Effect of salinity on food consumption and growth of juvenile Nile tilapia (Oreochromi niloticus L.)

The effect of salinity (0, lO and 20%o, water temperature 28 ± l oC) on food consumption and growth of juvenile Nile tilapia, Oreochromis niloticus L. (9.94 ± 0.15 g) were investigated by feeding group of 20 fish at 2% body weight day. Individual food consumption was measured using X-radiography. There were no significant differences in growth or white muscle protein concentrations among groups. During feed deprivation, weight loss was similar for fish held at O%o and 10 %o salinity, but after 7 days over 50% of the fish maintained at 20%o salinity developed lesions covering 5-25% of the body. No significant relationships were observed between individual specific growth rates and food consumption rates within the groups. The fish in all salinity groups showed a negative correlation between specific growth rate and food conversion ratio. The coefficient of variation for wet weight specific food consumption and the mean share of meal for each fish were used as a measure of social hierarchy strength. A negative correlation was observed between coefficient of variation in food consumption and mean share of meal. The social hierarchy structure was similar in all salinities; 25% of the fish were dominant (18.29% above an equal share of meal) and 30% were subordinate (16.19% below an equal share of meal) and the remainder 45% fish fed theoretical share of meal (MSM, 5.26%)

Effects of socking [sic] density on ammonia excretion and the growth of Nile tilapia (Oreochromis niloticus L.)

The effects of stocking density (10, 15, 50 & 75 fish in 65L tank) and ammonia excretion on the growth of Nile tilapia, Oreochromis niloticus (12.19 ± 1.21 g) were investigated. Increasing stocking density of Nile tilapia from 15 fish/tank (2.81 g fish/L) to 75 fish/tank (14.07 g fish/L) resulted in associated increase in ammonia level (1.48 ± 0.87 mg/L to 26.44 ± 11.4 mg/L) and significantly lower growth rates. Significantly better feed conversion ratios were found for fish reared at lower (15 fish/tank) stocking densities compared to higher (75 fish/tank) stocking densities. Individual growth rates were significantly better for fish reared at a lower stocking density 15 fish/tank compared to higher stocking density 75 fish/tank and size variation (coefficient of variation in weight) were positively correlated with stocking density. Although water exchange did not have a significant effect on the growth of Nile tilapia for fish stocked at 10 fish/tank (1.88 g fish/L) and 50 fish/tank (9.38 g fish/L), however, the fish in the higher stocking density (9.38 g fish/L) groups and without water exchange, significantly changed the coloration of their bodies (silver to black) which may be due to the lower oxygen levels combined with higher ammonia levels. Ammonia level increased with increasing stocking density and without water exchange. In this study, it may be suggested that when fish reared at higher stocking densities then water exchange must be taken in to consideration so as to help avoid environmental and physiological stress to the fish

Effect of salinity and food ration level on the growth of Nile tilapia (Oreochromis niloticus L.)

The effect of salinity (0, 10 & 20‰, water temperature 28 ± 1°C) and food ration (3 and 4.5% bw/day) on food consumption and growth of Nile tilapia, Oreochromis niloticus (10.77 ± 0.21g) were investigated. Individual food consumption was measured using X-radiography technique. Salinities (0, 10 & 20‰) did not have significant effect on the growth rate of groups of Nile tilapia fed at different ration levels (3 & 4.5% bw/day). This study showed that the growth of all-male fish was significantly better than all-female fish for all three salinities and two rations. Salinities from 0 to 20‰ had no effect on growth performance of males or female fish. In the present study, it was evident that fish fed at 3% bw/day ration ate all the food offered and fish fed at 4.5% bw/day did not consumed all amounts. Also, growth performance did not significantly differ among fish fed at 3% bw/day ration level and reared at different salinities. Fish reared under higher salinities (20‰) and fed at higher ration (4.5% bw/day) level had skin lesions and injuries on their body. It was assumed that fish fed at higher ration under higher salinities (20‰) and maintained higher osmoregulatory costs together with osmotic stress may have a negative influence on the appetite of fish. Another possibility that may have affected the appetite could be the unionized ammonia levels that were high. The high-unionized ammonia levels combined with the osmotic stress may have been the cause, or have aided, development of skin lesions and injuries on the fish at higher salinities

