Population structure, growth, mortality and estimated stock size of the introduced tench, Tinca tinca (L.), population in Lake Beyşehir, Turkey

Population structure, growth, length–weight relationship, mortality and stock size of tench, Tinca tinca (L.), was studied in Lake Beyşehir, Turkey in 2005. Totals of 3360 tench (1865 males; 1795 females) were captured with gill- and trammel-nets of various mesh sizes. Male to female ratio was 1.04 : 1. The study covered length year classes. Fork lengths and total weights ranged from 9 to 37 cm and 13 to 815 g. For all individuals, the von Bertalanffy growth equation and length–weight relationship were L _t = 54.2[1−exp(−0.1350( t  + 1.0281)] and W  = 0.0151  L ^2.9993, respectively. Growth performance index and mean condition factor of the tench population were 2.598 and 1.513, respectively. Mortality rates were Z  = 1.97 year⁻¹, M  = 0.29 year⁻¹ and F  = 1.68 year⁻¹ for total, natural, and fishing mortality, respectively. The exploitation rate was E  = 0.85, and the percentage of surviving fish was 13.9%. Tench stock was assessed as about 6–7 million individuals and 1450–1500 tonnes in biomass. It was determined that maximum sustainable yield could be obtained with an 80% level of the current fishing effort.     

Length–weight relationships for three species of mudskippers (Gobiidae: Oxudercinae) in the coastal areas of the Persian Gulf, Iran

Length–weight relationships, W  =  aL ^b , were calculated for three species of mudskippers: Scartelaos tenuis , Periophthalmus waltoni and Boleophthalmus dussumieri from the Iranian coast of the Persian Gulf. Values of b ranged from 2.10 to 2.86 for both sexes at seven sites for the three species.     

Growth and reproduction of Mesopotamian spiny eel (Mastacembelus mastacembelus Banks & Solander, 1794) in Ataturk Dam Lake (Şanliurfa), Turkey

Age at length, growth and reproduction of 220 Mastacembelus mastacembelus specimens from the Atatürk Dam Lake were studied from July 2005 to July 2006. Total lengths and weights ranged from 7.0 to 85.0 cm and from 6 to 1100 g, respectively. Maximum age was 13 years. The regression model fitted to length and weight data was W  =   0.0228  L ^2.43 for males and W  =   0.0029  L ^2.95 for females. The von Bertalaffy growth equations for males and females were L _t  = 99.2 [1−e^{−0.11 ( t −0.12)}] and L _t  = 69.2 [1−e^{−0.26 ( t −0.35)}], respectively. Males dominated especially at an older age; the overall sex ratio was 1 : 0.63 (M:F). The breeding period was from May to July. Fecundity ranged from 2540 to 24 000 eggs per female.     

Length–weight and length–length relationships of three endemic butterflyfish species (Chaetodontidae) from coral reefs of the Northwestern Hawaiian Islands, USA

Length–weight and length–length relationships are presented for three species of butterflyfish endemic to the Hawaiian Islands and Johnston Atoll. From specimens collected within the Papahānaumokuākea Marine National Monument (PMNM), the weight–length relationships were determined for Chaetodon fremblii as W  = 0.029SL^3.17, Chaetodon miliaris as W  = 0.042 SL^3.00, and Chaetodon multicinctus as W  = 0.029SL^3.19 where weight, W , is reported in grams and standard length, SL, in centimeters. Length-frequency data and equations to calculate total length from standard length are also presented.     

