Stressresistenz und -adaption von Forellen aus Intensiv- und Extensivhaltung unter definierten Haltungsbedingungen bei besonderer Berücksichtigung ökologischer Produktionspraktiken

Ziel war es Forellen unterschiedlicher Herkunft auf die bestmögliche Anpassungsfähigkeit und größte Stressresistenz in Bezug auf vorgeschriebene ökologische Haltungsbedingungen (ökologisch intensive Haltung mit maximal 25 kg/ m3 und extensive, maximal 6 kg/ m3) zu untersuchen und dabei neue valide, minimal invasiv messbare Stressparameter zu etablieren. Im Verbund der Agrar- und Ernährungswissenschaftlichen Fakultät der CAU mit der Gesellschaft für Marine Aquakultur mbH (GMA) und dem Institut für Fischerei der Bayerischen Landesanstalt für Landwirtschaft, sowie später dem Leibnitz Institut für Nutztierbiologie, Institut Genombiologie, Abteilung Fischgenetik (FBN) wurde nach Etablierung von molekularen Stressmarkern unter Nutzung eines Fütterungsstressmodellversuchs mit Sojabohnenmehl, die Stressresistenz und adaptation von zwei unterschiedlichen Forellenherkünften in intensiver und extensiver ökologischer Haltung untersucht. Stressparameter müssen immer Stressartspezifisch betrachtet werden. Es wurde als Nebenergebnis ein Modell zur Untersuchung von Stress entwickelt, das in der Futtermittelforschung angewendet werden kann. Insgesamt wurde die mRNA aus Blut von 88 verschiedenen Genen untersucht. Neben drei Haushaltsgenen, konnten die regulierten Gene den übergeordneten Signaltransduktionswegen wie der SERPIN G Superfamilie, der intrazelluläre PI3K/Aktin-, Toll-like Rezeptor-, NF-κ B-, MAP-Kinase- und JAK-STAT-Signaltransduktion oder intrazellulären Pathogenerkennungsrezeptoren zugeordnet werden. Es wurde die mRNA Expression der Blutzellen auf verschiede pro- und anti-inflammatorische Zytokine, Chemokine, Stoffe die an der Akuten-Phase-Reaktion beteiligt, der Komplementkaskade zugeordnet werden können oder an Entzündungsreaktionen beteiligt sind, sowie Hitzeschockproteine getestet. Abschließend wurden verschiedene Markergene für bestimmte Zellpopulation mit untersucht. Die Ergebnisse stellen eine wichtige Grundlage dar, um „animal welfare“ in der Forellenhaltung besser beurteilen zu können. Bisher beziehen sich die Parameter auf oftmals wenig standardisierbare Beobachtungen wie Verhalten, Farbveränderungen und ähnliches. Diese Ergebnisse hier stellen die Grundlage dar, um zukünftig praktische Detektionssysteme – vergleichbar mit einem Diabetestest – auch in Hinblick auf Aquakultur 4.0 entwickeln zu können

A Multidisciplinary Approach Evaluating Soybean Meal-Induced Enteritis in Rainbow Trout Oncorhynchus mykiss

This study evaluated a diverse range of markers of feeding stress to obtain a more precise assessment of the welfare of rainbow trout in relation to inadequate husbandry conditions. A feeding stress model based on dietary soybean meal was employed to identify suitable minimally invasive “classical” stress markers, together with molecular signatures. In a 56-day feeding experiment, rainbow trout were fed diets containing different levels of soybean meal. The impact of these different soybean meal diets on rainbow trout was assessed by water quality analyses, clinical health observations, classic growth and performance parameters, gut histopathology, blood-parameter measurements and multigene-expression profiling in RNA from whole blood. Soybean meal-induced enteritis was manifested phenotypically by an inflammatory reaction in the posterior section of the intestine and by diarrhoea in some trout. These inflammatory changes were associated with decreased supranuclear vacuolation. The haematocrit values and the levels of plasma cortisol and circulating lymphocytes in the blood were increased in trout that had consumed high amounts of SBM. Notably, the increased haematocrit depended significantly on the bodyweight of the individual trout. The transcript levels of certain genes (e.g., MAP3K1, LYG, NOD1, STAT1 and HSP90AB) emerged as potentially useful indicators in the blood of rainbow trout providing valuable information about inadequate nutrition. The expression-profiling findings provide a basis for improved, minimally invasive monitoring of feeding regimens in trout farming and may stimulate the development of practical detection devices for innovative aquaculture operations

