A biotest system for optimalization of environmental parameters for production of halibut fry

A system for controlled testing of different environmental parameters in seawater was made. Both the biotest system and an experimental setup using larvae of the Atlantic Halibut (Hippoglossus hippoglossus L.) are described

Effect of water temperature and exposure duration on detachment rate of salmon lice (Lepeophtheirus salmonis); testing the relevant thermal spectrum used for delousing

Thermal delousing has become the most applied method for treatment against salmon lice. However, the temperature range used is strongly aversive for salmonids, and the method is associated with increased mortality. Treatment temperature × duration combinations should be tailored to maximise delousing efficiency and minimize welfare impacts on the host fish. We tested the detachment rate of sessile, pre-adult and adult male and female salmon lice (Lepeophtheirus salmonis) as a function of ambient temperature (11–16 °C), exposure temperature (28–36 °C), and exposure duration (0–120 s). Dead Atlantic salmon (Salmo salar) hosts were used to avoid negative fish welfare and detachment of lice due to fish behaviour. Within the range tested, higher exposure temperatures were associated with higher detachment rates among pre-adult and adult lice, while no sessile lice detached at any temperature. Moreover, no treatment combination detached 100% of lice of any stage, and at 28 °C, detachment of adult females was negligible. Most detachments occurred within the first 30 s of exposure. We conclude that for a given delousing efficiency, lower temperatures must be compensated for by considerably longer exposure durations. This may be a higher risk for the welfare of the host fish than higher temperatures and shorter exposure durations.publishedVersio

Quantitative proteome profiling reveals molecular hallmarks of egg quality in Atlantic halibut: impairments of transcription and protein folding impede protein and energy homeostasis during early development

Background Tandem mass tag spectrometry (TMT labeling-LC-MS/MS) was utilized to examine the global proteomes of Atlantic halibut eggs at the 1-cell-stage post fertilization. Comparisons were made between eggs judged to be of good quality (GQ) versus poor quality (BQ) as evidenced by their subsequent rates of survival for 12 days. Altered abundance of selected proteins in BQ eggs was confirmed by parallel reaction monitoring spectrometry (PRM-LC-MS/MS). Correspondence of protein levels to expression of related gene transcripts was examined via qPCR. Potential mitochondrial differences between GQ and BQ eggs were assessed by transmission electron microscopy (TEM) and measurements of mitochondrial DNA (mtDNA) levels. Results A total of 115 proteins were found to be differentially abundant between GQ and BQ eggs. Frequency distributions of these proteins indicated higher protein folding activity in GQ eggs compared to higher transcription and protein degradation activities in BQ eggs. BQ eggs were also significantly enriched with proteins related to mitochondrial structure and biogenesis. Quantitative differences in abundance of several proteins with parallel differences in their transcript levels were confirmed in egg samples obtained over three consecutive reproductive seasons. The observed disparities in global proteome profiles suggest impairment of protein and energy homeostasis related to unfolded protein response and mitochondrial stress in BQ eggs. TEM revealed BQ eggs to contain significantly higher numbers of mitochondria, but differences in corresponding genomic mtDNA (mt-nd5 and mt-atp6) levels were not significant. Mitochondria from BQ eggs were significantly smaller with a more irregular shape and a higher number of cristae than those from GQ eggs. Conclusion The results of this study indicate that BQ Atlantic halibut eggs are impaired at both transcription and translation levels leading to endoplasmic reticulum and mitochondrial disorders. Observation of these irregularities over three consecutive reproductive seasons in BQ eggs from females of diverse background, age and reproductive experience indicates that they are a hallmark of poor egg quality. Additional research is needed to discover when in oogenesis and under what circumstances these defects may arise. The prevalence of this suite of markers in BQ eggs of diverse vertebrate species also begs investigation.publishedVersio

Welfare effects of environmental hypercapnia quantified by indicators based on morphology and allostatic load in Atlantic salmon (Salmo salar)

Water supply is a limited resource in most salmon hatcheries, which is compensated by reduced water flow and oxygenation. However, reduced water exchange can lead to accumulation of CO2, resulting in environmental hypercapnia, which may have negative impacts on fish welfare. Thus, environmental hypercapnia can be a common welfare problem for salmon in hatcheries, and particularly in recirculating systems (RAS). In this experiment, Atlantic salmon were exposed to chronic environmental hypercapnia during the last 68 days of the freshwater phase, whereupon effects on physiological stress coping mechanisms and morphological welfare indicators were investigated. Effects on stress coping mechanisms were quantified by measuring changes in brain serotonergic chemistry and plasma cortisol at basal levels and in response to a standardized acute stress test. The results show that exposure to elevated CO2 saturation in the water compromised stress responsiveness of brainstem serotonergic activity, altered osmotic homeostasis, and suppressed growth indicating that fish experience allostatic overload. However, no effects on morphological welfare indicators were observed. This accentuates the need for physiological measures, including physiological responses to controlled challenges to activate the stress axis, when investigating the welfare status of fish reared in systems with potential high CO2.publishedVersio

The effect of ambient salinity on the buoyancy of eggs from the Atlantic halibut (Hippoglossus hippoglossus)

The effect of ambient salinity on buoyancy and the formation of perivitelline fluid in eggs from the Atlantic halibut Hippoglossus hippoglossus have been investigated. The results clearly demonstrate that the water balance of the eggs are independant of the ambient salinity the first days after fertilization. The water loss from eggs fertilized in 17 ppt saline sea water was not less than from eggs fertilized in 34 ppt sea water in spite of a reduced osmotic gradient. Neither was the egg buoyancy altered by fertilization in low saline sea water. For proper fertilization, the eggs from the Atlantic halibut need concentrations of calcium near the concentration found in sea water

Antibiotic treatment and dose-response of bacterial activity associated with flatfish eggs

Newly stripped and fertilized eggs from Plaice (Pleuronectes platessa) and Atlantic Halibut (Hipppoglossus hippoglossus) were incubated in 34 ppt sea water. 150 eggs (Plaice), 30 eggs (Halibut) or 20 glass beads were incubated in 30 ml seawater in light at 5.5°C. The antibiotics Oxytetracycline (-HCl) and Flumiquil were added to end concentration ranges 0 - 105 ppm and 0 - 60 ppm, respectively. With a method modified from Somville and Billen (1983) it was possible to measure the activity both in the incubation water and on the chorion of the incubated eggs. The activity on egg surfaces was significant higher than the activity of a comparable surface aerea of the glass beads. The activity on the egg surfaces was greater than the activity in a water volume corresponding to the combined egg volume

Torskeeggets vann- og ionebalanse :: basalstudier og effekten av Ekofisk råolje

Hovedfagsoppgave i miljøfysiologi til Cand. scient.-eksamen ved Universitetet i Bergen, Zoologisk laboratoriu