Bioenergetics of juvenile whitespotted bamboo shark Chiloscyllium plagiosum [Anonymous (Bennett)]

This study establishes the bioenergetics budget of juvenile whitespotted bamboo shark Chiloscyllium plagiosum by estimating the standard metabolic rate (R_S), measuring the effect of body size and temperature on the R_S, and identifying the specific dynamic action (R_SDA) magnitude and duration of that action in juvenile whitespotted bamboo sharks. The mean ±s .d . (R_S) of six fish (500–620 g) measured in a circular closed respirometry system was 30·21 ± 5·68 mg O₂ kg^?1 h^?1 at 18° C and 70·38 ± 14·81 mg O₂ kg^?1 h^?1 at 28° C, respectively. There were no significant differences in R_S between day and night at either 18 or 28° C (t‐test, P > 0·05). The mean ±s .d . Q₁₀ for 18–28° C was 2·32 ± 0·06 (n = 6). The amount of oxygen consumed per hour changed predictably with body mass (M; 295–750 g) following the relationship: (n = 40, r²= 0·92, P < 0·05). The mean magnitude of R_SDA was 95·28 ± 17·55 mg O₂ kg^?1 h^?1. The amount of gross ingested energy (E_I) expended as R_SDA ranged from 6·32 to 12·78% with a mean ±s .d . of 8·01 ± 0·03%. The duration of the R_SDA effect was 122 h. The energy content of juvenile whitespotted bamboo shark, squid and faeces determined by bomb calorimeter were 19·51, 20·3 and 18·62 kJ g dry mass^?1. A mean bioenergetic budget for juvenile whitespotted bamboo sharks fed with squid at 18° C was 100C = 29·5G + 31·9R_S+ 28·2R_SDA+ 6·7F + 2·1E + 1·6U, where C = consumption, G = growth, F = egestion, E = excretion and U = unaccounted energy.     

ATP-driven Ca2+ transport in sealed plasma membrane vesicles prepared by aqueous two-phase partitioning from leaves of Commelina communis

Sealed plasma membrane vesicles were obtained in high purity from leaves of Commelina communis L. by aqueous two-phase partitioning. Based on the analysis of a range of markers, the preparations (U₃+U₃′ phases) were shown to be devoid of tonoplast, Golgi and thylakoid membranes, and showed only trace mitochondrial contamination. One-third of the vesicles were oriented inside out and exhibited ATP-driven ⁴⁵Ca²⁺ transport [? 15 pkat (mg protein)⁻¹]. Ca²⁺ uptake into the vesicles had a pH optimum of 7.2 and apparent K_m values for Ca²⁺ of 4.4 μM and for Mg-ATP of 300 μM. Ca²⁺ uptake, K⁺, Mg²⁺-ATPase (EC 3.6.1.3) activity as well as glucan synthase II (EC 2.4.1.34) activity were all maximal at the same equilibrium density (1.17 g cm⁻³) on continuous sucrose density gradients. The protonophore carbonylcyanide m-chlorophenylhydrazone (CCCP) did not inhibit the ATP-dependent Ca²⁺ transport into the vesicles, excluding a Ca²⁺/H⁺ exchange driven by a proton gradient. ATP-dependent Ca²⁺ uptake was inhibited by erythrosin B (I₅₀= 0.1 μM), ruthenium red (I₅₀= 30 μM), La³⁺ (I₅₀= 10 μM) and vanadate (I₅₀= 500 μM), but not by azide, cyanide and oligomycin. The calmodulin antagonists, trifluoperazine (I₅₀= 70 μM) and W-7 (I₅₀= 100 μM) were also inhibitory, However, this inhibition was not overcome by calmodulin. Trifluoperazine and W-7, on the other hand, stimulated Ca²⁺ efflux from the vesicles rather than inhibit Ca²⁺ uptake. Our results demonstrate the presence of a Ca²⁺-ATPase in the plasma membrane of C. communis. In the intact cell, the enzyme would pump Ca²⁺ out of the cell. Its high affinity for Ca²⁺ makes it a likely component involved in adjusting low cytoplasmic Ca²⁺ levels. No indications for a secondary active Ca²⁺/H⁺ transport mechanism in the plasma membrane of C. communis were obtained. Both, the nucleotide specificity and the sensitivity towards vanadate. distinguish the Ca²⁺-ATPase from the H⁺-translocating K⁺. Mg²⁺-ATPase in C. communis plasma membranes.     

