Metabolic interrelationships software application: Interactive learning tool for intermediary metabolism

We developed and implemented the software application titled Metabolic Interrelationships as a self-learning and -teaching tool for intermediary metabolism. It is used by undergraduate medical students in an integrated organ systems-based and disease-oriented core curriculum, which started in our medical faculty in 2001. The computer program provides an interactive environment in which students learn to integrate the major metabolic pathways as well as their hormonal control mechanisms as far as they depend on nutritional status. Students can explore the time- and tissue-dependent changes in mammalian intermediary metabolism during a feeding-fasting cycle. Starting from a whole-body view of interorgan nutrient fluxes, the student can make excursions to individual organs and, from there, to increasing levels of molecular detail and to explanatory animations. The application is well received by students and staff

Cultivation of Acartia tonsa with 3 different marine microalgae to optimize productivity and nutritional value

The conventional method for first feeding of marine fish is to use enriched rotifers (Brachionus spp.) in the beginning and followed with enriched Artemia, before transfer to dry feed. Recent researches have shown that fish larvae fed on calanoid copepods have higher growth rate, survival rate, fewer deformities and stronger pigmentation than larvae fed on rotifers and Artemia. The reason for the difference is discussed to be due to better nutritional quality of the copepods, which met the larvae requirement, mainly the Highly Unsaturated Fatty Acids (HUFAs); DHA, EPA and ARA. However, it is generally considered to be difficult, labour intensive and expensive to have a large-scale production of copepods. It is therefore important to continue to develop and optimize the cultivation methods of copepods, making the production inexpensive and simple. In this thesis, Acartia tonsa was cultivated with three different monoalgal diets with the microalgae species, Rhodomonas baltica, Tisochrysis lutea and Conticribra weissflogii, to optimize cultivation productivity and nutritional value of A. tonsa. Two separate studies were performed, first a nutritional study in a flow through system (FTS), and a second test study where A. tonsa was cultivated in a Recirculation Aquaculture System (RAS), integrated with a microalgae cultivation, a so-called copeponics system. In conclusion, the study of the nutritional value of A. tonsa and microalgae species, showed that it was possible to manipulate the fatty acid composition of A. tonsa through the diet. The survival and growth rate of A. tonsa was highest when reared on R. baltica and T. lutea. The fatty acid composition of A. tonsa reared on R. baltica resulted in the most suitable HUFA ratio of DHA/EPA (~2) and EPA/ARA (~6) for marine fish larvae. The copeponics system functioned when using the microalgae R. baltica and the results gave strong indication that it was possible to reduce the water and nutrient consumption by ~90% and ~53%, respectively. However, the copeponics system should be further investigated for optimization. Keywords: Acartia tonsa, Microalgae, Fatty acids, Cultivations methods, Copeponic

Hreinsun og nýting affallsvatns frá Silfurstjörnunni hf.

Fiskeldi hefur aukist mikið seinustu á árum og margt sem bendir til þess að það eigi eftir að aukast ennfrekar á næstu árum. Við fiskeldi fellur til úrgangur, rétt eins og við ræktun annarra dýra, en næringarefni eru í úrgangnum, aðallega fosfór og köfnunarefni. Silfurstjarnan er lax- og bleikjueldisstöð staðsett í Öxarfirði. Til þess að hindra losun á úrgangi frá stöðinni rennur affallsvatnið í settjörn en þar safnast úrgangurinn saman og myndar seyru. Tæma þarf tjörnina eftir þörfum þegar hún fyllist en tjörnin hefur aðeins einu sinni verið tæmd og var þá seyran urðuð innan lóðar Silfurstjörnunnar með samþykki Umhverfisstofnunar. Ef tæma ætti tjörnina reglulega þyrfti annað hvort að urða seyruna á viðurkenndu urðunarsvæði við Kópasker eða dreifa henni á örfoka land eins og t.d. á Hólssand. Báðar lausnir eru afar kostnaðarsamar og því vilja forsvarsmenn fyrirtækisins leita annarra leiða og nýta seyruna. Vegna næringarefna í seyrunni væri tilvalið að nýta hana sem áburð á tún en helstu næringarefna þarfir túna eru köfnunarefni, fosfór og kalí. Við núverandi aðstæður renna 1.100 l/s af vatni í gegnum Silfurstjörnuna og útreiknað magn uppleystra agna er 8,36 mg/l. Þetta er hlutfallslega lítið af úrgangi í miklu vatni og því þyrfti að hreinsa agnirnar í burtu úr vatninu og safna þeim saman ef nýta á úrganginn. Í þessu verkefni voru mögulegar leiðir athugaðar til þess að hreinsa affallið frá Silfurstjörnunni og safna tilfallandi úrgangi. Kostnaður við kaup á búnaði og tækjum var fundinn og mögulegur hagnaður af sölu seyru. Reiknuð voru tvö tilvik en í fyrra tilfellinu yrði notast við tromlusíur, settanka og steypt kar en með þeim hætti myndast um 3.100 tonn af seyru á ári með 6% þurrefnainnihald og sem inniheldur 0,79 g/kg fosfór og 1,57 g/kg köfnunarefni. Í seinna tilfellinu væri notast við svokallaðan geotube poka en með þeim safnast um 1.600 tonn af seyru á ári með 15% þurrefnainnihald og sem inniheldur 1,77 g/kg fosfór og 3,54 g/kg köfnunarefni. Í ljós kom að í hvorugu tilvikinu væri hagnaður á sölu seyru.Silfurstjarnan is a salmon and arctic charr aquaculture farm located in Öxarfjörður, North East Iceland. The wastewater from the farm flows through a settling basin in order to prevent discharge of waste into the environment. The waste in the settling basin forms a sludge and it needs to be emptied when it is filled up. The options for the producers are either to dispose of it in a burying site at Kópasker or spread on a land called Hólssand. Both options are expensive and alternative solutions are sought. The sludge holds some nutrients, mainly nitrogen and phosphorus, and is therefore ideal to use as fertilizer on grassland where the main nutrient needs are nitrogen, phosphorus and potassium. To be able to use sludge as a fertilizer it needs to be in a suitable form. In this work two ways to collect sludge are explored and analysed with respect to profitability. The first option is to use a drumfilter and a settling tank and the second one to use a geotube bag. Neither option showed profitability