Kreislaufanlagen - Positionen des Ökosektors

Geeignete Standorte für herkömmliche Formen der Aquakultur werden weltweit knapp, und eine Erhöhung der Produktion gerät zunehmend mit Zielen des Umwelt- und Naturschutzes in Konflikt. Der in Deutschland extrem geringe Selbstversorgungsgrad mit Fisch kann daher in erster Linie über eine Produktionssteigerung in Kreislaufanlagen (KLA), d.h. in geschlossenen, standortunabhängigen und entsprechend technisierten Systemen, erhöht werden. Im Nationalen Strategieplan Aquakultur für Deutschland wird insofern ein besonderer Fokus auf das Produktionspotential in KLA gelegt, bzw. ein deutliches Wachstum nur in diesem Bereich (Steigerung auf 20.000 t bis 2020) als möglich erachtet. Bei dem hier beantragten Vorhaben wird geklärt, wie relevante Interessensgruppen die Vereinbarkeit von Aquakultur in KLA mit der Ökologischen Lebensmittelwirtschaft bewerten. Die Frage stellt sich einerseits aus Sicht der Erzeuger, denn die Produktion in KLA ist durch hohe Umweltauflagen sowie komplexe Haltungssysteme aufwändig und benötigt daher Wege, ihre Alleinstellungsmerkmale (z.B. Transparenz, Regionalität, Verzicht auf Chemie und Tierarznei) auf glaubhaftem Weg an den Verbraucher zu kommunizieren. Andererseits aus Sicht der richtliniengebenden Ökoverbände und Institutionen, denn sie sind von Seiten des Marktes und der Gesellschaft aufgefordert, zu dieser immer wichtiger werdenden Zukunftstechnologie fundiert Stellung zu beziehen

Scale cortisol is positively correlated to fin injuries in rainbow trout (Oncorhynchus mykiss) reared in commercial flow through systems

Suboptimal farm management can lead to (chronic) stress and can result in external morphological damage, which both can have deleterious effects on fish performance and welfare. This study is the first to investigate a potential correlation between chronic stress and the occurrence of external morphological damage in rainbow trout (Oncorhynchus mykiss) reared commercial flow through systems. To quantify chronic stress in eight different farms, scales of 10 fish per farm were sampled for scale cortisol analysis using UPLC-MS/MS. Measured external morphological damage of fish included damage to the eyes, skin and fins, as well as deformities and emaciation. Further, the influence of management (water supply, water supply per kg fish, total water exchange duration, average stocking density, feeding frequency) and water quality (oxygen, temperature, pH, ammonium, ammonia, nitrite, nitrate, turbidity) on chronic stress level and external morphological damage was assessed. Measured eyeand skin damage, deformities and emaciation occurred less frequently, while fin injuries were common and differed significantly in severity between farms. Results on all fish across farms showed a highly positive correlation between scale cortisol and total fin injury. A limited water supply, -supply per kg fish and -exchange as well as higher stocking densities and feeding frequencies resulted in a comparably reduced water quality, indicated by correlations with lower oxygen levels, higher levels of nitrogen compounds, higher temperature and turbidity. After conducting a principal component analysis, multiple linear regression models showed that scale cortisol was mainly predicted by total fin injury, temperature and the pH, ammonia and nitrite component. Total fin injury was majorly predicted by the management component concerning water supply, -supply per kg fish and -exchange duration as well as by stocking density, scale cortisol, the pH, ammonia and nitrite component and feeding frequency. Findings on scale cortisol support fin injuries to be an important welfare issue and suitable on-farm welfare indicator. Higher scale cortisol levels and higher fin injuries, directly and indirectly influenced by farm management, are indicative for impaired welfare and support the necessity of reducing chronic stress and the occurrence of fin injuries in aquaculture settings

Epizootics in harbour seals (<i>Phoca vitulina</i>): clinical aspects

Epizootic diseases causing considerable mortality in harbour seal populations have mainly been reported from the waters of the United States and Europe. Such die-offs were largely attributable to viral infections. Several hundred individuals died from respiratory infections caused by Influenza A viruses at the coast of New England, USA, in 1979, 1980 and 1982. More than 53,000 harbour seals were killed in European waters by Phocine Distemper Virus (PDV), a morbillivirus,in two outbreaks in 1988 and 2002. For several other epizootics of smaller scale in the waters of the Atlantic and Pacific coast of the USA and, most recently, in Danish and Swedish waters in 2007 the causes remain unclear, although characteristic respiratory symptoms and interstitial pneumonia suspicious of viral etiology were detected as well as occasionally bacterial infections caused by Erysipelothrix rhusiopathiae and Pseudomonas aeruginosa. Mass mortalities caused by biotoxins, direct human interactions or changes in oceanographic conditions have so far not been described for harbour seals. However, high organochlorine loads detected in European harbour seal populations and suspected to impede immune functions, were considered an aggravating factor in the 1988 morbillivirus epizootic. Establishing supranational stranding networks is a key prerequisite for the detection of future unusual die-offs in marine mammals. Detailed post-mortem investigations of all organ systems are essential for targeted etiological studies towards the causes of mass mortalities in seals

Aspects of population biology: Epizootics in harbour seals (Phoca vitulina): clinical aspects

peer reviewe

Effects of plant-based proteins and handling stress on intestinal mucus microbiota in rainbow trout

