Environmental influences on the physiological and behavioural growth responses in salmonids; with reference to the growth-dip phenomenon

Photoperiod manipulations are widely used throughout the Atlantic salmon (Salmo salar) farming industry as a means of producing a product of uniform quality all-year round. However, farmers still remain sceptical over their effectiveness to regulate growth and maturation during the on-growing stage. Furthermore, reports of a characteristic growth-dip following light exposure suggest that light may negatively affect the physiological performance of fish in the short-term. Thus, this thesis investigates the effects of light characteristics (spectral quality, intensity and photoperiod) on growth and maturation of salmonid fish and addresses some of the uncertainties surrounding photoperiod use currently reported within the industry. Rainbow trout (Oncorhynchus mykiss) are seemingly an ideal model species for examining photoperiod effects on growth. Consequently, the application of constant light exposure (LL) at two different intensities (28W and 16W) during two different thermal conditions (summer and winter) was examined on individually tagged fish. Feed intake and growth appeared to be related to the ambient water temperature and did not appear to be affected by intensity or photoperiod, although the onset of constant light did appear to initially affect growth rate. This may indicate that LL has a limiting effect on the growth of trout or that the prevailing water temperature at which light is applied may override the photoperiodic effect. Furthermore, the lack of enhanced growth in trout exposed to LL, unlike that demonstrated for other salmonids, suggest that there may be a species-specific response to environmental variables. Thus, questions regarding photoperiod effects should be limited to the species in question. The main source of variation in results observed under photoperiod manipulations stems from the salmon industry. Atlantic salmon post-smolts were reared in seawater tanks and either maintained under a natural photoperiod (NP) or exposed to a simulated natural photoperiod (SNP), constant light superimposed on the natural light (NPLL) or constant light only (LL). Artificial light onset, irrespective of photoperiod, resulted in an apparent trend for a reduced appetite lasting up to 60 days. Furthermore, the onset of constant light resulted in a significant chronic elevation of plasma cortisol levels and changes to growth and thyroid hormone levels, providing direct evidence that constant light exposure induces stress. In addition, fish exposed to SNP failed to exhibit a stress response despite a low feed intake. However, differences in the plasma melatonin levels during twilight times, as compared to NP, suggest that gradual changes in the natural light intensity throughout the day, particularly around dawn and dusk, may be important for synchronizing daily events. No differences in growth were observed between the NP and NPLL regimes, although fish reared in an enclosed regime (SNP and LL) exhibited a significantly lower weight gain than fish in an open environment (NP and NPLL). This further highlights the impact that the rearing environment has on the growth performances of fish and the need for commercially run trials. Advances in lighting technologies and a greater understanding of how light is transformed through the water column have focussed research on the spectral sensitivity of fish. Therefore the lighting efficiency of novel blue narrow bandwidth LED lighting units through the water column and their effects on growth and maturation performances of salmon reared in commercial production cages were compared against the standard metal halide units currently utilized throughout the industry. LL application, irrespective of intensity or spectrum, reduced the numbers of fish maturing as compared to fish reared under a natural photoperiod. However, this was greatest under the standard metal halide units reflecting a greater light penetration and perception as determined by plasma melatonin levels. The metal halide groups exhibited the greatest relative weight gain over the trial period as compared to control fish. No evidence was observed for a growth-dip under metal halide light, although blue lit treatments exhibited an initial significant reduction in food consumption, suggesting a possible welfare issue. Nevertheless, the prototype blue LED units showed possible potential for commercial application by penetrating the water depth at half the distance of the metal halide units for only one eighth the power and one fifth the brightness. However, further tests of these prototype spectral units are required to examine the potential welfare and physiological growth and reproductive effects. These studies have shown that the efficacy of artificial light regimes is largely dependent upon the effectiveness of the light source through the underwater environment and its perception by fish, providing a sufficient intensity is emitted exceeding the physiological threshold level for the species cultured. Moreover, whilst the onset of artificial light may elicit a stress response and demonstrate a trend for a suppression of appetite for salmon reared in experimental tanks, no compelling evidence for a suppression of appetite or growth was found under normal commercial cage conditions. This suggests that the growth-dip observed within the industry may in part be a combination of a physiological response to the onset of light further exaggerated by the farmer’s perception and altered judgement in feeding. In addition, the results obtained from this study have helped to standardize the use of light regimes within the industry. Nevertheless, further studies are necessary to fully elucidate the underlying mechanisms which may govern growth and maturation in fish following the onset of light exposure.This research thesis was supported by Nutreco Aquaculture Research centre / Marine Harvest (Stavenger, Norway) and the University of Stirling, as well as the Fisheries Society of the British Isles for providing a small research grant towards the cost of the hormone analysis. by Nutreco Aquaculture Research Centre / Marine Harvest and University of Stirlin

