age of 5 years. In males a significant decrease in condition was observed from June to August, with a subsequent increase in September. In adult females, condition decreased from May to June and increased again from June to September. The conditional changes seen are likely to be due to the extra energetic cost and reduced food intake associated with reproduction, lactation and molt. Accepted: 28 July 1998     

Fed-batch production of unsaturated medium-chain-length polyhydroxyalkanoates with controlled composition by <Emphasis Type="Italic">Pseudomonas putida</Emphasis> KT2440

Unsaturated medium-chain-length polyhydroxyalkanoates (MCL-PHA) were produced at a productivity of 0.63–1.09 g PHA l⁻¹ h⁻¹ with final PHA content ranging from 42.6 to 55.8% in single-stage, carbon-limited, fed-batch fermentations of Pseudomonas putida KT2440. A mixture of nonanoic acid (NA) and 10-undecenoic acid (UDA⁼) was fed exponentially to control growth rate. Varying the specific growth rate (0.14 h⁻¹ vs. 0.23 h⁻¹) at similar substrate feed ratios (NA:UDA⁼ = 5:1) had little effect on the final PHA content and relative composition. However, decreasing the NA:UDA⁼ ratio decreased the final amount of PHA produced from 56% with NA:UDA⁼ = 5.07:1 to only 42% at NA:UDA⁼ = 2.47:1. The molar fraction of all 3-hydroxyalkanoate monomers in the PHA product was relatively constant throughout each fermentation, indicating that the final product was homogeneous rather than a mixture of different copolymers. A linear relationship between unsaturation of the PHA produced and unsaturation of the carbon feed was found, which demonstrates the feasibility of producing unsaturated MCL-PHAs with controlled polymeric composition in a fed-batch process.     

A novel method for characterisation of microbial growth kinetics on volatile organic compounds

A novel method for the determination of microbial growth kinetics on hydrophobic volatile organic compounds (VOC) has been developed. A stirred tank reactor was operated as a fed-batch system to which the VOC was continuously fed via the gas phase, assuring a constant VOC concentration in the mineral medium. A flow of air was saturated with the VOC, and then mixed with a further flow of air, to obtain a predetermined VOC concentration. Thus, different VOC concentrations in the mineral medium could be obtained by altering the VOC concentration in the feed gas. The growth kinetics of Xanthobacter autotrophicus GJ10 on 1,2-dichloroethane (DCE) and of Pseudomonas sp. strain JS150 on MonoChloroBenzene (MCB) were assessed using this method. The growth of strain JS150 was strongly inhibited at MCB concentrations higher than 160 mg l⁻¹, and the results were fitted using a piecewise function. The growth kinetics of strain GJ10 were described by the Luong model where maximum growth rate μ_max = 0.12 h⁻¹, substrate saturation constant K _S = 7.8 mg l⁻¹, and maximum substrate concentration S _m (above which growth is completely inhibited) = 1080 mg l⁻¹. Varying nitrogen and oxygen flows enabled the effect of oxygen concentration on the growth kinetics of Pseudomonas JS150 to be determined. Received: 30 November 1998 / Received revision: 19 March 1999 / Accepted: 20 March 1999     

Age and growth of Schizopygopsis younghusbandi younghusbandi in the Yarlung Zangbo River in Tibet, China

Schizopygopsis younghusbandi younghusbandi is an endemic species whose distribution is restricted to the middle reaches of the Yarlung Zangbo River, being one of the most important commercial fishes in this area. Age and growth of 606 specimens captured between October 2002 and April 2005 were studied. The range in standard length (L) was 65.7–387.3 mm and total weight (W) was 3.3–772.0 g. The relationship between L and W was W = 0.000909L^2.2493 for males and W = 0.000259L^2.4781 for females. Age, determined from anal scales and lapillus otoliths, ranged from 3 to 18 years. The parameters of von Bertalanffy growth functions, estimated by back-calculated length, were L_￥ = 442.7mm  LL_\infty = 442.7mm\;L, k = 0.0738 year⁻¹ and t ₀  = −1.4 year for males, and L_￥ = 471.4mm  LL_\infty = 471.4mm\;L, k = 0.0789 year⁻¹ and t ₀ = 0.2 year for females. Males and females exhibited statistically significant differences in growth. χ ²-test indicated that von Bertalanffy growth functions could well describe the growth of S. y. younghusbandi. The longevities were 39.2 and 38.2 years for males and females, respectively. Growth inflexion points were 10.2 and 12.0 years for males and females, respectively, but 84.8% of the captures were at the smaller ages. So conservation and management schemes for this population should be considered urgently. In addition, we found that populations from the upstream of the Lhasa River, the downstream of the Lhasa River and the middle reaches of the Yarlung Zangbo River showed statistically significant differences in growth patterns.     