Age, growth and mortality of the Mediterranean amberjack Seriola dumerili (Risso 1810) from the south-eastern Adriatic Sea

The age, growth and mortality of the Mediterranean amberjack Seriola dumerili (Risso 1810) were determined in 298 specimens collected in the south-eastern Adriatic Sea (Donji Molunat Bay) from 17 May to 26 June 1997. The total length ranged from 32.0 to 160.0 cm and weight from 0.5 to 46.5 kg. Ten age classes, ranging from 1° to 10° years were defined by scale readings. Mean total length and weight-at-age data were used to estimate the growth parameters of the von Bertalanffy equation: L _∞=174.6 cm, K =0.190, t ₀=–0.314; W _∞=79.01 kg, K =0.139 and t ₀=–0.746. The length–weight relationship was estimated at: W =0.000123 ×  L ^2.847. The overall sex ratio was 1 : 1.06 in favour of males. Total ( Z ) and natural ( M ) mortality were found to be 0.41 years⁻¹ and 0.30 years^–1, respectively. The exploitation ratio ( E =0.27) indicates that the fishing pressure on the Mediterranean amberjack was low in the investigated region.     

Age, growth and feeding of the common stingray (Dasyatis pastinaca, L., 1758) in the Cilician coastal basin, northeastern Mediterranean Sea

Growth and feeding of stingray ( Dasyatis pastinaca ) were studied using 346 specimens from the Cilician Basin coastal area (northeastern Mediterranean). Age classes between 0 to XII were found. The total length of all specimens ranged from 14.6 to 100.9 cm, and total weight was between 22.5 and 6800 g. Total length (TL)-weight (W) and disc width (DW)-weight (W) relationships were W = 0.0033*L^3.1429 and W = 0.0039*DW^3.4914, respectively. The age data, derived from central readings, were used to estimate the von Bertalanffy length and weight growth parameters. The results were L_∞ = 294.9 cm, W_∞ = 198690.1 g, K = 0.029 year⁻¹; t₀ = −2.2 year. The D. pastinaca diet was composed mainly of crustaceans.     

Allometric models for non-destructive leaf area estimation in coffee (Coffea arabica and Coffea canephora)

We aimed to evaluate the currently used allometric models, as well as to propose a reliable and accurate model using non-destructive measurements of leaf length (L) and/or width (W), for estimating the area of leaves of eight field-grown coffee cultivars. For model construction, a total of 1563 leaves were randomly selected from different levels of the tree canopies and encompassed the full spectrum of measurable leaf sizes (0.3–263 cm²) for each genotype. Power models better fit coffee leaf area (LA) than linear models. To validate the model, an independent data set of 388 leaves was used. We demonstrated that the currently used allometric models are biased, underestimating the area of a coffee leaf. We developed a single power model     based on two leaf dimensions [LA = 0.6626 (LW)^1.0116; standard errors: β₀ = 0.0064, β₁ = 0.0019; R² = 0.996] with high precision and accuracy, random dispersion pattern of residuals and also unbiased, irrespective of cultivar and leaf size and shape. Even when the L (but not width) alone was used as the single leaf dimension, the power model developed still predicted with good accuracy the LA but at the expense of some loss of precision, as particularly found for 8% of the leaves sampled with length-to-width ratios below 2.0 or above 3.0.     

Purification and biochemical characterization of a membrane-bound [NiFe]-hydrogenase from a hydrogen-oxidizing, lithotrophic bacterium, Hydrogenophaga sp. AH-24

Membrane-bound [NiFe]-hydrogenase from Hydrogenophaga sp. AH-24 was purified to homogeneity. The molecular weight was estimated as 100±10 kDa, consisting of two different subunits (62 and 37 kDa). The optimal pH values for H₂ oxidation and evolution were 8.0 and 4.0, respectively, and the activity ratio (H₂ oxidation/H₂ evolution) was 1.61 × 10² at pH 7.0. The optimal temperature was 75 °C. The enzyme was quite stable under air atmosphere (the half-life of activity was c . 48 h at 4 °C), which should be important to function in the aerobic habitat of the strain. The enzyme showed high thermal stability under anaerobic conditions, which retained full activity for over 5 h at 50 °C. The activity increased up to 2.5-fold during incubation at 50 °C under H₂. Using methylene blue as an electron acceptor, the kinetic constants of the purified membrane-bound homogenase (MBH) were V _max=336 U mg⁻¹, k _cat=560 s⁻¹, and k _cat/ K _m=2.24 × 10⁷ M⁻¹ s⁻¹. The MBH exhibited prominent electron paramagnetic resonance signals originating from [3Fe–4S]⁺ and [4Fe–4S]⁺ clusters. On the other hand, signals originating from Ni of the active center were very weak, as observed in other oxygen-stable hydrogenases from aerobic H₂-oxidizing bacteria. This is the first report of catalytic and biochemical characterization of the respiratory MBH from Hydrogenophaga .     