Maximum sustainable speed, energetics and swimming kinematics of a tropical carangid fish, the green jack Caranx caballus

Maximum sustained swimming speeds, swimming energetics and swimming kinematics were measured in the green jack Caranx caballus (Teleostei: Carangidae) using a 41 l temperature‐controlled, Brett‐type swimming‐tunnel respirometer. In individual C. caballus [mean ±s.d. of 22·1 ± 2·2 cm fork length (L_F), 190 ± 61 g, n = 11] at 27·2 ± 0·7° C, mean critical speed (U_crit) was 102·5 ± 13·7 cm s^?1 or 4·6 ± 0·9 L_F s^?1. The maximum speed that was maintained for a 30 min period while swimming steadily using the slow, oxidative locomotor muscle (U_max,c) was 99·4 ± 14·4 cm s^?1 or 4·5 ± 0·9 L_F s^?1. Oxygen consumption rate (M in mg O₂ min^?1) increased with swimming speed and with fish mass, but mass‐specific M (mg O₂ kg^?1 h^?1) as a function of relative speed (L_F s^?1) did not vary significantly with fish size. Mean standard metabolic rate (R_S) was 170 ± 38 mg O₂ kg^?1 h^?1, and the mean ratio of M at U_max,c to R_S, an estimate of factorial aerobic scope, was 3·6 ± 1·0. The optimal speed (U_opt), at which the gross cost of transport was a minimum of 2·14 J kg^?1 m^?1, was 3·8 L_F s^?1. In a subset of the fish studied (19·7–22·7 cm L_F, 106–164 g, n = 5), the swimming kinematic variables of tailbeat frequency, yaw and stride length all increased significantly with swimming speed but not fish size, whereas tailbeat amplitude varied significantly with speed, fish mass and L_F. The mean propulsive wavelength was 86·7 ± 5·6 %L_F or 73·7 ± 5·2 %L_T. Mean ±s.d . yaw and tailbeat amplitude values, calculated from lateral displacement of each intervertebral joint during a complete tailbeat cycle in three C. caballus (19·7, 21·6 and 22·7 cm L_F; 23·4, 25·3 and 26·4 cm L_T), were 4·6 ± 0·1 and 17·1 ± 2·2 %L_T, respectively. Overall, the sustained swimming performance, energetics, kinematics, lateral displacement and intervertebral bending angles measured in C. caballus were similar to those of other active ectothermic fishes that have been studied, and C. caballus was more similar to the chub mackerel Scomber japonicus than to the kawakawa tuna Euthynnus affinis.     

Coordination chemistry of lanthanides with cryptands. An X-ray and spectroscopic study of the complex Nd2(NO3)6 [C18H36O6N2]·H2O

By reacting neodymium nitrate hexahydrate with the cryptand 〈222〉 in methanol, the complex Nd₂-(NO₃)₆[C₁₈H₃₆O₆N₂]·H₂O was obtained and analyzed by single-crystal X-ray diffraction. The cell is triclinic P$\text{1}$ with a = 14.870(2) Å, b = 13.261(2) Å, c = 8.832(1) Å, α = 91.2(1)°, β = 93.4(1)°, γ = 87.6(1)°, Z = 2 and U = 1736.6 ų. The structure was refined by least-squares methods to the conventional R = 0.039 for 6177 observed reflections. The compound contains the cations [Nd〈222〉(NO₃)]²⁺ and the anions [Nd(NO₃)₅·H₂O]^2?, and is isostructural with the samarium analogue. Solid state fluorescence spectra of the title complex were measured at room and liquid nitrogen temperature, and the transitions ⁴F_3/2 → ⁴I_9/2 and ⁴F_3/2 → ⁴I_11/2 analyzed.     

A laboratory energy budget for the ormer Haliotis tuberculata L.