Effect of growth rate on α-amylase production by Streptomyces sp. IMD 2679

The α-amylase of Streptomyces sp. IMD 2679 was subject to catabolite repression. Four different growth rates were achieved when the organism was grown at 40 °C and 55 °C in the presence and absence of cobalt, with an inverse relationship between α-amylase production and growth rate. Highest α-amylase yields (520 units/ml) were obtained at the lowest growth rate (0.062 h⁻¹), at 40 °C in the absence of cobalt, while at the highest growth rate (0.35 h⁻¹), at 55 °C in the presence of cobalt, α-amylase production was decreased to 150 units/ml. As growth rate increased, the rate of specific utilisation of the carbon source maltose also increased, from 46 to 123 μg maltose (mg biomass)⁻¹ h⁻¹. The pattern and levels of α-glucosidase (the enzyme degrading maltose) detected intracellularly in each case, indicate that growth rate effectively controls the rate of feeding of glucose to the cell, and thus catabolite repression. Received: 17 February 1997 / Received revision: 29 April 1997 / Accepted: 11 May 1997     

Partitioning of foraging effort in Adélie penguins provisioning chicks at Béchervaise Island, Antarctica

Analyses of the body masses of Adélie penguins (Pygoscelis adeliae) departing on foraging trips of long and short duration (> and<40 h, respectively) during chick rearing showed that the departure weights of birds prior to long trips were significantly lighter than were those prior to short trips. Penguins, particularly males, were significantly heavier at the start of the guard stage than at the end and both sexes gained similar amounts of body mass during the crèche period. Results support the hypothesis that the foraging effort of Adélie penguins at Béchervaise Island is partitioned between the sexes, with males accepting a net rate of negative energy gain to provide regular meals for their offspring during the guard stage. Adélie penguin foraging behaviour may be driven by a trade-off between the allocation of food to chicks and the storage of parental body reserves, similar to that previously postulated for some species of flying seabirds. The relevance of such a foraging strategy to the breeding success of penguins in the Mawson region of eastern Antarctica is discussed in relation to micronekton distribution in the area. Accepted: 3 June 2000     

Using cross-dating techniques to validate ages of aurora rockfish (<Emphasis Type="Italic">Sebastes aurora</Emphasis>): estimates of age,growth and female maturity

Since fishery management regulations have shifted much of the groundfish trawl effort in the northeastern Pacific from the continental shelf to the slope, fishery impacts on unassessed demersal slope rockfish species like the aurora rockfish (Sebastes aurora) may have increased. Understanding the life history of these species is a critical first step in developing management strategies to protect them from overharvest. In this study we employ cross-dating methods to validate the annual periodicity of growth increments and investigate the age, growth and maturity of aurora rockfish, a species for which life history information is quite limited. Specimens were collected on an opportunistic basis from Oregon commercial landings and from research cruises, over the years 2003–2006. Age was estimated for 438 individuals using otoliths processed via the break-and-burn method. The maximum estimated age was 118 years for females (n = 324) and 81 years for males (n = 114). The von Bertalanffy growth function showed that males grow faster and reach a smaller maximum size than females (males: L _inf = 34, K = 0.09, t ₀ = −1.9; females: L _inf = 37, K = 0.06, t ₀ = −5.5), though both sexes demonstrate relatively slow growth. Visual assessment of ovaries showed that the aurora rockfish is a synchronous spawner with parturition occurring in May and June off Oregon. Female age and length at 50% maturity were calculated at 12.6 years and 26 cm, respectively (n = 307). Maturity and age data provided evidence for a protracted adolescence in this species.