Aquaponics is a food production system consisting of a consecutive cultivation of plants and aquatic animals, fish or shellfish, in recirculating water. The plants feed on the nutritious effluents from the fish tank and bacteria converts ammonia from the fish tank into nitrate that is absorbed by the plants. The plants receive nutrition and the fish gain purified water. The environmental impact of the production of fish meal and fish oil used in conventional fish feed includes a large consumption of fossil fuels with subsequent carbon dioxide emission. The aquaponic system can be made environmentally sustainable and self-supporting if supplemented with a vermicompost/vermiculture for the production of worm protein as a fish feed. Vegetable waste from the hydroponic part of the system can be reused as worm feed in the compost and the protein rich worms can be harvested, dried and grinded and brought back to the aquaculture as fish feed. As a first step in this direction, I have investigated the effect of recycling of vegetable waste in vermicomposts on the growth and number of earthworms (this was evaluated after harvesting). The hypotheses were that earthworms can be cultivated in the vegetable waste and that by adding manure to the vermicompost it is possible to obtain a nutrient content adequate to support a continuous worm harvest, in other words create a vermiculture. Eisenia fetida and Dendrobaena veneta were grown in 20 L bins containing peat mixed with either poultry or cattle manure. The proportions were 70% peat and 30 % manure. Discarded plant parts from lettuce cultivation was added to the vermicomposts (35 g per week) and water was supplied with 0.8 L per week.

Over the past 40 years 600 000 ha of lodgepole pine (Pinus contorta ssp. latifolia (Engelm.) Critchf.) has been planted in Sweden (280 000 ha on SCA's forest land alone which represents about 15% of the company's total forest land area). In the early 70's SCA situated a number of experimental stands in order to investigate different aspects of the exotic tree, primarily growth rate. To be able to compare the two Species plots with scots pine (Pinus sylvestris L.), this Species was also planted at the same time and under the same conditions. A number of questions should always be raised when exotic Species are introduced in an ecosystem. Invasiveness, the pathogen situation and purely ethical issues should be discussed.

Semi-natural grasslands are threatened biotopes in the landscape and without conservation measures high values of nature will be lost. Meanwhile, the biological values associated with cultural values of the traditional agricultural landscape in Sweden. Studies of land use history may help to understand how today biological diversity has evolved and how it can be preserved. Färsna farm in Norrtälje has left some of the old heritage of biological diversity in the form of nature - forest and grassland, which hosts an unusual herb-rich flora. Through the study of historic maps and från1673/1767/1801/1901 1952 and orthophoto of the area has a picture of how land use has changed over time emerged.

Contortatall (Pinus contorta ssp. latifolia) började planteras storskaligt i Sverige runt år 1970 men det dröjde till 1987 förrän Sverige lagstiftade begränsningar för hur den fick användas i skogsbruket. Detta gjordes bland annat på grund av att det saknades information om dess spridningsförmåga. Contortans spridningsförmåga i Sverige är fortfarande okänd och lagstiftningen är densamma. För att kunna beräkna spridningsförmågan och i förlängningen den potentiella etableringsframgången behövs kännedom om contortans fröproduktion i Sverige.

Animals in zoos live in more barren environments than their conspecifics in nature. In nature, elephants spend more than 75 % of the day foraging and have been observed lying down two hours during night. Stereotypies are common in many different Species in zoos. Stereotypic behaviors may constitute up to 50 % of the daily activity budget of zoo elephants. Modern zoos try to reduce stereotypic behaviors by means of environmental enrichment.

The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area.

The weather has been extremely rainy the last summers in Sweden. Because of the rain, a lot of harvested straw has been lost since it was too wet to store. When the pig producers couldn?t get enough straw to use as bedding, an alternative was requested. Silage is a realistic alternative to straw but since silage often contains clover, it may not be suitable to use in pig production since clover is rich in phytoestrogens.

Birch is the dominant deciduous tree Species in Sweden but only 16 % is found in pure birch stands. The majority of the birch (51 %) is to be found in conifer dominated stands. Swedish forest land comprises approximately of 23 % mixed stands and one problem is that for mixed stands there are few management recommendations. The underlying aim of this thesis was to study the management of mixed forest stands of spruce and birch to achieve good timber quality of birch. The study was based on a literature study and measurement in a field experiment launched in 1998 by the Swedish University of Agricultural Sciences (SLU).