The Role of Torsion/Torsion Coupling in the Vibrational Spectrum of Cis−Cis HOONO

A three-dimensional model of the vibrational dynamics of HOONO is investigated. This model focuses on the couplings between the OH stretch vibration and the two torsions. The model is based on electronic energies, calculated at the CCSD(T)/cc-pVTZ level of theory and basis and dipole moment functions calculated at the CCSD/aug-cc-pVDZ level. The resulting points were fit to explicit functional forms, and the energies, wave functions, and intensities were evaluated using an approach in which the OH stretching motion was adiabatically separated from the torsional modes. It is found that the HOON torsion is strongly coupled to both the OONO torsion and OH stretch. Despite this, many of the conclusions that were drawn from earlier two-dimensional treatments, which did not include the OONO torsion, hold up on a semiquantitative level. In addition, we use this model to investigate the assignment of recently reported matrix isolated spectra of HOONO and DOONO. Finally, by comparing the results of this three-dimensional calculation to two-dimensional calculations and to the results of second-order perturbation theory, we investigate the question of how one determines the size of the reduced-dimensional system that is needed to describe the vibrational spectrum of molecules, like HOONO, that contain several large amplitude motions

The Chopped Cheese: Traversing Upscale Foodways and the Struggle for Community Control

Senior Project submitted to The Division of Social Studies of Bard College

Health system weaknesses constrain access to PMTCT and maternal HIV services in South Africa: a qualitative enquiry

Background: HIV remains responsible for an estimated 40% of mortality in South African pregnant women and their children. To address these avoidable deaths, eligibility criteria for antiretroviral therapy (ART) in pregnant women were revised in 2010 to enhance ART coverage. With greater availability of HIV services in public health settings and increasing government attention to poor maternal-child health outcomes, this study used the patient’s journey through the continuum of maternal and child care as a framework to track and document women’s experiences of accessing ART and prevention of mother-to-child HIV transmission (PMTCT) programmes in the Eastern Cape (three peri-urban facilities) and Gauteng provinces (one academic hospital). Results: In-depth interviews identified considerable weaknesses within operational HIV service delivery. These manifested as missed opportunities for HIV testing in antenatal care due to shortages of test kits; insufficient staff assigned to HIV services; late payment of lay counsellors, with consequent absenteeism; and delayed transcription of CD4 cell count results into patient files (required for ART initiation). By contrast, individual factors undermining access encompassed psychosocial concerns, such as fear of a positive test result or a partner’s reaction; and stigma. Data and information systems for monitoring in the three peri-urban facilities were markedly inadequate. Conclusions: A single system- or individual-level delay reduced the likelihood of women accessing ART or PMTCT interventions. These delays, when concurrent, often signalled wholesale denial of prevention and treatment. There is great scope for health systems’ reforms to address constraints and weaknesses within PMTCT and ART services in South Africa. Recommendations from this study include: ensuring autonomy over resources at lower levels; linking performance management to facility-wide human resources interventions; developing accountability systems; improving HIV services in labour wards; ensuring quality HIV and infant feeding counselling; and improved monitoring for performance management using robust systems for data collection and utilisation

Interruptions in payments for lay counsellors affects HIV testing at antenatal clinics in Johannesburg