Each component of the energy budget (ingestion, egestion,somatic growth, reproductive investment, respiration, excretion, and mucus production) was measured for Haliotis tuberculata L. held at 15°C in a 12-h light: 12-h dark regime. Ulva lactuca L. was used as the food source throughout, and the budget was assessed over the whole size range of the animal. Ingestion rates ranged from 1.94 to 997.2 cal·animal⁻¹·day⁻¹ in 0.01 to 50 g dry wt (3.71 × 10⁻³ to 17.3 g dry flesh wt) animals, respectively. The major component of the energy budget was somatic growth (37.5% of I) in a 0.01-g dry wt animal while it was respiration (31.1% of I) in a 50-g dry wt animal. Mucus production formed a large part of the budget (from 23.3% of I in a 0.01-g dry wt animal to 29.l% of I in a 50-g dry wt animal). Scope for growth, I − (E + R + U + M), was calculated as ranging from 24.5% of ingestion in a 50-g dry wt animal to 36.8% in a 0.01-g dry wt animal.Each component was measured independently and allometric relationships with animal dry weight calculated. Exponents ranged from 0.60 (somatic growth) to 1.06 (reproductive investment).The calorific value of food was 3419 cal·g dry wt⁻¹ and for faeces was 2817 cal·g dry wt⁻¹. Absorption as a percentage of ingestion in terms of dry weight ranged from 78% for 95-mm length animals (50 g dry wt) to 81% in 6-mm animals (0.01-g dry wt⁻¹). Gross and net growth efficiencies (K₁ and K₂) were calculated on an energy basis and both were logarithmically related to animal dry weight.     

Comparison of the prolonged swimming performances of closely related, morphologically distinct three‐spined sticklebacks Gasterosteus spp.

Prolonged swimming performances of two as yet unnamed species of three‐spined stickleback, Gasterosteus spp., were compared. The two fishes (not yet formally described, referred to here as benthic and limnetic) inhabit different niches within Paxton Lake, Texada Island, British Columbia, Canada, and are recent, morphologically distinct species. Limnetics had longer endurance during prolonged swimming than did benthics. The mean regression of the log₁₀ of fatigue time (F_t, s) on swimming speed (U, standard length, L_S s^?1) for limnetics (log₁₀F_t = 7·03 ? 0·46U) had a similar slope, but a significantly higher intercept than that for benthics (log₁₀F_t = 5·55 ? 0·43U). Adult benthics were larger, heavier and deeper‐bodied fish than limnetics. Limnetics, however, had a significantly greater pectoral fin edge:base ratio (mean ± s .e .: limnetics, 4·58 ± 0·43; benthics, 3·63 ± 0·27). In addition, limnetics had significantly lower drag coefficients (C_D) than benthics (limnetics, log₁₀C_D = ?0·49log₁₀R_e + 0·66; benthics, log₁₀C_D = ?0·26log₁₀R_e ? 0·30) where R_e is the Reynolds number [(L_SU (ν^?1), where U and ν are swimming velocity and the kinematic viscosity of the water, respectively]. Compared to their ancestral form, the anadromous three‐spined stickleback Gasterosteus aculeatus L., limnetics and benthics had significantly longer and shorter endurance times, respectively. In addition, both these fishes had significantly higher fast‐start velocities than their ancestral form. Selection due to differential resource use may have lead to divergence of body form, and, therefore, of steady swimming performance. Therefore predation may be the selective force for the similar high escape performance in these two fishes.     

Hypoxia tolerance decreases with body size in red drum Sciaenops ocellatus

Mass‐specific oxygen consumption rate, i.e. standard metabolic rate (R_s) and critical oxygen tension (P_crit) of red drum Sciaenops ocellatus were measured and scaled over a 2500‐fold range in mass (M_F; 0·26–686 g). R_s conformed to well established models (R_s = 3·73·91 M_F^?0·21; r² = 0·86) while P_crit increased over the size range (P_crit = 3·15 log₁₀M_F + 16·19; r² = 0·44). This relationship may be ecologically advantageous as it would allow smaller S. ocellatus to better utilize hypoxic zones as habitat and refuge from predators.     

