Fysiske og kjemiske faktorer som påvirker dynamiken av planteplankton i en svært eutrof og turbid innsjø

The fact that nutrients limit primary production in aquatic ecosystems is widely accepted, and phosphorus is demonstrated as the main limiting nutrient in freshwaters. Strict control of phosphorus supply has therefore become the primary goal in the management of eutrophic freshwaters, regardless of differences in catchment properties, lake morphometry and hydrology, and lake physical characteristics. Various abiotic and biotic factors may, however, impact the primary production of phytoplankton and blooms of potentially toxic cyanobacteria. The majority of these factors vary both seasonally and annually, especially in highly dynamic lakes that respond rapidly to changing weather conditions. This thesis consists of three different approaches in limnology: (1) a lake survey, (2) an in situ experiment with the lakes natural phytoplankton community, and addition of either phosphorus, both phosphorus and nitrogen, or no nutrients, and (3) a dynamic model to better understand the effects of physical and chemical factors on the phytoplankton dynamics in eutrophic lakes. Phosphorus was the limiting nutrient for phytoplankton growth as long as the light conditions in the lake were satisfactory. Nitrogen addition had minor effect on phytoplankton growth. The concentration of phosphorus, however, did not affect the biomass of cyanobacteria. Neither nitrogen nor the nitrogen to phosphorus ratio could explain dominance of the nitrogen fixing cyanobacteria Aphanizomenon cf. klebahnii and Anabaena planctonica. Light significantly influenced phytoplankton growth during the whole growing season. Cyanobacteria development was supported by warm water, shallow euphotic depth and low water turbulence rather than by nutrients. Inter-annual variation in weather highly influenced thermal, mixing and light regimes, which further determined nutrients and phytoplankton dynamics in the lake. Risk of cyanobacteria blooms seem to be especially high if increased fluxes of suspended matter and phosphorus during mild and wet winters are followed by warm summers, increased water temperatures and stable thermal stratification. More frequent mild winters, as predicted by climate scenarios for Scandinavia, increase the risk of cyanobacteria blooms in eutrophic and turbid lakes.Det er allment akseptert at næringsstoffer begrenser primærproduksjonen i akvatiske økosystemer, og fosfor er hovedsaklig det begrensende næringsstoffet i ferskvann. Streng kontroll av fosfor har derfor blitt det primære målet i forvaltningen av eutrofe ferskvann, uavhengig av egenskapene til nedslagsfeltet og morfometriske, hydrologiske og fysiske egenskaper ved innsjøen. Flere abiotiske og biotiske faktorer kan imidlertid virke inn på primærproduksjonen av planteplankton og oppblomstring av potensielt giftige cyanobakterier. Flertallet av disse faktorene endres både sesongmessig og årlig, spesielt i svært dynamiske innsjøer som responderer raskt på skiftende værforhold. Denne oppgaven består av tre ulike tilnærminger innen limnology: (1) en innsjøundersøkelse, (2) et in situ eksperiment med innsjøens naturlige planteplanktonsamfunn og tilsetting av enten fosfor, både fosfor og nitrogen eller ingen næringsstoffer, og (3) en dynamisk modell for å bedre forstå effekten av fysiske og kjemiske faktorer på planteplanktondynamikken i eutrofe innsjøer. Fosfor var det begrensende næringsstoffet for vekst av planteplankton så lenge lysforholdene i innsjøen var tilfredsstillende. Tilsetting av nitrogen hadde ubetydelig effekt på tilvekst av planteplankton. Konsentrasjonen av fosfor påvirket derimot ikke biomassen av cyanobakterier. Hverken nitrogen eller forholdet mellom nitrogen og fosfor kunne forklare dominansen av de nitrogenfikserende cyanobakteriene Aphanizomenon cf. klebahnii og Anabaena planctonica. Lys påvirket signifikant tilveksten av planteplankton gjennom hele vekstsesongen. Utviklingen av cyanobakterier ble fremmet av varmt vann, grunt eufotiske dyp og lav turbulens, snarere enn av næringsstoffer. Årlige variasjoner i værforhold påvirket i høy grad varme-, sirkulasjons- og lysregimet, noe som videre påvirker dynamikken til næringsstoffer og fytoplankton i innsjøen. Faren for oppblomstring av cyanobakterier synes å være spesielt stor dersom økt avrenning av suspendert stoff og fosfor under milde og våte vintre etterfølges av varme somre, økte vanntemperaturer og stabil termisk sjiktdannelse. Høyere frekvens av milde vintre som indikert i klimascenarier for Skandinavia økter risikoen for oppblomstring av cyanobakterier i eutrofe og turbide innsjøer