HIV testing uptake at 3 antenatal clinics in Johannesburg was 53% (1 333/2 502) during 4 months when lay counsellors were unpaid, which was lower than the 7 months when payment was provided (79%; 3 705/4 722; p<0.001), and a subsequent 12-month period (86.3%, 11 877/13 767; p<0.001) when counsellors were paid. Consistent remuneration of lay counsellors could markedly improve services for preventing mother-to-child HIV transmission

Impact of sustainable feeds on omega-3 long-chain fatty acid levels in farmed Atlantic salmon, 2006–2015

As the global population and its demand for seafood increases more of our fish will come from aquaculture. Farmed Atlantic salmon are a global commodity and, as an oily fish, contain a rich source of the health promoting long-chain omega-3 fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Replacing the traditional finite marine ingredients, fishmeal and fish oil, in farmed salmon diets with sustainable alternatives of terrestrial origin, devoid of EPA and DHA, presents a significant challenge for the aquaculture industry. By comparing the fatty acid composition of over 3,000 Scottish Atlantic salmon farmed between 2006 and 2015, we find that terrestrial fatty acids have significantly increased alongside a decrease in EPA and DHA levels. Consequently, the nutritional value of the final product is compromised requiring double portion sizes, as compared to 2006, in order to satisfy recommended EPA + DHA intake levels endorsed by health advisory organisations. Nevertheless, farmed Scottish salmon still delivers more EPA + DHA than most other fish species and all terrestrial livestock. Our findings highlight the global shortfall of EPA and DHA and the implications this has for the human consumer and examines the potential of microalgae and genetically modified crops as future sources of these important fatty acids

Microbial and genetically engineered oils as replacements for fish oil in aquaculture feeds

As the global population grows more of our fish and seafood are being farmed. Fish are the main dietary source of the omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, but these cannot be produced in sufficient quantities as are now required for human health. Farmed fish have traditionally been fed a diet consisting of fishmeal and fish oil, rich in n-3 LC-PUFA. However, the increase in global aquaculture production has resulted in these finite and limited marine ingredients being replaced with sustainable alternatives of terrestrial origin that are devoid of n-3 LC-PUFA. Consequently, the nutritional value of the final product has been partially compromised with EPA and DHA levels both falling. Recent calls from the salmon industry for new sources of n-3 LC-PUFA have received significant commercial interest. Thus, this review explores the technologies being applied to producede novon-3 LC-PUFA sources, namely microalgae and genetically engineered oilseed crops, and how they may be used in aquafeeds to ensure that farmed fish remain a healthy component of the human diet

The potential of alternative lighting-systems to suppress pre-harvest sexual maturation of 1+ Atlantic salmon (Salmo salar) post-smolts reared in commercial sea-cages