Novel life‐history data for threatened seahorses provide insight into fishery effects

Life‐history variables for three incidentally captured species of seahorse (Kellogg's seahorse Hippocampus kelloggi, the hedgehog seahorse Hippocampus spinosissimus and the three‐spot seahorse Hippocampus trimaculatus) were established using specimens obtained from 33 fisheries landing sites in Peninsular Malaysia. When samples were pooled by species across the peninsula, sex ratios were not significantly different from unity, and height and mass relationships were significant for all species. For two of these species, height at physical maturity (H_M) was smaller than the height at which reproductive activity (H_R) commenced: H. spinosissimus (H_M = 99·6 mm, H_R = 123·2 mm) and H. trimaculatus (H_M = 90·5 mm, H_R = 121·8 mm). For H. kelloggi, H_M could not be estimated as all individuals were physically mature, while H_R = 167·4 mm. It appears that all three Hippocampus spp. were, on average, caught before reproducing; height at 50% capture (H_C) was ≥H_M but ≤H_R. The results from this study probe the effectiveness of assessment techniques for data‐poor fisheries that rely heavily on estimates of length at maturity, especially if maturity is poorly defined. Findings also question the sustainability of H. trimaculatus catches in the south‐west region of Peninsular Malaysia, where landed specimens had a notably smaller mean height (86·2 mm) and markedly skewed sex ratio (6% males) compared with samples from the south‐east and north‐west of the peninsula.     

Aerobic scope for activity in age 0 year Atlantic cod Gadus morhua

Key components of swimming metabolism: standard metabolism (R_s), active metabolism (R_a) and absolute aerobic scope for activity (R_a–R_s) were determined for small age 0 year Atlantic cod Gadus morhua. Gadus morhua juveniles grew from 0·50 to 2·89 g wet body mass (M_WB) over the experimental period of 100 days, and growth rates (G) ranged from 1·4 to 2·9% day^?1, which decreased with increasing size. Metabolic rates were recorded by measuring changes in oxygen consumption over time at different activity levels using modified Brett‐type respirometers designed to accommodate the small size and short swimming endurance of small fishes. Power performance relationships were established between oxygen consumption and swimming speed measurements were repeated for individual fish as each fish grew. Mass‐specific standard metabolic rates () were calculated from the power performance relationships by extrapolating to zero swimming speed and decreased from 7·00 to 5·77 μmol O₂ g^?1 h^?1, mass‐specific active metabolic rates () were calculated from extrapolation to maximum swimming speed (U_max) and decreased from 26·18 to 14·35 μmol O₂ g^?1 h^?1 and mass‐specific absolute scope for activity was calculated as the difference between active and standard metabolism () and decreased from 26·18 to 14·35 μmol O₂ g^?1 h^?1 as M_WB increased. Small fish with low R_s had bigger aerobic scopes but, as expected, R_s was higher in smaller fish than larger fish. The measurements and results from this study are unique as R_s, R_a and absolute aerobic scopes have not been previously determined for small age 0 year G. morhua.     

Thermal tolerance and metabolic physiology among redband trout populations in south‐eastern Oregon

Streamside measurements of critical thermal maxima (T_crit), swimming performance (U_crit), and routine (R_r) and maximum (R_max) metabolic rates were performed on three populations of genetically distinct redband trout Oncorhynchus mykiss in the high‐desert region of south‐eastern Oregon. The T_crit values (29·4 ± 0·1° C) for small (40–140 g) redband trout from the three streams, and large (400–1400 g) redband trout at Bridge Creek were not different, and were comparable to published values for other salmonids. At high water temperatures (24–28° C), large fish incurred higher metabolic costs and were more thermally sensitive than small fish. U_crit(3·6 ± 0·1 L_F s^?1), R_r(200 ± 13 mg O₂ kg^?0·830 h^?1) and metabolic power (533 ± 22 mg O₂ kg^?0·882 h^?1) were not significantly different between populations of small redband trout at 24° C. R_max and metabolic power, however, were higher than previous measurements for rainbow trout at these temperatures. Fish from Bridge Creek had a 30% lower minimum total cost of transport (C_min), exhibited a lower refusal rate, and had smaller hearts than fish at 12‐mile or Rock Creeks. In contrast, no differences in U_crit or metabolism were observed between the two size classes of redband trout, although C_min was significantly lower for large fish at all swimming speeds. Biochemical analyses revealed that fish from 12‐mile Creek, which had the highest refusal rate (36%), were moderately hyperkalemic and had substantially lower circulating levels of free fatty acids, triglycerides and albumin. Aerobic and anaerobic enzyme activities in axial white muscle, however, were not different between populations, and morphological features were similar. Results of this study: 1) suggest that the physiological mechanisms that determine T_crit in salmonids are highly conserved; 2) show that adult (large) redband trout are more susceptible to the negative affects of elevated temperatures than small redband trout; 3) demonstrate that swimming efficiency can vary considerably between redband trout populations; 4) suggest that metabolic energy stores correlate positively with swimming behaviour of redband trout at high water temperatures; 5) question the use of T_crit for assessing physiological function and defining thermal habitat requirements of stream‐dwelling salmonids like the redband trout.     