Rhythmical structures in music and body motion in Afro-Brazilian samba and Norwegian telespringar

Afro-Brazilian samba and Norwegian telespringar are both often characterized by their complex rhythmical patterns. More specifically, recent studies have identified the existence of systematic anticipation of the third and fourth sixteenth note in a beat in samba groove, while telespringar, normally notated in 3â„4, is recognized for a type of asymmetrical meter featuring a long – average – short (L – A – S) duration pattern at beat level. Considering the strong relationship between music and dance in both samba and telespringar, the present study proposes that, in addition to sound data, motion data from both musicians and dancers should be incorporated into analyses of these rhythmical structures.In this study, we investigate whether the microtiming features previously shown in samba and telespringar music are also represented in the body motion of performers who are playing and dancing. We derive our discussion from motion-capture experiments where skilled samba and telespringar performers were recorded using an advanced optical infrared motion-capture system. This system tracked the movements of reflective markers attached to the participants’ bodies. The sound and motion data were analyzed using the MIR and MoCap Toolboxes for MatLab, and our statistical analyses were performed using SPSS (IBM, Inc.).Our study’s audio analysis of samba confirms the existence of a systematic anticipation of the third and fourth sixteenth note in a beat. Moreover, it reveals a synchronized systematic microtiming pattern in both the musician’s heel-tapping and the dancer’s steps. Our study’s audio analysis of telespringar also confirms the L – A – S pattern at the beat level, with an average ratio of 38:34:28. A synchronized L – A – S pattern was also found in the foot-stamping of the musician, accompanied by upper-body swaying at bar level. It is therefore clear that the microtiming features found to be characteristic of the sound of samba and telespringar are also present in performers’ body movements. These observations support the view that these systematic microtiming features are not a matter of deviation from an underlying perceived pulse with isochronous subdivisions in samba or from an underlying isochronous pulse in telespringar. Instead, they actually constitute an essential feature of the samba and telespringar

Konsekvenser av direktedistribusjon : en studie av Tine Nord

Masteroppgave i bedriftsøkonomi - Universitetet i Nordland, 2012Sperra for utlån til 2017-05-142017-05-1

Improved fillet quality in harvest-size Atlantic salmon fed high n-3 canola oil as a DHA-source

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Effects of Bioactive Peptides from Atlantic Salmon Processing By-Products on Oxyntopeptic and Enteroendocrine Cells of the Gastric Mucosa of European Seabass and Gilthead Seabream

The present study was designed to evaluate the effects of dietary levels of bioactive peptides (BPs) derived from salmon processing by-products on the presence and distribution of peptic cells (oxyntopeptic cells, OPs) and enteric endocrine cells (EECs) that contain GHR, NPY and SOM in the gastric mucosa of European seabass and gilthead seabream. In this study, 27 seabass and 27 seabreams were divided into three experimental groups: a control group (CTR) fed a control diet and two groups fed different levels of BP to replace fishmeal: 5% BP (BP5%) and 10% BP (BP10%). The stomach of each fish was sampled and processed for immunohistochemistry. Some SOM, NPY and GHR-IR cells exhibited alternating “open type” and “closed type” EECs morphologies. The BP10% group (16.8 ± 7.5) showed an increase in the number of NPY-IR cells compared to CTR (CTR 8.5 ± 4.8) and BP5% (BP10% vs. CTR p ≤ 0.01; BP10% vs. BP5% p ≤ 0.05) in the seabream gastric mucosa. In addition, in seabream gastric tissue, SOM-IR cells in the BP 10% diet (16.8 ± 3.5) were different from those in CTR (12.5 ± 5) (CTR vs. BP 10% p ≤ 0.05) and BP 5% (12.9 ± 2.5) (BP 5% vs. BP 10% p ≤ 0.01). EEC SOM-IR cells increased at 10% BP (5.3 ± 0.7) compared to 5% BP (4.4 ± 0.8) (5% BP vs. 10% BP p ≤ 0.05) in seabass. The results obtained may provide a good basis for a better understanding of the potential of salmon BPs as feed ingredients for seabass and seabream.publishedVersio

