An assessment of morphometric indices,blood chemistry variables and an energy meter as indicators of the whole body lipid content in Micropterus dolomieu,Sander vitreus and Ictalurus punctatus

The effectiveness of several non‐lethal techniques as indicators of total lipid content in smallmouth bass Micropterus dolomieu, walleye Sander vitreus and channel catfish Ictalurus punctatus was investigated. The techniques included (1) the Fulton and relative condition factors, (2) relative mass, (3) plasma indicators of nutritional status (alkaline phosphatase, calcium, cholesterol, protein, triglycerides and glucose) and (4) readings from a hand‐held, microwave energy meter. Although simple linear regression analysis showed that lipid content was significantly correlated with several predictor variables in each species, the r² values for the relations ranged from 0·17 to 0·50 and no single approach was consistent for all species. Only one model, between energy‐meter readings and lipid content in I. punctatus, had an r² value (0·83) high enough to justify using it as a predictive tool. Results indicate that no single variable was an accurate and reliable indicator of whole body lipid content in these fishes, except the energy meter for I. punctatus.     

Di‐2‐ethylhexyl phthalate (DEHP) exposure disturbs lipid metabolism in juvenile yellow catfish Tachysurus fulvidraco

This study was conducted to determine the mechanism by which di‐2‐ethylhexyl phthalate (DEHP) exposure influences lipid metabolism of juvenile yellow catfish Tachysurus fulvidraco. Fish were exposed to three DEHP concentrations (0, 0·1 and 0·5 mg l^?1 DEHP) for 8 weeks. Fatty acid synthase (FAS) activity significantly decreased with increasing DEHP concentrations, the highest value was in the Tween control group, whereas the lowest activities of carnitine palmitoyltransferase (CPT) and lipoprotein lipase (LPL) were in this group. The messenger (m)RNA levels of 6‐phospho‐gluconate dehydrogenase (6PGD), FAS and acetyl‐CoA carboxylase a (ACCa) significantly increased with increasing DEHP concentration, the highest values were in the 0·5 mg l^?1 DEHP group. The mRNA level of peroxisome proliferator‐activated receptor γ (PPARγ) was lower in Tween control than in fish exposed to 0·1 and 0·5 mg l^?1 DEHP. The highest mRNA level of ACCb was in the 0·1 mg l^?1 DEHP group. These results indicate that DEHP exposure can disturb lipid metabolism at the enzymatic and mRNA levels in Pelteobagrus fulvidraco.     

Relationship of adiponectin with insulin sensitivity in humans, independent of lipid availability

Objective: To test in humans the hypothesis that part of the association of adiponectin with insulin sensitivity is independent of lipid availability. Research Methods and Procedures: We studied relationships among plasma adiponectin, insulin sensitivity (by hyperinsulinemic‐euglycemic clamp), total adiposity (by DXA), visceral adiposity (VAT; by magnetic resonance imaging), and indices of lipid available to muscle, including circulating and intramyocellular lipid (IMCL; by ¹H‐magnetic resonance spectroscopy). Our cohort included normal weight to obese men (n = 36). Results: Plasma adiponectin was directly associated with insulin sensitivity and high‐density lipoprotein‐cholesterol and inversely with plasma triglycerides but not IMCL. These findings are consistent with adiponectin promoting lipid uptake and subsequent oxidation in muscle and inhibiting TG synthesis in the liver. In multiple regression models that also included visceral and total fat, free fatty acids, TGs, and IMCL, either alone or in combination, adiponectin independently predicted insulin sensitivity, consistent with some of its insulin‐sensitizing effects being mediated through mechanisms other than modulation of lipid metabolism. Because VAT directly correlated with total fat and all three indices of local lipid availability, free fatty acids, and IMCL, an efficient regression model of insulin sensitivity (R² = 0.69, p < 0.0001) contained only VAT (part R² = 0.12, p < 0.002) and adiponectin (part R² = 0.41, p < 0.0001) as independent variables. Discussion: Given the broad range of total adiposity and body fat distribution in our cohort, we suggest that insulin sensitivity is robustly associated with adiponectin and VAT.     