Effects of temperature, body size and feeding on rates of metabolism in young‐of‐the‐year haddock

The mean rate of oxygen consumption (routine respiration rate, R _R, mg O₂ fish⁻¹ h⁻¹), measured for individual or small groups of haddock Melanogrammus aeglefinus (3–12 cm standard length, L _S) maintained for 5 days within flow‐through respiratory chambers at four different temperatures, increased with increasing dry mass ( M _D). The relationship between R _R and M _D was allometric ( R _R = α  M ^b ) with b values of 0·631, 0·606, 0·655 and 0·650 at 5·0, 8·0, 12·0 and 15·0° C, respectively. The effect of temperature ( T ) and M _D on mean R _R was described by     indicating a Q ₁₀ of 2·27 between 5 and 15° C. Juvenile haddock routine metabolic scope, calculated as the ratio of the mean of highest and lowest deciles of R _R measured in each chamber, significantly decreased with temperature such that the routine scope at 15° C was half that at 5° C. The cost of feeding ( R _SDA) was c . 3% of consumed food energy, a value half that found for larger gadoid juveniles and adults.     

Longevity of the freshwater anostracan Streptocephalus mackini (Crustacean: Anostraca) in relation to food (Chlorella vulgaris) concentration

SUMMARY 1. Temporary ponds are inhabited by a variety of invertebrates, of which anostracans are an important group. We studied the lifetables of male and female anostracan Streptocephalus mackini at 3 algal concentrations (0.5 × 10⁶, 1.0 × 10⁶ and 1.5 × 10⁶ cells mL⁻¹).
2. Regardless of sex, S. mackini showed better survivorship at lower food levels. The longest average lifespan observed was 85 ± 2 days for males fed Chlorella at 0.5 × 10⁶ cells mL⁻¹.
3. Both net reproductive rate and generation time decreased with increasing food level. The highest net reproductive rate was about 120 cysts per female. The longest generation time of about 40 days, observed at 0.5 × 10⁶ cells mL⁻¹, was more than three times that at 1.5 × 10⁶ cells mL⁻¹.
4. The rate of population increase ( r ) was nearly the same (0.31 ± 0.06) at high (1.5 × 10⁶ cells mL⁻¹) and intermediate (1.0 × 10⁶ cells mL⁻¹) food levels. The r -value at low food level (0.5 × 10⁶ cells mL⁻¹ of Chlorella ) was 0.20 ± 0.01 per day.     

Relationship between opercular girth, maximum girth and total length of fishes caught in gillnets in the estuarine and lower river sections of Shatt al-Arab River (Basrah Province, Iraq)

In fisheries, the two morphological parameters of opercular and maximum girth are related to the effectivity of capture methods in gilled and wedged fish, respectively. The present work investigates the relationship between opercular ( G _ope) and maximum girths ( G _max) to total length ( L _t) for 10 fish species captured from Shatt al-Arab River, Basrah, Iraq. Data were collected October 2005 to December 2006. Cyprinids were the best represented family with six species; engraulids, silurids, heteropneustids and mugilids were each represented by one species. G _ope and G _max were found to increase linearly with total length of all species, all r ² values being greater than 0.73 and statistically significant (P < 0.01). When G _ope and G _max for all species were plotted against total length, two groups were identified ( G 1, G 2), corresponding to general girth-length relationships: (a) G 1 = −0.252 + 0.424 L _t and G 2 = −0.262  +  0.600 L _t for opercular girth and, (b) G 1 = 1.538 + 0.419 L _t and G 2  =  1.538  +  0.696 L _t for maximum girth. These groups correspond to different body shapes of fishes: G 1-round and G 2-compressed. These relationships have implications when using length data and mesh size to determine size selectivity of gill nets.     

