Med stadig økning i produksjon av oppdrettslaks og et relativt lavt antall tilgjengelig vannkilder til smoltproduksjon, ser man økt bygging av RAS-anlegg. Ved rensing av produksjonsvannet er første vannbehandlingstrinn mekanisk filtrering etterfulgt av biofiltrering, rensesystemets flaskehals. Biofilteret renser vannet for nitrogenholdige molekyler (TAN), som er giftig for laks, og er sensitivt for ...

Denne oppgaven tar for seg manglende tilgang på kreditt blant rurale låntakere i utviklingsland. Årsaken er problemer knyttet til asymmetrisk informasjon og hånhevelsesproblemer. Alle utlånere har behov for sikkerhet for å kunne tilby kreditt. Pant er et eksempel på dette. I modelleringne blir det derfor vist hvordan pant kan redusere kredittrasjoneringen. Derimot er pant en mangelvare blant de aller ...

The commercial farming of juvenile lumpfish requires monitoring of gonadal development to achieve synchronized production. Conventional methods such as gonadosomatic index (GSI), sex hormone analyses, gonadal histology, endoscopy, and gene expression analyses are costly, invasive, and often involve sacrificing the fish. We assessed the efficiency of ultrasound as a non-invasive method for monitoring ...

Environmental variation across the range of wild species can lead to local adaptations. The Baltic Sea was formed when the Fenno-Scandian ice sheet retreated around 12 thousand years ago, creating a new brackish water habitat colonised by both marine and freshwater fish species. The European perch (Perca fluviatilis) is a predatory freshwater fish with a large geographical distribution across ...

Interactions involving parasites often account for large proportions of links within aquatic food webs, yet few studies integrate parasites into their food web analyses. This analysis compares three sets of highly resolved food webs that differ in taxa composition, space, and time for a subarctic lake system. Key topological food web metrics, including connectance, linkage density, and mean generality ...

Snow covers the ground over large parts of the world for a substantial portion of the year. Yet very few methods are available to quantify biotic variables below the snow, with most studies of subnivean ecological processes relying on comparisons of data before and after the snow cover season. We developed a camera trap prototype to quantify subnivean small mammal activity. The trap consists of a ...

Shortening winters and changing ice and snow cover conditions are examples of the many shifts expected in subarctic lakes due to climate change. Well-documented changes in ice and snow cover conditions highlight the need to understand under-ice ecosystems and the consequences a changing climate brings to the freshwater biota. This study investigated the impact of under-ice environmental conditions ...

Disturbance to ecosystems in parks and protected areas from nature-based tourism and recreation is increasing in scale and severity, as are the impacts of climate change—but there is limited research examining the degree to which these anthropogenic disturbances interact. In this perspective paper, we draw on the available literature to expose complex recreation and climate interactions that may ...

Danish seining is an important fishing method used to harvest demersal species. Knowledge about the size selectivity of different demersal species with this type of fishing gear is therefore of importance for managing the exploitation of marine resources. However, there are only limited data on size selection in cod ends in this fishery. Sea trials were therefore carried out to collect size selectivity ...

Scholarly publishing is the vessel for the dissemination of research articles. Contemporary scholarly publishing is achieved by two main models, open access (OA) and non-open access (non-OA). OA refers to articles that are available at no cost to the end-user; however, authors may incur a fee for accepted manuscripts. Non-OA articles are available at a cost, either via subscriptions or via individual ...