Using the robust design framework and relative abundance to predict the population size of pallid sturgeon Scaphirhynchus albus in the lower Missouri River

Several population viability models were constructed to aid recovery in endangered Scaphirhynchus albus, but these models are dependent upon accurate and precise input parameters that are not provided with standard catch per unit effort (CPUE) indices. Nine years of sampling efforts, under the robust design framework, provided 1223 unique captures with an 18·3% recapture rate. The annual population estimates varied from 4·0–7·3 fish rkm^?1 for wild and 8·4–18·4 fish rkm^?1 for hatchery‐reared S. albus. The relationship between abundance (N) and annual trot‐line CPUE indices (x = 70.726y + 2·533, R² = 0·91, P < 0·001) was used to predict an abundance of 13 616 ± 7142 s.e. S. albus in the lower Missouri River. The use of small‐scale intensive sampling to develop a relationship with relative abundance indices reported here, may provide a framework for other fisheries management applications where large‐scale intensive sampling is not feasible, but catch data are available.     

Postprandial metabolic increment of southern bluefin tuna Thunnus maccoyii ingesting high or low‐lipid sardines Sardinops sagax

This study examined the postprandial metabolism and swimming speed of southern bluefin tuna Thunnus maccoyii when fed sardines Sardinops sagax of either high‐lipid and high‐energy content or low‐lipid and low‐energy content. Five groups of two or three T. maccoyii (mean ±s.e. mass = 19·8 ± 0·5 kg, n = 14) were fed either low [2·2% lipid, 5·5 MJ kg^?1 gross energy (GE)] or high‐lipid (12·9%, 9·2 MJ kg^?1 GE) S. sagax. Before feeding, T. maccoyii swam at 0·74 ± 0·03 body lengths s^?1 (n = 5) and their routine metabolic rate was 305 ± 15 mg kg^?1 h^?1. Swimming speed and metabolic rate of T. maccoyii increased following feeding. Thunnus maccoyii swam 1·3 and 1·8 times faster during digestion of low and high‐lipid S. sagax, respectively. Postprandial peak metabolic rate, duration of elevated metabolism and total postprandial metabolic increment were all greater for T. maccoyii that ingested high‐lipid S. sagax. When total postprandial increment is represented as a proportion of ingested energy, there was no difference between high and low‐lipid meals, equating to between 30 and 35% of ingested energy. It was estimated that increased postprandial swimming costs account for 25 and 46% of the total postprandial metabolic response for low and high‐lipid S. sagax meals, respectively. Specific dynamic action (SDA) accounts for c. 20% of ingested energy regardless of S. sagax lipid level. These results confirm that the postprandial metabolic increment of T. maccoyii is greater than most other fish species. Much of the high cost of postprandial metabolic increment can be attributed to increased postprandial swimming costs. For T. maccoyii, it appears that activity and SDA are not independent, which complicates bioenergetic evaluation. High postprandial metabolic costs accentuate the great energetic requirements of T. maccoyii.     

Effects of dietary lipid levels on mitochondrial gene expression in low and high‐feed efficient families of rainbow trout Oncorhynchus mykiss

A 2 × 3 factorial study was conducted to evaluate the effects of dietary lipid level on mitochondrial gene expression in mixed sex rainbow trout Oncorhynchus mykiss. Practical diets with a fixed crude protein content of 42%, formulated to contain 10% (42/10), 20% (42/20) and 30% (42/30) dietary lipid, were fed to triplicate groups of either low‐feed efficient (F129; mean ± s.d. = 105·67 ± 3·04 g initial average mass) or high‐feed efficient (F134; mean ± s.d. = 97·86 ± 4·02 g) families of fish, to apparent satiety, twice per day, for 108 days. At the end of the experiment, diets 42/20 and 42/30 led to similar fish condition factors, which were higher than that observed with diet 42/10 (P < 0·05). F134 fish fed diet 42/10 showed the highest hepato‐somatic index, while there was no significant difference among all the other treatments (P < 0·05). When the group of F134 fish fed diet 42/10 was used as the calibrator for gene expression analysis, the five genes selected for their involvement in lipid metabolism (complex I‐nd1, complex III‐cytb, complex IV‐cox1, complex IV‐cox2 and complex V‐atp6) were up‐regulated in the muscle and down‐regulated in both the liver and the intestine. There was a significant family × diet interaction regarding nd1, cox2 and atp6 in the liver; nd1, cytb, cox1, cox2 and atp6 in the intestine, and nd1, cytb, cox1, cox2 and atp6 in the muscle (P < 0·05). The overall results of this study constitute basic information for the understanding of molecular mechanisms of lipid metabolism at the mitochondrial level in fishes.     