Growth and reproduction of the wedge clam (Donax trunculus) in the Sea of Marmara, Turkey

Reproduction, growth and mortality of the wedge clam Donax trunculus were studied in an unexploited population in the northern part of the Sea of Marmara. Age determination was based from counting shell increments by inspection of both the external ring structure and the internal structure on thin cross-sections of the shell. Maximum life span was observed as 6 years for the studied population, but 4 years (shell length 40–41 mm) were usually not exceeded. Maximum length was 44.8 mm. Growth parameters were estimated as L _∞   = 44.15 mm, k  =   0.62 year⁻¹, C  = 1 and WP = 0.83 from external ring structure, and L _∞   = 42.44 mm, k  =   0.75 year⁻¹, C  = 1 and WP = 0.79 from internal growth bands (thin section). Natural mortality ( M ) was estimated as 0.98 year⁻¹. Sex ratio was not significantly different from 1 : 1. The monthly maturation process was assessed macroscopically and from variation in the mean total ash-free dry weight per shell weight of adult individuals. Spawning occurred between April and July with a peak between May and June. The recruitment pattern was unimodal.     

Seasonal patterns of viruses, bacteria and dissolved organic carbon in a riverine wetland

SUMMARY 1. Viral and bacterial abundances were studied in relation to environmental attributes over an annual period, for both planktonic and attached (sediment, aquatic macrophyte and submerged wood) habitats, in a riverine wetland.
2. Annual mean abundance of planktonic viruses ranged from 2.3 × 10⁵−3.8 × 10⁵ particles mL⁻¹ and varied according to sampling site. Significant seasonal patterns in viral abundance were evident and appeared to be linked to variations in bacterial abundance, dissolved organic carbon and inorganic nutrients.
3. Annual mean abundance of viruses associated with surfaces ranged from 1.3 × 10⁶ particles cm⁻² on aquatic macrophytes to 1.1 × 10⁷ particles cm⁻² on wood and also showed seasonal patterns. The difference in viral dynamics among the different sites emphasizes the importance of considering habitat diversity within wetlands when examining microbial communities.     

Effect of feeding level and feeding frequency on specific dynamic action in Silurus meridionalis

The effect of feeding level ( F _L; 0·5 to 4% dry diet mass per wet fish body mass) and feeding frequency (once every 4 days to twice per day) on postprandial metabolic response was investigated in southern catfish Silurus meridionalis at 27·5° C. The results showed that there was no significant difference in the specific dynamic action (SDA) coefficient among the groups of different feeding levels ( P  > 0·05). The duration increased from 26·0 to 40·0 h and the peak metabolic rate increased from 207·8 to 378·8 mg O₂ kg⁻¹ h⁻¹ when the feeding level was increased from 0·5 to 4%. The relationship between the peak metabolic rate ( R _P, mg O₂ kg⁻¹ h⁻¹) and F _L could be described as: R _P = 175·4 + 47·3 F _L( r ² = 0·943, n  = 40, P  < 0·001). The relationship between the SDA duration ( D , h) and F _L could be described as D =30·97 F _L^0·248 ( r ²=0·729, n =40, P  < 0·001).     