Feline Odontoclastic Resorptive Lesions (FORL) is a painful disease that affects feline teeth and that is increasing in prevalence. The ethiology is still rather unknown. However, research on the ultra structure of the feline tooth may help us understand why FORL is so prevalent in cats and not in other Species. Since the ethiology is still unknown, there is yet no profylaxis. The pathogenesis is rather well known; the hard structure of affected teeth gradually undergo odontoclastic resorption and resorptive lesions are often partly replaced with bone- or cementum-like tissue.

The idea of using algae in different areas and exploring its possibilities is nothing new. Already in the early 1950s microalgae was explored as a possible food resource because of its high protein content. Lately there has been an increased interest in its potential for industrial use. Wastewater treatment is a possible use of algae since the algae grow well on the nutrients present in the water. This offers the possibility to grow algae for nutrient reduction and use the biomass for energy or animal feed since many alga Species has a good nutritional value. Approximately 800-1000 m3 water is applied per 1000 m2 of greenhouse area during one season in a tomato production.

The landscape in the interior of Norrland has undergone dramatic changes since the deglaciation as a consequence of faultings, earthquakes and tilting of the landscape westwards. Archaeological investigations along former shorelines by the use of models of isostatic land uplift, have revealed many Mesolitic settlements in northern Sweden. Döudden, in the county of Arjeplog, has been investigated by archaeologists that identified settlements from 5200 BC. The objective of this study was to analyse the history of the vegetation and if the vegetation showed traces of human activity during early Holocene, by pollen analysis. The results indicate that the area had an established vegetation c.

Eutrophication has been a problem in aquatic systems for a long time. It is well known that the key nutrient to control the eutrophication process is phosphorus. Lately, it has been possible to reverse the process and recover lakes from eutrophication.During a long time Lake Näsnaren in Katrineholms kommun, Södermanland, has been exposed of a large amount of phosphorus from the city's wastewater. The lake has a great value as a habitat of rare Species but also a high recreation value for people living in Katrineholm and Södermanland. Lake Näsnaren is situated in a Natura 2000 area.

The relationship between the pet and it's owner is a very important and interesting issue. Unfortunately there is not so much research on this and in addition to that Swedish veterinarian education does not put much emphasis on pet's role in society or their pattern of behaviour nor treatment. This thesis is based on an opinion poll that 20 dog owners and 20 cat owners contributed. The main purpose of the thesis was to compare the relationships that the pet (dog or cat) and its owner can have. The issues such as the pet owner's attitude to his/her pet, how the pet owner percieves and interprets the signals from the animal, and what they think about the natural behaviours and needs that their pets (might) have. The results show that dog- and cat owners are people who generally love animals, that they used to have even other animal Species in the past, but when it comes to choice between a new dog or a new cat they choose the one that they previously have had and that they are used to. Most of a dog owners choose the dog to be their pet because of the company while the majority of a cat owners choose cat because cats are independent and they are used to cats.

Pheromones are chemical substances representing very specific signal messages within a Species. Although a lot remains unknown about their precise effects, it is known that pheromones influence the behaviour of the receiver. Since the mid 1990s, when it was first possible to synthesise analogues of two fractions of feline facial pheromone, F3 (Feliway®) and F4 (Felifriend®), these have been used in so called pheromonotherapy to treat behavioural problems in cats. The initial use of pheromones for specific behavioural problems has been extended to cover the wide field of stress related issues. This studycontains a questionnaire where veterinary nurses and surgeons at 50 Swedish veterinary hospitals and clinics were asked about their use of synthetic analogues to feline facial pheromones in the care and treatment of cats.

The invasive Species raccoon dog (Nyctereutes procyonoides) is currently under establishment Sweden and it is vital to discover invading individuals to prevent colonization. The use of wildlife cameras to discover dispersing raccoon dogs have been implemented in the north-European raccoon dog management program. In this study, I test the ability of four commercially available scent lures to attract raccoon dogs to camera stations. The study was conducted in the Åland Islands where raccoon dogs are abundant and the results could improve the effectiveness of the camera stations used in the program. I used 12 sites with five camera stations in each and tested the four lures and one control with no lure in each site.