The aim of this study was to compare the efficiency of new candidate lighting-technologies (50W ‘blue’ light-emitting-diode (B, λmax = 465 nm); 232 W ‘green’ hot cathode, (G, λmax = 546 nm); 400 W ‘red’ tungsten-halogen, (R, λmax = 667 to 740 nm)) against a standard 400 W ‘white’ metal-halide used as control technology (C, broad spectrum) at suppressing sexual maturation of 1+ Atlantic salmon (Salmo salar) in sea-cages. A total of seven experimental set-ups were tested on a commercial-scale in three trials using a standardised photoperiod regime in the form of continuous artificial-light (LL) applied from winter to summer solstice during the second year at sea. The experimental stocks were raised under an ambient thermal regime that was similar across all trials. Technical performances (spectral output, light-attenuation and irradiance distance) of the individual light-units were measured and light-perception was assessed by quantifying plasma melatonin levels. Body-size parameters (BW, FL, K) were measured at the switch-on and turn-off of the photoperiod regimes. Maturation rates were estimated at the end of the light-treatments and at harvest. The B-unit provided the shortest effective irradiance distance (distance from the light-bulb to the minimum irradiance suppressing plasma melatonin to basal day-time level = 0.016 W m-2) but the longest relative to its energy consumption; while the G- and R-units did not offer a comparative advantage over the C-unit in that regard (B>C>G>R). Nocturnal plasma-melatonin and maturation rate decreased proportionally to the light-intensity provided using a range of technologies emitting distinct spectral profiles. Light-intensity rather than light-spectral composition appeared to be the prime parameter negatively affecting sexual maturation. Maximal suppression of maturation was observed in treatments depressing nocturnal plasma melatonin to a 1.2-fold but not to a 1.7-fold increase compared to daytime levels, confirming that a threshold level of light-irradiance is necessary to obtain the desired effect. Results suggest that this can be achieved under standard commercial practices by applying, over the photoperiod regime presently used, continuous artificial-illumination with an (electrical) energy consumption of 0.28 Wh m-3 generating a mean-irradiance of 0.012 W m-2 and providing a minimum volume of effective irradiance equivalent to 12% of the rearing-environment. Such a low volume of biologically effective irradiance was likely sufficient due to the strong photic attraction already reported in Atlantic salmon. Maximal suppression of pre-harvest sexual maturation can be achieved in the Atlantic salmon on-growing industry using alternative light-technologies. Present data provides methods and threshold values favouring the implementation of photoperiod-manipulation to suppress pre-harvest maturation at the most advantageous scale and cost

Encapsulated fish oil products available in the UK meet regulatory guidelines with respect to EPA + DHA contents and oxidative status

Encapsulated fish oil products continue to be of high interest, particularly concerning labelling claims and oxidative status. Thus, the present study analysed twenty‐three encapsulated fish oil products from the UK for their lipid and fatty acid composition as well as oxidation parameters. Oil contents ranged from 91.4‐118.9% of the manufacturers stated level. Lipid class analyses revealed three different types of oil products consisting of either triacylglycerol (TAG), ethyl ester (EE) or in combination (EE/TAG). Fatty acid profiles varied according to oil form with long‐chain omega‐3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), more concentrated in EE compared to TAG‐based oils with TAG/EE oils containing intermediary levels. Twelve products had EPA + DHA contents lower than advertised, although this was reduced to 11 when the actual measured capsule oil content was taken into consideration. All products had peroxide (PV) and anisidine values below those set by pharmacopeias, although four products had a PV above the industry set limit of 5 meq.kg−1. No relationships were found between oxidative parameters and missing EPA + DHA contents, although a significant relationship was observed between PV and days to expiry. In summary, encapsulated fish oil products on the UK market are not oxidized and meet regulatory guidelines with respect to EPA + DHA contents and oxidative status. Practical Applications: The study highlights the importance of quantifying the actual capsule oil content when determining EPA + DHA levels with respect to label claims. Furthermore, it also places results into context regarding regulatory guidelines demonstrating to regulatory bodies and consumers alike that UK fish oil products do meet specification and are not oxidised

Evaluation of barley protein concentrate and fish protein concentrate, made from trimmings, as sustainable ingredients in Atlantic salmon (Salmo salar L.) feeds

Barley protein concentrate (BPC) was tested as a protein source in the diets of Atlantic salmon post-smolts. Fish were fed one of four experimental diets consisting of a fish meal/soya protein concentrate control (CT) along with two feeds supplemented with increasing levels of BPC replacing the more costly SPC. A fourth diet partially replaced FM in the high BPC diet with a liquid fish protein concentrate (FPC) made from fish trimmings. No significant differences were observed in terms of growth at the end of the 12-week feeding period, although the protein efficiency ratio (ggaing&minus;1protein consumed) was significantly lower for the control compared to fish fed diets containing either BPC only or FPC and BPC. This suggests that diets containing BPC had a beneficial effect when compared to the control diet. Furthermore, the lack of any detriment to fish growth in diets containing BPC suggests there are no significant issues regarding any negative effects of potential antinutritional factors which can otherwise be the case with other plant origin products. The data presented in this study indicate that BPC and FPC are products which could be of benefit to salmon culture, and related species, in providing a valuable new raw material to the industry