Assessing effects of diel period, gear selectivity and predation on patterns of microhabitat use by fish in a mangrove dominated system in SE Australia

The relative value of temperate mangroves to fish, and the processes driving patterns of microhabitat use within this habitat, are unknown. There are 3 quickly identifiable microhabitats within temperate Australian mangroves: (1) forest (the area of mangroves with trees); (2) pneumatophores (the area directly seaward of the forest without trees but with pneumatophores [aerial roots]); and (3) channel (the area directly seaward of the pneumatophores without gross structural attributes such as trees or pneumatophores). Duplicate fyke and gill nets were both initially used to sample fish in the 3 microhabitats described above. Sampling took place across the seaward edge of mangroves on 10 sampling occasions (5 night and 5 day), in a large estuarine system in SE Australia. Fish assemblages (693 fish from 20 species and 15 families) varied significantly (p < 0.05) between the forest and the channel, and between diel periods for each gear (net type), but there was little difference in the assemblage structure of fish between forest–pneumatophore or pneumatophore–channel microhabitats. Juvenile lifestages (61% of all fish) and commercially important taxa (76%) were common. Abundance, biomass and species richness of fish were generally lower in the forest than the other microhabitats, but this pattern varied significantly (p < 0.05) between diel periods, among sampling occasions, and with water depth. Highly quantitative pop nets provided a preliminary assessment of whether differential gear selectivity caused patterns between microhabitats, but less rich fish assemblages were again recorded in forests than in pneumatophores. The importance of predation in structuring fish assemblages across microhabitats was assessed by measuring survival of juvenile fish tethered in 3 predation treatments (predator exclusion, cage control, and uncaged). Survival rates were high across the predator treatments and did not vary among microhabitats. The variation in fish assemblages across microhabitats within mangroves was not consistent with a model of mangrove structure providing a refuge for juvenile fish from predation, but instead could indicate differences in efficiency of gear types among microhabitats and/or other ‘edge effect’-driven processes such as the provision of food and/or shelter.

Understanding Concepts of Efficiency and Effectiveness in Architectural Facilities Space Planning and Design

Although contemporary literature treats efficiency and effectiveness extensively, virtually no objective understanding of both is found in architectural facilities space planning and design. It is imperative that both concepts are definitively explained as they apply to these disciplines. Hence, the contemporary views of both concepts are reviewed and attempts made to interpret them within more amenable contexts. The objectives are (1) to objectively elucidate the factual differences between efficiency and effectiveness; and (2) to contribute to their better understanding in architectural facilities space planning and design. Diagrammatic and mathematical means are engaged to demonstrate efficiency and effectiveness in these fields.

Farm-level efficiency and productivity measurement using panel data: wool production in south-west Victoria

In this article we explore some issues surrounding the use of farm-level efficiency and productivity estimates for benchmarking studies. Using an eight-year balanced panel of Victorian wool producers we analyse annual variation between estimates of farm-level technical efficiency derived using Data Envelopment Analysis and Malmquist estimates of Total Factor Productivity. We find that farms change their relative rank in terms of efficiency across years. Also, unlike aggregate studies of Total Factor Productivity, we find at best erratic and modest growth, a worrying result for this industry. However, caution is needed when interpreting these results, and for that matter, benchmarking analysis as currently practised when using frontier estimation techniques like Data Envelopment Analysis.

Growth performance, feed efficiency and fatty acid composition of juvenile Murray cod, Maccullochella peelii peelii, fed graded levels of canola and linseed oil

n two independent experiments, the effects of dietary inclusion of canola and linseed oil were evaluated in juvenile Murray cod (Maccullochella peelii peelii, Mitchell) over a 112-day period. In each experiment, fish received one of five semi-purified diets in which the dietary fish oil was replaced with canola oil (Experiment A) or linseed oil (Experiment B) in graded increments of 25% (0–100%). Murray cod receiving the graded canola and linseed oil diets ranged in final weight from 112.7 ± 7.6 to 73.8 ± 9.9 g and 93.9 ± 3.6 to 74.6 ± 2.2 g, respectively, and exhibited a negative trend in growth as the inclusion level increased. The fatty acid composition of the fillet and liver were modified extensively to reflect the fatty acid composition of the respective diets. Levels of oleic acid (18:1 n-9) and linoleic acid (18:2 n-6) increased with each level of canola oil inclusion while levels of α-linolenic acid (18:3 n-3) increased with each level of linseed oil inclusion. The concentration of n-3 highly unsaturated fatty acids in the fillet and liver decreased as the amount of vegetable oil in the diets increased. It is shown that the replacement of fish oil with vegetable oils in low fish meal diets for Murray cod is possible to a limited extent. Moreover, this study reaffirms the suggestion for the need to conduct ingredient substitution studies for longer periods and where possible to base the conclusions on regression analysis in addition to anova.

Apparent in vivo Δ-6 desaturase activity, efficiency, and affinity are affected by total dietary C18 PUFA in the freshwater fish Murray cod

Dietary fatty acids are known to modulate fatty acid metabolism in fish. However, the innate capability of fish to bioconvert short chain fatty acids to health promoting long chain fatty acids (LCPUFA) is insufficient to compensate for a reduced dietary intake. While many studies have focused on the dietary regulation of the fatty acid bioconversion pathways, there is little known regarding the effects of the dietary levels of C18 polyunsaturated fatty acids (PUFA) on fatty acid metabolism. Here, we show a greater degree of apparent enzyme activity (Δ-6 desaturase) in fish fed a diet with higher amounts of dietary C18 PUFA. In particular, fish receiving high amounts of dietary C18 PUFA had a greater amount of Δ-6 desaturase activity acting on 18:3n-3 than 18:2n-6. However, with the gradual reduction of dietary C18 PUFA there was a shift in substrate preference of Δ-6 desaturase from 18:3n-3 to 18:2n-6. This information will provide valuable insight for the implementation of low fish oil diets, which permit the maintenance of n-3 LCPUFA levels in farmed Murray cod.