Effect of fish length and nutritional condition on the fecundity of distressed Atlantic cod Gadus morhua from the Baltic Sea

The disappearance of larger individuals and the decrease in individual body condition suffered by Atlantic cod Gadus morhua in the eastern Baltic during the past two decades can be expected to affect the stock reproductive output. To investigate this, female G. morhua were collected during the spawning and pre‐spawning period in 2015?2016. The current individual potential fecundity (F_P) of eastern Baltic G. morhua was estimated and analysed in relation to total length (L_T) and indices of nutritional status such as body condition (K) and hepato‐somatic index (I_H) using generalized linear models. In addition, the current prevalence of atresia and its potential relation to K were investigated. Moreover, a calibration curve to estimate F_P from oocyte diameter, based on the autodiametric oocyte counting method, was established for the first time for eastern Baltic G. morhua and can be used for future fecundity studies on this stock. The results showed that F_P was mainly positively related to fish length, but K and I_H also contributed significantly to the variation in F_P. The model predicted that fish with K = 1·2 have a F_P 51% higher than fish of the same L_T with K = 0·8. The prevalence of fecundity regulation by atresia was 5·8%, but it was found only in fish in the pre‐spawning maturity stage and with low K. Temporal changes in biological features such as the length composition and individual body condition of eastern Baltic G. morhua, should be accounted for when estimating stock reproductive potential.     

Relationships between metabolic rate, muscle electromyograms and swim performance of adult chinook salmon

Oxygen consumption rates of adult spring chinook salmon Oncorhynchus tshawytscha increased with swim speed and, depending on temperature and fish mass, ranged from 609 mg O₂ h^?1 at 30 cm s^?1 (c. 0·5 BL s^?1) to 3347 mg O₂ h^?1 at 170 cm s^?1 (c. 2·3 BL s^?1). Corrected for fish mass, these values ranged from 122 to 670 mg O₂ kg^?1 h^?1, and were similar to other Oncorhynchus species. At all temperatures (8, 12·5 and 17° C), maximum oxygen consumption values levelled off and slightly declined with increasing swim speed >170 cm s^?1, and a third‐order polynomial regression model fitted the data best. The upper critical swim speed (U_crit) of fish tested at two laboratories averaged 155 cm s^?1 (2·1 BL s^?1), but U_crit of fish tested at the Pacific Northwest National Laboratory were significantly higher (mean 165 cm s^?1) than those from fish tested at the Columbia River Research Laboratory (mean 140 cm s^?1). Swim trials using fish that had electromyogram (EMG) transmitters implanted in them suggested that at a swim speed of c. 135 cm s^?1, red muscle EMG pulse rates slowed and white muscle EMG pulse rates increased. Although there was significant variation between individual fish, this swim speed was c. 80% of the U_crit for the fish used in the EMG trials (mean U_crit 168·2 cm s^?1). Bioenergetic modelling of the upstream migration of adult chinook salmon should consider incorporating an anaerobic fraction of the energy budget when swim speeds are ≥80% of the U_crit.     

Synthesis and crystal structure of the MgCl2(CH3COOC2H5)2· (CH3COOC2H5) adduct

The reaction of α-MgCl₂ with boiling ethyl acetate affords MgCI₂(CH₃COOC₂H₅)₂· (CH₃COOC₂H₅), which is obtained as crystals suitable for X-ray analysis only from the mother liquor. M=315.5, orthorhombic, space group P2₁22₁ (No. 18), a=25.077(3), b=8.616(1), c=7.345(1) Å, V=1587.0(3) ų, Z=4, D_x=1.32 g cm⁻³,λ A(Mo Kα)=0.71069 Å, μ=4.17 cm⁻¹, F(000)=664, T=298 K, observed reflections: 1667, R=0.059 and R_w=0.069. The structure is composed of polymeric chains of MgCl₂(CH₃COOC₂H₅₎₂ and the ethyl acetate molecules occupy a mutually trans position.     