Abstract Via 16S rRNA gene amplicon sequencing, this study explores whether the gut mucus microbiota of rainbow trout is affected by the interaction of a plant-protein-based diet and a daily handling stressor (chasing with a fishing net) across two genetic lines (A, B). Initial body weights of fish from lines A and B were 124.7 g and 147.2 g, respectively. Fish were fed 1.5% of body weight per day for 59 days either of two experimental diets, differing in their fish meal [fishmeal-based diet (F): 35%, plant-based diet (V): 7%] and plant-based protein content (diet F: 47%, diet V: 73%). No diet- or stress-related effect on fish performance was observed at the end of the trial. However, we found significantly increased observed ASVs in the intestinal mucus of fish fed diet F compared to diet V. No significant differences in Shannon diversity could be observed between treatments. The autochthonous microbiota in fish fed with diet V was dominated by representatives of the genera Mycoplasma, Cetobacterium, and Ruminococcaceae, whereas Enterobacteriaceae and Photobacterium were significantly associated with diet F. The mucus bacteria in both genetic lines were significantly separated by diet, but neither by stress nor an interaction, as obtained via PERMANOVA. However, pairwise comparisons revealed that the diet effect was only significant in stressed fish. Therefore, our findings indicate that the mucus-associated microbiota is primarily modulated by the protein source, but this modulation is mediated by the stress status of the fish

Table1_Salinity change evokes stress and immune responses in Atlantic salmon with microalgae showing limited potential for dietary mitigation.docx

Smoltification was found to impact both immune and stress responses of farmed Atlantic salmon (Salmo salar), but little is known about how salinity change affects salmon months after completed smoltification. Here, we examined (1) the effect of salinity change from brackish water to seawater on the stress and immune responses in Atlantic salmon and (2) evaluated if functional diets enriched with microalgae can mitigate stress- and immune-related changes. Groups of Atlantic salmon were fed for 8 weeks with different microalgae-enriched diets in brackish water and were then transferred into seawater. Samples of the head kidney, gill, liver and plasma were taken before seawater transfer (SWT), 20 h after SWT, and 2 weeks after SWT for gene-expression analysis, plasma biochemistry and protein quantification. The salmon showed full osmoregulatory ability upon transfer to seawater reflected by high nkaα1b levels in the gill and tight plasma ion regulation. In the gill, one-third of 44 investigated genes were reduced at either 20 h or 2 weeks in seawater, including genes involved in cytokine signaling (il1b) and antiviral defense (isg15, rsad2, ifit5). In contrast, an acute response after 20 h in SW was apparent in the head kidney reflected by increased plasma stress indicators and induced expression of genes involved in acute-phase response (drtp1), antimicrobial defense (camp) and stress response (hspa5). However, after 2 weeks in seawater, the expression of antiviral genes (isg15, rsad2, znfx1) was reduced in the head kidney. Few genes (camp, clra, c1ql2) in the gill were downregulated by a diet with 8% inclusion of Athrospira platensis. The results of the present study indicate that salinity change months after smoltification evokes molecular stress- and immune responses in Atlantic salmon. However, microalgae-enriched functional diets seem to have only limited potential to mitigate the related changes.</p

What caused the UK's largest common dolphin (Delphinus delphis) mass stranding event?

On 9 June 2008, the UK's largest mass stranding event (MSE) of short-beaked common dolphins (Delphinus delphis) occurred in Falmouth Bay, Cornwall. At least 26 dolphins died, and a similar number was refloated/herded back to sea. On necropsy, all dolphins were in good nutritive status with empty stomachs and no evidence of known infectious disease or acute physical injury. Auditory tissues were grossly normal (26/26) but had microscopic haemorrhages (5/5) and mild otitis media (1/5) in the freshest cases. Five lactating adult dolphins, one immature male, and one immature female tested were free of harmful algal toxins and had low chemical pollutant levels. Pathological evidence of mud/seawater inhalation (11/26), local tide cycle, and the relative lack of renal myoglobinuria (26/26) suggested MSE onset on a rising tide between 06:30 and 08∶21 hrs (9 June). Potential causes excluded or considered highly unlikely included infectious disease, gas/fat embolism, boat strike, by-catch, predator attack, foraging unusually close to shore, chemical or algal toxin exposure, abnormal weather/climatic conditions, and high-intensity acoustic inputs from seismic airgun arrays or natural sources (e.g., earthquakes). International naval exercises did occur in close proximity to the MSE with the most intense part of the exercises (including mid-frequency sonars) occurring four days before the MSE and resuming with helicopter exercises on the morning of the MSE. The MSE may therefore have been a "two-stage process" where a group of normally pelagic dolphins entered Falmouth Bay and, after 3-4 days in/around the Bay, a second acoustic/disturbance event occurred causing them to strand en masse. This spatial and temporal association with the MSE, previous associations between naval activities and cetacean MSEs, and an absence of other identifiable factors known to cause cetacean MSEs, indicates naval activity to be the most probable cause of the Falmouth Bay MSE