Efficiency and unbiasedness in the Indian stock index futures market

This paper explores potential efficiency and unbiasedness as well as the degree of efficiency in stock index futures of an emerging market using both monthly and daily data. Besides analyzing efficiency and unbiasedness with cointegration and error correction model, the degree of efficiency is further investigated after explicitly modeling the underlying state of the market (expansion or contraction) through the first-order Markov switching set-up. The results show that a relatively longer two-month horizon is more effective in eliminating arbitrage opportunities than the short run (one-month and daily) futures.

Influence of particle concentration on initial collection efficiency and surface coverage in porous media filtration

Four sizes (0.095, 0.53, 1.0 and 2.01 μm) of polystyrene latex particles were used to prepare monodispersed suspensions at three different ionic strengths (10−3, 10−2.5 and 10−2M KCl). Filtration experiments were conducted using those suspensions in a filter column with glass beads as porous medium. The filter bed depth and the filtration velocity were kept at 5 cm and 1 m/h, respectively. When suspensions with equal mass concentrations (0.2 mg/L) or equal surface area concentrations (0.12 cm2/mL) were filtered through the system, the largest particles exhibited higher initial single collector efficiency, η. The difference between the η of largest particles and the smaller particles was prominent for suspensions with equal surface area concentrations at higher ionic strengths. The collision efficiency, α of those particles exhibits higher values at higher ionic strengths. Both at equal mass concentration and equal surface area concentration, α is only slightly dependent on particle sizes when compared to its dependence on ionic strength. Further, it was found that the specific surface coverage was similar for 0.095 μm, 0.53 μm and 1.0 μm particles during the transient stage of filtration at any ionic strength when the surface area concentrations of those suspension were equal.

The whole-body fatty acid balance method : examples of its potential for feed efficiency and product quality optimisation in fish and poultry

Dietary lipids and fatty acids are not only fundamental in determining animal performance, but also determine the eating qualities of animal products. Several methods have been used to quantify fatty acid metabolism but most involve expensive in vitro approaches that are not suitable for most laboratories. Furthermore, there is considerable variation between methods with regard to enzyme activity, which makes comparison of results between studies difficult. The recently developed whole-body fatty acid balance method (WBFABM) is a simple and reliable in vivo method for assessing fatty acid metabolism, including rates of liponeogenesis and de novo fatty acid production, β-oxidation of fatty acids and bioconversion (elongation and desaturation) of fatty acids to long-chain polyunsaturated fatty acids. Initially developed for implementation with a fish model, the WBFABM has proven to be a simple and effective method that can be used in any laboratory equipped with a gas chromatography unit. Since its development, it has been used in several farmed finfish feeding trials and in broiler chicken feeding trials. The WBFABM is currently used at research institutions worldwide and its use is increasing in popularity among animal scientists. With this method, it is possible to track the fate of individual dietary fatty acids within the body. The WBFABM could contribute significantly to information generated by animal feeding trials.

π-Selective stationary phases: (III) Influence of the propyl phenyl ligand density on the aromatic and methylene selectivity of aromatic compounds in reversed phase liquid chromatography

The retention characteristics of phenyl type stationary phases for reversed phase high performance liquid chromatography are still largely unknown. This paper explores the retention process of these types of stationary phases by examining the retention behaviour of linear PAHs and n-alkylbenzenes on a series of propyl phenyl stationary phases that have changes in their ligand density (1.23, 1.31, 1.97, 2.50 μmol m⁻²). The aromatic and methylene selectivities increased with increasing ligand density until a point where a plateau was observed, overall the propyl phenyl phases had a higher degree of aromatic selectivity than methylene selectivity indicating that these columns are suitable for separations involving aromatic compounds. Also, retention characteristics relating to the size of the solute molecule were observed to be influenced by the ligand density. It is likely that the changing retention characteristics are caused by the different topologies of the stationary phases at different ligand densities. At high ligand densities, the partition coefficient became constant.

π-Selective stationary phases: (I) Influence of the spacer chain length of phenyl type phases on the aromatic and methylene selectivity of aromatic compounds in reversed phase high performance liquid chromatography

Phenyl type stationary phases of increasing spacer chain length (phenyl, methyl phenyl, ethyl phenyl, propyl phenyl and butyl phenyl, with 0–4 carbon atoms in the spacer chain, respectively) were synthesised and packed in house to determine the impact that the spacer chain length has on the retention process. Two trends in the aromatic selectivity, q_aromatic, were observed, depending on whether the number of carbon atoms in the spacer chain is even or odd. Linear log k′ vs ϕ plots were obtained for each stationary phase and the S coefficient was determined from the gradient of these plots. For the phenyl type phases, the S vs n_c plots of the retention factors of linear polycyclic aromatic hydrocarbons vs the number of rings exhibit a distinct discontinuity that between 3 and 4 rings, which increases with increasing spacer chain length for even phases but decreases for odd phases. Accordingly, we suggest that the retention factors depend differently on the number of carbon atoms in the spacer chain depending on whether this number is even or odd and that this effect is caused by different orientations of the aromatic ring relative to the silica surface.