Effects of surgically implanted acoustic transmitters >2% of body mass on the swimming performance, survival and growth of juvenile sockeye and Chinook salmon

The influence of surgical implantation of an acoustic transmitter on the swimming performance, growth and survival of juvenile sockeye salmon Oncorhynchus nerka and Chinook salmon Oncorhynchus tshawytscha was examined. The transmitter had a mass of 0·7 g in air while sockeye salmon had a mass of 7·0–16·0 g and Chinook salmon had a mass of 6·7–23·1 g (a transmitter burden of 4·5–10·3% for sockeye salmon and 3·1–10·7% for Chinook salmon). Mean critical swimming speeds (U_crit) for Chinook salmon ranged from 47·5 to 51·2 cm s^?1 [4·34–4·69 body lengths (fork length, L_F) s^?1] and did not differ among tagged, untagged and sham‐tagged groups. Tagged sockeye salmon, however, did have lower U_crit than control or sham fish. The mean U_crit for tagged sockeye salmon was 46·1 cm s^?1 (4·1 L_F s^?1), which was c. 5% less than the mean U_crit for control and sham fish (both groups were 48·6 cm s^?1 or 4·3 L_F s^?1). A laboratory evaluation determined that there was no difference in L_F or mass among treatments (control, sham or tag) either at the start or at the end of the test period, suggesting that implantation did not negatively influence the growth of either species. None of the sockeye salmon held under laboratory conditions died from the influence of surgical implantation of transmitters. In contrast, this study found that the 21 day survival differed between tagged and control groups of Chinook salmon, although this result may have been confounded by the poor health of Chinook salmon treatment groups.     

Effects of water temperature and initial weight on growth,digestion and energy budget of yellow catfish Pelteobagrus fulvidraco (Richardson, 1846)

The effects of water temperature and body weight on feeding, growth, and energy budget were inevitable in the yellow catfish Pelteobagrus fulvidraco (Richardson, 1846), an important fish cultivated in China. This study explores the interaction of water temperature and body weight on both energy utilization strategy and energy conversion efficiency to promote further healthy culture of yellow catfish. Fish with body weights of 6 g (Group S), 16 g (Group M) and 35 g (Group B) were reared in 15 circular glass steel cylinders 80 cm in diameter × 70 cm in height (180 L) at water temperatures of 21, 24, 27, 30 and 33°C (3 replicates for each temperature) for 42 days to investigate effects of water temperature and body weight on the feeding, growth, digestion and energy budget in yellow catfish. Results showed that the levels of dry matter, protein and energy in the body were significantly affected by water temperature (p < .05). Feeding, growth, feed conversion efficiency, digestion and energy allocation parameters were significantly related to both water temperature and body weight (p < .05). Yellow catfish had higher maximal food consumption (C_max), food intake rate, specific growth rate, food conversion efficiency, appear digestibility coefficient, and growth energy allocation (G) at 24–30°C, and optimal growth at a water temperature of 27°C. Two‐factor analysis of variance revealed that there was reciprocation of both water temperature and body weight on the above parameters. At the optimal temperature of 27°C, the value of energy for growth (G) was the highest, and the value of energy for feces (F) produced was the lowest. Yellow catfish with various body weights had energy budget equations of 100 A = 63.70 R + 36.30 G in Group S, 100 A = 62.54 R + 37.46 G in Group M, and 100 A = 67.47 R + 32.53 G in Group B if the equations were described as percentage of the proportion of the assimilation energy. Therefore, the optimal temperature was 27°C according to its feeding, growth and digestion.     