Growth performance,fatty‐acid composition,lipid deposition and hepatic‐lipid metabolism‐related gene expression in juvenile pond loach Misgurnus anguillicaudatus fed diets with different dietary soybean oil levels

A 10 week feeding trial was conducted to evaluate the effects of different dietary soybean oil (SO) levels on growth performance, fatty‐acid composition and lipid deposition in viscera, histology and histochemistry of liver, intestine and hepatic‐lipid metabolism‐related gene expressions in pond loach Misgurnus anguillicaudatus juveniles. Misgurnus anguillicaudatus (mean ± s.d. mass 0·40 ± 0·01 g) were fed five experimental diets containing SO at different concentrations: 0, 20, 32, 56 and 100% SO and a diet containing 100% fish oil (100% FO). The mass gains and specific growth rates of M. anguillicaudatus fed 20% SO and 100% FO diets were significantly higher than those of the other groups (P < 0·05). The lipid content of viscera and the amount of cytoplasmic vacuolation in the liver increased with incremental dietary SO level. Meanwhile, increasing dietary SO levels up‐regulated the messenger (m)RNA levels of lipogenic genes (such as Δ6fad, scd, pparγ, fas and srebp‐1) and down‐regulated the mRNA levels of the lipolytic genes (such as pparα, cpt1, atgl and hsl) in the liver. The percentage of 20:4n‐6 significantly (P < 0·05) increased with increasing dietary SO level, which might be correlated with the up‐regulation of the mRNA level of Δ6fad. The highest levels of dietary SO, however, had a negative effect on growth performance, lipid deposition of viscera and histology and histochemstry of liver and intestine. The increased lipid accumulation induced by incremental dietary SO level probably occurred through different strategies for lipid metabolism as a result of competition between lipolysis and lipogenesis and between export and import of lipids in this species.     

Effects of intraperitoneal injection of cortisol on non‐specific immune functions of Ctenopharyngodon idella

After grass carps Ctenopharyngodon idellus were injected with cortisol, with (CBC) and without (C) a cocoa butter carrier, the effects of both slowly and rapidly acting exogenous cortisol on their non‐specific immune functions were investigated. On the one hand, after injection with CBC, the cortisol concentration and lysozyme activity in fish serum were enhanced and were sustained at high levels for a long period (30 days). The killing activity in the serum declined with time, and phagocytosis of head kidney macrophages diminished significantly (P < 0·05 or P < 0·01). The leukocrit values in the high dose group (31·8 mg cortisol fish^?1) increased over time, however, with the maximum average being 5·6% at day 30. The spleen mass index in the high dose group was 0·93 × 10^?3 after 30 days, notably lower (P < 0·05) than that in the control group. In addition, a decrease in resistance to Aeromonas hydrophila infection in cortisol‐treated fish was shown, with the final cumulative mortalities being 54·5 and 66·7% in the low and high dose groups, respectively. On the other hand, there was a decrease in both serum cortisol concentration and lysozyme activity of the experimental fish within 2 weeks after injection with C, where plasma bactericidal activities in the high dose group (31·8 mg cortisol fish^?1) were remarkably lower (P < 0·01) than those in the control group at each sampling, but were increased slightly over time. The results of which were different from those in the CBC trial. Phagocytic activity of head kidney macrophages and spleen mass index decreased significantly (P < 0·05), while there were increases in leukocrit value and cumulative mortality due to A. hydrophila. The results of which were similar to those in the CBC trial. This study indicated that the injection of cortisol depressed the non‐specific immune functions of the grass carp and increased its susceptibility to disease.     

A morphometric method for estimation of total lipid level in live Arctic charr: a case study of its application on wild fish

Linear body measurements were made on wild Arctic charr Salvelinus alpinus parr (100–200 mm L_F) from two populations in northern Norway during spring (May), summer (June and July) and autumn (October). To reduce handling stress, a method was developed were dorsal and ventral body measurements could subsequently be taken easily from a single picture of the anaesthetized fish. Multiple regression analyses investigated the possible correlation between the body measurements and both total and percentage lipid content of the fish. For both populations and during all seasons, the regression equations gave better estimates for total lipid than for percentage lipid. The regression equations for total lipid accounted for between 67·7 and 89·5% of the variance in lipid content for the different seasons within the lakes. The pooled data within each lake accounted for 62·9 and 81·0% of the variance in total lipid, while the pooled data for both lakes accounted for 67·7% of the variance. In general, the condition factor alone did not give a satisfactory estimate of lipid content of the Arctic charr (r² = 0·003–0·521). Shrinkage on validation values was high (0·20–0·52). Employing a ridge regression method resulted in models with lower r² values and lower shrinkage values (indicating more stable models). Published equations used for hatchery‐reared Arctic charr could not be used on wild fish from the same population. The close correlations between actual and predicted lipid levels found in this study show that morphometric measurements can predict total lipid levels in wild Arctic charr with reasonable accuracy. The most accurate results were obtained when equations were derived from each data set. Therefore, the method has the potential within a single study to estimate lipid levels in live fish as long as some fish can be sacrificed to develop a unique regression equation for each population or experiment.     

Stress induced lipid production in Chlorella vulgaris: Relationship with specific intracellular reactive species levels

Microalgae have significant potential to be an important alternative energy source, but the challenges to the commercialization of bio‐oil from microalgae need to be overcome for the potential to be realized. The application of stress can be used to improve bio‐oil yields from algae. Nevertheless, the understanding of stress effects is fragmented due to the lack of a suitable, direct quantitative marker for stress. The lack of understanding seems to have limited the development of stress based strategies to improve bio‐oil yields, and hence the commercialization of microalgae‐based bio‐oil. In this study, we have proposed and used the specific intracellular reactive species levels (siROS) particularly hydroxyl and superoxide radical levels, separately, as direct, quantitative, markers for stress, irrespective of the type of stress induced. Although ROS reactions are extremely rapid, the siROS level can be assumed to be at pseudo‐steady state compared to the time scales of metabolism, growth and production, and hence they can be effective stress markers at particular time points. Also, the specific intracellular (si‐) hydroxyl and superoxide radical levels are easy to measure through fluorimetry. Interestingly, irrespective of the conditions employed in this study, that is, nutrient excess/limitation or different light wavelengths, the cell concentrations are correlated to the siROS levels in an inverse power law fashion. The composite plots of cell concentration (y) and siROS (x) yielded the correlations of y = k₁ · x^?0.7 and y = k₂ · x^?0.79, for si‐hydroxyl and si‐superoxide radical levels, respectively. The specific intracellular (si‐) neutral lipid levels, which determine the bio‐oil productivity, are related in a direct power law fashion to the specific hydroxyl radical levels. The composite plot of si‐neutral lipid levels (z) and si‐hydroxyl radical level (x) yielded a correlation of z = k₃ · x^0.65. More interestingly, a nutrient shift caused a significant change in the sensitivity of neutral lipid accumulation to the si‐hydroxyl radical levels. Biotechnol. Bioeng. 2013; 110: 1627–1636. © 2013 Wiley Periodicals, Inc.     

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.     

Biology of red mullet,Mullus barbatus (L. 1758), in the Gulf of Castellammare (NW Sicily,Mediterranean Sea) subject to a trawling ban

Under‐or non‐exploited areas are useful to aid in evaluating the potential productivity of fish stocks for sustainable fisheries. The Gulf of Castellammare (NW Sicily), where trawling has been banned since 1990, is a good site to study the biology and dynamics of low impacted fish populations. A total of 661 (595 female and 66 male) specimens of red mullet Mullus barbatus (95–245 mm total length, TL) obtained by monthly sampling from trammel net artisanal fishery, was collected in the Gulf of Castellammare from April 2006 to June 2007. Mature females occurred from April to September, with a peak in May. The mean Gonado‐somatic index (GSI) also showed a May peak for both sexes. From Sagittae (642) readings the age structure ranged from age class I to VII in females and I to V in males. Female growth parameters, estimated according to the classic von Bertalanffy model, were: L_∞ = 221.2 ± 11.51 mm standard error (SE), k_y^?1 = 0.38 ± 0.09 SE, t₀y = ?0.94 ± 0.38 SE. The growth performance index (ø’ = 2.27) was included in the range of values obtained by hard structure readings in the Central Mediterranean. Natural mortality (M_y^?1) of females estimated by different methods ranged between 0.62 and 0.87 (mean value = 0.71 ± 0.06 SE).     

Independent Influences of Central Fat and Skeletal Muscle Lipids on Insulin Sensitivity

Objective: Insulin resistance is closely associated with two disparate aspects of lipid storage: the intracellular lipid content of skeletal muscle and the magnitude of central adipose beds. Our aim was to determine their relative contribution to impaired insulin action. Research Methods and Procedures: Eighteen older (56 to 75 years of age) men were studied before elective knee surgery. Insulin sensitivity (M/ΔI) was determined by hyperinsulinemic–euglycemic clamp. Central abdominal fat (CF) was assessed by DXA. Skeletal muscle was excised at surgery and assayed for content of metabolically active long‐chain acyl‐CoA esters (LCAC). Results: Significant inverse relationships were observed between LCAC and M/ΔI (R² = 0.34, p = 0.01) and between CF and M/ΔI (R² = 0.38, p = 0.006), but not between CF and LCAC (R² = 0.0005, p = 0.93). In a multiple regression model (R² = 0.71, p < 0.0001), both CF (p = 0.0006) and LCAC (p = 0.0009) were independent statistical predictors of M/ΔI. Leptin levels correlated inversely with M/ΔI (R² = 0.60, p = 0.0002) and positively with central (R² = 0.41, p = 0.006) and total body fat (R² = 0.63, p = 0.0001). Discussion: The mechanisms by which altered lipid metabolism in skeletal muscle influences insulin action may not be related directly to those linking central fat and insulin sensitivity. In particular, it is unlikely that muscle accumulation of lipids directly derived from labile central fat depots is a principal contributor to peripheral insulin resistance. Instead, our results imply that circulating factors, other than nonesterified fatty acids or triglyceride, mediate between central fat depots and skeletal muscle tissue. Leptin was not exclusively associated with central fat, but other factors, secreted specifically from central fat cells, could modulate muscle insulin sensitivity.     

Investigation of biomass concentration,lipid production,and cellulose content in Chlorella vulgaris cultures using response surface methodology

The microalgae Chlorella vulgaris produce lipids that after extraction from cells can be converted into biodiesel. However, these lipids cannot be efficiently extracted from cells due to the presence of the microalgae cell wall, which acts as a barrier for lipid removal when traditional extraction methods are employed. Therefore, a microalgae system with high lipid productivity and thinner cell walls could be more suitable for lipid production from microalgae. This study addresses the effect of culture conditions, specifically carbon dioxide and sodium nitrate concentrations, on biomass concentration and the ratio of lipid productivity/cellulose content. Optimization of culture conditions was done by response surface methodology. The empirical model for biomass concentration (R² = 96.0%) led to a predicted maximum of 1123.2 mg dw L^?1 when carbon dioxide and sodium nitrate concentrations were 2.33% (v/v) and 5.77 mM, respectively. For lipid productivity/cellulose content ratio (R² = 95.2%) the maximum predicted value was 0.46 (mg lipid L^?1 day^?1)(mg cellulose mg biomass^?1)^?1 when carbon dioxide concentration was 4.02% (v/v) and sodium nitrate concentration was 3.21 mM. A common optimum point for both variables (biomass concentration and lipid productivity/cellulose content ratio) was also found, predicting a biomass concentration of 1119.7 mg dw L^?1 and lipid productivity/cellulose content ratio of 0.44 (mg lipid L^?1 day^?1)(mg cellulose mg biomass^?1)^?1 for culture conditions of 3.77% (v/v) carbon dioxide and 4.01 mM sodium nitrate. The models were experimentally validated and results supported their accuracy. This study shows that it is possible to improve lipid productivity/cellulose content by manipulation of culture conditions, which may be applicable to any scale of bioreactors. Biotechnol. Bioeng. 2013; 110: 2114–2122. © 2013 Wiley Periodicals, Inc.     

Myotube production in fast myotomal muscle is switched-off at shorter body lengths in male than female Atlantic halibut Hippoglossus hippoglossus (L.) resulting in a lower final fibre number

A sampling method is described to determine accurately the number of fast myotomal muscle fibres (N_F) in a large flatfish species, the Atlantic halibut Hippoglossus hippoglossus. An unusual feature of the fast myotomal muscle is the presence of internalized strips of slow muscle fibres. In fish of 1·5–3·5 kg (n = 24), the total cross‐sectional area (A_TC) of fast muscle was 18% greater in the dorsal than ventral myotomal compartments (P < 0·05), whereas there was no significant difference between left‐ and right‐hand sides of the body. Due the bilateral asymmetry, muscle blocks (5 × 5 × 5 mm) were prepared to systematically sample each myotomal quadrant (dorsal, ventral, left‐ and right‐side) and the diameters of 150 fast fibres measured per block. Smooth non‐parametric probability functions were fitted to a minimum of 800 measurements of fibre diameter per quadrant (n = 5). There were no significant differences in the distribution of muscle fibre diameters between myotomal compartments and therefore N_F could be estimated from a single quadrant. The number of blocks required to estimate N_F with a repeatability of ±2·5% increased from six at 300 g body mass to 17 at 96·5 kg, caused by variation within and between blocks. Gompertz curves were fitted to measurements of fibre number and fork length (L_F). The estimated final fibre number was 8·96 × 10⁵ (7·99–9·94 × 10⁵, 95% CI) for males and 1·73 × 10⁶ (1·56–1·90 × 10⁶, 95% CI) for female fish. The estimated L_F for cessation of fibre recruitment in the fast muscle of female fish (1775 mm) was almost twice that in males (810 mm), reflecting their greater ultimate body size.     

Decrease in winter respiration explains 25% of the annual northern forest carbon sink enhancement over the last 30 years

Aim Winter snow has been suggested to regulate terrestrial carbon (C) cycling by modifying microclimate, but the impacts of change in snow cover on the annual C budget at a large scale are poorly understood. Our aim is to quantify the C balance under changing snow depth. Location Non‐permafrost region of the northern forest area. Methods Here, we used site‐based eddy covariance flux data to investigate the relationship between depth of snow cover and ecosystem respiration (R_eco) during winter. We then used the Biome‐BGC model to estimate the effect of reductions in winter snow cover on the C balance of northern forests in the non‐permafrost region. Results According to site observations, winter net ecosystem C exchange (NEE) ranged from 0.028 to 1.53 gC·m^?2·day^?1, accounting for 44 ± 123% of the annual C budget. Model simulation showed that over the past 30 years, snow‐driven change in winter C fluxes reduced non‐growing season CO₂ emissions, enhancing the annual C sink of northern forests. Over the entire study area, simulated winter R_eco significantly decreased by 0.33 gC·m^?2·day^?1·year^?1 in response to decreasing depth of snow cover, which accounts for approximately 25% of the simulated annual C sink trend from 1982 to 2009. Main conclusion Soil temperature is primarily controlled by snow cover rather than by air temperature as snow serves as an insulator to prevent chilling impacts. A shallow snow cover has less insulation potential, causing colder soil temperatures and potentially lower respiration rates. Both eddy covariance analysis and model‐simulated results show that both R_eco and NEE are significantly and positively correlated with variation in soil temperature controlled by variation in snow depth. Overall, our results highlight that a decrease in winter snow cover restrains global warming as less C is emitted to the atmosphere.     

Are morphometric indices accurate indicators of stored energy in herring Clupea harengus?

The accuracy of the morphometric indices Fulton's K, somatic K and relative condition factor, K_n, as measures of individual North Sea herring Clupea harengus muscle fat content was investigated using the Distell Fish Fat meter. The accuracy of fat‐meter readings from an individual fish was validated by comparison with Soxhlet extraction analysis. The studies conducted demonstrated that Fulton's K is not consistently or strongly correlated with individual C. harengus muscle fat content, as defined by the fat‐meter estimates. The study shows that somatic K and K_n may be better indices of individual North Sea C. harengus muscle fat content than Fulton's K. These morphometric indices, however, should only be used after prior validation against a more direct measure of fat content.     