Effect of Lactobacillus gasseri BNR17 on blood glucose levels and body weight in a mouse model of type 2 diabetes

Aims:  To investigate the effect of Lactobacillus gasseri BNR17 isolated from human breast milk on blood glucose and body weight in type 2 diabetic animals.
Methods and results:  db/db mice were divided into one control group and five sample groups; the sample groups received BNR17 (10⁷, 10⁸, 10⁹ and 10¹⁰ CFU) or rosiglitazone (8 mg kg⁻¹) orally twice a day for 12 weeks. BNR17 groups had a dose-dependent reduction in food, water intake and amount of excrement. Body weight loss was not seen in the BNR17 groups. Fasting and postprandial 2 h blood glucose levels were significantly lower in the BNR17 (10¹⁰ CFU) group compared with the control group. HbA1c decreased in the BNR17 group, although it was not statistically significant. During the oral glucose tolerance test, the BNR17 groups exhibited dose-dependent improvement in glucose sensitivity.
Conclusions:  Lactobacillus gasseri BNR17 has a suppressing effect on blood glucose levels and improved diabetic symptoms in db/db mice.
Significance and Impact of the Study:  Blood glucose-lowering lactic acid bacteria are expected to be useful as a therapeutic for treating type 2 diabetes in humans.     

Assessment of transpiration efficiency in peanut (Arachis hypogaea L.) under drought using a lysimetric system

Transpiration efficiency (TE) is an important trait for drought tolerance in peanut ( Arachis hypogaea L.). The variation in TE was assessed gravimetrically using a long time interval in nine peanut genotypes (Chico, ICGS 44, ICGV 00350, ICGV 86015, ICGV 86031, ICGV 91114, JL 24, TAG 24 and TMV 2) grown in lysimeters under well-watered or drought conditions. Transpiration was measured by regularly weighing the lysimeters, in which the soil surface was mulched with a 2-cm layer of polythene beads. TE in the nine genotypes used varied from 1.4 to 2.9 g kg⁻¹ under well-watered and 1.7 to 2.9 g kg⁻¹ under drought conditions, showing consistent variation in TE among genotypes. A higher TE was found in ICGV 86031 in both well-watered and drought conditions and lower TE was found in TAG-24 under both water regimes. Although total water extraction differed little across genotypes, the pattern of water extraction from the soil profile varied among genotypes. High water extraction within 24 days following stress imposition was negatively related to pod yield ( r ²   =   0.36), and negatively related to water extraction during a subsequent period of 32 days ( r ²   =   0.73). By contrast, the latter, i.e. water extraction during a period corresponding to grain filling (24 to 56 days after flowering) was positively related to pod yield ( r ²   =   0.36). TE was positively correlated with pod weight ( r ²   =   0.30) under drought condition. Our data show that under an intermittent drought regime, TE and water extraction from the soil profile during a period corresponding to pod filling were the most important components.     

Cloning, molecular characterization and heterologous expression of AMY1, an α-amylase gene from Cryptococcus flavus

A Cryptococcus flavus gene ( AMY1 ) encoding an extracellular α-amylase has been cloned. The nucleotide sequence of the cDNA revealed an ORF of 1896 bp encoding for a 631 amino acid polypeptide with high sequence identity with a homologous protein isolated from Cryptococcus sp. S-2. The presence of four conserved signature regions, (I) ¹⁴⁴DVVVNH¹⁴⁹, (II) ²³⁵GLRIDSLQQ²⁴³, (III) ²⁶³GEVFN²⁶⁷, (IV) ³²⁷FLENQD³³², placed the enzyme in the GH13 α-amylase family. Furthermore, sequence comparison suggests that the C. flavus α-amylase has a C-terminal starch-binding domain characteristic of the CBM20 family. AMY1 was successfully expressed in Saccharomyces cerevisiae . The time course of amylase secretion in S. cerevisiae resulted in a maximal extracellular amylolytic activity (3.93 U mL⁻¹) at 60 h of incubation. The recombinant protein had an apparent molecular mass similar to the native enzyme ( c . 67 kDa), part of which was due to N-glycosylation.     