Biochemical composition of a dominant detritivorous fish Prochilodus lineatus along pollution gradients in the Paraná-Río de la Plata Basin

The biochemical composition of muscle, liver and stomach contents of a detritivorous fish Prochilodus lineatus was analysed and compared to settling particles and sediments along pollution gradients over 1500 km of the Río de la Plata Basin to evaluate the effects of anthropogenic discharges in a detritus food chain. The stomach contents of P. lineatus collected in the polluted Metropolitan Buenos Aires coast were enriched in proteins, carbohydrates and lipids, similar to settling particulates collected in the sewer area, and two to five times higher than underlying sediments, supporting the interpretation that P. lineatus feeds on unconsolidated organic flocs freshly decanted from mixed industrial and sewage outfalls. Fish from Buenos Aires had consistently higher standard length (L_S) and mass (M_T) slopes (b = 3·5), condition indexes (K = 3·01 ± 0·47, mean ±s.d .) and muscle fat content (fat = 23·8 ± 13·8% wet mass, mean ±s.d .) relative to northern fish (b = 2·7, K = 2·22 ± 0·39, fat = 3·4 ± 3·2% wet mass, respectively), suggesting that sewage‐derived organic matter was an enriched diet, which allowed an enhanced body mass gain and fat accumulation compared to organic‐poor vegetal detritus in the north Paraná area. Buenos Aires fish also showed higher hepato‐somatic indices (mean ±s.d . I_H 1·41 ± 0·49 v. 0·70 ± 0·32, respectively), which correlated with their two to three orders of magnitude higher hydrocarbon and polychlorinated biphenyl (PCB) loads, suggesting an enhanced detoxifying metabolism. The northward migration of fatty P. lineatus was evidenced by the presence of clear outliers in the L_S and M_T relationship, K and fat content along the Paraná River.     

Microsatellite loci within sixgill sharks, Hexanchus griseus

Novel sixgill shark (Hexanchus griseus) microsatellite loci were developed and tested on five shark species. A suite of microsatellite loci previously developed for lemon sharks (Negaprion brevirostris) was also tested. Data on 15 microsatellites are presented including primer sequences, number of alleles (a), observed (H_O) and expected heterozygosities (H_E), and F_IS values for sixgill sharks (a = 10–69, H_O = 0.24–1.00, H_E = 0.76–0.96 and F_IS = –0.21–0.60), sevengill sharks (Notorynchus cepedianus) (a = 6–40, H_O = 0.20–0.73, H_E = 0.59–0.94 and F_IS = –0.47–0.58), Pacific spiny dogfish (Squalus acanthias) (a = 3–13, H_O = 0.00–0.96, H_E = 0.24–0.93 and F_IS =–0.52–1.00), angle sharks (Squatina californica) (a = 1–4, H_O = 0.00–1.00, H_E = 0.60–1.00 and F_IS =–1.00–0.25), and leopard sharks (Triakis semifasciata) (a = 3–16, H_O = 0.20–1.00, H_E = 0.53–0.92 and F_IS = –0.57–1.00). A final suite of 14 microsatellites (13 developed from sixgill sharks and one from lemon sharks) were found to be polymorphic and conform to Hardy–Weinberg equilibrium within sixgill sharks.     

Intramolecular hydrogen bonding: synthesis and crystal structure of nickel(II) and copper(II) complexes of a tetradentate amine oxime

In the reaction of the tetradentate ligand 3,3′-(1,4- butanediyldiamino) bis (3-methyl-2-butanone)-dioxime (BnAO) with nickel(II) and copper(II), the monomeric [Ni(BnAO-H)]I·H₂O and a mixed monomer/dimer salt [Cu(BnAO-H)H₂O]₂[(Cu(BnAO-H))₂](ClO₄)₄, respectively, are formed, and all complexes have an intramolecular hydrogen bond between cis oxime groups. The OHO bonds give the characteristic infrared absorptions as well as the downfield proton-NMR signal (Ni complex). [Ni(BnAO-H)]I·H₂O crystallizes in space group P2₁/a with a=13.511(2), b=10.599(2), c=14.096(2) Å, β=97.52°, Z=4 and D_c=1.623 g/cm³. The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to a final R of 0.021 for 2124 reflections with I 2σ(I). The nickel(II) atom in the complex has slightly distorted square planar geometry with an intramolecular O···O contact of 2.417(7) Å. The copper(II) complex crystallizes in space group P2₁/c with a =13.425(2), b=21.446(3), c=14.349(4) Å, β= 104.4(5)°, Z=8 (monomers) and D_c=1.485 g/cm³. The final R value for this complex was 0.053 for 3033 reflections with I 2σ(I). This structure contains a monomeric [Cu(BnAO-H)H₂O]⁺ ion and a dimeric [(Cu(BnAO-H))₂]²⁺ ion, having intramolecular O···O hydrogen bonds of 2.421(5) and 2.531(5) Å, respectively. The copper(II) ions have square-pyramidal coordination with the axial positions occupied by an oxygen of the water of hydration in the monomer and by an oxime oxygen atom in the dimer. A center of symmetry relates the two halves of the dimer. The copper atom in each case is out of the plane of the four nitrogen atoms toward the axial site. The copper(II) complex is unusual in that the crystal contains both a monomer and a dimer.     