Estimating lipid and lean body mass in small passerine birds using TOBEC,external morphology and subcutaneous fat‐scoring

To assess regression models for lipid and lean body mass in small birds, we recorded live body mass ±0.1 g, total body electrical conductivity (TOBEC; from “third generation” TOBEC machine EM‐SCAN® SA‐3000) or E‐Value, visual fat score (VisFat), and seven body measurements for 52 migratory passerine birds of 13 species (5–40 g). We determined lipid and lean mass of each bird after petroleum‐ether extraction of lipids. We obtained “net”E‐Value (NEV) for each scanned bird by subtracting the E‐Value of the empty bird‐restraining tube, because these showed an inverse temperature dependence (P<0.005). Leave‐one‐out cross validation was used to assess model selection and construct 95% confidence intervals. Although precision of TOBEC increased with bird size (CV of NEV vs. live mass: r=−0.276, P=0.002) and it explained an increasing proportion of variation in lean mass moving from small‐ to medium‐ to large‐bird classes of our data, it did no better than head length in single‐variable prediction of lean or lipid mass and was included in five of the 14 multivariate models we developed. The best multiple regression to predict lean mass included live weight, VisFat, bill length, tarsus and lnNEV (adjusted R²=99.0%); however, the same model lacking only lnNEV yielded aR²=98.9%. A parallel to the above pair of models, but predicting lipid mass, yielded aR²=90.3% and 90.0%, respectively. Subdividing the data by three size classes and three taxa (American redstart Setophaga ruticilla, ovenbird Seiurus aurocapilla, warblers), best‐subset multiple‐regression models predicted lean mass with aR² from 94.7 to 99.6% and lipid mass with aR² from 85.4 to 98.3%. Best models for the size‐ and species‐groups included VisFat and zero to five body measurements, and most included live weight. lnNEV was included only in the models for ovenbird (lipid), warblers (lipid), all birds (both), and large birds (both). Actual lipid mass of all birds was more highly correlated with multiple‐regression‐predicted lipid mass (r=0.955) than with visual subcutaneous fat‐scoring (r=0.683). These multiple‐regression models predicting lipid content using live‐bird measurements and visual fat score as independent variables represent more accurate and precise estimates of actual lipid content in small passerines than any previously published. They are particularly accurate for placing birds into percentage body‐fat classes.     

Biotechnological conversion of waste cooking olive oil into lipid-rich biomass using Aspergillus and Penicillium strains

Aims: In this study, we have investigated the biochemical behaviour of Aspergillus sp. (five strains) and Penicillium expansum (one strain) fungi cultivated on waste cooking olive oil. The production of lipid‐rich biomass was the main target of the work. In parallel, the biosynthesis of other extracellular metabolites (organic acids) and enzyme (lipase) and the substrate fatty acid specificity of the strains were studied. Methods and Results: Carbon‐limited cultures were performed on waste oil, added in the growth medium at 15 g l^?1, and high biomass quantities were produced (up to c. 18 g l^?1, conversion yield of c. 1·0 g of dry biomass formed per g of fat consumed or higher). Cellular lipids were accumulated in notable quantities in almost all cultures. Aspergillus sp. ATHUM 3482 accumulated lipid up to 64·0% (w/w) in dry fungal mass. In parallel, extracellular lipase activity was quantified, and it was revealed to be strain and fermentation time dependent, with a maximum quantity of 645 U ml^?1 being obtained by Aspergillus niger NRRL 363. Storage lipid content significantly decreased at the stationary growth phase. Some differences in the fatty acid composition of both cellular and residual lipids when compared with the initial substrate fat used were observed; in various cases, cellular lipids more saturated and enriched with arachidic acid were produced. Aspergillus strains produced oxalic acid up to 5·0 g l^?1. Conclusions: Aspergillus and Penicillium strains are able to convert waste cooking olive oil into high‐added‐value products. Significance and Impact of the Study: Increasing fatty wastes amounts are annually produced. The current study provided an alternative way of biovalourization of these materials, by using them as substrates, to produce added‐value compounds.