Molecular Detection of Phytophthora cryptogea on Calendula officinalis and Gerbera jamesonii Artificially Inoculated with Zoospores

In this work, a protocol for zoospores production of Phytophthora cryptogea , an economically important plant pathogen was optimized. Five different concentrations of zoospores (5 × 10⁵, 5 × 10⁴, 5 × 10³, 5 × 10², 5 × 10¹ zoospores/ml) from four different isolates of P. cryptogea (Maria 1, Maria 2, S3 1-A, Amazzone) were used as inoculum on pot marigold ( Calendula officinalis ) and gerbera ( Gerbera jamesonii ) plants. Maria 1 was the most virulent isolate both on pot marigold and gerbera plants according to disease severity. A rapid and sensitive pathogen DNA extraction protocol suitable for large quantities of plant samples was adopted. Conventional polymerase chain reaction (PCR) was able to detect the pathogen in artificially inoculated symptomless pot marigold (collected day 12) and gerbera plants (day 8) after pathogen inoculation, with the suspension of 5 × 10⁵, 5 × 10⁴, 5 × 10³ P. cryptogea  zoospores/ml. Real-time PCR showed the possibility to detect the pathogen in artificially inoculated symptomless pot marigold (collected day 8) and gerbera plants (day 4) after pathogen inoculation, with the suspension of 5 × 10⁵, 5 × 10⁴ P. cryptogea  zoospores/ml. The first symptoms appeared on pot marigold plants 14 days after pathogen inoculation and on gerbera plants 10 days after inoculation. Real-time PCR showed the possibility to detect the pathogen 4 days before conventional PCR and 6 days before the appearance of disease symptoms both on pot marigold and gerbera plants.     

Allometric growth and condition factor of Atlantic cod (Gadus morhua) fed to satiation: effects of temperature and body weight

The effect of thermal environment on condition factor was examined for six different size-classes of Atlantic cod Gadus morhua fed to satiation. A weight–length relationship for 8 to 1303 g fish reared at 4–20°C indicated an allometric growth ( W  =  aL ^b , a  = 0.0045, b  = 3.257) of cod. Changes in relative condition factor ( K _rel) with temperature were described with a second order polynomial. The most pronounced effect of temperature on body condition was found in the smallest size-classes, but the curves flattened with increased size. Temperature had size-dependent effects on the relative condition factor obtained from an overall weight–length relationship for all fish in the experiment, i.e. K _rel increased with weight at 4°C, but decreased with weight at 16 and 20°C. K _rel remained high for most size-classes at 8 and 12°C. The slopes ( b -values) of the weight–length relationships decreased linearly with temperatures from 4 to 16°C.     

Feeding and growth of early juvenile Japanese sardines in the Pacific waters off central Japan

Larval and early juvenile growth was backcalculated for individual Japanese sardines Sardinops melanostictus using the biological intercept method based on the allometric relationship between otolith radii and fish lengths. Sardines grew at 0·81 mm day⁻¹ during the larval stage. In the early juvenile stage, they grew from 32·3 to 45·4 mm fork length ( L ) over a 20-day period (0·64mm day⁻¹). Using the observed relationship between L and wet body weight ( W ), W = 0·00942 L ^2.99, W of the sardine juveniles was calculated to increase from 306 to 832 mg during the 20-day period. The carbon (C) requirement to achieve this growth in weight was estimated to increase from 5·7 to 9·6 mg day⁻¹. Stomach contents of the sardines were composed mostly of copepods (73%) and larvaceans (25%). Wet stomach content weight ( W_s ) was expressed by a power function of the W , W_s=0·731 W ^0·658. Carbon and nitrogen constituted 41·7 ± 1·5 and 10·0 ± 0·4% of the dry W_s , respectively. Stomach C content increased from 2·0 to 3·9 mg during the 20-day period. Three to four cycles of the daily turnover of stomach contents during the 16 h of daytime, corresponding to a gastric evacuation rate of 0·2–0·3 h⁻¹ under continuous feeding, met the C requirement to achieve the backcalculated growth in early juvenile sardines. The Kuroshio frontal waters seem to provide Japanese sardine juveniles with favourable growth conditions.