The annual marine feeding aggregation of Atlantic sturgeon Acipenser oxyrinchus in the inner Bay of Fundy: population characteristics and movement

Atlantic sturgeon Acipenser oxyrinchus aggregate to feed from May to October in Minas Basin (45° N; 64° W), a large, cul‐de‐sac embayment of the inner Bay of Fundy. The aggregation consists mainly of migrants from the Saint John, NB and Kennebec Rivers, ME (99%). During 2004–2015, 4393 A. oxyrinchus were taken as by‐catch by commercial fish trawlers or at intertidal fishing weirs, and 1453 were marked and/or sampled and released. Fork length (L_F) ranged from 458 to 2670 mm, but 72·5% were <1500 mm. Mass (M) ranged from 0·5 to 58·0 kg. The mass‐length relationship for fish ≤50 kg was log₁₀M = 3·32log₁₀L_F ? 5·71. Observed growth of unsexed A. oxyrinchus recaptured after 1–8 years indicated fish of 90–179 cm L_F grew c. 2–4 cm a year. Ages obtained from pectoral spines were from 4 to 54 years. The Von Bertalanffy growth model predicted K = 0·01 and L_∞ = 5209 mm L_F. Estimated annual mortality was 9·5–10·9%. Aggregation sizes in 2008 and 2013 were 8804 and 9244 individuals, respectively. Fish exhibited high fidelity for yearly return to Minas Basin and population estimates indicated the total at‐sea number utilizing the Basin increased from c. 10 700 in 2010 to c. 37 500 in 2015. Abundance in the Basin was greatest along the north shore in spring and along the south shore in summer, suggesting clockwise movement following the residual current structure. Marked individuals were recaptured in other bays of the inner Bay of Fundy, north to Gaspé, Quebec, and south to New Jersey, U.S.A., with 26 recoveries from the Saint John River, NB, spawning run. Fish marked at other Canadian and U.S. sites were also recovered in Minas Basin. Since all A. oxyrinchus migrate into and out of the Basin annually they will be at risk of mortality if planned tidal power turbines are installed in Minas Passage.     

Concentration‐dependent studies of Nd3+‐doped zinc phosphate glasses for NIR photoluminescence at 1.05 μm

Nd³⁺‐doped lead‐free zinc phosphate glasses with the chemical compositions (60‐x) NH₄H₂PO₄ + 20ZnO + 10BaF₂ + 10NaF + xNd₂O₃ (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) were prepared using a melt quenching technique. Vibrational bands were assigned and clearly elucidated by Raman spectral profiles for all the glass samples. Judd–Ofelt (J–O) intensity parameters (Ω_λ: λ = 2, 4, 6) were obtained from the spectral intensities of different absorption bands of Nd³⁺ ions. Radiative properties such as radiative transition probabilities (A_R), radiative lifetimes (τ_R) and branching ratios (β_R) for different excited states were calculated using J–O parameters. The near infrared (NIR) photoluminescence spectra exhibited three emission bands (⁴F_3/2 level to ⁴I_13/2, ⁴I_11/2 and ⁴I_9/2 states) for all the concentrations of Nd³⁺ ions. Various luminescence properties were studied by varying the Nd³⁺ concentration for the three spectral profiles. Fluorescence decay curves of the ⁴F_3/2 level were recorded. The energy transfer mechanism that leads to quenching of the ⁴F_3/2 state lifetimes was discussed at higher concentration of Nd³⁺ ions. These glasses are suggested as suitable hosts to produce efficient lasing action in NIR region at 1.05 μm.