Effects of Bioactive Peptides from Atlantic Salmon Processing By-Products on Oxyntopeptic and Enteroendocrine Cells of the Gastric Mucosa of European Seabass and Gilthead Seabream

The present study was designed to evaluate the effects of dietary levels of bioactive peptides (BPs) derived from salmon processing by-products on the presence and distribution of peptic cells (oxyntopeptic cells, OPs) and enteric endocrine cells (EECs) that contain GHR, NPY and SOM in the gastric mucosa of European seabass and gilthead seabream. In this study, 27 seabass and 27 seabreams were divided into three experimental groups: a control group (CTR) fed a control diet and two groups fed different levels of BP to replace fishmeal: 5% BP (BP5%) and 10% BP (BP10%). The stomach of each fish was sampled and processed for immunohistochemistry. Some SOM, NPY and GHR-IR cells exhibited alternating "open type" and "closed type" EECs morphologies. The BP10% group (16.8 ± 7.5) showed an increase in the number of NPY-IR cells compared to CTR (CTR 8.5 ± 4.8) and BP5% (BP10% vs. CTR p ≤ 0.01; BP10% vs. BP5% p ≤ 0.05) in the seabream gastric mucosa. In addition, in seabream gastric tissue, SOM-IR cells in the BP 10% diet (16.8 ± 3.5) were different from those in CTR (12.5 ± 5) (CTR vs. BP 10% p ≤ 0.05) and BP 5% (12.9 ± 2.5) (BP 5% vs. BP 10% p ≤ 0.01). EEC SOM-IR cells increased at 10% BP (5.3 ± 0.7) compared to 5% BP (4.4 ± 0.8) (5% BP vs. 10% BP p ≤ 0.05) in seabass. The results obtained may provide a good basis for a better understanding of the potential of salmon BPs as feed ingredients for seabass and seabream

Digital phenotyping of individual feed intake in Atlantic salmon (Salmo salar) with the X-ray method and image analysis

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Mechanical processing of Phaeodactylum tricornutum and Tetraselmis chui biomass affects phenolic and antioxidant compound availability, nutrient digestibility and deposition of carotenoids in Atlantic salmon

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Physiological roles of fatty acyl desaturases and elongases in marine fish: Characterisation of cDNAs of fatty acyl delta6 desaturase and elovl5 elongase of cobia (Rachycentron canadum)

In the present paper, we investigated the expression of fatty acyl desaturase and elongase genes in a marine teleost, cobia, a species of great interest due to its considerable aquaculture potential. A cDNA was cloned that, when expressed in yeast, was shown to result in desaturation of 18:3n-3 and 18:2n-6, indicating that it coded for a Δ6 desaturase enzyme. Very low desaturation of 20:4n-3 and 20:3n-6 indicated only trace Δ5 activity. Another cloned cDNA enabled elongation of 18:4n-3, 18:3n-6, 20:5n-3 and 20:4n-6 in the yeast expression system, indicating that it had C18-20 and C20-22 elongase activity. Sequence comparison and phylogenetic analysis confirmed that it was homologous to human ELOVL5 elongase. However, the cobia Elovl5 elongase also had low activity toward C24 HUFA. The cobia Δ6 desaturase had a preference for 18:3n-3, but the elongase was generally equally active with both n-3 and n-6 substrates. Expression of both genes was 1-2 orders of magnitude greater in brain than other tissues suggesting an important role, possibly to ensure sufficient docosahexaenoic acid (DHA, 22:6n-3) synthesis in neural tissues through elongation and desaturation of eicosapentaenoic acid (EPA; 20:5n-3)