Climate-smart fisheries: CO2 emissions reduction and food security are complementary

In the global north, climate-smart fisheries (CSF) policies prioritise steps to combat CO2 emissions from SSF, in a response to the fact that globally, CO2 emissions from small-scale fisheries (SSFs) increased by over 5.8 times between 1950 and 2016. However, in the global south, CSF policies on SSF prioritise food and income security over CO2 emission reduction. In this paper, we examine this apparently contrasting interpretation of CSF as a conceptual framework to interpret the case study of Sierra Leone, one of Africa's poorest countries where we found that small-scale coastal fishers are preoccupied with mitigating the impact of climate change on their food and income security rather than with lowering their CO2 emissions. The self-image of SSF in Sierra Leone is that of being victims of climate change rather than perpetrators of it, and they justify this stance by claiming their livelihoods are being threatened by climate change. However, it could be argued that the best way to keep Sierra Leonean SSF CO2 emissions low is to prioritise their food and income security: in other words, that food security and CO2 reductions are complementary not contradictory. This, at any rate, is the argument of the current paper. The fieldwork for this study entailed co-created research in Sierra Leone and it involved 103 stakeholders who met face-to-face and online between January and March 2022 and through village meetings. The results of this fieldwork showed that food and income security and not CO2 emissions are the priorities in the stakeholders’ interpretation of CSF. However, if food and income security are not prioritised, communities are likely to adopt maladaptive strategies which undermine marine protected areas (MPAs) and exacerbate overfishing, thereby increasing CO2 emissions. Moreover, investment in aquaculture as a supplementary or alternative livelihood can directly increase food security and incomes and at the same time indirectly serve as a CO2 mitigation measure. In addition, weather information communication is an important CSF measure which both protects fishers from the impact of climate change and reduces their CO2 emissions. Accordingly, we argue that the contrast between reducing CO2 emissions and protecting food security from climate change may be more apparent than real in Sierra Leone coastal fisheries, since both policies may work in tandem together. This study therefore contributes a new interpretation of CSF in the global south: instead of seeing it as posing a conflict between CO2 emissions reductions and food security, we have shown the two objectives can be complementary. The wider implication of this paper is that CSF strategies for SSFs do not have to be polarised between the global north's focus on the reduction of CO2 emissions from fishing vessels and the global south's focus on the mitigation of the impact of global warming on SSFs. There are circumstances when the two objectives may be in harmony

A place-based approach to payments for ecosystem services

Payment for Ecosystem Services (PES) schemes are proliferating but are challenged by insufficient attention to spatial and temporal inter-dependencies, interactions between different ecosystems and their services, and the need for multi-level governance. To address these challenges, this paper develops a place-based approach to the development and implementation of PES schemes that incorporates multi-level governance, bundling or layering of services across multiple scales, and shared values for ecosystem services. The approach is evaluated and illustrated using case study research to develop an explicitly place-based PES scheme, the Peatland Code, owned and managed by the International Union for the Conservation of Nature’s UK Peatland Programme and designed to pay for restoration of peatland habitats. Buyers preferred bundled schemes with premium pricing of a primary service, contrasting with sellers’ preferences for quantifying and marketing services separately in a layered scheme. There was limited awareness among key business sectors of dependencies on ecosystem services, or the risks and opportunities arising from their management. Companies with financial links to peatlands or a strong environmental sustainability focus were interested in the scheme, particularly in relation to climate regulation, water quality, biodiversity and flood risk mitigation benefits. Visitors were most interested in donating to projects that benefited wildlife and were willing to donate around £2 on-site during a visit. Sellers agreed a deliberated fair price per tonne of CO2 equivalent from £11.18 to £15.65 across four sites in Scotland, with this range primarily driven by spatial variation in habitat degradation. In the Peak District, perceived declines in sheep and grouse productivity arising from ditch blocking led to substantially higher prices, but in other regions ditch blocking was viewed more positively. The Peatland Code was developed in close collaboration with stakeholders at catchment, landscape and national scales, enabling multi-level governance of the management and delivery of ecosystem services across these scales. Place-based PES schemes can mitigate negative trade-offs between ecosystem services, more effectively include cultural ecosystem services and engage with and empower diverse stakeholders in scheme design and governance

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease